Freeway Micro-simulation Calibration: Case Study Using Aimsun and VISSIM with Detailed Field Data

Abstract

A microscopic simulation model is needed to support the development of Variable Speed Limit/Advisory (VSL/VSA) and Speed Harmonization algorithms. The prospective algorithms will be field implemented and tested so the model needs to match the real traffic conditions well before the algorithm can be developed. Detailed field data were collected at key locations along the freeway mainline and onramps and off-ramps for over a week, including flow, speed and occupancy. The compatibility of the data at all locations has been cross-checked by flow conservation, which is accurate enough for system modeling. Simulation models have been built in both Aimsun and VISSIM and quantitatively calibrated. Both flow and speed should be matched at critical locations. The calibration criteria for flow include GEH Flow calibration criteria, Relative Root Mean Square Error (RRMSE), and accumulated flow; and for speed the Fundamental diagram is used. Simulation results are presented, showing that the two models match the field data at critical locations reasonably well.