MEASUREMENT OF RECURRING VERSUS NON-RECURRING CONGESTION

A research effort was initiated to develop and test a methodology to estimate the extent to which urban congestion is produced by the routine presence of large numbers of vehicles on a facility (so-called recurring congestion) versus unexpected disruptions or other events (non-recurring congestion), particularly lane blocking incidents. An analysis was performed using a preliminary methodology to estimate the magnitude, extent, and relative causes of congestion on urban freeways in the central Puget Sound region of Washington State. This information is designed to assist transportation agencies in 1) selecting the most appropriate strategies to improve freeway operations, and 2) allocating available resources to achieve those improvements. This paper documents the preliminary methodology and results from this ongoing research project.