Extension and Application of Prosser-Dunne Model to Traffic Operation Analysis of Oversaturated, Closely Spaced Signalized Intersections

Abstract

Traffic congestion continues to have a serious impact on the productivity of the nation’s transportation system. Signalized arterials and service interchanges in urban areas serve as critical surface street facilities. These facilities often experience serious congestion problems because of high traffic demands that exceed capacity and also because of their common, closely spaced intersections and ramp terminals. Moreover, service interchanges are usually part of a signalized cross arterial and also may have short spacings to adjacent signalized intersections. Major deficiencies exist in the analysis technology and software tools available for analyzing potential traffic congestion problems at signalized arterials and service interchanges having closely spaced ramp terminals. This paper presents extensions of work originally published by Prosser and Dunne in Australia for analyzing the operational impacts of queue spillback on the capacity and delay of closely spaced signalized intersections. Coding of the described algorithm into FORTRAN was conducted, followed by experimental testing of the model using a calibrated version of the microscopic computer simulation program TRAF-NETSIM. Satisfactory comparisons were obtained between the initial version of the newly developed Prosser-Dunne Extended (PDX) model and NETSIM, but more testing and enhancement of the PDX model are recommended before implementation in existing operational software packages is considered.