A three-stage procedure for validating microscopic simulation models

This paper introduces a novel approach to the validation of microscopic simulation models. Most of the validation efforts of microscopic simulation models were to achieve agreements between "aggregate" observed values and model outputs on variables such as volume served, average travel time, average speed, density, and average and maximum vehicle queue length. The validation based on averages of traffic variables however has several shortcomings. Hawas (2007) presented a microscopic simulation model for incident management in urban networks, i-SIM-S. This paper describes the methodology adopted to validate the model. The methodology combines field data-simulation spatial-temporal analysis, simulation-simulation spatial-temporal analysis, and simulation-simulation aggregate measures validation. A three-stage procedure is devised for model validation. The purpose of the first stage is to validate a benchmark simulator (NETSIM) using field data. The purpose of the second stage is to validate the microscopic traffic patterns extracted from the -SIM-S vis-à-vis those extracted by the benchmark simulator NETSIM. This is particularly done by comparing the spatial-temporal disthbution of the vehicles along links and accounting for various factors such as traffic volume, link speeds, signal timing, etc. The purpose of the third stage is to validate the aggregate measures of traffic patterns (e.g. travel time, and delay) extracted from the -SIM-S vis-à-vis those extracted by the benchmark simulator NETSIM. This is to ensure the adequacy of the procedures and formulae used to estimate such measures.