Empirical Freeway Queuing Duration Model

Abstract

An empirical, three-regime, freeway queuing duration model is developed from a database of 161 observations. The explanatory variable is the ratio of the annual average daily traffic volume to hourly capacity (AADT/C). The daily recurring queuing duration, in hours, is estimated to within 0.5 h of the actual at 51% of the 161 observations. The model potentially represents an improvement to the volume-delay function traditionally used in traffic assignment, because the entire peak period, not just the peak hour, is considered. The model may be useful where resources prevent the direct measurement of recurring congestion. The model's form may be considered for application in real-time traffic management. A residuals analysis indicates recommendations for model improvement, including additional explanatory variable, a larger database, careful identification of bottlenecks, circumstantial freeway capacity calculations, consideration for the day-to-day variability of recurring congestion, and nonlinear regression.