A PC microsimulation of a gap acceptance model for turning left at a T-junction

Vehicles are controlled by sub-behavioral models in a microsimulation model, this includes the gap acceptance model where the decision about how to cross a junction is made. The critical gap in these models must serve as a threshold value to accept or reject the space between two successive vehicles in traffic. The aim of this study is to improve an existing gap acceptance model for turning left at a T junction so that the traffic safety can be more accurately estimated. This is achieved by modeling more factors that affect a driver’s decision. The gap acceptance model is elaborated for a driver turning left on to a main road. The original gap acceptance model only incorporates the first gap in the decision. In the new gap acceptance model several gaps in the traffic are evaluated in the decision of the driver. Simulations using the original and new model reveal a decrease in the number of conflicts the more gaps that are incorporated in the decision. The average waiting time hardly differs. In the new model some gaps are rejected when a more appealing gap follows. One unexpected effect is the acceptance of a number of gaps rejected in the original model. The new gap acceptance model is more realistic since the traffic flow is incorporated in the decision of the driver. Validation of the model and extension of the other driver behavior models with real world data is a next step to more realistic driver behavior in microsimulation models