MEMORANDUM - Rhythm Engineering...#28990, (Cornell Road Adaptive Signal System) and Washington...

FILENAME: H:\PROJFILE\11075 - INSYNC ADAPTIVE EVALUATION - HILLSBORO\REPORT\FINAL\CORNELL ROAD INSYNC

EVALUATION_DRAFT 3-19-12.DOCX

MEMORANDUM

Date: March 12, 2012 Project #: 11075

To: Galen McGill and Amy Mastraccio-Lopez

Oregon Department of Transportation

800 Airport Road SE

Salem, OR 97301

From: Eric Hathaway, P.E., Tom Urbanik, P.E., and Shing Tsoi, P.E.

Project: Transportation Operation Innovation & Demonstration Evaluation/Statewide

Subject: Cornell Road InSync System Evaluation

Executive Summary

The purpose of this technical memorandum is to present a comparison of operations between the

previously optimized time-of-day (TOD) operation signal timing plans and the InSync adaptive signal

system operation on Cornell Road in Hillsboro, Oregon. This memorandum pertains to the

Transportation Operation Innovation and Demonstration Evaluation/Statewide Work Order Contract

#28990, (Cornell Road Adaptive Signal System) and Washington County Project # 100103, and is

provided for your review and input. This memorandum presents a summary of the corridor

evaluation based on a travel time analysis performed using Bluetooth-enabled media access control

(MAC) address readers, as well as a performance measures evaluation at key locations along the

corridor.

Upon implementation of the InSync system, the traffic signals no longer operated using the

traditional concept of cycle lengths and coordination. Instead, InSync chooses a “state”, a pair of non-

conflicting phases, based on traffic demand and does not follow a set rotation of these states. In place

of offsets, the individual intersections communicate to create dynamic “green tunnels” with the

purpose of progressing vehicles from one end of the system to the other in platoons.”

Transportation Operation Innovation & Demonstration Evaluation/Statewide Project #: 11075 March 12, 2012

Kittelson & Associates, Inc. Portland, Oregon

Figures 1 through 12 illustrate the evaluation results on the Cornell Road corridor from Brookwood

Parkway to Butler Street. During this project, this 1.7 mile stretch of road experienced main street

traffic volumes of approximately 1,500 to 2,000 vehicles per hour during the a.m. and p.m. peak

hours, respectively. Figures 1 through 3 summarize the travel time and delay results of this

evaluation and are provided in the body of this memorandum, while Figures 4 through 12 provide

additional detailed results and are provided in Appendix A. The evaluation team has observed the

following trends in comparing the adaptive system to the previous TOD operations:

Travel time improvement for weekday and weekend average daily periods, both eastbound

and westbound directions, though larger eastbound, possibly due to the location of the

sampling point which did not capture the delay due to holding vehicles for the eastbound

tunnel. Improvements ranging from 4 to 24 percent (9 to 54 seconds).

The InSync system appears to meter traffic at the entrance points to the corridor in order to

create platoons for the green tunnels and progress traffic better along the corridor.

TOD operations experienced very little delay at the video study intersections with no

intersection operating worse than 27 seconds of delay per vehicle. Average intersection delay

experienced little change (less than 5 seconds overall) at all video evaluation intersections

with InSync.

The InSync system generally increased period time (time between successive tunnels) by 15

to 20 seconds on average compared to cycles under TOD operations during the a.m. and p.m.

peak periods.

Based on the findings documented herein, the InSync adaptive signal system had an overall positive

effect on through traffic by improving through vehicle travel time on the corridor. The individual

intersections experienced small changes in overall delay with the InSync system, with more

degradations than improvements.

Introduction

The project evaluation corridor includes nine traffic signals and serves a variety of retail, residential

and office land uses to the north and south of the corridor. 231st Avenue provides access to the MAX

light rail line to the south. The Intel site north of Cornell Road is served by 229th Avenue, Shute Road

and Butler Avenue, while the Intel site to the south is served by Elam Young Parkway (East and

West). 48th Avenue serves Costco traffic to the north and Butler Street serves a large retail center to

the south. Orenco Station Parkway experiences higher pedestrian activity than the rest of the

corridor intersections. The project evaluation corridor was recently retimed in February of 2011,



which provides a reasonable basis for comparison of the implemented adaptive signal system. Along

with the retiming effort, the existing 170 traffic signal controllers were replaced by 2070 controllers.

Ethernet communication was installed and flashing yellow arrows were added at some locations. The

TOD plans operated according to the schedule listed below:

Monday – Friday

6 – 11 AM – Coordination Plan 1

11 AM – 4 PM – Coordination Plan 2

4 PM – 7:30 PM – Coordination Plan 3

7:30 PM – 6 AM – Fully Actuated

Saturday – Sunday

9 AM – 7 PM – Coordination Plan 4

7 PM – 9 AM – Fully Actuated



Corridor Modifications with InSync Implementation

Several changes to the Cornell Road corridor were made in order to implement the InSync adaptive

signal system, including modifications to the signalized intersection detection equipment, as well as

installation of InSync processors. The existing 2070 signal controllers in place before InSync was

installed were maintained, as were yellow and all-red timing setting from the TOD plans. The

maximum time between green tunnels was set at 130 seconds. Before installation of InSync, all

intersections along the evaluation corridor used loop detection, except for the 231st Avenue

intersection, which used video detection. Upon installation of InSync, the 2070 controllers running

Voyage software were set to free operations (i.e., controlled by InSync) throughout the day. Loop

detection was replaced with video detection zones of 150 to 250 feet on all intersection approaches.

A DSL subscriber line was installed for system access. These changes were made consistent with

InSync requirements to ensure that the system provided the necessary data for the InSync

algorithms.

InSync Strategies

The InSync adaptive signal system has a few unique operational characteristics that differentiate it

from a traditional signal system and other adaptive systems. Understanding the terminology and

strategy for the system is helpful in interpreting the analysis results in this report. InSync processors

are installed into the signal cabinet and interact with the existing controller using detector cards

plugged into the controller detector racks. The detector cards are specific to InSync and are

networked to the processor. The processor then places calls to the controller in the same manner as

an inductive loop does in a traditional setup.

The InSync system collects information via video detection at each intersection and reports it to a

“facilitator” intersection (231st Avenue). The facilitator makes decisions globally by creating “green

tunnels” where vehicles are intended to progress along the main line with minimal stops. This

sometimes requires that vehicles be metered at the entrance points to the system wait for the green

tunnel to start. The system also measures queues and percent occupancy at the intersection level to

decide how best to meet local demands. In place of phases, InSync assigns a “state”, which is a pair of

non-conflicting phases, based on traffic demand and does not follow a set rotation of these states. A

rotation of states between green bands is referred to as a “period.”

InSync is preprogrammed to meet typical changes in traffic conditions observed by the designing

engineers before installation of the system. During certain portions of the day, the system will



operate with a specific set of operating parameters, which is called a “configuration”. For instance, on

Cornell Road, a configuration operated from 11 p.m. to 6 a.m. on weekdays with the green tunnel

algorithm disabled (adaptive uncoordinated), in order to allow for better side street operations

during this period where main street volumes are typically lower than other times of the day.

However, during the weekday p.m. peak period from 3:15 p.m. to 7:15 p.m., the system is attempting

to create green tunnels in both directions and has a set of green tunnel parameters that are different

from the midday and morning peak hour settings. Because InSync operates in real time states, it does

not cause phases to dwell during transitions between configurations, as happens with traditional

TOD operations. The list below summarizes the configurations and the corresponding period length

settings. InSync may begin a green tunnel early or late based on demand, so the observed period does

not always match the values identified below, however, the periods are generally consistent (within 5

seconds) of this value during a configuration. Exhibit 1 later in the report provides a sample of the

periods that occurred on a specific day during the study period.

Monday – Friday

6 - 7:15 AM – AM Peak 1 (105 Second Period)

7:15 – 10 AM – AM Peak 2 (115 Second Period)

10:00 – 11:15 AM - MID (105 Second Period)

11:15 – 12:45 PM – MID Peak (115 Second period)

12:45 – 3:15 PM – MID (105 Second Period)

3:15 – 7:15 PM – PM (130 Second Period)

7:15 – 11:00 PM – Off Peak (105 Second Period)

11 PM – 6 AM – Tunnel-less (Adaptive Uncoordinated)

Saturday – Sunday

6:30 AM – 7:15 PM – MID

7:15 – 11:00 PM – Off Peak

11:00 PM – 6:30 AM – Tunnel-less (Adaptive Uncoordinated)

Corridor Travel Time Evaluation

Travel time along the Cornell Road corridor was evaluated using Bluetooth-enabled MAC reader

technology before and after the InSync adaptive signal system implementation. The MAC readers

were placed at 48th Avenue and Butler Street to detect vehicles traveling along the corridor with a

time stamp to track their progress along the corridor. Table 1 summarizes the evaluation periods.



Table 1 Cornell Road Travel Time Evaluation Periods

Periods Number of Days Exclusion Days

Before February 8, 2011 (Tuesday) to February 20, 2011 (Sunday) 13 February 14, 2011 (Monday)

After May 17, 2011 (Tuesday) to May 21, 2011 (Saturday) 5 None

Figures 13 through 14 below compare the TOD and InSync system travel times along 1.5 miles of

Cornell Road between the signalized Butler Street intersection at the east end of the project and the

48th Avenue intersection near the west end of the project for several time-of-day periods during

weekdays and weekends, respectively. These evaluation periods are referenced to the time-of-day

based coordination plan time periods prior to the implementation of the InSync adaptive signal

system. By organizing the travel time data in this way, it is possible to compare how the InSync

system operated to the TOD plans previously in place. These time periods are shown along the x-axis

in Figures 13 and 14 and were consistently applied for the TOD and InSync system conditions.



Figure 13 Cornell Road Weekday Travel Time Before-and-After Comparison

Figure 14 Cornell Road Weekend Travel Time Before-and-After Comparison



Table 2 Cornell Road Travel Time TOD Versus InSync Comparison

Pre-InSync Plan

Eastbound Westbound

Periods

Travel Time

Before (mm:ss)

Travel Time After

(mm:ss)

Travel Time ∆

(seconds)

Confidence Level for

Significant Change

Travel Time

Before (mm:ss)

Travel Time After

(mm:ss)

Travel Time ∆

(seconds)

Confidence Level for

Significant Change

Weekdays

Free 12:00 AM - 6:00 AM 2:40 2:34 -6 71% 2:34 2:54 21 89%

Coord 6:00 AM - 11:00 AM 3:09 2:57 -12 100% 3:29 3:10 -19 100%

Coord 11:00 AM - 4:00 PM 3:31 3:20 -11 100% 4:00 3:38 -22 100%

Coord 4:00 PM - 7:30 PM 3:57 3:08 -49 100% 3:48 3:45 -3 59%

Free 7:30 PM - 11:59 PM 3:28 2:52 -35 100% 3:12 2:59 -14 100%

24 Hour Average 3:30 3:06 -24 100% 3:42 3:26 -16 100%

Weekends

Free 12:00 AM - 9:00 AM 3:03 2:33 -29 100% 3:10 2:53 -17 98%

Coord 9:00 AM - 7:00 PM 3:54 2:57 -57 100% 3:34 3:28 -6 94%

Free 7:00 PM - 11:59 PM 3:20 2:43 -37 100% 3:04 3:16 12 90%

24 Hour Average 3:46 2:52 -54 100% 3:28 3:19 -9 100%

Bold indicates there is at least 95% confidence that average travel time change is significant

Table 3 Cornell Road Travel Time Reliability TOD Versus InSync Comparison

Pre-InSync Plan

Eastbound

Westbound

Periods Buffer

IndexBefore1

Buffer IndexAfter

1

∆ in Buffer Index

Buffer IndexBefore

1

Buffer IndexAfter

1

∆ in Buffer Index

Weekdays

Free 12:00 AM - 6:00 AM 35% 37% 2% 32% 52% 20%

Coord 6:00 AM - 11:00 AM 43% 50% 7% 38% 30% -8%

Coord 11:00 AM - 4:00 PM 41% 42% 1% 37% 36% -1%

Coord 4:00 PM - 7:30 PM 40% 41% 0% 34% 36% 2%

Free 7:30 PM - 11:59 PM 36% 34% -2% 39% 35% -4%

24 Hour Average 47% 44% -4% 39% 40% 1%

Weekends

Free 12:00 AM - 9:00 AM 46% 39% -6% 46% 36% -10%

Coord 9:00 AM - 7:00 PM 37% 32% -5% 34% 31% -2%

Free 7:00 PM - 11:59 PM 36% 46% 10% 34% 47% 13%

24 Hour Average 40% 37% -3% 36% 37% 1%

1 Buffer Index is the difference between the 95th percentile travel time and the average travel time, normalized by the average travel time.



Figures 1 through 3 show that travel times along Cornell Road generally decreased with the InSync

adaptive signal system in place. Table 2 compares the change in travel time (seconds) between TOD

and InSync operations to the confidence level that the change is statistically significant. Confidence

levels are generally 95 percent or greater, due to large sample sizes and travel time changes of 10

seconds or more. Table 3 presents the change in buffer index between TOD and InSync conditions.

The buffer index is a measure of travel time reliability based on the 95th percentile travel time and the

average travel time. The buffer index is expressed as a percentage and “represents the extra time (or

time cushion) that travelers must add to their average travel time when planning a trip to ensure on-

time arrival.”1 For example, a motorist planning a trip that takes 20 minutes on average with a buffer

index of 20 percent should plan an additional four minutes for potential delay to ensure on-time

arrival 95 percent of the time. Therefore, a higher buffer index represents a less reliable travel

condition. A complete summary of travel time metrics for each time period is located in Appendix B.

PEAK PERIOD OPERATION

Observed travel time generally improved with the InSync adaptive system during the time periods

when traffic volumes were highest, i.e. between 6:00 a.m. and 7:30 p.m. on weekdays, and 9 a.m. and

7p.m. on weekends. Coordinated TOD plans were in operation during these time periods before

implementation of the InSync system. Savings were relatively consistent in both directions between

6 a.m. and 4 p.m. during weekdays, and were biased to eastbound between 4:00 p.m. and 7:30 p.m. on

weekdays and during weekend peak periods. A maximum saving of 57 seconds (24 percent) was

observed eastbound during the 9 a.m. to 7 p.m. weekend period. Travel time did not experience a

large change in the westbound direction from 4:00 p.m. and 7:30 p.m. during weekdays, nor between

9 a.m. and 7 p.m. during weekends. The decreases in travel time during these peak volume periods

are associated with only minor changes in the buffer index, typically around 0 to 5 percent (less than

10 seconds) with the exception of the 6 a.m. to 11 a.m. time periods, where the buffer index increases

by 7 percent (13 seconds) eastbound and reduces by 8 percent (17 seconds) on westbound Cornell

Road.

OFF-PEAK OPERATION

Travel time data shows that the InSync adaptive signal system generally has a positive effect on travel

times during lower volume periods in the early mornings and evenings as well. Under TOD

1 FHWA: Travel Time Reliability: Making it There on Time, All the Time.



operations, the signals operated as fully actuated, or “free” during these lower volume periods.

Despite the lower volumes during these off-peak periods, travel time changes during weekday and

weekend early mornings and late evenings are comparable to changes during the peak periods.

Eastbound travel times improved more than westbound times during all off-peak periods and

resulted in overall corridor improvements, except during the weekday early morning period (12 a.m

to 6 a.m.) where overall travel time increased by 15 seconds. Buffer index values increased during

some lower volume time periods and decreased during others. The increases in buffer index were

higher than during the peak time periods and reached 20 percent (21 seconds) in the westbound

direction during the weekday early morning period.

A camera error was discovered after the study period that caused the system to operate in fog mode

at night. During this mode, the timing and phasing were based on historical data instead of the

current traffic conditions and no phases could be skipped, regardless of demand. The issue has been

addressed since the study was completed, so it is likely that current travel times, especially during

the off-peak periods, are different today than during the study period.

DAILY AVERAGES

Daily weekday and weekend averages show decreases in eastbound and westbound travel times,

with greater improvement in the eastbound direction. The larger eastbound improvements could be

influenced by the placement of the MAC readers. The MAC reader placed at Butler Street captured

delay of vehicles entering the corridor from the east; however, due to potential interference from the

high side street volumes, no reader was placed at Brookwood Parkway at the western end of the

system, Therefore, any metering of the system at Brookwood Parkway would not be captured with

the MAC readers. Average daily buffer index value changes are low in the eastbound and westbound

directions.

Intersection Analysis

Intersection level operations were analyzed to determine the effect of the InSync adaptive signal

system on intersection major and minor movements to complement the corridor-level travel time

analysis (MAC reader findings), and assess overall improvements or degradations to the

intersections, including impacts on minor side street movements and left-turning traffic.



DATA COLLECTION

The following three intersections were chosen as representatives of the variety of traffic conditions

and signal operations along the corridor for analysis before and after implementation of the InSync

adaptive signal system. A brief description of each intersection is provided below:

Cornell Road and Brookwood Parkway – Four-legged intersection at the west end of the InSync

corridor serving east-west and north-south commuter traffic.

Cornell Road and Elam Young Parkway – Three-legged intersection serving the Intel campus

located south of Cornell Road.

Cornell Road and Orenco Station Parkway – Four-legged lower traffic volume intersection

serving retail land uses to the north and south. Serves a high number of pedestrians during

peak periods.

Video footage was collected at all approaches to the above intersections from 7 a.m. to 7 p.m. on the

following weekday dates:

Before conditions with TOD coordinated-actuated plans in place

Wednesday, February 9th, 2011

Thursday, February 10th, 2011

After conditions with InSync adaptive system operation

Wednesday, May 18th, 2011

Thursday, May 19th, 2011

Weekday a.m., midday off-peak, and p.m. peak video analysis periods were chosen based on 24-hour

tube counts (Appendix C) and loop counts provided by Washington County staff for conditions before

(TOD without advanced features) and after installation of the InSync system. The loop counts are

provided electronically under separate cover. The following peak and off-peak periods were chosen

to represent the varying traffic volume levels and patterns during a typical weekday. Weight was also

given to how closely the TOD and InSync traffic volumes correlated to diminish the effect of traffic

volume changes between the conditions.

AM peak hour = 7:45 - 8:45 a.m

PM peak hour = 3:15 - 4:15 p.m.

Midday off-peak period = 10:45 a.m. - 11:45 p.m.



The number of vehicles at the evaluation intersections during the a.m., midday off-peak, period and

p.m. peak hour vary by a few hundred vehicles or less at lower volume intersections and by up to 700

vehicles per hour at the Brookwood Parkway intersection.

INTERSECTION MEASURES OF EFFECTIVENESS

Appendix D contains a list of all measures of effectiveness (MOEs) calculated at the video evaluation

intersections as well as the definition of each measure. Spreadsheets comparing each MOE for the

InSync and TOD conditions are found in Appendix E. Traffic operations were assessed at the three

video evaluation intersections to compare operations of the TOD plan to the InSync adaptive system.

Figures 1 through 12 (4-12 in Appendix A) summarize the change in operations at the intersection

level and along the corridor main line.

A normalization comparison was undertaken using Synchro to account for the impact of changes in

traffic volumes and patterns from the TOD analysis dates in February 2011 to the InSync adaptive

system analysis dates in May 2011. The volumes from both periods were entered into a Synchro

model provided by Washington County staff that was used to develop the TOD plans in place during

the video observations in February 2011. The change in delay between the February 2011 and May

2011 volume conditions, as calculated by Synchro, was used to estimate the delay changes that would

have occurred under TOD operations had the InSync system not been installed. The potential changes

due to volume only are provided in addition to the actual results, to give additional perspective to the

observed data. The normalization results show that traffic volume variations did not impact overall

intersection delay by more than 1-2 seconds at any location. Synchro worksheets are provided in

Appendix F.

WEEKDAY MORNING PEAK HOUR FINDINGS

Traffic volume levels at the video evaluation intersections remained fairly consistent during the a.m.

peak period, changing less than six percent before and after implementation of the InSync adaptive

signal system.

Before implementation of the InSync system, all traffic signals from Brookwood Parkway to Butler

Street were running on a coordinated system with a 100 second cycle length between 6 a.m. and

11 a.m. Upon implementation of the InSync system, the traffic signals no longer operated using the

traditional concept of cycle lengths and coordination. Instead, InSync choses a “state”, a pair of non-

conflicting phases, based on traffic demand and does not follow a set rotation of these states. In place

of offsets, the individual intersections communicate to create dynamic “green tunnels” with the



purpose of progressing vehicles from one end of the system to the other in platoons. More

information on InSync operations can be found on the Rhythm Engineering website

(http://rhythmtraffic.com/index.php/insync/).

TOD Intersection Operations

As summarized in Figures 4 through 6 in Appendix A, the TOD video operations analysis shows that

the average vehicle (main and side street) at the Elam Young Parkway (West) and Orenco Station

Parkway intersections experienced 5-6 seconds of delay/vehicle, while vehicles at the Brookwood

Parkway intersection experienced 20 seconds of delay/vehicle. In terms of Highway Capacity

Manual2 standards for signalized intersections, this equates to level of service A at Elam Young

Parkway and Orenco Station Parkway, and level of service C at Brookwood Parkway.

Average delay for Cornell Road through traffic at the three video study intersections was quite low at

Brookwood Parkway (9-11 seconds/vehicle), and even lower at Elam Young Parkway (1-2

seconds/vehicle) and Orenco Station Parkway (2-3 seconds/vehicle). Average vehicle delay on side

street approaches were generally higher than main street approaches at all of the evaluation

intersections, and only one lane group (Cornell Road eastbound left-turn at Brookwood Parkway)

experienced more than 55 seconds of average delay/vehicle, which is the threshold between level of

service D and E operations according to the Highway Capacity Manual standards for signalized

intersections.

InSync Intersection Operations

A review of InSync operations shows only minor delay changes compared with TOD at the video

study intersections on both the main street and side street movements. Variations in delay would be

expected even if a new signal system were not installed, as traffic volumes and patterns changed

slightly between TOD and InSync operations along the corridor. No movements experience greater

than 55 seconds of delay per vehicle under InSync control, whereas one approach experienced

greater than 55 seconds of delay under TOD operations. Phase failures remain low at Orenco Station

Parkway and Elam Young Parkway, and decrease slightly at the Brookwood Parkway intersection (15

to 10). A phase failure is defined as when one or more queued vehicles are not able to depart an

intersection as a result of insufficient capacity during the cycle in which they arrive.

2 FHWA: 2010 Highway Capacity manual

http://rhythmtraffic.com/index.php/insync/



As shown in Table 4, the normalization of delay values for traffic volume changes between the TOD

and InSync conditions results in a change of 1 second or less. The adjusted delay increases average

dealy by 5 seconds or less at the study intersections. The increase in delay at the Brookwood

Parkway intersection appears to be related to the creation of eastbound “green tunnels”. Brookwood

Parkway is the westernmost intersection along the InSync corridor. The eastbound through

movement at this location consistently experiences approximately 10 seconds of additional delay per

vehicle during the a.m., p.m., and midday off-peak hours, which could reflect the InSync system

holding these vehicles to enable better progression along the rest of the corridor.

Table 4 A.M. Peak Hour Overall Intersection Delay – TOD Versus InSync

Intersection

TOD Plan Observed Delay

(Seconds Delay/Vehicle)

Delay Change Observed (Seconds

Delay/Vehicle)

Synchro Projected Delay Change (Seconds

Delay/Vehicle)

Normalized Delay Change (Seconds Delay/Vehicle)

Brookwood Parkway/Cornell Road 20 +4 -1 +5

Elam Young Parkway (West)/Cornell Road 6 +1 +1 0

Orenco Station Parkway/ Cornell Road 5 +2 0 +2

Corridor Travel Times

As shown in Figure 1, MAC readers reported travel time along Cornell Road between 48th Avenue and

Butler Street. The travel time was decreased with InSync by 12 seconds eastbound and 19 seconds

westbound (6-9 percent) during the morning peak period between 6 a.m. and 11 a.m., the period

when Coordination Plan 1 ran under TOD operations. This equates to an average savings of 1-2

seconds at each intersection along the InSync corridor.

Green Band Analysis

A review of the Synchro TOD Coordination Plan 1 (6 a.m. to 11 a.m.) 70th percentile traffic volume

band width diagrams (Figure 15) provide some insight into the progression improvements realized

under InSync operations. Band width diagrams illustrate the TOD implemented timing plans and

associated progression of vehicles along a corridor based on the phasing and offsets at the individual

intersections. The figure below shows that westbound vehicles would have a narrow window of 9

seconds where they could enter the corridor at Butler Street and progress through the entire corridor

without stopping, while eastbound vehicle progression provided a 30 second window. These



illustrations represent how the system is designed to operate; however, individual driver behavior

and traffic variations will change the green windows occurring on the corridor.

The limited TOD westbound progression windows presented a potential for improved operations

(percent arriving on green) with the InSync system. Main street progression is a function of allocation

of green time at an individual intersection, and is also tied to how well the timing is coordinated

between signals to allow vehicles to arrive on green. Looking at the a.m. peak period TOD plans, the

three video study intersections at Brookwood Parkway, Elam Young Parkway (West), and Butler

Street were reasonably well situated in the eastbound progression, with vehicles arriving near or just

after the start of green on Cornell Road. Westbound, had relatively poor progression at Elam Young

and Brookwood Parkway (West). The progression diagram also shows that Cornell Road received a

majority of the green time under TOD operations at Elam Young (West) and Orenco Station, so if a

vehicle did not arrive on green, the delay for that vehicle awaiting the next green would be short.

Conversely, other intersections on the corridor had a large allocation of green time to the side street

(Butler Street, 231st Avenue, and Brookwood). Percent arrival on green eastbound (Figures 4, 5, and 6

in Appendix A) decreased significantly at Brookwood Parkway (likely due to the beginning of the

eastbound tunnel), and was largely unchanged at Elam Parkway (West) and Orenco Station Parkway.

Westbound TOD progression on the diagram is poor overall; however, percent arrival on green

observed in the video study only improved at Brookwood Parkway (likely due to holding eastbound

traffic for the eastbound tunnel) and was largely unchanged (slightly lower) at the other two

intersections.

WEEKDAY MIDDAY OFF-PEAK FINDINGS

Traffic volume levels at the video evaluation intersections (Brookwood Parkway, Elam Young

Parkway (West), Orenco Station Parkway) remained fairly consistent during the off-peak period,

changing less than 5 percent before and after implementation of the InSync adaptive signal system.

Before implementation of the InSync system, all traffic signals from Brookwood Parkway to Butler

Street were running on a coordinated system with a 110 second cycle length during the midday off-

peak hour. Upon implementation of the InSync system, the system no longer operated using the

traditional concept of cycle lengths and coordination as previously described.







Parkway intersection experienced 17 seconds of delay/vehicle. In terms of Highway Capacity Manual

standards for signalized intersections, this equates to level of service A at Elam Young Parkway and

Orenco Station Parkway and level of service B at Brookwood Parkway. Average delay for Cornell

Road through traffic at the three video study intersections was quite low at Brookwood Parkway (7-

10 seconds/vehicle) and even lower at Elam Young Parkway (3 seconds/vehicle) and Orenco Station

Parkway (2-4 seconds/vehicle). Average vehicle delay on side street approaches were generally

higher than main street approaches at all of the evaluation intersections and no lane groups

experienced more than 55 seconds of average delay/vehicle, which is the threshold between level of

service D and E operations according to the Highway Capacity Manual standards for signalized

intersections.



study intersections on both the main street and side street movements. As under TOD operations, no

movements experience greater than 55 seconds of delay per vehicle under InSync control. Phase

failures remained low at Orenco Station Parkway and Elam Young Parkway, however failures

increased from one under TOD operations to ten under InSync at the Brookwood Parkway

intersection, mostly on the eastbound and northbound approaches.

As shown in Table 5, the normalization for traffic volumes between the TOD and InSync conditions

results in average delay changes of 2 seconds or less for all vehicles entering the Elam Young

Parkway and Orenco Station Parkway intersections and 4 seconds at the Cornell Road/Brookwood

Parkway intersection. As under a.m. peak conditions, the small increase in delay at the Brookwood

Parkway intersection might be related to the creation of eastbound “green tunnels” as it is the

westernmost intersection along the InSync corridor. The eastbound through and left-turn movements

experience 10 seconds of additional delay per vehicle and six additional phase failures compared to

TOD operations during the midday off-peak hour, which could reflect the InSync system holding these

vehicles to enable better progression along the rest of the corridor.



Table 5 Midday Off-Peak Overall Intersection Delay – TOD Versus InSync

Intersection




Delay/Vehicle)


Delay/Vehicle)


Brookwood Parkway/Cornell Road 17 +3 -1 +4

Elam Young Parkway (West)/Cornell Road 7 -2 -1 -1

Orenco Station Parkway/ Cornell Road 5 +2 0 +2


As shown in Figure 2, MAC readers reported travel time along Cornell Road between 48th Avenue and

Butler Street. The travel time was decreased with InSync by 22 seconds eastbound and 11 seconds

westbound (5-9 percent) during the midday off-peak period between 11 a.m. and 4 p.m., the period

when Coordination Plan 2 ran under TOD operations. Similar to the a.m. peak period, this equates to

an average savings of 1-2 seconds at each intersection along the InSync corridor.

Green Band Analysis

A review of the Synchro Coordination Plan 2 (11 a.m. to 4 p.m.) 70th percentile traffic volume band

width diagrams (Figure 16) provides some insight into the progression improvements realized under

InSync operations. Band width diagrams illustrate the designed progression of vehicles along a

corridor based on the phasing and offsets at the individual intersections. The figure below shows that

westbound vehicles would have essentially no progression (a window of 1 second) where they could

enter the corridor at Butler Street and progress through the entire corridor without stopping, while

eastbound vehicle progression provided a 23 second window. As previously mentioned, these

illustrations represent how the system is designed to operate; however, individual driver behavior

and traffic variations will change the green windows occurring on the corridor.

The non-existent TOD westbound progression presented a larger potential for improved operations

with the InSync system than during the a.m. period. Looking at the midday off-peak period TOD plans,

the three video study intersections at Brookwood Parkway, Elam Young Parkway (West) and Butler

Street were already well situated in the eastbound progression with vehicles arriving just after the

start of green on Cornell Road.

The diagram also shows that Cornell Road received a majority of the green time under TOD

operations at these locations, so even if a vehicle did not arrive on green, the delay for that vehicle



awaiting the next green would be short. As shown in Figures 7, 8, and 9, Eastbound arrivals on green

are largely unchanged, except at Brookwood Parkway which is the beginning of the tunnel.

Westbound, percent arrivals on green increased slightly at Brookwood Parkway and Orenco Station

Parkway.

WEEKDAY AFTERNOON PEAK HOUR FINDINGS

Traffic volume levels at the video evaluation intersections remained fairly consistent during the p.m

peak period and changed by 3 percent or less at all locations before implementation of the InSync

adaptive signal system.

Before implementation of the InSync system, all traffic signals from Butler Street to Brookwood

Parkway were running on a coordinated system with a consistent 110 second cycle length. Upon

implementation of the InSync system, the system no longer operated using the traditional concept of

cycle lengths and coordination as previously described.





Parkway intersection experienced 27 seconds of delay/vehicle. In terms of Highway Capacity Manual

standards for signalized intersections, this equates to level of service A at Elam Young Parkway and

Orenco Station Parkway and level of service C at Brookwood Parkway. Average delay for Cornell

Road through traffic at the three video study intersections was quite low at Brookwood Parkway (14-

17 seconds/vehicle) and even lower at Elam Young Parkway (1-2 seconds/vehicle) and Orenco

Station Parkway (4-5 seconds/vehicle). Average vehicle delay on side street approaches were

generally higher than main street approaches at all of the evaluation intersections and two lane

groups experienced more than 55 seconds of average delay/vehicle, which is the threshold between

level of service D and E operations according to the Highway Capacity Manual standards for

signalized intersections.



study intersections on both the main street and side street movements. Three movements experience

greater than 55 seconds of delay per vehicle under InSync control, compared to two under TOD

operations. Phase failures increased slightly at Orenco Station Parkway and Elam Young Parkway,



however failures decreased from eleven under TOD operations to five under InSync at the

Brookwood Parkway intersection. Westbound left-turn movement phase failures decreased from five

under TOD operation to none under InSync operations. The reduced failures is likely a result of the

increased green time provided to this movement while the eastbound through movement was being

held before releasing vehicles in green tunnels through the corridor.

As shown in Table 6, the normalization for traffic volumes between the TOD and InSync conditions

results in average delay changes of 1 second or less for all vehicles entering the Brookwood Parkway

and Orenco Station Parkway intersections and 3 seconds at the Elam Young Parkway intersection.

Table 6 P.M. Peak Hour Overall Intersection Delay – TOD Versus InSync

Intersection




Delay/Vehicle)


Delay/Vehicle)


Brookwood Parkway/Cornell Road 27 0 +1 -1

Elam Young Parkway (West)/Cornell Road 5 +3 0 +3

Orenco Station Parkway/ Cornell Road 6 +3 +2 +1


The p.m. peak analysis period (3:15 p.m. to 4:15 p.m.) was chosen based on the traffic volume levels

under TOD and InSync operations. This period spans two TOD coordination plans, Coordination Plan

2 (11 a.m. to 4 p.m.) and Coordination Plan 3 (4:00 p.m. to 7:30 p.m.), with a majority of the video

analysis occurring during Coordination Plan 2. During the hours that Coordination Plan 2 operated

under the TOD scheme, the travel time was decreased with InSync by 22 seconds eastbound and 11

seconds (5-9 percent) westbound. As shown in Figure 3, during Coordination Plan 3, the travel time

was decreased with InSync by 49 seconds (21 percent) eastbound and 3 seconds (1 percent)

westbound. Accounting for the majority of the analysis period occurring during Coordination Plan 2,

this equates to an average savings of 2-3 seconds eastbound and 1-2 seconds westbound at each

intersection along the InSync corridor.

Green Band Analysis

The video analysis period (3:15 p.m. to 4:15 p.m.) spans two TOD coordination plans. A review of the

Synchro Coordination Plan 2 (11 a.m. to 4 p.m.) and Coordination Plan 3 (4:00 p.m. to 7:30 p.m.) 70th

percentile traffic volume band width diagrams (Figures 16 and 17) provides some insight into the



progression improvements realized under InSync operations. Arterial bandwidth diagrams illustrate

the designed progression of vehicles along a corridor based on the phasing and offsets at the

individual intersections. The figures show that westbound vehicles would have essentially no

progression (a window of 0-1 second) where they could enter the corridor at Butler Street and

progress through the entire corridor without stopping, while eastbound vehicle progression provided

a 23-32 second window. As previously mentioned, these illustrations represent how the system is

designed to operate; however, individual driver behavior and traffic variations will change the green

windows occurring on the corridor.

The limited TOD westbound progression window present a large potential for improved operations

with the InSync system. Looking at the midday off- peak period TOD plans, the three video study

intersections at Brookwood Parkway, Elam Young Parkway (West), and Butler Street were

reasonably well situated in the eastbound progression with vehicles arriving after the start of green

on Cornell Road.

As in earlier time periods, eastbound percent arrival on green decreased at Brookwood (likely due to

beginning of tunnel). Eastbound percent arrival on green at Elam Parkway (West) was largely

unchanged and was improved at Orenco Station. Again, as in earlier time periods, westbound percent

arrival on green improved at Brookwood Parkway. However, westbound arrival on green decreased

significantly at Elam Parkway (West) and Orenco Station Parkway.

INTERSECTION CYCLE LENGTH EVALUATION

Cycle lengths under TOD operations were compared to the time between tunnels/green bands (time

for complete period until next tunnel) under InSync operations at Brookwood Parkway. While cycle

lengths for the TOD operation are documented here as reference, the purpose of this cycle time

evaluation is to study how InSync responds to volume fluctuations.

TOD Operation

The entire corridor between Brookwood Parkway and Butler Street was coordinated under TOD

operation. Table 7 summarizes the weekday cycle lengths used during the TOD operation.



Table 7 Cornell Road Weekday Cycle Length Summary under TOD

Time Period (Weekdays Only) Cycle Length (sec) under TOD

12:00 AM - 6:00 AM Free

6:00 AM - 11:00 AM 100

11:00 AM - 4:00 PM 110

4:00 PM - 7:30 PM 120

7:30 PM - 11:59 PM Free

As shown, the corridor was running with fairly consistent cycle lengths throughout the day. The cycle

lengths range from 100 seconds to 120 seconds during weekday peak periods.

InSync Operation

As mentioned previously, InSync signals do not operate on a traditional order of phases. Instead,

InSync choses a “state”, a pair of non-conflicting phases, based on traffic demand. There is no set

rotation of these states. In place of offsets, the individual intersections communicate to create “green

tunnels” that progress vehicles from one end of the system to the other. Exhibit 1 summarizes the

time between green tunnels (period) under InSync operation on May 18. The periods reported below

were taken from the 15 minute averages reported by the Voyage logs provided by Washington

County. Tube counts on Cornell Road are also plotted on the same graphs to better illustrate the

period fluctuations with respect to traffic volume fluctuations.



Exhibit 1 Cycle Time-Volume Plot for Cornell Road and Brookwood Parkway

Exhibit 1 shows that periods (time between green tunnels) under InSync operation generally did not

vary by more than 5 seconds within a configuration and followed the period setting for each

configuration, as identified below:

6 - 7:15 AM – AM Peak 1 (105 Second Period)

7:15 – 10 AM – AM Peak 2 (115 Second Period)

10:00 – 11:15 AM - MID (105 Second Period)

11:15 – 12:45 PM – MID Peak (115 Second period)

12:45 – 3:15 PM – MID (105 Second Period)

3:15 – 7:15 PM – PM (130 Second Period)

7:15 – 11:00 PM – Off Peak (105 Second Period)

11 PM – 6 AM – Tunnel-less (Adaptive Uncoordinated)

The periods ranged from approximately 100 seconds to 120 seconds during most of the morning and

early afternoon and increased up to the preset maximum of 130 seconds during the p.m. peak period.

The minor period length variation within a configuration appeared to generally react to variations in

traffic volumes smoothly with the prescribed constraints. The sharp increase in period time from 100



seconds at 3 p.m. to approximately 125 seconds by 3:30 p.m is a result of the increase in traffic

volumes and the change in signal settings (period, global tunnel duration and offsets) from the “MID”

configuration to the “PM” configuration at 3:15 p.m. The gray shaded portions of the graph from 11

p.m, until 6 a.m. represent the “adaptive uncoordinated” configuration, during which the traffic

signals only optimize locally and do not attempt to create green bands.

INTERSECTION DATA COLLECTION

Before installation of the InSync adaptive system, traffic volume data was collected by induction

loops along Cornell Road and the side streets. After installation of InSync, traffic volumes were

recorded by the detection video cameras.

Traffic Volumes

As shown in Table 8, the absolute difference between the manual counts from the video recordings

and automatic counts (loop or video detection counts) range from 10 percent to 19 percent at most

intersections. At Orenco Station Parkway, the differences between manual counts and loop counts

were lower, in the range of 3 percent to 9 percent. In general, differences between loop counts and

manual counts were consistent, i.e. either positive or negative differences were observed across all

three time periods at each intersection. However, video detection counts may show a positive

difference from manual counts at one time period and negative difference at another time period at

the same intersection. Video detection counts and loop counts have similar degree of difference from

manual counts at Brookwood Parkway and Elam Young West. A more detailed breakdown of the

volume differences are provided in Appendix G. Not surprisingly, it is clear that the advanced loops

and video detection systems do not report traffic volumes uniformly, as they have different

configurations and methods by which they count traffic.

Table 8 Comparison of Intersection Total Entering Volumes between Manual and Loop Detection/Video Detection Counts

Intersection

TOD (2/10/2011) InSync (Video) (5/18/2011) InSync (Loop) (5/18/2011)

Manual Counts

Loop Counts

Difference |Loop -

Manual|* Percentage Difference

Manual Counts

Video Detection

Counts

Difference |Video -


Manual Counts

Loop Counts

Difference |Loop -


AM (7:45 - 8:45 AM)

Brookwood Parkway/

Cornell Road 3,187 3,266 485 15% 3,080 3,468 412 13% 3,080 2,762 442 14%

Elam Young West/ Cornell

Road 2,063 1,934 317 15% 2,183 2,245 408 19% 2,183 1,853 348 16%

Orenco Station/

Cornell Road 1,876 2,035 159 8% 1,855 2,105 250 13% 1,674** 1,577** 97 6%



Intersection

TOD (2/10/2011) InSync (Video) (5/18/2011) InSync (Loop) (5/18/2011)

Manual Counts

Loop Counts

Difference |Loop -


Manual Counts

Video Detection

Counts

Difference |Video -


Manual Counts

Loop Counts

Difference |Loop -


Off Peak (10:45 - 11:45 AM)

Brookwood Parkway/

Cornell Road 2,758 2,867 355 13% 2,730 2,629 419 15% 2,730 2,532 392 14%


Road 2,130 1,948 312 15% 2,118 1,922 222 10% 2,118 1,900 218 10%

Orenco Station/

Cornell Road 2,084 2,154 70 3% 1,977 2,049 196 10% 1,836** 1,708** 128 7%

PM (3:15 - 4:15 PM)

Brookwood Parkway/

Cornell Road 3,520 3,574 376 11% 3,530 3,192 398 11% 3,530 2,798 842 24%


Road 2,350 2,242 274 12% 2,415 2,166 435 18% 2,415 2,042 373 15%

Orenco Station/

Cornell Road 2,263 2,382 119 5% 2,259 2,479 220 10% 2,080** 1,900** 180 9%

* Values shown under "Total Entering Volumes" are sum of differences in absolute terms on each approach. For example, during the AM peak hour under TOD operations at Brookwood Parkway, the eastbound approach has a negative difference of 203 vehicle counts, while other approaches have a total positive difference of 282 vehicle counts; difference under "Total Entering Volumes" would be the sum of 203 and 282 which is 485 vehicle counts.

** At Orenco Station, traffic volumes from loops during InSync deployment periods do not include side street traffic due to missing data.

Percent Arrival on Green

Voyage logs recording the percentage of main street vehicles arriving on green were collected before

and after implementation of the InSync system at all 10 intersections along the corridor, except for

Brookwood Parkway, where the TOD plans were not able to be retrieved. Table 9 summarizes the log

data for the three video study periods (7:45-8:45 a.m., 10:45-11:45 a.m., 3:15-4:15 p.m.). The table

shows that percent arrival in green was generally unchanged in the westbound direction and shows

improvements of 2 to 4 percent eastbound. As mentioned previously, the manual percent arrival on

green counts consistently showed that the percent arrival on green eastbound at Brookwood

Boulevard decreased by approximately 15 to 25 percent due to metering of vehicles entering the

corridor from the west. Therefore, it is likely that if the Brookwood Parkway data were incorporated,

the eastbound percent arrival on green would be lower. A more detailed chart is included in Appendix

H showing the percent arrival on green at all 10 intersections in the eastbound and westbound

directions for the three study periods. This more detailed chart clearly illustrates the metering effect



at the eastern end of the corridor (Butler Avenue), where westbound vehicles entering the corridor

experienced decreases in percent arrival on green of between 11 and 26 percent.

Table 9 Average Improvement of Percent Arrival with InSync

AM Midday PM

EB % Arrival on Green Change

+4% +2% +3%

WB % Arrival on Green Change

0% 0% 0%

Appendix H also includes a comparison of the manual counts and Voyage log percent arrival on green

calculations at the video study intersections. At Orenco Station Parkway and Elam Young Parkway

(West), the trends of decreases or increases in arrival on green percentage were the same in both

data sets, except for the midday westbound approach at the Elam Young Parkway intersection. The

change in percent arrival on green documented by the manual counts and Voyage logs were within

10 percent in all but two instances. Based on these findings, the percent arrival on green documented

by Voyage provides generally consistent results with the manual observations.

Stakeholder Interview

The project team conducted an interview with Stacy Shetler, the Traffic Engineering Manager for

Washington County, Oregon. Stacy oversaw the installation of the InSync system on Cornell Road and

currently monitors operations of the system. The interview regarding his experiences with the InSync

system is summarized in Appendix I. Some of the major findings from the interview are summarized

below:

The cost for installation of InSync was about $48,000 per intersection, including licensing, the

pedestrian module and cabinet changeouts.

Routine maintenance hours are similar to a traditional signal system once the system is

configured.

InSync can be configured to send system alerts via e-mail or text messages.

Technician maintenance is not very different than under TOD, as InSync still uses a 2070

controller with Voyage software.

Rhythm Engineering customer service can be reached 24-hours a day.

The success of the InSync system is highly related to the quality of detection on the corridor

and skill of the fine tuner.



The system is preset to operate with different timing settings called operates “Configurations”

based on time of day.

Summary and Conclusions

A comparison of updated TOD plan operations and InSync adaptive signal system operations on

Cornell Road in Hillsboro, Oregon, reveals differences in performance between the two systems. The

InSync adaptive signal system provided travel time savings in both directions on Cornell Road of up

to 57 seconds from 48th Avenue to Butler Street (1.5 miles) during the higher volume time periods on

weekdays and weekends. Overall corridor travel times improved during all off-peak periods except

for the early morning (12 a.m. to 6 a.m.), where westbound increases outweighed the eastbound

decreases. Camera errors that occurred during the study period night-time hours that have since

been corrected were likely a contributing factor to the less efficient nighttime off-peak operations.

Average daily vehicular travel time for weekdays and weekends are all reduced with implementation

of InSync. The video analysis shows metering of vehicles entering the corridor from the west that was

not accounted for in the corridor travel time observations. For this reason, it is likely that actual

eastbound improvements were 5 to 10 seconds lower than those provided in the report. Changes to

the buffer index between TOD operations and the InSync adaptive system were mixed between

improvements and degradations and were generally less than 10 percent. Some buffer index

increases of 10 - 20 percent were recorded during off-peak periods. The improved travel times come

at the expense of a small increase in overall delay.

An evaluation of main street and side street weekday a.m. peak and p.m. peak operations at three

intersections along the corridor shows that the InSync cycle times between tunnels (periods) were

generally 10 to 20 seconds longer than the cycle lengths observed during TOD operations along the

corridor. Weekday midday TOD cycle lengths and InSync period lengths were similar. The length of

periods under InSync operation was strongly correlated to the configurations settings, but did vary

by about five seconds within configurations based on traffic demand.

The Brookwood Parkway intersection experienced between 17-27 seconds of delay per vehicle under

TOD operation, while the Orenco Station Parkway and Elam Young Parkway intersections

experienced less than 7 seconds of delay per vehicle. With implementation of the InSync system

overall delay per vehicle changed by less than 5 seconds (normalized for volume changes) per vehicle

at Brookwood Parkway and less than 3 seconds at Orenco Station and Elam Young Parkway in all

cases. Increases in delay at the Brookwood Parkway intersection appear to be tied to metering of

traffic on the eastbound approach while preparing green tunnels for the system.



Based on the above findings, the InSync adaptive signal system had an overall positive effect on the

Cornell Road through traffic by improving through vehicle travel time on the corridor without large

increases to side street or main line left-turn movements.

MEMORANDUM - Rhythm Engineering...#28990, (Cornell Road Adaptive Signal System) and Washington...

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