This report contains the evaluation results for three projects undertaken during the Metropolitan Model Deployment Initiative in Phoenix, Arizona (collectively known as AZTech). Investigators noted that Phoenix does not generally experience the severe levels of congestion common in some other metropolitan areas; this could be a contributing factor to the minimal benefit achieved by some of the implemented systems. The authors particularly noted that the freeway system provides numerous alternate routes for avoiding incidents that might occur on a traveler’s intended route. Evaluation efforts determined customer satisfaction with two Advanced Traveler Information Systems (ATIS) deployed during the project and the impacts of coordinated signal control on delay, safety, and the environment.
The evaluation report contained and assessment of the impact of traffic signal coordination among two jurisdictions along the same arterial corridor. The evaluation team measured the impacts of partial signal coordination along 9.6 km/5.7 mile Scottsdale/Rural road corridor. The corridor contains 21 signals, 16 in Tempe and 5 in Scottsdale. To test the impacts of coordinated signal timing, three signals in Tempe were re-timed to use the same cycle length as the Scottsdale signals, moving the break in signal progression along the corridor south beyond a major freeway access point.
The impacts of this adjustment in signal timing were measured using the floating car technique, with vehicles equipped with GPS receivers for enhanced data collection. This data, combined with a newly developed methodology for estimating emissions impacts and crash risk using speed and acceleration data, allowed assessment of the impacts of the signal coordination on travelers along the mainline of the corridor. Computer simulation allowed assessment of these impacts for the entire corridor, including side streets.
- Mainline analysis using test vehicles indicated a small 6.2 percent increase in vehicle speeds. Simulation models, however, that considered the entire corridor did not show statistically significant impacts.
- Simulation of additional optimized coordinated signal timing plans indicated potential benefits of a 21 percent reduction in AM peak delay through complete coordination along the corridor. Results for independent optimizations without coordination indicated a potential for a 16 percent reduction in AM peak delay.
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