Evaluating Recurring and Non-Recurring Congestion Impacts within the Phoenix Metropolitan Region

摘要

Traffic delay results from recurring congestion and non-recurring congestion (NRC). Recurringcongestion—when demand exceeds the roadway capacity—is regular which makes its delay morepredictable to measure. NRC is generally random making its delay more difficult to identify, measure,and counteract. With NRC estimated to be as much as 70% of total congestion per national studies,there is a need to ascertain and mitigate its effects. This study developed a low-cost methodology toestimate NRC and its causes for a region.The first objective of this study was to identify and quantify NRC on freeway and arterial systems in thePhoenix region relating to causes such as traffic incidents, construction, severe weather, special events,and signal malfunctions. The second was to identify countermeasures to mitigate NRC, although thispaper focuses only on the NRC determination methodology and results.Travel times were obtained from 2009 sensor data along five freeway study sections. Over five monthsof travel time data was obtained using Bluetooth™ matching technology along five arterial studysections. The difference in recurring and non-recurring travel times represented NRC, which was thenclassified by cause.Incidents and construction were the primary NRC causes on the study sections—their combined share ofNRC ranged from 72 to 96%. NRC represented 40 to 60% of the regional congestion based on anextrapolation of the study data. Thus, the mitigation of NRC—focused on incident and constructioncountermeasures—is instrumental for improving traffic operations, reducing emissions, and deferringcostly roadway capacity expansion.