Urban interchanges are a means of facilitating traffic movements between arterial streets and freeway ramps. The single point diamond interchange (SPDI) and the conventional diamond interchange are two specific interchange designs. Essentially, both designs can be treated as signalised intersections. Deviation from the standard signalised intersection operation can be attributed to factors such as longer clearance interval, larger turning radii, different phasing schemes, and different signal offsets between adjacent intersections. Available computer software was reviewed to determine its ability to simulate the operation of the urban diamond interchanges. Data collected at two sites in the Phoenix metropolitan area were used. Five programs were chosen: PASSER II-87, PASSER III-88, TRANSYT-7F, TRAF-NETSIM, and TEXAS. An assessment of each program was conducted to determine its ability to simulate both the SPDI and the conventional diamond interchange. It was concluded that the PASSER III-88 and the TEXAS models simulated the SPDI fairly well. All models except the TEXAS model were able to simulate the conventional diamond design.
Abstract