Simulation and Evaluation of Freeway Traffic Using Interchangeable Behavioral Models

Abstract

Microscopic simulation of traffic flow has spawned many different behavioral models, some of them commercially distributed, some developed at academic institutions for scientific purposes. These models are either kept secret (for commercial products) or substantially lacking in terms of usability and visualization. In this paper, we introduce the simulation environment BABSIM that allows for different driving behaviors to be integrated into one common simulation package. An overview of microscopic simulation is given, and several existing models and their implementations are being discussed. The fundamental structure of the BABSIM package, its user interface and the calibration of the model parameters are presented. Introduction The number of motorized vehicles on this planet is steadily increasing, and there is no indication that this trend is going to abate in coming years. The German federal highway network alone consists of about 12100 kilometers of road, with a planned growth of 15 % in the next couple of years (BMVBW, 2004), not counting the inevitable maintenance efforts. To cope with these complex planning tasks, t raffic engineers are increasingly using traffic simulation as a means for effectively evaluating the capacity of new road designs. Numerous established microscopic simulation packages exist for emulating the flow of individual vehicles on a more or less complex road network. Some of these programs are being commercially developed and distributed. As the targeted market segment is relatively small, the competition is rather fierce, and the underlying simulation models are often not disclosed. Such a black-box concept discourages the use of traffic simulation for public road planning projects, as no certified model exists and the validity of simulation results cannot be verified. The project BABSIM, carried out in joint research between the ICE and the Institute for Traffic Engineering at the Ruhr-University, addresses this problem by integrating several well-documented and established car-following and lane-change behaviors into one common simulation environment. Furthermore, the user is enabled to introduce new behavioral strategies to address his specific planning requisites. BABSIM specializes in simulating the traffic on multi-lane freeways, including the complex weaving behaviors in proximity of freeway junctions.