Assessing Longitudinal Arterial Performance and Traffic Signal Retiming Outcomes

Agencies often find it difficult to justify investments in active traffic management. Historically, it has been a challenge to obtain data that would help make the case for those investments. Although new data sources have emerged recently, there remains very little documentation of the potential long-term benefits from signal retiming using associated performance measures. This paper presents a use case for an active traffic management strategy on a signalized corridor over a 5-year period, during which traffic volumes increased by approximately 36% and offset optimization was performed every 2 to 3 years. Despite the considerable volume growth, the number of vehicles arriving on green increased by more than 41%, and the percentage of vehicles arriving on green increased by 10%, a gain of 6 percentage points. Furthermore, drivers experienced an average of 5% reduction in travel time and travel time reliability costs after each optimization. The retiming resulted in a 5-year net present value of approximately $3.7 million and a benefit–cost ratio of 52. Agencies can use these strategies to quantitatively assess how traffic performance and signal timing degrade over time, in a manner similar to physical infrastructure assets. The results highlight the benefits and associated business case of adopting a long-term active traffic management strategy that is based on data-driven performance monitoring and decision making.