Pavement Preservation and Maintenance Assessment Final Report€¦ · APTech to review spending,...

AN INDEPENDENT ASSESSMENT OF THE

WASHINGTON COUNTY, OREGON PAVEMENT

PRESERVATION AND MAINTENANCE PROGRAM

Final Report

Prepared By:

Applied Pavement Technology, Inc. 115 West Main Street, Suite 400

Urbana, IL 61801 217-398-3977

www.appliedpavement.com

May 2013

p r o v i d i n g e n g i n e e r i n g s o l u t i o n s t o i m p r o v e p a v e m e n t p e r f o r m a n c e

http://www.appliedpavement.com/

Washington County, OR P&M Assessment May 2013

TABLE OF CONTENTS

TABLE OF CONTENTS................................................................................................................. i

INTRODUCTION .......................................................................................................................... 1

Project Goals and Objectives ...................................................................................................... 2

Report Organization.................................................................................................................... 3

OBJECTIVE 1. SPENDING ......................................................................................................... 4

Introduction................................................................................................................................. 4

Washington County Spending and Network Condition.............................................................. 5

Survey Findings and Comparison to Washington County.......................................................... 9

Growth, Demographics, and Other Outside Influences ............................................................ 10

Summary ................................................................................................................................... 11

OBJECTIVE 2. STRATEGIES ................................................................................................... 13

Introduction............................................................................................................................... 13

Washington County Treatment Strategies ................................................................................ 13

Survey Findings – Treatments in Similar Agencies ................................................................. 14

Industry Practice – Treatment Strategies .................................................................................. 18

Treatment Matrix ...................................................................................................................... 20

Summary ................................................................................................................................... 20

OBJECTIVE 3. COST EFFECTIVENESS ................................................................................. 22

Introduction............................................................................................................................... 22

Washington County - Return on Investment ............................................................................ 22

Industry Statistics – Return on Investment ............................................................................... 23

Summary - Strategy Recommendations to Improve Cost Effectiveness .................................. 24

OBJECTIVE 4. PAVEMENT CONDITION (PCI) TARGETS ................................................. 25

Introduction............................................................................................................................... 25

Washington County PCI Targets .............................................................................................. 25

PCI Targets for Similar Agencies ............................................................................................. 28

Industry State of the Practice .................................................................................................... 30

Targets by Functional Class and Public Satisfaction................................................................ 32

Summary ................................................................................................................................... 32

OBJECTIVE 5. LIFECYCLE COST .......................................................................................... 33

OBJECTIVE 6. PAVEMENT MANAGEMENT SYSTEM SUPPORT .................................... 35

Introduction............................................................................................................................... 35

Components of a Pavement Management System.................................................................... 35

Maintaining a Pavement Management System......................................................................... 36

Applied Pavement Technology, Inc. i

Pavement Evaluation of East Washington St. September 2011

Applied Pavement Technology, Inc. ii

Washington County PMS Resources and Status ...................................................................... 37

Pavement Management System ............................................................................................ 37

PCI Surveys and Schedule .................................................................................................... 38

Staffing and Training ............................................................................................................ 38

Similar Agency Resources and Pavement Management Status................................................ 39

Needs and Opportunities for Improvement............................................................................... 40

Summary ................................................................................................................................... 41

CONCLUSIONS AND RECOMMENDATIONS ....................................................................... 42

References..................................................................................................................................... 45

Appendix A. Treatment Selection Guidelines and Considerations .............................................. 46

Identification of Feasible Preservation Treatments .................................................................. 47

Crack Filling ............................................................................................................................. 51

Crack Sealing ............................................................................................................................ 53

Fog Seal .................................................................................................................................... 55

Slurry Seal................................................................................................................................. 57

Microsurfacing.......................................................................................................................... 59

Chip Seal................................................................................................................................... 61

Cape Seals................................................................................................................................. 63

Thin HMA Overlay................................................................................................................... 65

Cold Milling.............................................................................................................................. 67

Mill and Overlay ....................................................................................................................... 69

Washington County, OR. P&M Assessment May 2013

INTRODUCTION In response to a request from the Washington County (the County) Department of Land Use and Transportation (DLUT), Applied Pavement Technology, Inc. (APTech) conducted an independent assessment of the pavement preservation and maintenance (P&M) program being used to maintain the County’s road network. The County expressed a desire to identify ways in which it may more effectively utilize available resources (funding and manpower), and asked APTech to review spending, strategies, cost effectiveness, performance goals, and pavement management system utilization. This project consisted of a review of work efforts in the County and gathering information from industry and similar agencies for comparisons. The work effort was divided into the following tasks:

Task 1: Gather required information from Washington County, OR― APTech senior staff interviewed the County staff to gather information about the network pavement condition, pavement management practices, and P&M spending levels. The County made all required staff available for both group and individual interviews. Detailed information on spending and condition by year was provided and additional information and clarification were received upon request. APTech staff was provided access to the County pavement management system, which contains information on the status of the pavement network. The County also identified other transportation agencies similar in size and environment to invite to participate in a survey of practice.

Task 2: Survey of similar agencies―The project team developed and distributed a detailed survey of pavement management practices to selected agencies identified by the County as having similar location, fiscal constraints, and geo-political challenges.

The survey solicited information on the following topics:

o Network information―Centerline miles of pavement by type, approximate

age, and functional classification.

o Pavement management system―Platform, staff use and training, level of satisfaction.

o Condition surveys―Frequency, performance, and quality assurance.

o Past and current information on condition―PCI information for past five years.

o PCI targets―Goals and sustainability at expected funding levels.

o P&M treatments―Types, unit costs, expected life, and triggers for use.

o Spending―Amount/percentage spent on P&M total and by functional class, and by category of action.

Twelve agencies in Washington and Oregon were identified and contacted to solicit their participation. The twelve agencies included six cities, and six counties, with nine of the agencies located in Oregon, and three in Washington. Initial agency contacts were made by the County DLUT staff. This contact was followed by an invitational email explaining the intent of the survey, and providing a link to the online survey. Data from

Applied Pavement Technology, Inc. 1


the eight responding agencies were used for comparisons that will be discussed in the following sections of this report.

Task 3: Synthesis of information―In addition to the survey information gathered specifically for this study, two additional sources of information were reviewed and considered in the analysis. In August 2012 the Municipal Research and Services Center of Washington conducted a survey of 60 agencies in Washington and 11 agencies in Oregon (MRSC 2012) similar in scope to the one conducted in this project. Among other subjects, the MRSC survey sought information on spending and treatment types used that provided valuable additional information. A second source of information is a January 2013 report from an updated survey of California transportation agencies (Nichols 2013). Of the agencies surveyed, 238 responded with financial information that provided comparisons of revenue expectations and current/anticipated spending levels. While the interpretation of this agency financial information was challenging due to differences in reporting and summarization techniques, every effort was made to identify and analyze the survey results in a manner consistent with the intent and objectives of the County for this study.

Task 4: Report of results and recommendations―This report details the results of the task 1 through 3 activities, providing recommendations for the County’s consideration as they work to improve their P&M program. Detailed information is provided on treatment strategies, advantages, and limitations for consideration and use by the County.

Task 5: Executive summary and PowerPoint presentation―Following approval of the final report, APTech will prepare an executive summary and PowerPoint presentation providing an overview of the study and findings suitable for presentation to policy/decision makers. These documents will provide clear and concise coverage of the study and findings.

Task 6: Presentations/Meetings with decision/policy makers―To support the County in its presentation of the study and recommendations to policy and decision makers, provisions have been included for participation in an in-person meeting with decision/policy makers, to present the study and respond to questions about the process, analysis, findings, conclusions, and recommendations. The details of this presentation/meeting were not defined at the time of preparation of this report, and will be coordinated with County DLUT staff.

This report is provided in fulfillment of the requirements for Task 4. Project Goals and Objectives

The County established the following goals for this work effort.

To complete a comprehensive review of the DLUT Operations and Maintenance Division (Division) historical spending on pavement P&M and the results.

To evaluate the pavement P&M strategies currently used by the Division to ensure the most cost effective use of available funds.

To review and compare current and long-term spending needs for pavement P&M to expected revenue.



In order to accomplish these goals, DLUT established six objective areas, with specific requirements for each objective. A seventh objective provides for generation of a comprehensive report of findings. The defined objectives for the study were:

Objective 1. Spending―Review the County’s historical spending on pavement P&M, including work done by both private contractors and County forces. Compare the County’s level of spending and outcomes (resulting road conditions) to similar agencies in Oregon and Washington. The comparison will include the percentage spent on pavement P&M to the overall Road Funds available, spending per mile, and resulting PCI.

Objective 2. Strategies―Review the County’s current pavement P&M strategies. Compare the County’s pavement P&M strategies, by functional class, to other similar agencies in Oregon and Washington, and industry best practices.

Objective 3. Cost effectiveness―Review the County’s pattern of spending on pavement P&M. Compare the return on the County’s investment in pavement P&M using their current strategies to effective maintenance plans used by similar agencies in both Oregon and Washington and industry best practices. Provide the basis for recommending an ongoing pavement P&M plan by functional class based on the least cost and highest resulting PCI over the next 20-years.

Objective 4. Pavement condition (PCI) targets―Review the County’s adopted PCI targets. Compare those targets to similar agencies in Oregon and Washington. Recommend appropriate PCI targets for Washington County.

Objective 5. Lifecycle cost―Analyze and determine the estimated cost to implement the pavement P&M strategy recommended in Objective 3 and achieve the target PCIs recommended in Objective 4 over a 20-year period. The analysis will provide an estimated cost for each fiscal year and resulting PCI forecast.

Objective 6. Pavement management system (PMS) support―Analyze and determine the appropriate level of staffing required to adequately maintain the County’s PMS. Evaluate possible changes and improvements to support functions to optimize the system.

Objective 7. Report and summary―Provide a report and summary of the information and recommendations developed in Objectives 1 through 6.

Report Organization

This report has been developed in chapter form, with chapters corresponding to each of the stated project objectives (Objectives 1 through 6). A final chapter provides conclusions and recommendations of approaches the County may consider to improve operations and more efficiently utilize resources.



OBJECTIVE 1. SPENDING

Review the County’s historical spending on pavement preservation and maintenance (P&M). Compare the County’s level of spending and outcomes (resulting road conditions) to similar agencies in Oregon and Washington. The comparison will include the percentage spent on pavement preservation and maintenance to the overall Road Funds available, spending per mile, and resulting PCI.

Introduction

The County has two primary funding sources for P&M: the Road Fund and the Urban Road Maintenance District (URMD). The Road Fund is used for P&M of arterial and collector roadways, and rural local roadways. The URMD funding is used for maintenance of the urban local and urban neighborhood roadways in the County. The Road Fund is supported by a combination of County gas taxes, state motor vehicle apportionment (the main source), and timber revenue. An analysis provided by the County showed the Road Fund revenue varying from about $16.8 million in 2001 to about $23 million in 2012 (figures for 2011 and 2012 are estimates). Expenditures for pavement P&M have averaged about 19.5 percent of the Road Fund over that period, ranging from a minimum of $3.2 million to a maximum of just under $5 million. The comparison of Road Fund income to expenditures for P&M of the roadway network is shown in figure 1-1.

Figure 1-1. Comparison of road fund revenues to expenditures for pavement maintenance (provided by County staff during interviews).

The County is concerned about the stability of the funding sources that support the Road Fund. The combined impact of a regional drop in motor vehicle registrations, improving fuel economy of newer vehicles, and public programs supporting the use of alternate modes are expected to



result in a further reduction in the Road Fund revenue. Road Fund revenue reductions will likely result in a cutting-back of available funds for P&M activities on county roadways. The reduction in available revenue comes at a time of growing maintenance requirements for County facilities. While the roadway P&M needs continue, many recent capital improvement efforts have resulted in roadway widening (less than 2400 lane miles in 2002 and over 2600 lane miles in 2013) and increased areas of vegetation (as of this writing almost 130 acres on arterial roadways). Roadway widening increases the area of pavement to be maintained per unit length, thereby reducing the centerline miles of roadway that may be addressed per dollar spent. While attractive, vegetation requires significant maintenance to remain healthy and attractive. This need must be balanced with all of the others in the allocation of available resources. The second primary source of funding for a large percentage of county urban roadways (430 centerline miles) is the URMD. Taking information from the 2010-2011 URMD Annual Report, the URMD is the funding mechanism for maintenance of local roads within the urban unincorporated area. The URMD was created by the Board of County Commissioners and approved by voters within the District. At the time the URMD was formed the urban local roads had deteriorated due to lack of funding for preventive maintenance, but since then the condition has improved significantly. The URMD is supported by a $0.25/$1,000 tax levy on properties in the District. Available information shows that URMD spending for P&M has varied from a low of about $725,000 in 2012, to a high of just under $2.9 Million in 2007. In general, the condition of roadways in the URMD has been improved and maintained at a very high level. Recently, the Urban Road Maintenance District Advisory Committee (URMDAC) recommended the Board of County Commissioners establish performance measures for the District. The Board of Commissioners adopted a pavement condition index (PCI) target of 75 which is below the current average PCI of 85. In September 2011 the Board of Commissioners adopted a revised resolution and order that expands allowable uses of URMD funds to include safety improvements on all public roads within the URMD boundary. This has resulted in the reassignment of funds from strictly P&M activities to a significant investment in safety improvements ($2.7 million in FY 2013-14). The URMDAC takes an active role in development of the annual work program with a goal of efficiently using available funds for immediate needs without jeopardizing the long-term viability of the URMD road system. Washington County Spending and Network Condition

Table 1-1 provides a detailed breakdown of County spending and pavement condition by year and by roadway functional class. In an effort to provide a basis for comparison with survey results, the average spending on P&M per centerline mile was calculated. Because there are two distinct funding sources, calculations were prepared separately for Road Fund and URMD roadways. This allows comparison of level of spending by roadway group. Where information was unavailable, “NA” is indicated. It will be noted that some of the condition information is shaded grey. The grey shaded cells represent condition information based on pavement management system predictions instead of actual network surveys. Network surveys were completed in 2001, 2004, 2010, and 2012. These years represent ground truth information, and were used as real indicators of condition (rather



than predictions). Note that there was a significant change in apparent condition between the 2009 predicted condition and the 2010 observed condition. The County PMS (StreetSaver) incorporates a self-calibrating feature and updates predictions based on the most recent PCI surveys by roadway segment. Because of this feature, it is imperative that surveys be done on a regular and fairly frequent basis. This time period (2004 – 2010) corresponded with a period of significant growth in the county, with a great deal of construction traffic supporting the growth. Without surveys, the PMS was unable to adjust predicted performance in response to the accelerated wear on the roadways.

Table 1-1. Spending and condition data by year and functional class.

% RF Spent on

P&M 19.48 29.69 16.65 19.53 19.12 18.7 16.88 24.41 11.49 13.73 21.55 NA Avg

$ Spent on P&M

($x1,000) $3,272 $5,177 $3,195 $3,711 $3,861 $3,822 $3,309 $4,260 $2,217 $3,159 $4,906 NA $/CL Mile

CL Miles 581 590 588 597 596 599 601 606 615 617 624 622

$/CL Mile $5,632 $8,775 $5,434 $6,216 $6,478 $6,381 $5,506 $7,030 $3,605 $5,120 $7,862 NA

CL Miles Treated 51 43 51 49 50 48 46 32 29 37 39 37

Treated/$1M 16 8 16 13 13 13 14 8 13 12 8 NA

FC

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012UA 86 81 82 86 86 88 89 90 90 75 76 76UC 86 83 84 87 88 89 89 90 89 77 79 79RA 88 80 88 91 91 92 92 92 93 78 77 77RC 91 83 85 91 91 92 92 92 92 82 83 83RL 71 64 67 87 87 89 91 92 93 75 76 76Avg 84 78 81 88 89 90 91 91 91 77 78 78 $6,185

URMD $ for P&M

(x 1,000) NA NA NA NA $1,829 $1,575 $2,888 $2,597 $1,514 $1,815 $1,431 $725

CL Miles 406 407 409 414 414 418 426 427 424 424 429 429

$/ CL mile NA NA NA NA $4,418 $3,768 $6,779 $6,082 $3,571 $4,281 $3,336 $1,690

CL Miles Treated NA NA NA NA 43 45 60 36 23 33 22 13

Treated/$1M NA NA NA NA 24 28 21 14 15 18 15 18

NR 77 82 87 87 87 83 84 87 87 83 84 85UL 80 83 86 87 87 86 88 89 88 85 85 86Avg 78 83 86 87 87 84 86 88 88 84 85 85 $4,241

PCI By Year

URMD

Road Fund

PCI by Year

The County reports pavement conditions using Pavement Condition Index (PCI) values. PCI is an industry standard summary statistic for pavement condition based on ASTM D6433, Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys, and varies from a high of 100 for a new pavement with no distress, to a low of 0. There are a number of different general ways that PCI condition and typical treatment implications may be displayed. For the purposes of this study, and given that the County is using StreetSaver as a platform for its pavement management, the PCI representation and typical treatment recommendation for each PCI range is shown in figure 1-2 for reference. As may be seen, at condition levels below 70, pavements are considered to be “at risk.” At this point condition levels typically start to deteriorate at a more accelerated rate. Care needs to be exercised to maintain or preserve a network condition above this level to most effectively use resources for pavement P&M. A general representation of the typical pavement life cycle, and where the County roadway network currently is on that continuum, is shown in figure 1-3.



Figure 1-2. PCI thresholds (Nichols 2013). Figure 1-3. General pavement life cycle. Overall, based on PCI, the County’s pavements are in good shape. As seen in figure 1-3, the current PCI level of the County Road Fund pavement network is in the good/excellent range, but it is important to note that it is in decline. Typically, when the PCI level drops below 70 more extensive treatment applications (e.g., thicker overlays, reconstruction) are required to restore the pavement to acceptable levels. The roadways in the URMD are currently in slightly better condition and the District enjoys a much more reliable revenue source. As shown in table 1-1, Road Fund roadways spending per centerline mile has ranged from a low of $3,605 in 2009 (excluding ARRA funds) to a high of $7,862 in 2012, with an average of $6,185 per centerline mile for the eleven years of available data. Though still in relatively good condition, the pavement condition has deteriorated from a high average PCI value of 88 in 2004 to a current average PCI value of 78. Comparing PCI values from the last two network surveys it appears conditions are remaining relatively stable for all functional classifications, but the arterial roads remain below the target PCI (80) established in the 2020 Transportation Plan (Article 21.4). Referring back to previous comments about road widening and the impact on spending, table 1-1 also shows trends in the centerline miles of roadways with treatments applied for the P&M expenditures. For the Road Fund roadways this trend is shown in figure 1-4. While there is some volatility, the trend line clearly indicates a decline over time in the mileage of roadways treated per dollar. There are many possible reasons for this, including increases in unit costs for treatments, the different types of treatments used, and increases in roadway width requiring greater cost per mile. What can be said is that if this trend continues, the County will reach a point where the desired levels of service are not sustainable without additional resources.



Figure 1-4. Road fund miles treated per $1M.

In comparison, URMD spending per centerline mile has ranged from a low of $1,690 to a high of $6,779, with an average annual expenditure for the eight years of available data of $4,241. From 2001 to 2012 the condition has remained relatively stable, with average PCI values in the mid-80s. One might wonder why the expenditure per centerline mile was significantly less, while the condition was notably better and more stable over time. This is attributed to the functional classification of the roadways and assumed traffic levels in the URMD. These are urban local and neighborhood roads, which typically see less heavy traffic, and are narrower and therefore require less costly treatments. In short, these pavements are typically less expensive to maintain at a higher level of performance. At the same time, looking at the spending for the URMD roadways in terms of centerline miles of roads treated per dollar spent on P&M, figure 1-5 shows a very similar trend to that for the Road Fund roadways. The number of miles treated per amount spent has shown similar volatility, and is on the decline. This trend may be attributable to recent economic conditions or may be a reflection of the decrease in the amount of treatments being performed. Reduced quantities often result in increased unit costs.

Figure 1-5. URMD miles treated per $1M.



Survey Findings and Comparison to Washington County

Table 1-2 provides an overview of the survey results from the six agencies responding to the County preservation survey with spending and condition information. There is significant variation in the spending levels indicated. The surveyed agencies spend $1,136 to over $20,000 per centerline mile for P&M on paved roadways, with an average of about $11,018. Condition levels range from a low of 63 to a high of 86, and there does not appear to be a direct correlation between the level of spending and the network condition. As with the County, many of these agencies indicated significant volatility in their spending levels to account for variations in revenue and needs, and these numbers may reflect current levels that are not representative of average conditions.

Table 1-2. Survey results―spending and network condition.

Network Length (CL mi)

Dollars Spent on P&M ($/CL mi) Network PCI

148 $10,811 70 218 $15,571 81 220 $1,136 84 519 $20,424 NA 579 $10,363 63 1525 $7,803 86

Another interesting finding of the survey was that over half of the agencies indicated that funding for P&M had increased in the past 10 years. Figure 1-6 displays a breakdown of responses to this question.

Figure 1-6. Survey results―P&M funding trends over the past 10 years.

In an effort to gather additional relevant information for comparison, two other sources were considered. First, in 2012 the Municipal Research and Services Center (MRSC) of Washington conducted a Pavement Preservation/Maintenance Program Survey (MRSC 2012). Survey questionnaires were distributed through three main methods: an internal city-county email distribution list, the WSDOT “Pavement Community Listserv,” and through the Northwest Pavement Management Association (NWPMA). The MRSC survey resulted in responses from almost 60 city and county agencies in Washington and 11 agencies in Oregon. A review of the results of that study found similar significant variability in the provided responses associated



with funding levels; however, it was possible to develop some agency estimates for comparison with costs for the County. Reported spending levels ranged from a low of $1,729 to $4,444 per centerline mile. Condition (PCI) levels were stated more as goals than as current values, and tended to indicate a desired value of above 70, or an average of 80 as a desired result. In addition, when asked if current funding levels were sufficient to attain or maintain stated goals, most respondents indicated that it would not be possible to attain or maintain current condition levels with the current level of available funding. A second resource is a January 2013 report, California Statewide Local Streets and Roads Needs Assessment (Nichols 2013). This report provides updates to a survey of over 500 city and county agencies in California and includes information related to pavement condition and spending levels. In review of the California study it was reported that “on average, anticipated pavement expenditures for the next ten years are expected to be $5,711 per lane-mile for counties, and $7,400 per lane-mile for cities.” While there is not a direct conversion from lane-mile to centerline mile, it is estimated that this conversion would result in values of approximately $13,100 and $17,760, respectively (assuming lane widths and number of lanes). The report goes on to predict that at the reported funding levels, the PCI of the network is predicted to steadily deteriorate to an average level of 53 by 2022, and the unfunded backlog was predicted to increase by 50 percent. Growth, Demographics, and Other Outside Influences

The County has a current population of about 545,000, of which the urban unincorporated population is approximately 240,000. The County is home to several large corporations, including Intel, Nike, and Genentech. Intel alone represents about 17,000 workers with an average salary of $125,000, which speaks to the affluence and potential elevated expectations of many of the residents. A review of available demographic information found that the County has experienced population growth of approximately 2 percent per year, with projections indicating this level will continue or increase over time. The County is located just west of Portland and significant growth is expected over time there as well. Current and planned growth in the area appears to indicate steady or increased pressure on the roadway network. Both commercial and residential growth was clearly evident from the type and number of construction vehicles on the roadways in and around the County. All indications are that this growth will continue for the near future. The County’s road network currently comprises about 1300 centerline miles of roads, almost evenly split between urban and rural classifications. About 1065 centerline miles of roads are paved, with approximately 220 centerline miles of gravel-surfaced roads. The road network was in relatively poor shape in the 1980’s. There was a significant investment by the County starting in the early 1990’s to recover the system, which resulted in improvements to the network condition, reaching a peak PCI value of 88 in 2004. Since that time the County has seen a decline in the Road Fund roadway network, with a drop in PCI scores of 10 points in eight years. The County would like to determine if the average PCI is sustainable at current funding levels. If these levels are not considered sustainable, the County would like to address changes necessary to adjust the average PCI to match projected funding levels, or increase funding to maintain the current target PCI targets.



Summary

Objective 1 of the assessment of the County P&M was to review the historical spending levels and network conditions in the County and compare those to other similar agencies to determine if guidance could be provided in terms of spending levels and network condition expectations. The review focused on a survey of similar agencies, and on review of two additional sources of information that appeared relevant, timely, and pertinent to this study. The results show a significant degree of variability in reported spending levels, ranging from $1,136 to over $20,000 per centerline-mile. Part of this variability is likely due to the volatility in spending among agencies. Furthermore, differences in reporting methods make direct comparisons very difficult. In the case of the referenced California study, conversions were necessary to develop estimates per centerline-mile, and there are significant assumptions in these conversions. Expenditures may also vary based on factors that were not necessarily captured in the reporting, including the condition of the roadway network, their general structural capacity, traffic volumes, and environmental factors. The available sources of information indicate that the County is spending less per centerline mile on Road Fund roadways ($6,185) than the average of agencies responding to the survey conducted for this study ($11,018), and above what was seen from both the MRSC survey (approx. $4,000) and California report (approx. $5,700), which indicated that funding levels were insufficient to meet expected demand. At the same time, the current average PCI on Road Fund roadways in the County (78) is very near the median value for the surveyed agencies (76). After a drop of 11 points in PCI between 2004 and 2010, the PCI conditions appear to be remaining reasonably stable at a level just within the good to excellent category where preservation and maintenance approaches are generally considered appropriate. It is believed that the drop in PCI between 2004 and 2010 occurred as a result of significant growth in the County, and the lack of periodic condition surveys during that time prevented the StreetSaver PMS from adjusting predictions properly. Although it is difficult to estimate the exact point when pavement deterioration will have a direct and adverse impact on the cost of maintenance, it is generally assumed to occur when the PCI level is in the low 70’s. The closer an agency gets to this condition level, the higher the risk for being unable to respond to unforeseen circumstances, such as environmental changes or traffic volume increases that have notable effects on the network. Caution should be exercised when the roadway network begins to approach an increased rate of deterioration. Referring to figure 1-3, as the rate of deterioration increases it becomes harder and more expensive (treatment options become more expensive per unit area) to maintain good conditions, and more likely for conditions to change rapidly. Once significant deterioration initiates, the County may find that resources are not available to regain the levels of service desired. Strategies that incorporate use of preservation treatments and maintain the PCI levels within the desired levels of service should be actively considered prior to further network decline. Figures 1-4 and 1-5 show trends in spending that will need to be addressed, indicating reductions in the number of miles treated per dollar spent on P&M. This trend shows that spending may not be keeping pace with requirements and costs for treatments, and would appear to indicate that the desired levels of service will not be sustainable over time without adjustments to the treatment types being used (lowering costs per mile or unit area) and increased funding. Consideration must also be given to the trends in declining current sources of revenue as indicated by the combined impact of improving fuel economy of newer vehicles and public



programs supporting the use ofalternate modes. If strategies lowering costs per mile are insufficient to maintain the system at the desired levels of service, the County may need to consider additional sources of revenue to address the decline and maintain the system. This is of particular concern for the Road Fund maintained portions of the system.



OBJECTIVE 2. STRATEGIES

Review the County’s current pavement P&M strategies. Compare the County’s pavement P&M strategies, by functional class, to other similar agencies in Oregon and Washington, and industry best practices.

Introduction

The strategies used to preserve and maintain roadway conditions in effect define an agency’s practice for managing its pavements. In interviews the County provided information on the treatment types typically used for P&M by funding group and functional classification, performance expectations by treatment type, and triggers for treatment consideration. This section of the report reviews County P&M strategies and compares those to similar agencies in Washington and Oregon as well as to best practices. Washington County Treatment Strategies

The County categorizes work in two primary areas based on their funding mechanism: Road Fund roadways (arterials, collectors, and rural local roads) and URMD roadways (urban local and neighborhood roadways). Work may be done by contract or County crews. The use of various P&M treatments to this point has typically been based on roadway functional classification. Road Fund strategies typically include contracted overlays 2 to 3 inches thick on the arterial and collector roadways. This process generally includes a mill and HMA inlay in the urban areas to maintain grade and curb reveal. In rural areas where roadside ditches are more common, HMA overlays may be accompanied by restoration of the gravel shoulders. The County has recently investigated consideration of full-depth reclamation with cement-treated base, completing two such projects in 2011. They have recently started using warm-mix asphalt (WMA) and consider it equal in performance to conventional HMA. Chip seals are used for rural arterial and collector routes. Crack sealing is also used where required. Overlays, chip seals, and crack sealing are used in rural areas. The County has also had recent success using thin-lift (1-inch) overlays in rural areas and intends to do more of these. The strategies employed on URMD roadways are crack sealing, Type II slurry seals, and 1.5-inch HMA overlays. These treatments follow a 10-10-10 model, with crack seals and slurry seals programmed at the 10 and 20-year marks, and an overlay at the 30-year mark. This process is then repeated. Force account work is done by County crews, mainly on rural roadways, and typically consists of machine patching and chip seals. Force account crews have done crack sealing in the past, but it is not one of their primary functions. These crews will also do pavement excavation and repair (PER) work when required to address an immediate need. In summary, the County has made extensive use of a few treatments, focusing on what has worked well in the past. Previous efforts to branch out and use microsurfacing led to disappointments and slowed efforts to implement them as a viable strategy in the County. However, the County does intend to reconsider the use of microsurfacing as an alternative.



The County has expressed a desire to consider a broader range of treatment alternatives if they are cost effective. Table 2-1 summarizes the treatment types typically used in the County, the life expectation, the approximate unit cost, and the functional class of roadways where the treatment may be considered.

Table 2-1. Typical P&M strategies in Washington County.

Functional Class Treatment

Type Cost

($/SY) Life (Yr.) Trigger Arterial Collector

Urban L/NR

Rural Local

Mill & Inlay 13.00 12 Distress X

Thick Overlay

13.00 15 Distress X X

Thin Overlay 10.00 12 Time/Distress X X X X

Chip Seal 1.50 7 Time/Distress X (rural) X (rural) X

Type II Slurry Seal

1.50 7 Time/Distress X

Crack Seal ($/lf)

0.84 3 Distress X X X

To this point all discussions have been focused on treatment strategies associated with HMA pavements. The County has about 6 miles of PCC pavements under their care. These pavements were built in the late 1980s or early 1990s, and are performing very well with current PCI values reportedly in the mid to high 80s. In review of the decision tree for the PCC pavements, no preservation or maintenance treatments are planned, and activities are only considered the condition category reaches a level of poor to very poor. Strong consideration should be given to a program of routine joint care, including cleaning and sealing as required for maintenance of these roadway conditions. Given the extremely good performance of these roadways (excellent condition after 20 years) one might also consider why there isn’t greater use of concrete pavements for new construction. This should be a life-cycle cost decision that fully considers the user impacts during construction, post-construction maintenance requirements, and salvage value at life’s end. Survey Findings – Treatments in Similar Agencies

The survey conducted for the County gathered a significant amount of data regarding treatments used in similar agencies. The first consideration must include the types of pavements in these agency’s networks. Nine agencies provided a breakdown of their roadway network by pavement type. The options were: hot-mix asphalt (HMA), portland cement concrete (PCC), HMA over PCC, and Other. Figure 2-1 summarizes the percent of each pavement type. The average network distribution of all responding agencies is 94% HMA, 2% PCC, 1% HMA/PCC, and 3% Other. Washington County is shown as agency 10 in figure 2-1. As previously suggested, the predominant pavement type in the County is HMA (there are approximately 6 miles of PCC pavements in the County, and the remaining pavements are all HMA.) Applied Pavement Technology, Inc. 14


Figure 2-1. Breakdown of pavement type by network. The survey responses on treatment use reflect a somewhat shared approach to how these agencies manage their pavements. Eight agencies provided responses about the types of treatments used for arterials, collectors, urban local roads, and rural local roads. The results are summarized in figure 2-2 as number of agency responses by treatment type and functional class.

Figure 2-2. Treatment types used by functional class. Responding agencies are clearly using the same treatments as the County, and in much the same manner. One general trend is that on the arterials and collectors widely used treatments include mill and inlay, thick overlays, localized repairs, and crack sealing; none of the remaining treatments are used by more than half of the respondents. Somewhat in contrast, on the local urban roads the most commonly used treatments are localized repairs, crack sealing, slurry seals,



and thin overlays, while there does not seem to be much shared experience treating rural local roads. Further generalizing from these results, the most common treatments on the higher traffic volume roadways are HMA-based, while on the lower volume roadways they are a combination of HMA and emulsion-based treatments. This corresponds with common practice among most agencies, where there is a long history of HMA treatments on heavily traveled roads and emulsion-based surface seals on lower volume roads. Two specific survey comments for “Other” regard the use of chip seals on minor arterial roadways and the consideration of cape seals on local roads. These represent a departure from typical practice and it is expected that, if successful, they would see more widespread use. Time and apparent distress were the predominant triggers used in determining when a specific treatment would be used. Figure 2-3 demonstrates that distress type plays an important role in determining treatment for almost all treatment types, and time has a significant impact on the placement of crack seals, chip seals, and slurry seals. This is consistent with County practices.

Figure 2-3. Survey findings – treatment triggers by type. These results show that age is the primary trigger of slurry seals and is also used to trigger crack sealing and chip seals, while condition is the primary trigger of HMA overlays and inlays, of crack sealing, and localized repairs (and, to a lesser extent, chip seals and slurry seals). Public feedback is the primary trigger of localized repairs (e.g., pothole patching). Table 2-2 provides a combined summarization of the cost, life, usage, and trigger data gathered in the County survey and discussed previously for comparison purposes.



Table 2-2. P&M treatment data from survey.

Cost ($/SY) Typical Usage by FC (Note 2)

Treatment Min Max Avg.

Life (yrs.) (Avg.)

Avg. Cost/SY/Yr.(See Note 1) Arterial Collector

Urban Local/NR

Rural Local

Trigger (Primary/Secondary)

Mill/Inlay 17.00 35.25 24.50 10-20 1.63 7 7 4 1 Distress/Func. Class

Thick OL 14.70 21.23 17.84 12-20 1.12 6 6 2 1 Distress

Thin OL 10.91 18.00 14.00 15-20 0.80 3 5 5 3 Distress

Crack Seal ($/LF)

0.49 0.87 0.62 2-5 0.18 8 8 8 4 Distress/Time

Chip Seal 1.10 5.50 2.67 7-8 0.36 3 4 3 3 Distress/Time

Slurry Seal 1.10 3.69 2.00 6-10 0.25 1 2 7 2 Time/Distress

Microsurface 4.50 5.00 4.65 5-8 0.72 2 2 0 0 Distress/Time

In-place Recycle

20.00 25.00 22.50 15-20 1.29 1 1 2 0 Distress

Local Repair NA NA 35.00 Variable NA 8 8 8 4 Distress

Note 1 - Average costs were calculated using average cost values and average expected life. Costs and life expectancy may be heavily influenced by material availability and contractor experience, among other factors. Note 2 - Typical usage figures represent number of agencies indicating usage by functional class.



Results from the MRSC survey were also examined to investigate the type of treatments used by Washington and Oregon agencies as reported in that study. Figure 2-4 lists treatments and frequency of use. The most commonly used treatments are crack sealing, thick and thin overlays, and chip seals. Slurry seals are used predominantly on local roads, with very little application elsewhere. Fog seals showed fairly significant use, mainly on local and collector roadways, but with almost as much use on arterials. In general, the MRSC survey showed primary use of treatments was similar to the strategies in place in the County, although in some cases there are a few additional treatments added to the list of alternatives.

Figure 2-4. Treatment types used in Washington agencies (MRSC 2012)

Industry Practice – Treatment Strategies

The general practice of treatment use and triggers described above follows that observed in agencies throughout the US. On higher volume roadways (such as the arterials and collectors as defined by the County), there is a long history of using HMA overlays, often in combination with patching and crack sealing. Following this practice allows agencies to take advantage of years of experience, with the results being both predictable and acceptable. This experience in effect highlights significant barriers to trying alternate treatments, including the fear of unexpected failure, shorter treatment life, increased public complaints, and industry resistance. However, it makes it difficult to realize one of the primary advantages from using alternate treatments, and especially preventive maintenance, which is a more cost-effective pavement management strategy. On lower volume roads County practice also mirrors common practice, in which the most commonly used treatments have a lower initial cost and shorter life, and include chip seals, crack sealing, slurry seals and microsurfacing, patching, and thin overlays.



While these general practices have worked well in the past they also pose certain challenges that should be recognized and considered in determining future plans. The implications of these practices are highlighted in the following points:

An HMA-only strategy (overlays and mill/inlay) for arterials and collectors presents the greatest challenge to constrained budgets. As shown in both table 2-1 and 2-2, the HMA-based strategies have the highest initial cost. When expressed in terms of costs per area it can be seen that for any given budget the least number of lane-miles will be treated with these treatments.

The widespread use of an HMA treatment approach often goes hand-in-hand with a

worst-first approach to managing pavements, in which an HMA overlay is placed, allowed to deteriorate until it is no longer functional, and then is either milled and replaced or another HMA overlay is placed on top.

It is recognized that HMA overlays also provide the longest life among the most

commonly used treatments. However, focusing solely on treatment life ignores the cost of obtaining that life. For that reason, some agencies look at the cost per year of treatments to help to identify treatments to use, rather than focus on the lowest initial cost or the longest life. An even better approach is to consider the cost effectiveness of various treatments (where the effectiveness or treatment benefit is defined as the improvement in pavement condition versus doing nothing until some defined threshold is reached). While cost effectiveness does not end up as the only factor that is considered in selecting treatments or determining the timing of their placement, it does introduce very important concepts into the decision process.

Agencies interested in improving their pavement management practices introduce a mix

of different treatments into their decision process. This approach recognizes that there is not a single treatment that addresses all pavement needs and that different treatments may be appropriate at different times or when different types of distresses are present.

The use of preservation treatments on higher volume roads represents a combination of

the best practices described herein. While there is a widespread aversion to this practice, there are also well-documented cases of agencies that have extended the use of treatments that would normally only be considered for lower volume roads to collectors and arterials. Two recently published reports provide extensive documentation of this practice and provide guidance (Peshkin 2011a, Peshkin 2011b). This extended application of thin surfacings in particular is based on implementing more cost-effective strategies by treating pavements while they are still in good condition.

Guidance on treatment selection should take into consideration a multitude of factors. Ideally these would include the age (time since last major rehabilitation) and condition of the pavement, the cost and expected performance of the treatment, and traffic volume. Note that while preservation is considered it is assumed that the pavement is in good structural condition, and therefore traffic volumes are more important than traffic loadings.



Treatment Matrix

In an effort to provide the County with complete information on current P&M treatments that may be used in developing strategies, Appendix A includes treatment selection guidelines and considerations. Table A-1 provides a treatment feasibility matrix that may be used to determine which treatments may be appropriate given existing traffic levels and type of distress. Treatment types shown in table A-1 are described in detail in the pages following the matrix, with advantages, limitations, and estimates of unit cost. These unit cost estimates represent average market conditions and may vary regionally due to availability of materials and contractor experience and capabilities. However, the costs should be accurate relative to one another, allowing qualitative understanding of the relative costs when comparing treatments. Summary

Objective 2 of the assessment of the County P&M practices is to review the County treatment strategies and experiences and compare those to practices in other similar agencies and with industry practice. The review focused on a survey of similar agencies, and on general knowledge of pavement preservation strategies used industry-wide. Findings revealed that County strategies are employed by functional class, and are limited to a relatively few treatments that have worked well in the past. The County has expressed a desire to consider a broader range of treatment alternatives if they are cost effective, although there is reluctance to be too broad with this list. County practice is not altogether divergent from either similar agencies in the area or industry practice. It is common for agencies to focus on treatments that they are confident that local contractors can successfully build and that will provide reliable performance. Predominant treatments on higher volume roadways include crack sealing and HMA overlays, with milling employed where necessary to maintain grade and curb reveal. Chip seals are used on rural arterials and collectors, and on urban local roads. Thin overlays are used when distresses warrant on collectors and local roads. Slurry seals are used primarily on local roads. The County has been reluctant to make more extensive use of preservation treatments on urban arterial and collector routes to avoid impacts to the driving public and surrounding businesses. The inference is that it is better to stay out of these more heavily traveled roadways for as long as possible, and use more substantial treatments (HMA mill and overlay) on a less frequent schedule. However, preservation-type treatments such as slurry seals and microsurfacing take less time to place and preserve the condition of the roadways, so while they may be placed more frequently, the placement process is generally much faster and the unit cost is much lower, so the net effect is a more cost effective approach of greater benefit to the driving public. It is recommended that the County employ as broad a range of treatment alternatives as reasonably possible. Slurry seals (conventional or polymer-modified), microsurfacing, and thin overlays should be considered for greater usage on urban arterial and collector routes. Another potential treatment that might be considered is cape seals (chip seal followed closely by a slurry seal). These and other preservation treatments can be used on roads of many different traffic levels and have the potential to make a positive contribution to the cost effectiveness of the county’s program.



It is also recommended that consideration be given to preservation treatments on the PCC pavements in the County. While there are only about 6 miles of these pavements, they are in very good condition currently after over 20 years of life, and may last much longer if properly maintained. The current decision tree includes treatments only after these pavements reached poor to very poor condition. This is not recommended. Treatments that maintain clean and sealed joints and cracks will help prolong the life of these roadways.



OBJECTIVE 3. COST EFFECTIVENESS

Review the County’s pattern of spending on pavement P&M. Compare the return on the County’s investment in pavement P&M utilizing their current strategies to effective maintenance plans used by similar agencies in both Oregon and Washington and industry best practices. Provide the basis for recommending an ongoing pavement P&M plan by functional class based on the least cost and highest resulting PCI over the next 20 years.

Introduction

Previous discussions have shown that the investment made by the County over the past 20 years in its roadway network has resulted in a network in very good condition. The question at this point is if the levels of service defined by the County Transportation Plan and the strategies employed by the County are sustainable in light of decreasing revenue and increasing pressure on roadways and resources. It would appear that strategies incorporating more cost-effective approaches for preservation will be required to maintain the network within the stated levels of service given current revenue trends and projections. It is uncertain if this approach will fully address the needs, and the possibility of adjustments to revenue may also have to be considered. It is the intent of this discussion to provide recommendations for strategies that will result in more cost effective use of available resources. Beyond that, considerations to address resource limitations will have to be considered in light of long-term budget scenarios and competing County goals and objectives. For the purpose of this discussion, cost effectiveness will be considered as achieving the mandated or required results (performance) at the lowest possible cost. Unfortunately there are intangible cost impacts that may only be subjectively considered, such as the impacts of pavement strategies on surrounding businesses and other facilities, available construction time, user delays, and local preferences. This assessment will focus primarily on costs associated with treatments. Washington County - Return on Investment

A review of the County P&M strategies found that, in general, a minimal range of P&M treatments is used on the arterial and collector routes. Referring to previous discussions, crack sealing is used on arterials and collectors, and chip seal treatments are used on rural arterials and collectors in Condition Category I. Treatments employed on the urban arterial and collector routes have focused primarily on thin overlays when pavements are in Condition Category I and thicker overlays when pavements are in Condition Category II. For the rural roads in Condition Category II overlays are used. As defined by StreetSaver, Condition Categories I and II are characterized by non-load related distresses with PCI values in the good range. Typical deterioration according to input from County staff is primarily longitudinal and transverse cracking. Oxidation and fatigue cracking were not noted as primary concerns. The types of distresses observed supports greater use of surface treatments for preservation of all arterial and collector routes. It is believed that the County’s practices for arterial and collector routes have been more substantial than required, and as such may not be the most cost effective treatments available to address the observed conditions.



As stated previously, the use of preservation treatments on higher volume roads represents a combination of the best practices described herein. While the County is reluctant to implement this practice, there are also well-documented cases of agencies that have extended the use of treatments that would normally only be considered for lower volume roads to collectors and arterials. Two recently published reports provide extensive documentation of this practice and provide guidance (Peshkin 2011a, Peshkin 2011b). This extended application of thin surfacings in particular is based on implementing more cost-effective strategies by treating pavements while they are still in good condition. In contrast to the arterial and collector routes, the County actively applies chip and slurry seals to Local and Neighborhood routes. The use of preservation treatments has maintained these roadways in very good condition. Looking at table 1-2, it is clear that the County is spending less per CL mile of road than most of the surrounding agencies, and is maintaining average network PCI values in the same general range as most of these agencies (below three, above two reporting agencies). Allowing for some variability in reported PCI values and recognized volatility in spending over time, this suggests that the County is using funds more cost effectively compared to similar agencies in the area. Still, there does appear to be room for improvement or greater opportunity for return on investment through the use of less expensive treatments when condition categories are suited to it. The County has about 4.2 million square yards of paved urban arterial and collector roadways, and another 3.4 million square yards of paved rural arterial and collector roadways. These roadway classifications combined (7.6 million square yards) represent just less than half of the total square yardage of pavements that the County maintains (16.8 million square yards). Arguably, these are also the most expensive roadways to maintain, given their widths, traffic levels, and associated facilities (curb and gutter, vegetation, etc.). Table 2.2 shows what it costs to use various treatments to manage those pavements. Conceding that those treatments don’t all do the same thing, by definition the most cost effective use of County funds is to use the treatments that provide the greatest benefit or improvement in condition at the lowest cost. In doing so, the County will either be able to treat the greatest number of miles for a fixed amount of funding, or make the greatest improvements in condition forthe least cost. Industry Statistics – Return on Investment

There is little to no known available industry statistics specifically on cost effectiveness of various strategies. In the section discussing treatment strategies, discussions were provided that touched on industry practice and cost effectiveness that are appropriate here as well. On higher volume roadways (such as the arterials and collectors as defined by the County), there is a long history of using HMA overlays, often in combination with patching and crack sealing. Following this practice allows agencies to take advantage of years of experience, with the results being both predictable and acceptable. This experience in effect highlights significant barriers to trying alternate treatments, including the fear of unexpected failure, less tolerance of imperfections or failures in those treatments, shorter treatment life, increased public complaints, and industry resistance. However, it makes it difficult to realize one of the primary advantages from using alternate treatments, and especially preventive maintenance, which is a more cost-effective pavement management strategy.



At the same time, there is a strong movement in the industry to break out of the collective comfort zone and make greater use of preservation treatments. As agencies across the US seek to make better use of constrained funds, they are finding that a planned preservation strategy allows them to maintain roadway networks in good condition with less cost by applying the proper treatment at the right time, achieving greater cost effectiveness. Summary - Strategy Recommendations to Improve Cost Effectiveness

Given that the County has prior and successful experience with both chip and slurry seals, it would seem to be a reasonable assumption that contractors and materials in the area support greater use of these treatment types. In addition, while prior attempts at microsurfacing have not led to overwhelming success, it is still believed that this treatment type may be well suited to the needs of the County. Greater interest in use should support development of contractor resources, capabilities, and competitiveness in the area that will benefit the County. Application of treatments like surface (slurry) seals on pavements in Condition Category I, or treatments with greater durability (e.g. microsurfacing, cape seals) on pavements in Condition Category II will address the distress conditions observed at a lesser cost. The County has expressed reservations about the impacts of P&M treatments on businesses and other entities along treated routes, implying that placement of such treatments would not generally be acceptable by the public. Interviews with the County indicated that typical treatments along routes where businesses are primarily located (arterials and collectors) generally consist of overlays (1.0 to 2.0 inches thick), sometimes including milling. Use of preservation treatments in lieu of overlays will extend the life of the existing pavements without milling, reducing the resulting construction impacts. It is believed that once the public understands the approach they will be accepting of the County’s concerns for cost effectiveness, and selection of treatment strategies on that basis. In general, this review found that the strategies employed on local and neighborhood routes is excellent, but greater consideration needs to be given to the use of P&M treatments on arterials and collectors. Treatments currently used on these routes are more akin to rehabilitation approaches, and they are being applied when the pavements are in condition categories where rehabilitation is not necessarily an appropriate course of action. Stated otherwise, the timing of treatments is good, but the selected treatments provide more benefit than may be required. Use of preservation approaches, including surface seals (slurry, cape, or microsurfacing), will preserve pavements and extend the time between overlays. This will reduce the County’s pavement rehabilitation costs, and it is recommended that the County modify its strategies to reflect this approach.



OBJECTIVE 4. PAVEMENT CONDITION (PCI) TARGETS

Review the County’s adopted PCI targets. Compare those targets to similar agencies in Oregon and Washington. Evaluate the public’s expectations and desired PCI targets by functional class. Recommend appropriate PCI targets for Washington County.

Introduction

The PCI method was developed in 1980’s by the U.S. Army Corps of Engineers and later standardized as ASTM D6433, Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys. The PCI procedure is the current standard used by the pavement engineering industry for management purposes, providing engineers with a consistent, objective, and repeatable method to represent pavement conditions. In general, pavements with PCIs greater than 70 are considered good candidates for routine maintenance and preservation activities. Pavements with PCIs between 40 and 70 are more likely to benefit from major rehabilitation activities (such as a structural overlay), and pavements with PCIs below 40 are most likely candidates for reconstruction. Table 4-1 provides additional details related to ranges in PCI and recommended treatments.

Table 4-1. Description of PCI rating categories (adapted from AFCESA 2004).

PCI Range Rating Definition

86 – 100 Good Pavement has minor or no distresses and should require only routine maintenance.

71 – 85 Satisfactory Pavement has scattered low-severity distresses, which should require only routine maintenance.

56 – 70 Fair Pavement has a combination of generally low- and medium-severity distresses. Treatment needs range from routine maintenance to major rehabilitation.

41 – 55 Poor Pavement has low-, medium-, and high-severity distresses, which probably cause some operational problems. Will require major rehabilitation.

26 – 40 Very Poor Pavement has predominantly medium- and high-severity distresses that cause considerable maintenance and operational problems. Treatment needs range from major rehabilitation to reconstruction.

11 – 25 Serious Pavement has mainly high-severity distresses, which cause vehicle operational restrictions. Treatment needs range from major rehabilitation to reconstruction.

0 – 10 Failed Pavement deterioration has progressed to the point that safe vehicle operations are no longer possible. Complete reconstruction is required.

Washington County PCI Targets

The Washington County 2020 Transportation Plan is one of several elements that comprise the County’s Comprehensive Plan. The Transportation Plan is a comprehensive analysis and identification of transportation needs associated with the development patterns described in the



community plans and the Rural/Natural Resource Plan. Prepared from both the county-wide and community planning area perspectives, the Transportation Plan addresses the major roadway system, transit, pedestrian and bicycle transportation issues and focuses on specific and system requirements. Policy 21 of the Transportation Plan calls for maintaining the roadway pavement condition at certain base-level standards, and establishes priorities for determining how available resources should be allocated to achieve and maintain these condition levels. It recognizes that adequate roadway maintenance is critical, noting that in the long-term it is much less expensive to maintain the surface and integrity of the roadway than it is to allow it to deteriorate and have to replace it prematurely. Policy 21 provides the County “Road Maintenance/Reconstruction Prioritization Policy,” and states that:

“It is the policy of Washington County to establish annual road maintenance and reconstruction programs that protect public safety and property, make effective use of available funds and preserve the County’s investment in its transportation system.”

Subsection 4 of Policy 21 provides a “Base Condition” concept for the maintenance of paved roads under which the average PCI of all paved roads within a functional class are at or above the levels shown in table 4-2:

Table 4-2. County PCI targets (2020 Transportation Plan).

Functional Class Average PCI Local roads 65 (with 90 percent of road miles 50) Neighborhood routes 70 (with 90 percent of road miles 55) Collectors 75 (with 90 percent of road miles 65) Arterials 80 (with 90 percent of road miles 70)

As an additional source of guiding information, the County staff provided a copy of a draft document entitled “Target Service Levels for Transportation Assets.” The stated purpose of this internal document is to provide guidelines for use by DLUT as they establish the annual road maintenance program, responding to emergencies and service requests, selecting projects, and developing budgets. The target service levels provided in the guidelines supplement the priority matrix established in the Transportation Plan to improve the process for selecting maintenance activities that occur on the County’s road (and bridge) system. For paved roadways, the following service levels are defined:

Service Level A―Few or no unrepaired potholes, ruts, or unsealed cracks. The shoulder is generally clean and free of debris. PCI ranges from 85 to 100 (very good condition).

Service Level B―Minor amount of unrepaired potholes, ruts, or unsealed cracks. The paved shoulder contains a small amount of debris build-up at the edge. PCI ranges from 70 to 84 (good condition).

Service Level C―Moderate amount of unrepaired potholes, ruts, or unsealed cracks. The paved shoulder contains noticeable debris build-up that may be unsightly. PCI ranges from 55 to 69 (fair condition).



Service Level D―Significant amount of unrepaired potholes, ruts, or unsealed cracks. The paved shoulder contains significant debris that would restrict bicycle or pedestrian use, and be unsightly. PCI ranges from 25 to 54 (poor condition).

Service Level E―Extensive amount of unrepaired potholes, ruts, or unsealed cracks. The paved shoulder contains debris build-up that would prevent bicycle or pedestrian use, be a hazard to vehicles, and be unsightly. PCI ranges from 0 to 24 (very poor condition).

In consideration of these service level definitions, the County has established the target service levels and associated PCI ranges shown in table 4-3 below.

Table 4-3. Target service level and PCI range by functional class. (Washington County 2012)

Functional Class Target Service

Level PCI

Range Arterial B 70 to 84 Collector B 70 to 84 Rural resource B 70 to 84 Neighborhood route (URMD) B 70 to 84 Neighborhood route B 70 to 84 Local (URMD) B 70 to 84 Local C 55 to 69

As shown in table 4-3, target service levels correspond to a PCI greater than 70 for all functional classes except local roads. Two County sources provided information related to the network pavement condition. First, a September 2010 publication provided data on target PCI levels compared to current PCI values. The second source of data obtained from the County provided current (2012) PCI values by functional class (previously presented in table 1-1, portions are repeated here for reference). This data is aggregated in table 4-4 for review and discussion purposes.

Table 4-4. Comparison of target and current PCI levels.

Functional Class Target PCI 2010 PCI 2012 PCI Arterials 80 76 77 Collectors 75 80 81 Neighborhood Routes 70 83 85 Urban Local Roads 65 85 86 Rural Local Roads 65 75 76

In review of the current conditions as indicated by the PCI levels, table 4-4 shows that the arterial roadways (both urban and rural) are below the target PCI value both in average and percent above minimum (not shown), and the collector routes are slightly above the PCI target but fall below the percent above minimum (not shown). Rural collector routes are in slightly better condition that the urban collectors, with an average PCI just above the target value. While the PCI values for these critical routes are still in the good range, it appears they are starting to show the effects of the strategies employed (high initial cost in general) and the reduction in revenue discussed previously (limiting miles treated). Based on the data presented previously it appears this combination of PCI target, treatment strategy and funding does not provide a



sustainable approach for meeting target service levels defined by the County for these route functional classifications. Addressing this issue will require consideration and possible adjustment of all three variables (PCI target, treatment strategies, and funding mechanisms). While a reduction in the PCI target would return the roadways into the acceptable range, the effect would likely be short-lived as the funding shortfalls and treatment strategies fail to keep pace with declining conditions in light of the impacts of continued residential and commercial growth on the network and declining revenue. An approach involving reduction of the PCI target value would also move the allowable lower limit closer to the threshold where the rate of deterioration increases, and more costly treatments are typically required to address needs, as has been discussed previously. In contrast to the arterial and collector routes, local roads and neighborhood routes are well above PCI targets for both rural and urban areas. PCI Targets for Similar Agencies

Table 4-5 provides an overview of the survey findings related to current PCI values and targets established by the agencies. A total of seven agencies provided at least partial responses, with five of the agencies reporting target PCI values. Of the five agencies responding to the project survey, the majority reported a PCI target of 70 to 80, regardless of functional class (see table 4-5).

Table 4-5. PCI targets by functional class―similar agencies.

Agency Arterials / Collectors

Urban Local / Neighborhoods Rural Local

City of Beaverton, OR 80 80 NA City of Hillsboro, OR 70 – 100 70 – 100 70 – 100

City of Tigard, OR 75 75 NA City of Vancouver, WA 75 70 NA

Clark County, WA 801 Franklin County, WA 80 – 1001

Pierce County, WA 75 75 75 Spokane County, WA 701

Walla Walla County, WA > 701 Washington County, OR 75 – 80 65 – 70 65 1 Based on the 2012 survey conducted by the MRSC, functional class was not specified.

Note that the target PCI values for arterial and collector routes for other agencies are very similar to those established by Washington County. For local and neighborhood routes, target values are near or slightly higher than those established by Washington County. Table 4-6 provides a comparison of similar agency current PCI values to reported target values. In review of current conditions, it appears that the agencies providing target PCI information are about evenly split in their ability to achieve those targets. Comments provided by a number of them indicate that funding limitations have not allowed them to maintain their desired levels, and there has been a decline over the years. This data supports that target values currently in place in Washington County are reasonably representative of those in similar agencies surveyed. Also,



while insufficient data is available to support a conclusive argument to this fact, it would appear that agencies with lower target PCI values are struggling more to meet those targets.

Table 4-6. Similar agency current PCI values and targets.

Current PCI Target PCI

Overall Arterials/ Collectors

Urban Local/Neighborhood

Roads

Rural Local Roads

Arterials/ Collectors

Urban Local/ Neighborhood

Roads

Rural Local Roads

84 83 86 80 80 81 86/80 82 59 70 – 100 70 – 100 70 – 100 79 80 79 79 69 74 66 66 63 65 62 NA 75 70 NA 70 72 69 75 75 86 89 82 86 75 75 75

In review of the MRSC survey results for Washington and Oregon agencies, their survey asked respondents if the agency had an overall goal for its Pavement Condition Index. Responses were varied in format and typically consisted of comments rather than numerical results, but there were general statements about expectations that are pertinent here. For those agencies referencing PCI as their summary statistic, the stated overall goals tended to establish either 70 or 75 as a minimum value, with goal statements averaging either 75 or 80 not uncommon. Again, these findings support the target values in use in Washington County as generally representative of agencies in the area. Having previously referenced the survey of California agencies conducted and reported in January 2013 by Nichols, there are some extremely interesting results provided regarding current conditions and trends since the 2008 report. Quoting from that report:

“The results show that California’s local streets and roads are moving ever closer to the edge of a cliff. On a scale of zero (failed) to 100 (excellent), the statewide average pavement condition index (PCI) has deteriorated from 68 in 2008 to 66 (“at risk” category) in 2012.

This trend is represented by figure 4-1, which is taken from that report. The report goes on to say that if funding remains the same, the statewide condition is expected to deteriorate to a PCI of 53 by 2022, and the unfunded backlog will increase by over 30 percent to an estimated $66 billion. The State of California’s financial woes have been covered extensively in the news, and this is yet another indication of the fallout as a result of inadequate attention to maintenance of the infrastructure. It has been estimated that the cost of even a minor resurfacing is up to four times more expensive than maintenance of a pavement in good condition. With the cost of pavement repairs estimated to increase exponentially as the condition deteriorates, it can’t be stressed enough that the current condition of Washington County’s roadway network represents a significant investment and valuable asset, and should be maintained as such.



Figure 4-1. California local agency reported PCI conditions (Nichols 2013). Industry State of the Practice

One of the keys to an effective preventive maintenance program is to understand how pavements perform. Figure 4-2 illustrates the typical life cycle of a pavement and the categories of treatments that are appropriate at different times during the life of the pavement. The application of these treatments is also based upon the condition of the pavement, as preventive maintenance treatments are used early on in the life of a pavement while a pavement is still in relatively good condition.

Preventive Maintenance

Reconstruction

Routine/Corrective Maintenance

Rehabilitation

Pavement Condition

Good

Poor

Time (years)

Figure 4-2. Relationship between pavement condition and typical types of treatment.



If, during the life of the pavement, preventive maintenance or minor rehabilitation is not used, the pavement will deteriorate to the point that major rehabilitation (structural restoration, such as full-depth repairs or thick overlays, or even reconstruction is necessary. When a pavement develops significant levels of distress, preventive maintenance activities are no longer viable treatment options. If preventive maintenance or minor rehabilitation is used on a pavement that is highly deteriorated, the treatment may have some effectiveness as a “stop-gap” measure or short-term fix; however, it will not provide the benefit of a preventive maintenance application. Figure 4-2 depicts a generic pavement performance curve (similar in concept to figure 1-3). There can be significant differences in the shape of the performance curve for different pavements due to differences such as environment, design, and construction. The philosophy of preventive maintenance is to address pavements while they are still in good condition and without any serious structural damage. A preventive maintenance treatment applied at the right time can restore the pavement almost to its original condition. Systematic, successive treatments applied correctly help prolong the service life of the asset and delay more expensive major rehabilitation treatments and reconstruction. Figure 4-3 depicts how the application of successive preventive maintenance treatments (shown as the solid line) can help maintain a pavement in good condition for a longer period of time as compared to a pavement without treatments (depicted by the dashed line performance curve). Additionally, performing a series of successive preventive maintenance treatments during the life of a pavement is less disruptive to traffic than the long closures normally associated with reconstruction projects.

Pavement Condition

Time (Years)

Good

Poor

Figure 4-3. Pavement performance extended by preventive maintenance.

In terms of industry standard practice, the best guidance available indicates that a pavement with a PCI of 70 or above may be a good candidate for P&M treatments, although that is dependent on a number of factors, not the least of which is the type of distresses being observed. A pavement with load-related distresses is showing signs of structural inadequacy, and application of P&M treatments will typically not address structural inadequacy concerns.



Targets by Functional Class and Public Satisfaction

In general, the driving public has little concern for the roadways they are driving on until the ride quality or roadway condition deteriorates to the point where it is either uncomfortable or unsafe. At this point the roadway will be well beyond the point of maintenance and preservation, and into the area of rehabilitation or reconstruction, requiring a much greater cost per unit of area than it would have to maintain the roadway in an acceptable condition. With this in mind, it is reasonable to say that public satisfaction may not be a good indicator of reasonable targets for pavement condition. Summary

From the results of the survey conducted and from additional sources of information reviewed it may be said that the PCI targets established by the County are very similar to those of similar agencies. The real question related to PCI targets is not what they are, but if they are sustainable in light of ongoing commercial and residential growth, declining revenue, increasing costs of treatments, increases in area requiring treatment per unit length, and current/potential treatment strategies. It would appear from this analysis that for the local and neighborhood routes the answer is that the current PCI targets are sustainable. These roadways have been maintained in a very good condition and are generally well above stated target values. For arterial and collector routes the same does not appear to be true. These routes are generally at or below defined target values, and while their condition has been stable over the past two years, there was significant decline in condition during preceding years. These are also typically the routes that are considered for widening and aesthetic vegetation, so the cost for maintenance per unit length has increased resulting in a decrease in length of roadway that can be treated per dollar, as depicted in figures 1-4 and 1-5 and as previously discussed. While it appears the public is generally accepting of the current conditions, the County will need to consider potential adjustments to PCI targets, treatment strategies, and revenue to maintain the collector and arterial roadways at target service levels in accordance with the requirements of the County Transportation Plan. It is recommended that attention be focused on the treatment strategies and revenue needs rather than making any significant adjustments in the PCI targets. Reduction of the PCI target for arterial roadways to 75 consistent with the collector routes may be considered, and will ease some of the pressure in terms of comparing current conditions to requirements, but it is believed that any benefit of this will be short-lived and the same concerns will resurface as the impact of treatment strategy (use of preservation treatments on arterial and collector routes) and funding needs (addressing the required funding to meet the combination of increasing costs of treatments and higher cost per unit length of roadway for required maintenance) still need to be addressed for long-term sustainability of condition.



OBJECTIVE 5. LIFECYCLE COST

Analyze and determine the estimated cost to implement the pavement P&M strategy recommended in Objective 3 and achieve the target PCIs recommended in Objective 4 over a 20-year period. The analysis will provide an estimated cost for each fiscal year and resulting PCI forecast.

The analysis to this point has shown that the County, while maintaining their network in generally good condition, may be able to be more effective in application of preservation and maintenance treatments for arterial and collector roadways. The discussions in Objective 3 showed that use of more cost effective strategies may help the County address more constrained budgets in light of growing needs and potential reductions in available resources. With that in mind this discussion looks at the life cycle cost impacts of a number of treatment strategies. For the purposes of this discussion, calculations have been based on typical paved widths for an urban arterial in the County (45 ft.), for a centerline mile of pavement. Pavement width will have a linear effect, so the relative costs should be the same for other roadway functional classifications. These values were used to determine square yardage estimates and typical unit rates for construction activities were used to estimate costs at the time of construction. Using that information a present worth analysis was conducted to determine the life cycle cost of each treatment strategy option. Calculations resulted in the amount one would need to put in a savings account today at 5% interest to pay for the treatment strategy across the life of the facility. A life cycle of 45 years was considered, assuming that the strategy was starting at initial construction. It was assumed that the initial pavement would perform for 15 years with minimal activity, after which a treatment strategy would be required to maintain the roadway in acceptable condition. Given that the focus of this analysis was on preservation and maintenance, reconstruction options were not considered. A simplistic graphical representation of the life cycle cost approach is shown in figure 5-1.



Figure 5-1. General comparison of treatment strategy life cycles.

Treatment strategies of the type being considered may be combined in a variety of ways over time, creating the potential for a very large set of possible combinations for consideration. For this analysis the treatment options were limited to a relatively few options, which indicate the potential when a preservation strategy is employed. Other treatment combinations may easily be considered. Life cycle cost comparisons were developed for the following treatment strategies:

Mill/Inlay – 15 year assumed life, unit cost $20.00/SY Overlays – 15 year assumed life, unit cost $13.00/SY Microsurfacing – 10 year assumed life, unit cost $4.65/SY Slurry Seals – 7 year assumed life, unit cost $1.50/SY

For the roadways in consideration (urban arterial) the use of thick overlays without milling may not be feasible due to curb and gutter and grade considerations. However, their use and associated costs have been displayed here for comparison purposes. As indicated in table 5-1, from a theoretical life cycle cost calculation perspective it can be easily seen that the strategies actively employing preservation treatments in lieu of structural repairs (when conditions do not require structural repairs) will significantly decrease costs to the County. Strategies being used by the County for URMD roadways on a 10-10-10 model may be well suited to the needs of the collector and arterial routes throughout the County, with slurry seals (or micro/cape for greater structural capability) placed at 10-year intervals, and an overlay placed at the 30-year mark.

Table 5-1. Life cycle cost values.

Treatment Strategy

Number and Life Expectancy Unit Cost ($/SY)

Present Value ($)

Mill/Inlay 2 @ 15 yrs. $20.00 $376,144

Thick Overlay (2”)

2 @ 15 yrs. $13.00 $244,494

Microsurfacing 3 @ 10 years $4.65 $117,556

Slurry Seals 5@ 7 years $1.50 $53,902

With all of this information in mind, it seems clear that if a more proactive preservation strategy can be implemented that delays the need for structural HMA overlays, the life cycle cost will be lower. At the same time, it is also conceded that these treatments do not necessarily do the same things, and real needs must be considered in development of strategies. The thin overlays and mill/inlay treatments maintain or add structural capacity, while the slurry/micro strategies maintain the surface and assume that sufficient structural capacity exists. Put another way, it’s unlikely that the PCI over the life of each of these strategies would be similar. Careful consideration needs to be given to the needs of the facility, and address those needs with the applied treatment strategy.



OBJECTIVE 6. PAVEMENT MANAGEMENT SYSTEM SUPPORT

Analyze and determine the appropriate level of staffing required to adequately maintain the County’s PMS. Evaluate possible changes and improvements to support functions to optimize the system.

Introduction

The pavement management concept has evolved significantly since its inception in the 1970s, from a “simple” condition assessment process to a methodology for aiding in identifying project and treatment selection to budget estimation, and finally, to support an agencies asset management program. The following provides a summary of potential benefits of a pavement management system (AASHTO 2001, FHWA 2010b):

Objective basis for developing strategies to improve pavement performance.

Ability to justify funding needs for pavement maintenance and rehabilitation activities.

Improved access to road network information.

Systematic approach to identifying current and future road conditions and needs.

Availability of data to communicate agency decision impacts on pavement condition.

Improved response to queries from internal and external stakeholders.

More cost-effective maintenance and rehabilitation decisions.

Better understanding of pavement performance.

Improved decisions based on sound technical data.

Increased credibility with various stakeholders. Components of a Pavement Management System

Although pavement management features can vary dramatically from agency to agency, there are a number of common components, including the following (AASHTO 2012):

Inputs―include pavement segment inventory information (e.g., road number or street name, location, number of lanes, lane with, pavement type), pavement condition (e.g., PCI), construction/work history (e.g., layer type and thickness, construction year), and traffic (e.g., ADT, percent trucks).

Database―although the type of data platform can vary from agency to agency (typically depends on size and complexity of the pavement network and can vary from a simple spreadsheet to a data warehouse that contains all agency data), the ability to store, sort, and retrieve information greatly improves the use of the pavement management data.

Analysis Parameters―include pavement deterioration models (predict future changes in network conditions), treatment rules (define pavement condition/timing and application of agency-specified treatments), impact rules (quantify expected increase in pavement condition from treatment application and treatment performance with time), and cost models (individual treatment costs and anticipated budget levels).



Analysis Module―conducts the analysis of pavement management data to support agency decisions on project selection and treatment type. Analysis module complexity is dependent on agency needs and can vary from a priority ranking using a spreadsheet to optimization routines for multi-year analysis. The common outputs for the analysis module include: funding level needs to meet performance target goals, recommendations to optimize available funding, and future condition estimates based on different treatment application and investment scenarios.

Reporting Module―generates various pavement management reports (e.g., pavement condition, list of recommended projects and treatment type, results of “what-if” strategies, funding needs).

Feedback Loop―includes the process for updating construction information, treatment completion dates, condition changes, and so on.

Maintaining a Pavement Management System

There are a number of features within a pavement management system that should be updated annually or at least on a regular basis. As a minimum, the following provides suggested updates for maintaining a pavement management system.

Update pavement management database to reflect any changes in the roadway network (i.e., additions, deletions, combines, or divisions).

Update inventory data (as needed).

Add current years’ work history to the pavement management database.

Conduct pavement condition survey training for survey crew members.

Conduct pavement condition surveys.

Conduct quality assurance of pavement condition surveys.

Upload pavement condition survey information into the pavement management database.

Conduct condition analysis. Determine the PCI for each section included in the pavement management database, and determine the overall PCI for the pavement network.

Conduct needs analysis. Develop a list of recommended work to maximize condition and minimize costs.

Conduct impact analysis. Determine the impact of different budget scenarios on overall network condition. This will aid in the evaluation of how funding levels impact the improvement or deterioration of the overall pavement network with time.

Distribute proposed work recommendations to review committee/staff and obtain feedback.

Produce a final list of recommended work.

Review treatment types, treatment rules, and unit costs. Pavement management recommendations are dependent on what treatments types are applied, when they are applied, and how much they cost. Therefore, accurate treatment-related information is essential for obtaining meaningful analysis results. The treatment types, treatment rules, and unit costs should periodically be reviewed and updated to reflect the current maintenance and rehabilitation practices utilized by the County.



Performance models. Performance models should be reviewed to check how well the models reflect actual performance. In addition, current models should be evaluated to determine if any new models should be added for any new treatment types. Any recommended changes in existing models or the development of new models should be based on statistics.

Washington County PMS Resources and Status

Pavement Management System

The County uses the Metropolitan Transit Commission (MTC) StreetSaver Pavement Management Software for their pavement management application. This system provides reasonably good functionality, and is used extensively by an estimated 600 agencies in the US, mostly along the west coast. Some of the system’s features can be somewhat frustrating in their limitations. If used properly those limitations may also be considered strengths, but the program must be used with consideration given to its underlying assumptions to achieve the full benefit of the capabilities. One such feature is the self-calibration function of the performance models. Models cannot be manually updated or adjusted; this is done internally in the program. StreetSaver dynamically updates performance predictions each time PCI values are entered for a segment. In this way the performance curves provided by pavement family are as up-to-date as they can be. However, what this also means is that routine and periodic PCI surveys must be conducted to adequately represent the system performance. An excellent example of the importance and potential impact of this system characteristic may be clearly seen in the County data shown in table 1-1, between 2004 and 2010. During this time the County did not perform PCI surveys to update the system. This corresponded with a period of significant growth in the County, with accompanying construction traffic. The program cannot be externally adjusted to account for increased traffic loading (even though there is an input value for traffic, it has no effect on the predicted performance) or other influences (i.e. unusual weather events). These impacts are represented by their impact on the PCI values. When surveys were done in 2010, a significant drop in PCI scores was observed, and the results surprised the County. In recognition of this observation, it is imperative that periodic surveys be performed to keep the system current. MTC recommends that surveys be conducted every 2 years on arterial and collector roadways, and every four years on local and neighborhood routes. During periods of unusual traffic it may be prudent to conduct surveys more frequently if economically possible, at least for the highly traveled and key roadways. It should also be noted that StreetSaver updates the system for only those segments with updated PCI values. If only a portion of the network is surveyed, only those segments are updated and there is no opportunity to update predictions for similar roads based on the ground truth data collected. In short, it is very important that a strict schedule of PCI surveys and network updates be performed. Another point of concern expressed by the County is the inconsistencies between the decision tree within StreetSaver and the decision tree used in the County Asset Management System, VUEWorks. The StreetSaver program is pavement-focused, and the decision tree bases its decision criteria off of condition categories, with subdivisions recognizing load and non-load related distresses. VUEWorks is broader based, and only considers PCI values without consideration of relationship to load or environmental impacts. Within StreetSaver, different



approaches are considered more appropriate for load versus non-load related conditions. This subtle difference creates an inconsistency in the performance predictions and associated cost impacts that it may not be possible to fully overcome. To explore possibilities, Mr. Sui Tan of MTC was contacted and asked about approaches to deal with these inconsistencies. No solutions were forthcoming. Given the fundamental difference in focus of these two applications, close alignment of predictive capabilities may be as good as it gets. In terms of use of the system, County staff generates a network management plan and budget projection within StreetSaver, and make adjustments to that plan through a process of internal coordination and review. Changes are made to address specific needs where required. Once the County has a plan in hand, they coordinate the planned work with local utility companies so that their plans can be advanced in consideration of the County paving plans to the greatest degree possible. Efforts are made to encourage utilities to complete any planned work that might involve roadways cuts prior to the pavement program. PCI Surveys and Schedule

The County currently plans condition surveys on 50 percent of the arterials and collectors, and on 25 percent of the local and neighborhood routes each year. This survey schedule is in alignment with the MTC-recommended survey frequency. This survey schedule is also generally consistent with practices among other agencies in the area and in the industry. However, referring back to previous remarks, situations may require more frequent surveys for key routes during periods of unusual growth, traffic, or other factors affecting pavement performance to ensure that models within StreetSaver are accurately predicting network needs. The County uses contractors for manual PCI surveys as required. Surveys are performed in accordance with MTC standard for surveys, which is based on seven modified ASTM D6433 distresses for pavement evaluation, and is used by many agencies. Recent developments with StreetSaver allow full compliance with ASTM D6433 for pavement evaluation, but this may not be a good idea for the County given their historical database of PCI values based on the modified definitions. While there is general confidence in the contractor’s ability to collect accurate data, there does not appear to be a defined quality assurance program in place on which to base this assumption of quality. This is an area of potential improvement. Establishment of a surveyor workshop or calibration activity, and periodic field audits by County staff or their impartial representatives would provide quality assurance and help maintain consistency in the collection of survey data. Staffing and Training

The County reported having three staff members assigned to manage the StreetSaver PMS, including entering data, conducting analyses, and producing reports. Observations seemed to reveal one of these staff supervised and did the bulk of the entry and analyses, and was supported by a second staff member who performed tasks as assigned. The third appears to use the system primarily for generation of reports for needs analyses and planning. Staff reported receiving about four to eight hours of training per year on average, but no specifics were provided on the type of training received. The MTC offers semi-annual training through user conferences in the Spring and Fall of each year (for 2013, these are scheduled March 25-28 and November 6-7). These user conferences include workshops and discussions in program use, and provide a forum for StreetSaver users to



learn about new technologies, discuss implementation issues, and receive updates on capabilities and planned development. Even more important is the networking opportunities between users, to learn from their experiences. It is recommended that the County attend one of these User Week conferences annually to maintain a current understanding of program capabilities, limitations, and developments.

Similar Agency Resources and Pavement Management Status

Table 6-1 provides a summary of agency responses related to pavement management support. The majority of agencies indicated a pavement management staff that is comprised of 1 or 2 people. Only the cities of Hillsboro and Tigard reported having as many or more staff dedicated to pavement management activities (4 and 3 personnel, respectively). It is likely that these agencies have multiple people who perform these activities, but they are not fully dedicated to maintenance and update of the systems. Of the seven agencies (excluding the County) responding to the survey, four agencies use StreetSaver, one agency uses CenterLine, one agency uses Hansen 7, and the final agency is transitioning from CenterLine to either StreetSaver or MicroPaver. For the most part, all agencies are satisfied with their current pavement management system. StreetSaver users seemed particularly complimentary of the user-friendliness and support provided for this system.

Table 6-1. Comparison of pavement management support.

Condition Survey Agency

CenterlineMiles

StaffSize System Collection Assurance

SystemUpdates

City of Vancouver, WA 579 1 Hansen 73 Agency Agency Agency City of Beaverton, OR 221 2 1 Agency Agency Agency City of Eugene, OR 519 1 CenterLine2 Contractor Agency Agency Marion County, OR 926 1 StreetSaver Agency Agency Agency Lane County, OR 1,281 1 StreetSaver Agency Agency Agency Washington County, OR 1,300 3 StreetSaver Contractor Agency Agency City of Hillsboro, OR 218 4 StreetSaver Agency Agency Agency City of Tigard, OR 148 3 StreetSaver Agency Agency Agency 1 Transitioning to MicroPaver. 2 No longer supported. Will more than likely be switching to StreetSaver or MicroPaver. 3 Very simplistic with limited reporting capabilities.

It is also interesting to note that all agencies conduct the PCI condition surveys in-house (excluding the city of Eugene and Washington County), assure the quality of the condition data, and provide for system updates. Quality assurance generally consists of field checks of condition ratings and comparisons of PCI values with past measurements, with six of the seven responding agencies indicating these approaches. Five of the six agencies reported these reviews were conducted by the agency, and one indicated that both agency and contractor personnel perform quality assurance reviews of collected data. There was a wide degree of variability in the responses from agencies on survey schedules. In an attempt to summarize the feedback received, responses were broken down by functional class of roadway. Responses indicated the following:

Arterials o Annual – 3 agencies



o Biennial – 3 agencies o Other – one agency reported rating all roads on a 6-year cycle, divided by area

and functional class. Collectors

o Annual – 1 agency o Biennial – 1 agency (half of the network rated each year) o Triennial – 2 agencies o Other – 6-year cycle for all routes.

Other routes (Industrial, Commercial, Neighborhood, Local) o Biannual – 1 agency (half of the network rated each year) o Triennial – 1 agency o Quadrennial – 2 agencies o Other – 6-year cycle for all routes.

In short, it can be seen that priority is generally given to arterials, collectors, and local/neighborhood routes, in that order in establishment of survey schedules. This appears consistent with the practices of the County. Survey participants reported staff training ranging from an average of 0 hours per year to a maximum of 16 hours per year. It appears there are no set schedules, and training is scheduled on an as needed or as requested basis. Needs and Opportunities for Improvement

During the previous discussions there were a number of opportunities for improvement in County practices recognized and recommended. These and others are summarized here for emphasis and ease of reference.

In consideration of the importance of the frequency of PCI surveys to the capability of the StreetSaver models to accurately represent network conditions, it is recommended that the program for surveying be reviewed to consider if it is sufficient. While the frequency of surveys meets the minimum recommended by MTC, it may not be adequate to capture periods of unusual network activity, such as environmental events or heavy construction traffic. Table 1-1 shows that the predictions from 2010 to 2012 were very close, so this may be a low priority. However, for key arterial and collector routes consideration might be given to annual surveys. Whatever is decided in this regard, regular and frequent surveys should be conducted as per the assumptions of StreetSaver for the program to accurately represent the network and provide the best possible budget predictive capabilities.

The County uses contractor resources for PCI data collection. While this is different

from most of the agencies surveyed (most use agency staff), it is also noted that (1) the County network is significantly larger than most of the others, thereby requiring a number of field surveyors to complete, and (2) many agencies across the US contract out their field data collection services with great success. What is important is the need to ensure accurate field data collection, because the success of the PMS depends on the quality of this data. It is recommended that a QC/QA program be established for the PCI survey activities. This program might include a certification course for field surveyors requiring a passing score prior to being allowed to perform surveys, field audits of PCI



score accuracy by QA staff (either County or an independent representative), and documentation requirements. Consistency of distress calls in the field, and accuracy of PCI data will only improve as a result of these efforts, which will have a direct impact on the County’s network management capabilities.

In review of the StreetSaver decision tree it was recognized and acknowledged that crack

sealing costs and schedule are not recorded in the work items. While it is recognized that there is a very small impact in terms of PCI points as a result of crack sealing, it should also be recognized that crack sealing is used extensively in the County, and there are real costs associated with the activity. While quantification of the effect is not possible, there may also be a cumulative effect in performance from including that treatment in the work items. It is recommended that crack sealing be treated as any other treatment, with unit costs and record of work items in StreetSaver.

County staff using the PMS does not have a formal schedule of training that would allow

them to remain completely abreast of program feature enhancements and innovations. It is recommended that County staff attend at least one StreetSaver User Week conference a year. This will provide the opportunity to network with other users and potentially find ways of improving use with the system. For example, other users may have experience with both VUEWorks and StreetSaver, and be able to provide guidance in making bringing greater consistency to the decision trees in these two applications. Users of the PMS in the County might maintain a list of questions, issues, and concerns, with examples of impact for discussion to maximize the return on this training opportunity.

Summary

Objective 6 of the Washington County P&M assessment sought to review the pavement management practices and staffing to determine if they were adequate to the future needs of the County. The system in place in the County, maintenance practices supporting that system, and the County staff using the system were reviewed and compared against those of similar agencies in the area. Needs and opportunities for potential improvement were recognized. The review found that in general, staffing, training and PCI scheduling were consistent with those of others in the area. However, there were some noted potential areas for improvement, most notable in the establishment of a QC/QA process to ensure quality of manually collected PCI data. Recommendations were also provided for a more formal schedule for training, to include attendance by the County at the StreetSaver User Week conference once a year. This will provide a face-to-face opportunity for the County to learn how to better make use of the PMS that helps guide their decision process.



CONCLUSIONS AND RECOMMENDATIONS

This section of the report summarizes the observations and recommendations from each of the project objectives presented in the previous sections of this report. Conclusions and recommendations are summarized by objective, including an item for general recommendations.

Spending

o The County is spending less per centerline mile on Road Fund roadways than the average of surveyed agencies, and above what was seen from other sources of information where funding levels were insufficient to meet expected demand. This would imply that options for increased funding may be required even with adjustments to treatment strategies.

o The current average PCI on Road Fund roadways in the County (78) is very near the median value for the surveyed agencies (76). After a drop of 11 points in PCI between 2004 and 2010, the PCI conditions appear to be remaining reasonably stable at a level just within the good to excellent category where preservation and maintenance approaches are generally considered appropriate.

o Figures 1-4 and 1-5 clearly indicate a trend of declining miles treated per dollar spent. This appears due to wider roads, increased costs of treatments, and increased additional costs to support needs not associated with the pavement in the right of way.

Strategies

o County strategies are applied by functional class, and are limited to a relatively few treatments that have worked well in the past.

o County practice is similar to that of other agencies in the area or industry practice. It is not at all uncommon for agencies to focus on treatments that they are confident that local contractors can successfully build and that will provide reliable performance. Predominant treatments on higher volume roadways include crack sealing and HMA overlays, with milling employed where necessary to maintain grade and curb reveal. Chip seals are used on rural arterials and collectors, and on urban local roads. Thin overlays are used when distresses warrant on collectors and local roads. Slurry seals are used primarily on local roads.

o The County has been reluctant to make more extensive use of preservation treatments on urban arterial and collector routes to avoid perceived impacts to the driving public and surrounding businesses.

o It is recommended that the County employ as broad a range of treatment alternatives as reasonably possible. Slurry seals (conventional or polymer-modified), microsurfacing, and thin overlays should be considered for greater usage on urban arterial and collector routes. Another potential treatment that might be considered is cape seals (chip seal followed closely by a slurry seal). These and other preservation treatments can be used on roads of many different traffic levels and have the potential to make a positive contribution to the cost effectiveness of the county’s program.



o Preservation treatments should be proactively considered for the PCC pavements in the County. While there are only about 6 miles of these pavements, they are in very good condition currently after over 20 years of life, and may last much longer if properly maintained. The current decision tree includes treatments only after these pavements reached poor to very poor condition. This is not recommended. Treatments that maintain clean and sealed joints and cracks will help prolong the life of these roadways.

Cost Effectiveness

o The strategies employed on local and neighborhood routes are excellent. Greater consideration needs to be given to the use of P&M treatments on arterials and collectors. Treatments currently used on these routes are generally considered rehabilitation approaches, and they are being applied when the pavements are in relatively good condition. The timing of treatments is good, but the selected treatments are more than is required.

o Use of preservation approaches, including surface seals (slurry, cape, or microsurfacing), will preserve pavements and extend the time between overlays. This will reduce the County’s pavement costs, and result in greater cost effectiveness.

PCI Targets

o County PCI targets are very similar to those of similar agencies surveyed.

o It would appear from this analysis that for the local and neighborhood routes the current PCI targets are sustainable. These roadways have been maintained in a very good condition and are generally well above stated target values.

o For arterial and collector routes the same does not appear to be true. These routes are generally at or below defined target values, and while their condition has been stable over the past two years, there was significant decline in condition during preceding years.

o It is recommended that attention be focused on the treatment strategies and revenue needs rather than making any significant adjustments in the PCI targets. Reduction of the PCI target for arterial roadways to 75 consistent with the collector routes may be considered, and will ease some of the pressure in terms of comparing current conditions to requirements, but it is believed that the use of preservation treatments on arterial and collector routes and funding needs (addressing the required funding to meet the combination of increasing costs of treatments and higher cost per unit length of roadway for required maintenance) still need to be addressed for long-term sustainability of condition.

Life Cycle Cost

o Strategies actively employing preservation treatments in lieu of HMA overlays (when conditions do not require the addition of structure) will decrease life cycle costs to the County.

o Strategies being used by the County for URMD roadways on a 10-10-10 model may be well suited to the needs of the collector and arterial routes throughout the County, with surface seals (slurry, microsurfacing, or cape seals) placed at 10-year intervals, and an overlay placed at the 30-year mark.



Pavement Management System

o In consideration of the importance of the frequency of PCI surveys to the capability of the StreetSaver models to accurately represent network conditions, it is recommended that the program for surveying be reviewed to consider if it is sufficient. While the frequency of surveys meets the minimum recommended by MTC, it may not be adequate to capture periods of unusual network activity, such as environmental events or heavy construction traffic.

o The County uses contractor resources for PCI data collection. While this is different from most of the agencies surveyed (most use agency staff), it is also noted that (1) the County network is significantly larger than most of the others, and (2) many agencies across the US contract out their field data collection services with great success. Still, the importance of this data to the County decision process requires accurate field data collection. Regardless of whether the data collection is completed in-house or under contract, it is recommended that a QC/QA program be established for the PCI survey activities.

o There is not a formal schedule of training for County staff using the PMS that would allow them to remain abreast of program feature enhancements and innovations. It is recommended that County staff attend at least one StreetSaver User Week conference a year.

General Comments/Recommendations

o During the review it was found that there are a few segments of roadway in dispute between jurisdictions that are not currently being maintained by anyone. These roads are in serious decline due to lack of attention. While these roadways are not specifically the responsibility of the County, the lack of attention to them will reflect badly on the County. Efforts should be made to address these, either through resolution of jurisdictional responsibility, or simply addressing the needs of these few facilities.

o A better defined coordination loop should be established between design and maintenance. This review found that the design staff assumed that their designs were lasting as intended, but there was no feedback mechanism in place to advise them of issues or concerns. Closing the loop is an integral part of pavement management. Both design and maintenance staff would benefit from a more structured feedback mechanism between these two groups.

o PCC pavements appear to be performing exceptionally well with little to no maintenance in key facilities. While outside the objectives of this review, consideration may be given to PCC pavement alternatives in life cycle cost evaluations for new construction.



REFERENCES Air Force Civil Engineer Support Agency (AFCESA). 2004. Pavement Engineering Assessment (EA) Standards. Engineering Techncial Letter 04-9. Department of the Air Force. Tyndall Air Force Base, Florida. American Association of State and Highway Officials (AASHTO). 2012. AASHTO Pavement Management Guide, 2nd Edition. American Association of State Highway and Transportation Officals, Washington, DC. Municipal Research and Services Center (MRSC); Pavement Preservation/Maintenance Program Survey – Oregon; August 2012. Municipal Research and Services Center (MRSC); Pavement Preservation/Maintenance Program Survey – Washington; August 2012. Nichols Consulting Engineers, Chtd. (Nichols); California Statewide Local Streets and Roads Needs Assessment; January 2013. Peshkin, D., K. Smith, A. Wolters, J. Krstulovich, J. Moulthrop, and C. Alvarado. (2011a). Preservation Approaches for High Traffic Volume Roadways. SHRP2 Report S2-R26-RR-1. Peshkin, D., K. Smith, A. Wolters, J. Krstulovich, J. Moulthrop, and C. Alvarado. (2011b). Guidelines for the Preservation of High Traffic Volume Roadways. SHRP2 Report S2-R26-RR-2. Washington County, Oregon; Washington County 2020 Transportation Plan; February 2010. Washington County, Oregon; Target Service Levels for Transportation Assets (Draft); November 2012.



APPENDIX A. TREATMENT SELECTION GUIDELINES AND CONSIDERATIONS




Identification of Feasible Preservation Treatments

The appropriate treatment strategy for those pavement sections identified as candidates for preventive maintenance can be determined by considering the type of distress, the severity of the observed distresses, and the extent of distress. Guidelines for determining feasible treatments are provided in table A-1. This table provides a basis for treatment selection that considers key attributes, including distress (type, severity level, and extent) and average daily traffic (ADT) level. These feasible treatment options are based primarily on a relationship between a single distress and various feasible preventive maintenance treatments. When multiple distresses exist, engineering judgment is required to identify the most appropriate treatment that addresses each distress type. (Of course, if more distresses exist, the pavement is less likely to be a good candidate for preventive maintenance). Following is a description of the preventive maintenance treatment codes used in table A-1.

1. CF – Crack Fill 2. CS – Crack Seal 3. FS – Fog Seal 4. SS – Slurry Seal 5. MS – Microsurfacing 6. CH – Chip Seal 7. CA – Cape Seal 8. TO – Thin Overlay 9. CM – Cold Milling 10. MO – Mill and Overlay

A capital letter in any given cell of table A-1 indicates that the associated preventive maintenance treatment may be a valid candidate for that distress condition and traffic level. The letter sequence identifies the order of preference associated with the treatment (e.g., A=First preference, B=Second preference, and so on). Lower case letters are used to identify treatments that are considered marginal for the distress condition and traffic level. In this context, marginal means that the treatment will have some effectiveness, but is not likely to give the same performance as it would in a true preventive maintenance application. The cross-hatched cells represent distress conditions that are not suited for preventive maintenance and, in turn, are used to reject treatments that might otherwise be selected based for other conditions. Descriptions, advantages, limitations, and approximate costs are provided for each treatment in the pages following table A-1. Please note that costs provided are typical costs experienced in a variety of agencies and locations, and may not be representative of your location.


Table A-1. Treatment feasibility guidelines for HMA pavements.

CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MOLow a b d e f a b cMod a b d e f a b cHigh a b c a b cLow a b c a b cMod HMA PatchHigh ReconstructLow HMA PatchMod ReconstructHigh ReconstructLow A B C D A B C D A B C DMod A B C D A B C D A B C DHigh A B C D A B C D A B C DLow A B C D A B C D A BMod A B C D A B C D A BHigh A B C D A B C D A BLow HMA PatchMod A A AHigh A A ALow A B D C A B D C A B C D EMod A B a C D E a A C B D E A B CHigh a b A B C D E B A C D E A B C DLow A B C a A D C B A B C DMod a A B C D C B A A B C DHigh a B C A a b A ALow a A AMod ReconstructHigh ReconstructLow B C D E A F B C D E A F B C D E A FMod B C D E A F B C D E A F B C D E A FHigh B C D E A F B C D E A F B C D E A FLow B A C B A C B A CMod B A C C B A C B AHigh B A C C B A C B ALow B A B A B AMod B A B A B AHigh B A B A B A

Olathe Distress Type

CommentsSeverity

of Distress

Extent of Distress

High

Low

Mod

High

Mod

High

Low

Mod

Low

Mod

High

Low

Alligator/ Fatigue

Cracking

Bleeding

Block Cracking

Bumps & Sags

ADT Level

Preventive Maintenance Treatment RecommendationsLow (<2500) Moderate (2,500 to 10,000) High (>10,000)



Table A-1. Treatment feasibility guidelines for HMA pavements (continued).

CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MOLow B C D E A F B C D E A F B C D E A FMod B C D E A F B C D E A F B C D E A FHigh B C D E A F B C D E A F B C D E A FLow B C D E A F B C D E A F B C D E A FMod B C D E A F B C D E A F B C D E A FHigh B C D E A F B C D E A F B C D E A FLow B A C B A C B A CMod B A C B A C B A CHigh B A C B A C B A CLow A B A B A BMod A B C a A B AHigh a b A A ALow A B C a A B A BMod a A B A AHigh ReconstructLow a A B A B A BMod ReconstructHigh ReconstructLow A A AMod A A AHigh A A ALow A A AMod A A AHigh A A ALow aMod aHigh aLow A B C D E F a A C B D E A B C D EMod A B a C D E A C B D E A B C D EHigh a b A B C D a B A C D E A B C DLow A B C a A B C D A B C DMod A B C D E F B C D A B C D AHigh B C D A a b A ALow a A AMod HMA PatchHigh HMA Patch


Severity of

Distress

Extent of Distress

Comments

ADT Level


Linear Cracking

(Trransverse/ Longitudinal)

Low

Mod

High

Joint Reflection Cracking

Low

Mod

High

Edge Cracking

Low

Mod

High

Corrugations and Shoving

Low

Mod

High




Table A-1. Treatment feasibility guidelines for HMA pavements (continued).

CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MO CF CS FS SS MS CH CA TO CM MOLow A B A B A BMod A B A B A BHigh A B A B B ALow HMA PatchMod HMA PatchHigh HMA PatchLow HMA PatchMod HMA PatchHigh HMA Patch

Low - A B C A B C A B C

Mod - A B C A B C A B C

High - A B C A B C A B CLow B A C D E a a B A C D E b A B C D aMod B A C D E a a B A C D E b A B C D aHigh B A C D E a a B B C D E b A B C D aLow a A B C D a a A B C D b E A B C D a EMod a A B C D a a A B C D b E A B C D a EHigh a A B C D a a A B C D b E A B C D a ELow A B C D a E A B C D a E B a AMod A B C D a E A B C D a E B a AHigh A B C D a E A B C D a E B a A

Low - a A b c B d A a b B c A a b B c

Mod - A B a D A B a C A B a C

High - A B a D A a B A a B


Severity of

Distress

Extent of Distress

Comments

ADT Level


Polished Aggregate

Rutting

Raveling & Weathering

Low

Mod

High

Deteriorated Patching

Low

Mod

High


Crack Filling

Crack filling is effective at reducing or delaying moisture damage, further crack deterioration, roughness, and rutting. However, it can also have a negative impact on roughness and friction. Treatment Description: Crack filling is the process of placing material into non-working cracks to substantially reduce infiltration of water and to reinforce the adjacent pavement. (Note: Non-working cracks are those that open and close very little with changes in pavement temperature). Crack filling is characterized by minimal crack preparation and the use of lower quality bituminous sealant materials (compared to crack sealing). Pavement Conditions Addressed: Adds no structural benefit, but does reduce moisture infiltration through cracks. Only practical if extent of cracking is minimal and if there is little to no structural cracking. Filling may not be appropriate for cracks experiencing significant movement. Limitations: These treatments are not recommended when structural failures exist (i.e., extensive fatigue cracking or high severity rutting) or if there is extensive pavement deterioration, or little remaining life. Crack filling is appropriate for cracks 0.13 to 1 inch wide. Non-working cracks narrower than 0.13 inches that do not exhibit spalling should not be sealed. These cracks generally do not penetrate through the surface nor do they pose a source of pavement deterioration. The practice of filling this type of crack by the method of pouring sealant on the pavement surface is seldom of value. A crack analysis should be performed to determine whether crack sealing would be effective. Construction Considerations: Placement should occur during cool, dry weather conditions. Application during cool weather (50 to 75 F) will allow for expanded crack widths. Proper crack cleaning and a dry crack are essential to good bond and maximum performance. Traffic Considerations: Performance is not significantly affected by varying ADT or truck levels. However, improper installation can result in failure of the sealant after opening to traffic. Special Considerations: Crack filling may have negative effects. These include a surface that is not visually appealing, and performance problems such as tracking of sealing material by tire action, obscured lane markings, and lower friction/skid resistance. Crack filling may result in a rougher pavement surface when the sealant material is forced out of the cracks during hot weather. Timing: Generally placed 2 to 10 years after HMA construction, after non-load associated longitudinal cracks, longitudinal paving joints, and other non-working cracks develop. Resealing is typically performed at 2- to 4-year intervals thereafter. Performance Period: 2 to 4 years. Cost: $0.60 to $0.80 per linear foot.



Step 1. Crack cleaning. The crack-filling process requires minimal crack preparation. This typically consists of using compressed air to clean the cracks.

Step 2. Application of crack filler. This photo shows the application of a crack filler using an “overbanded” configuration.

Step 3. Application of blotter. For hot-applied materials, a blotter coat of sand is often used to reduce “tracking” of the material by vehicle tires. Liquid de-tackifying agents are also commonly used.

Figure A-1. Crack filling steps.



Crack Sealing

Crack sealing is effective at reducing or delaying moisture damage, further crack deterioration, roughness, and rutting. However, it can also have a negative impact on roughness and friction. Treatment Description: Crack sealing is the process of placing higher-quality material into “working” cracks (i.e., those that open and close with changes in temperature) in order to reduce water infiltration into a pavement. In contrast to crack “filling,” crack sealing requires more substantial crack preparation procedures and uses higher quality sealant materials. Thermosetting and thermoplastic materials are both used for crack sealing. Pavement Conditions Addressed: Adds no structural benefit, but does reduce future intrusion of incompressible materials, water, and soluble chemicals (e.g., salts and brines) into the cracks. It is only practical if extent of cracking is minimal and if there is little to no structural cracking. Limitations: These treatments are not recommended when structural failures exist (i.e., extensive fatigue cracking or high severity rutting) or if there is extensive pavement deterioration, or little remaining life. Crack sealing is appropriate for cracks 0.13 to 1 inch wide. Non-working cracks narrower than 0.13 inches that do not exhibit spalling need not be sealed. These cracks generally do not penetrate through the surface nor do they pose a source of pavement deterioration. The practice of filling this type of crack by the method of pouring sealant on the pavement surface is seldom of value. Construction Considerations: Placement should occur during cool, dry weather conditions with moderate air temperatures (50 to 75 F). Proper crack preparation and cleaning is essential to good bond and maximum performance. A hot compressed air lance may be used prior to sealing to help improve the bond between the sealant and the pavement. Also, crack routing may be effective for cracks that open and close significantly with changes in temperature. Traffic Considerations: Performance is not significantly affected by varying ADT or truck levels. However, improper installation can result in failure of the sealant after opening to traffic. Special Considerations: Crack sealing may have negative effects. These include a surface that is not visually appealing, and performance problems such as tracking of sealing material by tire action, obscured lane markings, and lower friction/skid resistance. Crack sealing may result in a rougher pavement surface when the sealant material is forced out of the cracks during warm months. Sealing is best accomplished several months in advance of other surface treatments. Timing: Generally placed 5 to 10 years after HMA construction, after transverse cracking has developed. Resealing is typically required at 2- to 4-year intervals thereafter. Performance Period: 2 to 5 years. Cost: $0.70 to $1.00 per linear foot.



Step 1. Crack refacing. A uniform sealant reservoir increases the probability of a neater, better performing sealant installation.

Step 2. Cleaning and drying. Cracks must be clean and dry to facilitate sealant bonding.

Step 3. Material application. This photo shows the application of sealant using a “simple band-aid” configuration.

Step 4. Application of blotter. For hot applied materials, a blotter coat of sand is often used to reduce “tracking” of the material by vehicle tires. A liquid de-tackifying agent is also commonly used.

Figure A-2. Crack seal steps.



Fog Seal

Fog seals are effective at sealing the pavement, inhibiting raveling, enriching the hardened/oxidized asphalt, and providing some pavement edge-shoulder delineation. However, fog seals can have a negative impact on friction and stripping. Treatment Description: Fog seals are very light applications of a diluted asphalt emulsion placed directly on the pavement surface with no aggregate. Typical application rates range from 0.05 to 0.10 gal per yd2. Pavement Conditions Addressed: Fog seals are placed primarily to seal the pavement surface, inhibit raveling, slightly enrich a hardened/oxidized asphalt, and provide some pavement edge-shoulder delineation. No structural benefit is added by this treatment. Limitations: This treatment is not recommended when structural failures exist (e.g., significant fatigue cracking) or if there is flushing/bleeding, friction loss, or significant thermal cracking. Construction Considerations: Typically, a slow-setting emulsion (e.g., CSS-1H, SS-1H) is used, which requires time to “break.” Because of this, the pavement is sometimes closed for several hours for curing before being re-opened to traffic. Traffic Considerations: Increased ADT or truck levels can increase surface wear. Timing: Generally placed 1 to 5 years after HMA construction, after asphalt aging/oxidation and/or raveling have developed. Additional applications may be applied at 1- to 3-year intervals thereafter (if the pavement remains a valid candidate). Performance Period: 1 to 2 years. Cost: $0.20 to $0.40 per square yard. Recommended Guidelines and Specifications: “A Basic Asphalt Emulsion Manual,” Manual Series No. 19 (Third Edition), Asphalt Institute and Asphalt Emulsion Manufacturers Association.



Step 1. Surface preparation. The surface must be free of dust, dirt, and debris prior to applying the emulsion.

Step 2. Application of emulsion. The emulsion is applied using a distributor truck.

Step 3. Sand blotter and sweeping (if necessary). Sand blotters can help address a problem with delayed curing, as well as early opening to traffic. Sweeping may be required to remove excess sand.

Figure A-3. Fog seal construction steps.



Slurry Seal

Slurry seals are effective at sealing low-severity cracks, waterproofing the surface, and restoring friction. However, they can also accelerate the development of stripping in susceptible HMA pavements. Treatment Description: Mixture of crushed, well-graded aggregate (fine sand and mineral filler) and asphalt emulsion that is spread over the entire pavement surface with either a squeegee or spreader box attached to the back of a truck. Slurry seals are effective in sealing low-severity surface cracks, waterproofing the pavement surface, and improving skid resistance at speeds below 30 mph. Thickness is generally less than 0.5 inch. Pavement Conditions Addressed: Low-severity cracking; raveling/weathering (loose material must be removed); asphalt oxidation and hardening; friction loss; and moisture infiltration. While slurry seals add no structural capacity, they can temporarily seal cracks (if severity is low) or fill very minor rutting (if the ruts are not severe and are stable). Patching and crack sealing should be completed before slurry seal placement. Limitations: Slurry seals are not recommended when structural failures exist (e.g., significant fatigue cracking and deep rutting) or if there is high-severity thermal cracking. They also can accelerate the development of stripping in susceptible HMA pavements. Construction Considerations: Surface must be clean. Aggregates must be clean, angular, durable, well-graded, and uniform. Avoid placement in hot weather (potential flushing problems) or when freezing temperatures expected. Avoid premature opening to traffic. Quick setting emulsions may cure in as little as 1 hour, but others may require from 2 to 4 hours depending upon the environmental conditions. A process called “dusting” may be used for earlier traffic at intersection and turning lanes where slurry is tender. Traffic Considerations: Performance in terms of surface wear is affected by increasing ADT, turning traffic, and truck traffic levels. Slurry mix properties (i.e., aggregate quality, gradation, and emulsion content) can be modified to accommodate the higher traffic volumes, including the use of polymer-modified emulsions. Areas of heavy truck turning or down grade locations are best avoided as there is a high potential for early damage. The dusting of a blotter material can be used to allow for earlier opening of intersections and turning lanes. Timing: Generally placed 4 to 8 years after HMA construction and at 4 to 7-year intervals thereafter (if the pavement remains a valid candidate). Performance Period: 4 to 8 years. Cost: $1.35 to $2.00 per square yard Recommended Guidelines and Specifications: “Recommended Performance Guidelines for Emulsified Asphalt Slurry Seal,” A105 (Revised), June 2004, International Slurry Seal Association, Annapolis MD.



Step 1. Repair existing distress. Any structural failures should be patched and non-working cracks >0.25 in. (6 mm) wide should be sealed.

Step 2. Prepare surface. Surface must be clean, and striping must be removed. All other in-pavement fixtures (e.g., manholes) need to be protected prior to paving.

Step 3. Slurry placement. This photo shows the placement of material using a slurry seal spreader box.

Step 4. Hand work. Some handwork is required to smooth edges. Excessive handwork can segregate the mix as well as leave an unsatisfactory finish.

Figure A-4. Slurry seal construction steps.



Microsurfacing

Microsurfacing is effective at correcting or inhibiting raveling and oxidation of the pavement surface, improving surface friction, sealing the pavement surface, and filling minor surface irregularities and wheel ruts up to 1.25 inches deep. Treatment Description: Applied in a process similar to slurry seals, microsurfacing consists of a mixture of polymer-modified emulsified asphalt, mineral aggregate, mineral filler, water, and additives. Microsurfacing material is mixed in specialized, compartmented, self-powered trucks and placed on the pavement using an augered screed box. Pavement Conditions Addressed: Low-severity cracking; raveling/weathering (loose material must be removed); low- to medium-severity bleeding; minor roughness; friction loss; and moisture infiltration. Temporarily seals fatigue cracks (if severity is low) and can serve as a rut-filler (if the existing ruts are stable). A scratch coat of the microsurfacing can be used for light profile repairs. Limitations: Microsurfacing is not recommended when the pavement contains structural failures (e.g., significant fatigue cracking), high-severity thermal cracking, or extensive pavement deterioration. This treatment can also accelerate the development of stripping in susceptible HMA pavements. Construction Considerations: Avoid placement in hot weather if there is potential for flushing problems. Placement in cool weather (pavement temperature less than 50 F) can lead to early raveling. Do not place when freezing temperatures are expected, or just prior to precipitation. Microsurfacing typically breaks within a few minutes of placement and can carry traffic after approximately one hour. Traffic Considerations: Very successful on both low and high volume roadways. However, areas of heavy truck turning or down grade locations are best avoided as there is a high potential for early damage. The dusting of a blotter material can be used to allow for earlier opening of intersections and turning lanes. Timing: Generally placed 4 to 8 years after HMA construction and at 6 to 8-year intervals thereafter (if the pavement remains a valid candidate). Performance Period: 4 to 10 years. Cost: $1.85 to $2.50 per square yard Recommended Guidelines and Specifications: “Recommended Performance Guidelines for Micro-Surfacing,” A143 (Revised), June 2004, International Slurry Seal Association, Annapolis MD.



Step 1. Repair existing distress. Any structural failures should be patched, and non-working cracks > 0.25 in. (6 mm) wide should be sealed.

Step 2. Prepare surface. Surface must be clean, and striping must be removed. All other in-pavement fixtures (e.g., manholes) need to be protected prior to paving.

Step 3. Microsurfacing placement. This photo shows the placement of material using a microsurfacing spreader box.

Step 4. Hand work. Some handwork may be required to smooth edges. Excessive handwork can segregate the mix as well as leave an unsatisfactory finish.

Figure A-5. Microsurfacing construction steps.



Chip Seal

Chip seals are effective at improving poor friction, inhibiting raveling, correcting minor roughness and bleeding, and sealing the pavement surface. Chip seals can accelerate the development of stripping in susceptible HMA pavements. Treatment Description: Asphalt (commonly an emulsion) is applied directly to the pavement surface (0.26 to 0.46 gal/yd2) followed by the application of aggregate chips (16 to 30 lb/yd2), which are then immediately rolled to imbed chips (50 to 70 percent). Application rates depend upon aggregate gradation and maximum size. Can be applied in multiple layers (e.g., double chip seals) and in combination with other treatments. Pavement Conditions Addressed: Longitudinal, transverse, and block cracking; raveling/ weathering (loose material must be removed); friction loss; minor roughness; low-severity bleeding; and moisture infiltration. The impermeable surface helps reduce cracking (associated with moisture-related weakening of the underlying layers) and is somewhat effective at sealing medium-severity fatigue cracks in comparison with other treatments. Limitations: Not recommended for pavements with the following conditions: structurally deficient; cracks greater than 0.25 in wide; medium- to high-severity alligator cracking; many potholes; rutting greater than 1 in deep; very rough surface. Chip seals can also accelerate the development of stripping in susceptible HMA pavements. Construction Considerations: Surface must be clean. Treatment should be placed during warm weather with chip spreader immediately behind asphalt distributor and rollers close behind the spreader. Approximately 2 hours of cure time are required before roadway may be re-opened to normal speed traffic. Brooming is usually required to remove loose chips. Traffic Considerations: With special design and proper placement, chips seals can perform well on high-volume roads. However, use is sometimes limited to lower-speed, lower-volume roads because of the propensity for loose chips to crack windshields. Timing: Generally placed 8 to 12 years after HMA construction and at 6- to 10-year intervals thereafter (if the pavement remains a valid candidate). Performance Period: Single seals: 5 to 10 years; double seals; 6 to 12 years. Cost: $2.00 to $2.80 per square yard. Recommended Specifications and Guidelines:

“A Basic Asphalt Emulsion Manual,” Manual Series No. 19 (Third Edition), Asphalt Institute and Asphalt Emulsion Manufacturers Association.

“Chip Seal Best Practices,” NCHRP Synthesis 342, National Cooperative Highway Research Program, Transportation Research Board, Washington, DC, 2005.



Step 1. Surface preparation. Surface must be clean and dry to ensure good bond with the asphalt.

Step 2. Binder application. The asphalt binder is applied to the surface with a distributor truck.

Step 3. Aggregate application. A self-propelled, pneumatic-tired, motorized unit has a hopper on the front where the chips are dumped.

Steps 4 & 5. Rolling and brooming. After the application of the aggregate, the surface is rolled with pneumatic-tired rollers and broomed to remove excess aggregate.

Figure A-6. Chip seal construction steps.



Cape Seals

A cape seal combines a chip seal with slurry or microsurfacing to provide a smooth, quiet wearing surface at a lower cost than an HMA overlay. Treatment Description: The treatment consists of a chip seal, followed within a few days by a slurry seal or microsurfacing treatment to cover the chips and lock them in place. Pavement Conditions Addressed: Longitudinal, transverse, and block cracking; raveling/ weathering (loose material must be removed); friction loss; minor roughness; low-to medium-severity bleeding; and moisture infiltration. Somewhat effective at sealing medium-severity fatigue cracks in comparison with other treatments. Limitations: Not recommended for pavements with the following conditions: structurally deficient; cracks greater than 0.25 in wide; medium- to high-severity alligator cracking; many potholes; rutting greater than 1 in deep; very rough surface. This treatment can also accelerate the development of stripping in susceptible HMA pavements. Construction Considerations: Construction should be done in summer months, and the slurry seal or microsurfacing should follow the chip seal by no more than 12 days. Temperature and placement time of year details for chip seals and slurry seal or microsurfacing apply to the use of this treatment. The existing surface should be cleaned and any areas requiring pavement repairs should be corrected using partial depth repairs prior to application of the chip seal. Traffic Considerations: No traffic concerns, since the application of the microsurfacing removes the hazard of loose chips on high-volume or high-speed roadways. Timing: Generally placed 8 to 12 years after HMA construction and at 6- to 10-year intervals thereafter, if the pavement remains a valid candidate. Performance Period: 6 to 10 years. Cost: $3.50 to $4.70 per square yard (slurry seal finish), $4.00 to $5.20 per square yard (microsurfacing finish) Recommended Guidelines and Specifications: “A Basic Asphalt Emulsion Manual,” Manual Series No. 19 (Third Edition), Asphalt Institute and Asphalt Emulsion Manufacturers Association.



Step 1. Surface preparation. Surface must be clean and dry to ensure good bond with the asphalt.

Steps 2 & 3. Binder and aggregate application. The asphalt binder is applied to the surface with a distributor truck. A self-propelled, pneumatic-tired, motorized unit has a hopper on the front where the chips are dumped.

Steps 4 & 5. Rolling and brooming. After the application of the aggregate, the surface is rolled with pneumatic-tired rollers and broomed to remove excess aggregate.

Step 6. Slurry placement. This photo shows the placement of material using a microsurfacing spreader box. This material should be placed within 12 days after the placement of the chip seal.

Figure A-7. Cape seal construction steps.



Thin HMA Overlay

The application of a thin HMA overlay is a viable option for improving rideability and surface friction, reducing hydroplaning and tire splash (using an open graded friction course), and improving the profile, crown, and cross slope. Treatment Description: Plant-mixed combinations of asphalt cement and aggregate applied to the pavement in thicknesses between 0.75 and 1.5 inches. Dense-graded mixes are preferred, but open-graded mixes can also be used. Pavement Conditions Addressed: Low-severity cracking; raveling/weathering (loose material must be removed); friction loss; roughness; low-severity bleeding; low-severity block cracking (may perform better with a prior cold milling operation). Thin overlays may also be used to correct rutting; however, a separate rut-fill or leveling course application is required. Limitations: Thin HMA overlays are not recommended where there are significant structural failures (e.g., fatigue cracking, potholes, base failures, and so on), extensive pavement deterioration, or if there is high-severity thermal cracking. Surface should be uniform to ensure uniform compaction. Construction Considerations: Surface must be clean. A tack coat prior to overlay placement will help improve the bond to the existing surface. Thin HMA overlays dissipate heat rapidly and, therefore, depend upon minimum specified mix placement temperatures and timely compaction. Special attention should be given to the maximum size aggregate used in the mix. Generally, the maximum size should be no more than one-third the thickness of the overlay. Traffic Considerations: Performance is not affected by different ADT or percent trucks. Thin HMA overlays are not structural layers and, as such, should not be subjected to strain from loadings. Such layers may be subject to top-down cracking under certain combinations of loadings, environmental conditions, and pavement structures. Timing: Generally placed 8 to 12 years after HMA construction and at 6- to 10-year intervals thereafter, if the pavement remains a valid candidate. Performance Period: 6 to 10 years, depending upon thickness. Cost: $6.00 to $11.00 per square yard (depending on thickness and mix type)



Step 1. Pre-overlay repair & surface preparation. Localized areas of distress are repaired prior to overlay placement and milling may be used.

Step 2. Tack coat. A tack coat is used to promote bonding between the overlay and the existing pavement.

Step 3. HMA Overlay. Material is placed with conventional equipment.

Step 4. Compaction. Steel-wheeled rollers are used to compact the overlay.

Figure A-8. Thin HMA overlay construction steps.



Cold Milling

Cold milling is effective at removing distresses in the surface of the pavement, providing a smoother surface by removing surface distortions, and improving surface friction. Treatment Description: Cold milling involves the removal of part of the existing HMA surface. This treatment is frequently used to prepare an existing HMA surface for an HMA overlay. A special double or triple wrap milling head should be used if the completed surface will be turned over to traffic for an extended period of time. Pavement Conditions Addressed: Reduces structural capacity (depending on depth), but addresses most surface cracking and roughness, corrugations, and restores friction. It can also be used to restore proper grades and cross-slopes on existing pavement. Limitations: This treatment is not recommended for structurally deficient pavements. Construction Considerations: The following are keys to obtaining a quality milled surface:

Use a good working milling machine with a 12-ft recommended width. Control milling speed to achieve a smooth uniform surface (30 ft. /min or slower for deep

cuts). Use a 30-ft ski to control grade and a stringline for longitudinal grade control. Perform pavement patching prior to milling. Remove pavement castings and cover holes prior to milling. Adjust casting after milling to meet final surface elevation. Consideration should be given to the use of a fine-toothed milling drum as it will improve

the smoothness and safety of the milled surface. Traffic Considerations: Cold milling can be used at all traffic levels. Special Considerations: While not generally suggested as a stand-alone treatment, this option may be considered. In order for the milled surface to be used as stand-alone treatment, the pavement must be structurally sound with at least 3 inches of the existing HMA remaining in place. Also, the existing mixture must have a high fines content and low air voids content to avoid raveling. Timing: Generally used in conjunction with another treatment. Performance Period: Remaining life of the pavement (does not extend life). Cost: $1.50 to 3.00 per square yard (depending on depth of mill)



Step 1. Prepare surface. Patching should be completed before milling. All other in-pavement fixtures (e.g., manholes) need to be protected prior to cold milling.

Step 2. Milling. Milling is used to remove distresses such as segregation, rutting, raveling, or block cracking.

Figure A-9. Cold milling construction steps.




Mill and Overlay

The combination of cold milling followed by the application of a thin HMA overlay (inlay) is a viable option for removing surface distress in the existing pavement, improving rideability and surface friction, reducing hydroplaning and tire splash (using an open graded friction course), and improving the profile, crown, and cross slope. Cold milling is also performed to maintain the original surface profile, curb reveal, and bridge clearance. Treatment Description: The existing pavement is milled to a depth of up to 2 inches using cold milling equipment. Plant-mixed combinations of asphalt cement and aggregate are applied to the return the pavement surface to the original profile. Dense-graded mixes are preferred, but open-graded mixes can also be used. Pavement Conditions Addressed: Low-severity cracking, raveling/weathering, friction loss, corrugations, rutting, roughness, low-severity bleeding, and low-severity block cracking. Limitations: Not recommended where there are significant structural failures (e.g., fatigue cracking, potholes, base failures, and so on), extensive pavement deterioration, or if there is high-severity thermal cracking. Surface should be uniform to ensure uniform compaction. Construction Considerations: Milled surface must be thoroughly cleaned. A tack coat prior to overlay placement will help improve the bond to the existing surface. The thin HMA inlay will dissipate heat rapidly; therefore, proper compaction depends upon a minimum specified mix placement temperatures and timely rolling. Traffic Considerations: Performance is not adversely affected by different ADT or percent trucks. The HMA inlay is not a structural layer and, as such, should not be subjected to strain from loadings. Such layers may be subject to top-down cracking under certain combinations of loadings, environmental conditions, and pavement structures. Timing: Generally placed 10 to 12 years after HMA construction and at 8- to 10-year intervals thereafter, if the pavement remains a valid candidate. Performance Period: 8 to 10 years, depending upon thickness and mix type. Cost: $7.50 to $13.00 per square yard, depending upon thickness and mix type.

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