SPONSOR: Oregon Department of Transportation

BUDGET: $2,000

ABSTRACT: This report has documented experience with the use of a computerized microscopic stochastic traffic simulation tool (Quadstone PARAMICS) as means of evaluating a small urban traffic network including a diamond interchange on an interstate highway. From the analysis of results, the following conclusions were drawn. Simulated interchange delay results from the PARAMICS model appear to be consistent with delays predicted by HCM 2000 methodologies. Model to model comparisons in themselves are not entirely meaningful. However, it appears that the microscopic simulation and the animation that is inherent in the simulation provide a good tool for evaluating the movement of traffic at diamond interchanges. The importance of modeling nearby intersections that influence the diamond interchange intersections was clearly observed. The PARAMICS model generates traffic according to a random distribution, therefore it is vital that the metering effects of nearby intersections be included in the analysis of an interchange. The ramp terminals studied had non-random arrival patterns and only by modeling adjacent intersections were these non-random arrivals properly simulated. The stochastic nature of the PARAMICS simulation models will result in unique results each time the model is executed with new random seed numbers. It is vital, therefore, that a statistically sound method be followed in determining the required number of model runs. Due to the stochastic nature of actual traffic, all studies of real traffic for validation and calibration must also include a large number of observations.

PRODUCTS:

report Bertini, R., Lindgren, R. and Tantiyanugulchai,, "Application of Paramics Simulation to a Diamond Interchange." Portland State University, Transportation Research Group, Research Report, April 2002.