Evaluating ASCT operations for Dodge Street Corridor

Background Maintaining arterial corridors that has a high volume of traffic and high density of intersections , is a matter of primary importance to the Traffic Division of any city. Traditionally Traffic Division maintained these traffic signals in three ways - entirely pre-programmed (pre-timed signals), partially based on actuations (partially actuated) , or entirely based upon sensor actuations (fully actuated) (Koonce et al. 2010). However, all these type of signals need some retiming every three to five years which involves a lot of human effort in solving complicated optimization problems (Gordon 2010). In order to circumvent the effort of retiming, Adaptive Control Signal Technology (ASCT) was developed. ASCT tends to maximize the capacity of the existing system which reduces the cost to both the users and the system operating agencies. ASCT has been seen to reduce the number of stops by 28%-41% (Hicks and Carter 1997), reduce crashes by 35% (Anzek, Kavran, and Badanjak 2005),and reduce the travel time on the corridors by 35%-39% (Sims and Dobinson 1980). However, the agencies implementing ASCT ends up spending $6,000 to $65,000 per intersection. Further, one-third of the agencies find ASCT to malfunction in over-saturated conditions (Stevanovic 2010). Also, the initial set-up has also been found to be labor intensive. The City of Omaha has planned to set up the ASCT the Dodge Street corridor. This will involve setting up adaptive signals along 9 intersections of the corridor and 6 along other major roads along the corridor. A detailed evaluation of the performance of the ASCT is to be studied in this project to determine its benefits to the City of Omaha. Objective The objectives of this study is to determine the efficiency of the ASCT on Dodge Street. The following benefits of the Dodge Street are to be studied in details: •Operational Efficiencies during normal conditions - the ASCT is expected to improve the operation of a corridor under normal condition. The before after study will involve dealing in the study of both the peak period and the off-peak period operation of the ASCT. Performance measures like number of stops, avg. approach delay etc. will be used for a before and after comparison. In addition, impacts on the pedestrians will be assessed for pedestrian heavy signals. • Operational Efficiencies during anomalous situations - the ASCT should not only be able to perform better during normal conditions but also it should align itself so as to provide maximum capacity under anomalous conditions. Anomalous conditions for the Dodge Street will be poor weather (snow days), traffic incidents, pre-emptions of traffic, and handling of the Bus Rapid Transit. • Performance during over-saturation - Apart from these the performance of the ASCT during the over-saturation is a major concern. It has been seen occasionally that ASCT fails under over-saturated condition. Hence the performance of the ASCT under over-saturation will also be evaluated. Usually, over saturated conditions occur during morning peak hours when the office going traffic are trying to enter the network. Measures such as number of cycle failures, time to return to normal etc. will be used to evaluate before and after conditions. • Safety concerns - ASCT has seen to reduce the number of crashes in the past. It will be difficult to assess the impact on crashes as it crash history takes time to develop. Instead, camera feeds will be used to evaluate most common types of conflict observed at each of the intersections. This will be done by observing multiple hours of clips for each approach for each intersection. In addition, special observation will be made for the intersections where the flashing yellow arrow is being implemented. The study will detail out the performance gains and any observed shortcomings of the ASCT with respect to the four categories listed above.


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    • Status: Completed
    • Funding: $103,025.00
    • Sponsor Organizations:

      Nebraska Department of Transportation

      1500 Nebraska 2
      Lincoln, NE  United States  68502
    • Project Managers:

      Halsey, Lieska

    • Performing Organizations:

      Iowa State University, Ames

      Center for Transportation Research and Education
      2711 South Loop Drive, Suite 4700
      Ames, IA  United States  50010-8664
    • Principal Investigators:

      Sharma, Anuj

    • Start Date: 20190701
    • Expected Completion Date: 20210531
    • Actual Completion Date: 20210501
    • USDOT Program: Transportation, Planning, Research, and Development

    Subject/Index Terms

    • TRT Terms: Signaling
    • Subject Areas: Operations and Traffic Management;

    Filing Info

    • Accession Number: 01705673
    • Record Type: Research project
    • Source Agency: Nebraska Department of Transportation
    • Files: RIP, STATEDOT
    • Created Date: May 23 2019 3:16PM