A Statistical Approach for Calibrating a Microsimulation Model for Freeways

In this paper the calibration of a traffic microsimulation model based on speed-density relationships is presented. Hypothesis test was applied in the calibration process to measure the closeness between empirical data and simulation outputs and determine whether the difference between (observed and simulated) speeddensity relationships was statistically significant. Statistical regressions between the variables of traffic flow were developed by using traffic data observed at the A22 Brenner Freeway, Italy. Similar relationships were obtained for a test freeway segment in uncongested conditions of traffic flow by using the Aimsun microscopic simulator; thus on field conditions were reproduced varying some selected parameters until a good match between measurement and simulation was achieved. Key-Words: freeway, traffic, microsimulation, speed-density relationship, calibration, Aimsun