Implementation of Adaptive Signal Control Technology in Florida Resulted in an Overall Travel Time Reduction of 9.36 Percent for Eight Corridors.
Before and After Study of Adaptive Signal Control Technology in Eight Florida Cities Analyzed Impacts on Traffic Operations and Safety.
Made Public Date
07/25/2021
Identifier
2021-B01579
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Before and After-Implementation Studies of Advanced Signal Control Technologies in Florida

Summary Information

Adaptive Signal Control Technology (ASCT) systems collect data, evaluate traffic signal performance based on functional objectives, and then update signal timing in response. Florida DOT commissioned a project to evaluate the effectiveness of ASCT across Florida using a before and after study approach and document the advantages and disadvantages of different approaches and implementations. The study evaluated the implementation of two ASCT systems at selected arterial corridors in eight different locations in Florida: Gainesville, Deland, Panama City Beach, Sarasota, Panama City, Pinellas, Manatee, and Bartow. The eight corridors included in the study varied in length from 1.1 to 9.2 miles and most had a relatively low density of intersections. Annual average daily traffic (AADT) on the corridors ranged from 28,750 to 52,185 vehicles/day.

Methodology

To evaluate the impact of ASCT on traffic operations, two critical intersections and three critical time periods (AM, PM and Off-Peak) were identified in each of the eight corridors. Before and after analysis was conducted using five performance measures:

  • Link/route travel time
  • Intersection delay
  • Queue length
  • Queue to lane storage ratio
  • Passenger Car Equivalent (PCE) flows

Crash data, available for six of the eight corridors, were collected over a period of 59 months (2013 to 2017) for safety analysis. Crash data were examined to assess changes in total crashes, crash severity, crash type, and time of day for crashes. Depending on the date of ASCT implementation, the sites had varying ranges for “before” and “after” crash data, and researchers considered these data as representing a “long term” comparison. In addition, a “short term” comparison used data for seven months before implementation and seven months after deployment. A Benefit-Cost analysis was also conducted by monetizing the estimated safety and mobility benefits. The summary results were also used to build regression models of performance measures as functions of corridor characteristics to help identify corridors that are good candidates for ASCT.

Findings

  • Implementation of ASCT led to an average overall reduction in travel time of 9.36 percent. All corridors showed travel time reductions in at least one direction of travel and four corridors showed a reduction in both directions.
  • The ASCT implementation generally helped increase major street throughput (6.96 percent) and reduce major street queues (15.57 percent). ASCT was able to maintain the same levels of side street flows despite an increase in minor street queues (16.98 percent).
  • Regression analysis showed that higher AADT, higher corridor intersection density, and higher operating speed were associated with less operational traffic improvement. Corridors with minimal detection or construction issues, low-volume side streets, and simpler geometry were associated with consistent improvements in traffic operations. Overall, ASCT performed well for most of the corridors.
  • As the “after” crash data was only collected shortly after implementation, and because volume data did not always align with installation timelines, there was uncertainty in the analysis of factors affecting safety in the studied corridors. The study results suggest that external factors such as increasing tourist traffic and regional trends can also influence patterns for a corridor. The research team expected that future analysis with more post-implementation data would allow for development of region-specific crash modification factors (CMFs) with a more robust quantitative measurement. While the project calculated estimated safety benefits based on available crash severity data, researchers noted that the resulting estimates were highly variable due to the sensitivity to high-severity crash outcomes.
  • The benefit-cost analysis revealed an overall net positive monetized benefit/cost ratio of 12.8 considering safety, and 5.4 without including the safety benefit estimates.

 

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