In the United States, signal timing is fixed (unlike the Sydney Coordinated Adaptive Traffic System SCATS). This means for traffic signal timing to be measured and evaluated, transport agencies traditionally conduct floating car surveys (FCS).
FCS are when a vehicle drives through a route multiple times during different peak periods to measure travel times and signal performance.
Dr Zong Tian, a signal timing researcher from the University of Nevada, wanted raw trajectory data to measure, assess, and fix signal timing on major corridors across several states. Specifically, he wanted to see if connected vehicle data could provide a more accurate ground truth without needing to do a FCS and deploy test vehicles.
Using Compass’ self-service API, Dr Tian extracted raw trajectories including travel times, speeds, time of day and day of week information. This raw data was then imported to Waysync, a modelling software which US agencies routinely use to evaluate their signal performance.
Assessing signals across Houston, Orange County and Boca Raton, Dr Tian made changes which resulted in large financial benefits to the local economy by decreasing travel times. Along one corridor, the financial savings were estimated to be roughly USD$1.7 million.
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Traffic signal timing adjustments require unbiased, independent data to evaluate their effectiveness. Agencies conducting their own FCS risk skewing data to favor existing approaches. Connected vehicle data offers an objective measure, providing insight into how signal timing impacts traffic flow, congestion, and network performance. This can be used to improve urban mobility and reduce environmental impact.