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Research Projects (2006-07)

Identifying Number


Project Title

Adaptive Signal Control V


University of Utah

Project Investigator:

Peter T. Martin, Associate Professor
Dept. Of Civil and Environmental Engineering
University of Utah

External Project Contact

Rukhsana (Shana) Lindsey, P.E.
Director of Research & Bridge Operations
4501 S. 2700 W. - Box 148410
Salt Lake City, UT 84114-8410
Office: (801) 965-4196
Fax: (801) 965- 4564
E-mail: rlindsey@utah.gov

Project Objective

The goal of the project is to provide system software with algorithmic intelligence, high reliability real-time detection, reliable communications between the system's components and the database for traffic data, timings, and system effectiveness. Another, equally important, goal of the project is to deploy a system that meets or exceeds expectations to serve as a "showcase" for future installations.

The UTL has developed a scope for a comprehensive evaluation of the ATCS. The UTL proposed performing a before and after study to evaluate the effectiveness and benefits of the SCAT installation. A "with and without" approach was also discussed with the UDOT Technical Advisory Committee (TAC) members. This approach assumed waiting for SCATS to be installed and then collecting data with SCATS running (with) and to also collect data with SCATS turned off (without) and fixed-time plans running instead. This approach was abandoned by the UDOT TAC members due to political issues of turning SCATS off only a few months after it was installed. Therefore, the UTL went on and performed a before data collection in August 2005. The scope of the initial study, objectives and tasks, and comprehensive report of collected data were reported to UDOT in the UTL report UTL-0505-83 "Adaptive Signal Control IV - Evaluation of the Adaptive Traffic Control System in Park City, UT".

However, only a few months after the before data collection was finished, UDOT installed a new intersection on the SR-224 corridor. The UTL has also received information that local municipalities are planning to install a new intersection and realign one of the existing intersections on the same corridor. All three intersection projects going to happen before or slightly after the SCATS is installed. Therefore, the new installations ruin the chance for a fair comparison of the traffic performance before and after the system is installed. The data collection becomes almost useless. All system-wide Measures of Effectiveness (MOEs) that the UTL team collects before the SCATS is installed are going to be invalid if they are compared with the after data on the different configuration of the intersections in Park City.

This is a major reason for the need to restart this project with a new approach. The UTL has to meet with UDOT TAC members and discuss a new scope for the new evaluation of the SCATS control. The scope is going to be very similar to the one that the UTL developed for the last project on the same topic. However, this time an approach of doing studies with "SCATS on" and "SCATS off" (rather than before and after) has to be considered with more attention. This shift in the approach is likely to create other issues regarding fixed-time plans that will be used when the SCATS is switched off. The data collection methods will also slightly differ. The new SCATS system will have an automatic tool for reporting some of the traffic metrics that the UTL had to collect. Therefore, the UTL has to discuss a plan for data collection with the UDOT TAC members.

Project Abstract

The Utah Department of Transportation (UDOT) has been planning its first implementation of an ATCS in the state for the last five years. The Utah Traffic Lab (UTL) has been involved in this process since the very beginning. The UTL has proven, in a few empirical studies on the arterials in Salt Lake County, that ATCS works better than fixed-time control. Furthermore, the UTL helped UDOT develop a Request For Proposal for the first ATCS installation in Park City, UT. Based on the RFP, UDOT has procured SCATS as the ATCS to be installed in Park City. After the procurement, the UTL obtained a contract with UDOT to evaluate the installation of SCATS in Park City.

Research Objectives

ATCSs are designed to overcome the limitations of pre-timed control and respond to changes in traffic flow by adjusting signal timings in accordance with fluctuations in traffic demand. The purpose of this project is to deploy and evaluate the effectiveness of the future UDOT ATCS on an arterial street network that experiences both everyday and unpredictable changes in traffic flow.

The project has two principal components: traffic measurements and institutional aspects. The objective of the first component is to assess the effectiveness of the future UDOT ATCS relative to the existing traffic control system. The objective of the second component is to assess the transfer of ATCS expertise fro ma vendor to UDOT personnel. The assessments should be conducted in a way that will respond to all the requirements that the future ATCS should meet which were stated in the UDOT's request for proposal. The research objectives are:

  1. Define traffic efficiency and safety criteria that Utah's first ATCS should meet.
  2. Define MOEs to assess these criteria.
  3. Conduct "with" and "without" evaluations to assess the effect of the ATCS on the efficiency and safety of traffic flow.
  4. Assess operators' acceptance of ATCS technology.

Task Descriptions

  1. Draft, submit and acquire approval of a detailed scope.
  2. Establish a working relationship with the traffic management technical subcommittee.
  3. Design an ATIS evaluation. Specify:
    • What type of traffic data to collect
    • Data collection procedures and technologies (manual, video, GPS, etc.)
    • Data collection time periods (AM & PM peaks, off peak, weekends, special events)
    • Data collection sample sizes
    • Data reduction and analysis (formulas, statistical tests, etc.)
    • Questionnaires for interviews with drivers
  4. Draft, submit, and acquire approval of a detailed evaluation design
  5. Analyze data and produce results
  6. Meet with UDOT's TAC and present findings
  7. Deliver report

Milestones, Dates

ItemTo Be Completed ByPayment (%Effort)
Formation of Technical Advisory CommitteeJuly 1, 20060%
Agreement on Work Task/Project ScopesJuly 30, 200610%
Submit Draft Technical ReportDecember 30, 200660%
Submit Final Technical reportJune 30, 200730%

Yearly and Total Budget


Student Involvement

Six graduate research assistants will be employed on the project.

Relationship to other Research Projects

This project is the fifth in a series of research projects that have taken Adaptive Signal Control from feasibility, to modeling, to field trials, to procurement, to evaluation. All four prior projects have been supported by the MPC and matched by the Utah DOT.

Technology Transfer Activities

Data sharing, database development

Potential Benefits of the Project

Traffic signal systems that respond in real-time to changes in traffic patterns are known as "adaptive." Adaptive Traffic Control Systems (ATCSs) belong to the latest generation of signalized intersection control. ATCSs continuously detect vehicular traffic volume, comput "optimal" signal timings based on this detected volume, and simultaneously implement them. Reacting to these volume variations generally results in reduced delays, shorter queues and decreated travel times.

TRB Keywords

Traffic operations; traffic control; driver behavior

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