Statewide Access Management Coordination GoToWebinar April ... · Statewide Access Management...
40
4/25/2017 1 Statewide Access Management Coordination GoToWebinar Promoting innovative, efficient, and exceptional work since 1988 April 26, 2017 ( 2:30 EST, 1:30 CST) Answers to Common Questions • Yes we will provide a handout of the slides • Yes we will record this session and it should be available in a few days
Transcript of Statewide Access Management Coordination GoToWebinar April ... · Statewide Access Management...
4/25/2017
1
Statewide Access Management Coordination
GoToWebinar
Promoting innovative, efficient, and exceptional work since 1988
April 26, 2017 ( 2:30 EST, 1:30 CST)
Answers to Common Questions
• Yes we will provide a handout of the slides
• Yes we will record this session and it should be available in a few days
4/25/2017
2
Agenda• Introductions – Amie Longstreet and Gary Sokolow
• Safety Analysis of Driveway Characteristics Along Major Urban Arterial Corridors in South Carolina. Wayne Sarasua – Clemson University
• Buc‐ee’s – Time permitting
Your Friendly Webinar Team
Our Special GuestWayne Sarasua, Ph.D., P.E.Clemson University
4/25/2017
3
Regular Statewide Access Management
Coordination Webinar
• Usually the 4th Tuesday @ 2:30 pm to 3:30pm (Eastern Time)
• For FDOT staff (and their consultants) to discuss questions on
• Access Management
• Site Impact
• Trip Generation
Poll •Who do you represent?
4/25/2017
4
SAFETY ANALYSIS OF DRIVEWAYCHARACTERISTICS IN SOUTH
CAROLINA USING GIS
Wayne A. Sarasua, Ph.D., P.E.
Glenn Department of Civil Engineering
Clemson University
Overall Goal
The overall goal of this project is to enhance SCDOT’s current access management practices resulting in a reduction in crashes, injuries, and fatalities on South Carolina roadways as well as improved traffic flow
4/25/2017
5
Literature Review
Access Management studies generally fall into three categories : • Impacts on Safety
• Median
• Access point density
• Sight distance
• Intersection & Interchange
• Turn prohibition
• Impacts on Traffic Operations• Level of service
• Capacity
• Impacts on Residents and Business
Literature Review –Access point density:
• Schultz et al., “Safety impacts of access management techniques in Utah, ” (2007) evaluated the safety performance of arterials in which access management techniques have been implemented. They concluded that the relationship between access points per mile and crash rate has a positive correlation in Utah.
• Frawley and Eisele, “Crash analyses of raised medians and driveway density: How access management makes communities safer,” (2004) completed an evaluation of 11 case studies in Texas and Oklahoma and showed that implementing raised medians and performing driveway consolidation would reduce the potential number of conflicts points along roadways.
Conclusion: reducing access point density reduces crash rates, reduces speed differential between vehicles, enhances operation and could improve roadway capacity and reduce need of new capacity improvement
4/25/2017
6
Literature Review –Medians:
• Gattis et al., “Roadway median treatments,” (2010) examined relationships among crash rates and different types of median (None with occasional left turn lanes, two‐way left‐turn lane, Raised, Depressed) of roadways in Arkansas. They concluded that raised or depressed median yield the lowest crash rates.
• Mauga and Kaseko (2010) evaluated and quantified the impact of types of medians, including raised medians and two‐way‐left‐turn‐lanes on traffic safety in the midblock sections. The results showed that segments with a raised median had lowered the crash rate by 23% compared to segments with a TWLTL.
• Schultz et al., “Safety benefits of median installations in Utah,” (2012) analyzed safety at locations where raised medians are installed. They concluded that raised medians significantly reduce crash frequency and severity.
• Frawley, “Raised median economic impact and safety research findings: Application for Cooper street,” (2010) studied the benefit of converting a two‐way left turn lane to a raised median for particular locations in Bryan, Temple and Tyler, Texas. The benefits include lower crash frequency, fewer crashes involving left‐turns, no migration of crashes to intersections, very few U‐turn crashes, and fewer severe crashes.
Conclusion: Raised medians reduce crash frequency and severity with no migration of crashes to intersections. Traffic operations are improved.
A Methodology for Determining the Economic Impacts of Raised MediansWilliam L. Eisele, P.E., and William E. Frawley, AICP (TTI 1999)
• Business owners who were present before, during, and after the median installation felt that their regular customers continued to use their businesses
• In contrast, those businesses that were interviewed prior to the installation of the raised median thought their customers would be less likely to continue to use their businesses
Perceptions appear worse than reality
4/25/2017
7
Data Collection Procedures and Data Summary
30 Preliminary Corridors
4/25/2017
8
SC Geocoded Crashes
Problems with hand-held GPS data1. Several crash records were missing either
longitude or latitude or both
2. Some crash records were in state plane coordinates, not latitude and longitude
3. Several crash records were in Decimal Degrees (DD), not DMS
4. Some crash records had their longitude and latitude values swapped
5. Most of the latitude values did not include a negative sign
6. Several coordinates were recorded with insufficient precision by one or two decimal places
7. Some crash records had spaces and letters as part of the coordinate entry
8. Some coordinates included additional zeroes to make up for the insufficient precision
9. Some crash records had erroneous coordinate values
4/25/2017
9
Percent of Crash Data by Geocoded Category and by Year
Rear-end and angle crashes on US 25 in Greenville, SC for 2010 (left) and 2012 (right)
4/25/2017
10
SC 9 Spartanburg (2010 – Blue Star VS 2014 – Orange Circle)
US 17 Berkeley (2010 – Blue Star VS 2014 – Orange Circle)
4/25/2017
11
Symbol Table
2010 2011 2012
Driveway Related Crash
Angle Crash
Rear‐end Crash
Greenville US 25• Length ‐ 66
• Driveway Crashes ‐ 309
• Rank – 2
• Rear End ‐ 880
• Angle – 693
• Clusters – 9
4/25/2017
12
Greenville US 25
Greenville SC 146• Length – 13.9
• Driveway Crashes ‐ 294
• Rank – 3
• Rear End – 676
• Angle – 373
• Clusters – 20
4/25/2017
13
Greenville SC 146
Greenville SC 146
4/25/2017
14
Greenwood US 25
Richland US 1• Length – 22.0
• Driveway Crashes ‐ 353
• Rank – 1
• Rear End – 1270
• Angle ‐ 715
• Clusters ‐ 30
4/25/2017
15
Richland US 1
4/25/2017
16
Before and After Results
4/25/2017
17
Richland US 176
Final 11 Corridors
COUNTYROUTE TYPE
ROUTE NUMBER
LENGTH (MILES)
3 YEAR DRIVEWAY AVG RANK
DRIVEWAY CRASHES
Richland US 1 18.5 1 353
Greenville US 25 18.7 2 309
Greenville SC 146 13.5 3 294
Richland US 176 15.8 4 274
Lexington US 1 17.6 5 214
Horry US 17 55.4 6 195
Spartanburg SC 9 15.8 7 173
Greenville US 29 15.4 8 159
York US 21 35.6 9 147
Berkeley US 17 18.8 11 149
Florence US 52 20.4 12 131
4/25/2017
18
Map of 11 Corridors
Corridor Analysis Data Collection Process
Geometric Data were collected for selected corridors in three categories
• Segment ‐intersection to intersection
• Driveway
• Intersection
All data were geocoded into ArcGIS
4/25/2017
19
Sample Driveway with Attributes
Driveway Spacing
4/25/2017
20
Skew Angles
Safety Analysis
4/25/2017
21
Right In Right Out Buffers
Full Access Buffers
4/25/2017
22
Proximity AnalysisAverage Distance from Reported Route by Year
RouteAverage Distance (FT)
2010 2011 2012
US 1, Richland 14.6 3.7 3.2
US 25, Greenville 17.8 2.4 1.3
SC 146, Greenville 18.6 1.8 1.0
US 176, Richland 15.3 1.7 1.1
US 1, Lexington 14.7 4.4 4.7
Buffers with Crash Overlay
4/25/2017
23
Annual Crash Frequency by Driveway Class
Annual Crash Frequency Full Access vs Right-in, Right-out
4/25/2017
24
Negative Binomial Estimation Results for Crashes per Driveway
Negative Binomial Estimation Results for Crashes per Driveway
4/25/2017
25
Crash Modification Factors
Crash Modification Functions
4/25/2017
26
Crash Modification Functions
0
0.5
1
1.5
2
2.5
3
3.5
4
-60 -40 -20 0 20 40 60
CM
FD
W
DWa-DWb
Driveway Width
Crash Modification Function
4/25/2017
27
Crash Modification Function
Safety Performance Function
4/25/2017
28
Crash Modifications Function
Corner Crash Analysis
4/25/2017
29
Corner ClearanceAnnual crash frequency 0 to 150 feet from an intersection vs crash frequency 150 feet to 300 feet
# of driveways HP 2012 Crashes Crash frequency
Distance from Intersection
0-150ft
150-300ft
0-150ft150-300ft
0-150ft150-300ft
US 1 Richland
238 124 112 32 0.47 0.26
US 25 Greenville
188 141 169 45 0.90 0.32
SC 146 Greenville
53 42 75 38 1.42 0.90
US 176 Richland
117 95 74 63 0.63 0.66
SC 9 Spartanburg
100 74 58 22 0.58 0.30
US 17 Berkeley
113 86 37 5 0.33 0.06
Other Project Components
Waiver Analysis
Operational Analysis
Economic and Benefit Cost Analysis
4/25/2017
30
Recommendations for SCDOT ARMS
Sample Specific Changes to ARMS
4/25/2017
31
Findings & Conclusions
• Problems result when developers circumvent standard adherence through the waiver process
• Comprehensive driveway database critical to analysis
• Precise crash data is critical to analysis• Makes it possible to associate crashes with driveways
• Can also facilitate corridor level and even statewide analysis with more robust results
• Reading crash narratives is time consuming and it is sometimes difficult to associate a crash with a particular driveway
• Use junction type with caution. Many driveway related crashes may be overlooked.
4/25/2017
32
Research Golden Nuggets for Practical Application
• Research Findings: Raised medians can cut driveway related crashes in half (CMF of 0.49).
• Right‐in, right‐out driveways eliminate 3 conflict points that are the most critical with respect to crash severity and RIRO driveways have less than half the crash frequency of full access driveways.
• Reducing access point density improves roadway capacity and reduces need for new capacity improvements.
• Driveways within 150’ of a an intersection have nearly twice the crash frequency of driveways 150’ to 300’ from an intersection.
Research Golden Nuggets for Practical Application (cont.)
• Better access policies result in lower crash severity, not just frequency.
• Approval of access waivers from adherence to good design practice often result in higher crash frequency.
• High turnover land use such as fast food restaurants have much higher crash frequency over other land uses such as small businesses.
4/25/2017
33
Thank you!Questions?
Updates of Interest
4/25/2017
34
www.fdot.gov/planning/systems/programs/sm/accman/default.shtm
4/25/2017
35
4/25/2017
36
Buc-ee’sGas andConvenienceStores
Markets over 50,000 sq. ftFueling Positionsover 100
Buc-ee’s - over 100 Fueling Positions
4/25/2017
37
Buc-ee’s
Buc-ee’s
4/25/2017
38
What Help do You Need?
4/25/2017
39
USB Library
Questions & Comments
4/25/2017
40
Poll slide
Poll slide
