ICM diversion route strategies can reduce average delay up to 26 percent, reduce average number of stops up to 42 percent, and increase average speeds up to 9 percent on arterials with traffic signal control.

Experience modeling Integrated Corridor Management (ICM) systems in Minneapolis.

Date Posted
05/15/2014
Identifier
2014-B00915
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Improving Traffic Signal Operations for Integrated Corridor Management

Summary Information

This study evaluated an ICM control strategy designed to diagnose congestion and adjust signal timing as needed to improve traffic conditions on arterial alternate routes during periods of freeway incident congestion. The project area included a 3.5 mile section of I-394 and the TH-55 corridor in Minneapolis. The design included 10 intersections equipped with SMART-Signal systems and decision support logic that used 30-second traffic data sets from freeway surveillance systems and traffic demand profiles recorded at equipped intersections.

To evaluate traffic conditions with and without ICM, a microscopic traffic simulation model (VISSIM) was built and calibrated using field data collected during morning peak hours (7:00 AM – 9:00 AM) from 6-9 June 2009. The model was designed to demonstrate how ICM control strategies can use real-time traffic data from freeways and arterials to establish baseline conditions and manage response plans during periods of congestion.

The model compared the results of two scenarios; a base scenario (independent control strategy) and an ICM control scenario (integrated control strategy). To evaluate performance during an incident, a freeway car crash was introduced to each scenario decreasing freeway travel speeds to 10 mi/h along an 800 ft section of eastbound I-394 from 7:30 AM to 8:30 AM. Metrics including average delay per vehicle, average number of stops per vehicle, and average vehicle speed were used to assess performance on the freeway and the diversion route.

Without incident congestion, freeway travel times were shorter than diversion route travel times, and diversion controls were not needed. However, once a freeway incident occurred, freeway travel times increased and became longer than diversion route travel times until a sufficient freeway traffic diverted, and the travel times equalized. The diversion control logic for the system was set up to remain active until the diversion route travel time was longer than the freeway route travel time.

FINDINGS

Summary of network performance during the whole simulation period (7-9 AM)

Performance Measure
Base Scenario
With Diversion
Percentage Change
Average Delay (sec/vehicle)
55.69
41.14
-26.13%
Average Number of Stops (per vehicle)
2.21
1.28
-42.13%
Average Speed (mi/h)
42.12
45.86
8.89%


The ICM control strategies were found to smooth traffic flow and reduce congestion at varied levels of demand.

Results with freeway demand increased by 5 percent.
Performance Measure
Base Scenario
With Diversion
Percentage Change
Average Delay (sec/vehicle)
76.79
64.27
-16.31%
Average Number of Stops (per vehicle)
3.45
2.13
-38.20%
Average Speed (mi/h)
37.63
40.26
7.00%


Results with freeway demand decreased by 5 percent.
Performance MeasureBase ScenarioWith DiversionPercentage Change
Average Delay (sec/vehicle)
40.27
28.32
-29.67%
Average number of Stops (per vehicle)
1.41
0.73
-47.97%
Average Speed (mi/h)
45.98
49.58
7.82%