Investigating and Calibrating the Dynamics of Vehicles in Traffic Micro-simulations Models

Abstract The accuracy of the micro-simulation modelʼs generated vehicle activity data used in the emissions modelling depends on how the dynamic behaviours of vehicles are being represented in the model. The dynamic behaviour of every single vehicle is constantly modelled during the simulation phase in accordance with different vehicle internal behaviour models. It is therefore imperative that the model reproduces the same variability of these behaviours in the real-world. This research paper investigated two main approaches in studying how car dynamics are represented in AIMSUN traffic micro-simulation model. The first approach was to use field trajectories data in the calibration of car dynamics parameters of the car-following internal behavioural model in AIMSUN, the second approach was to compare the simulated vehicles activity modelsʼ outputs with field vehicles activity data obtained from an Instrumented Vehicle (IV) driving along the study route. The field-obtained vehicle trajectories contained second-by-second speeds and acceleration data, which have been utilised in the evaluation of the AIMSUN model performance at both macro and micro levels. The findings showed that the calibration of vehicle dynamics in car-following models has reduced the values of accelerations and decelerations in the simulations. However, this did not influence the vehicle trajectories behaviour that continued to show sharp accelerations and decelerations, which are not representative of the real-world behaviours. The research showed that the use of IV real-world data to evaluate the car-following internal behaviour model provided an effective and computationally efficient validation methodology, which offered a further level of accuracy to the available standard validation procedures.