Anaheim Advanced Traffic Control System Field Operation Test Task A: Evaluation of SCOOT Performance

Problem

The city of Anaheim, California, implemented SCOOT (Split, Cycle, and Offset Optimizer Technique) as part of a larger Field Operational Test which included several other related technologies. This part of the FOT was meant to evaluate SCOOT, which controls systems of signals rather than just isolated intersections, in terms of the following issues: its limited implementation as an option for Anaheim traffic controllers, the development of operational policies, and the evaluation of its operational effectiveness.

Evaluation Task A1 assessed the value of existing loop detectors for SCOOT (the detectors were already in place, but closer to intersections than SCOOT is designed to use them), and assess the quality of SCOOT's internal representation of traffic flow. We did this by comparing SCOOT's performance to videotapes of actual conditions at intersections.

Evaluation Task A2 assessed the performance of traffic under SCOOT in terms of delay. We posted observation teams at intersections to measure delay and used floating cars to measure running, stopped, and total travel time, both before and after the implementation of SCOOT, during PM peak and evening off-peak hours, and for special event and nonevent traffic.

Findings

SCOOT successfully models traffic conditions, but there is room for improvement. In general, SCOOT performed better off peak, for special events at smaller-volume intersections, and very well at specific intersections with heavy traffic during special events.

When SCOOT performed worse than the baseline system, it did so rarely more than ten percent, and when it performed better, the difference was normally less than five percent. (It must be kept in mind that the existing traffic control system in Anaheim is considered state-of-the-art, and that SCOOT was using information from loop detectors in nonstandard locations.)

Delays between the two systems were generally comparable, and SCOOT caused no unacceptable delays or catastrophic problems.