A computer program for simulating the braking and directional response of heavy vehicles has been developed for the Federal Highway Administration as a tool for investigation of the effects of increased truck size and weight. Designated as the "Truck and Tractor-Trailer Dynamic Response Simulation-T3DRS;V1," the program is capable of simulating trucks, tractor-semitrailers, doubles and triples combinations. Modeling for the vehicle components has been adapted from earlier simulations produced under sponsorship of the Motor Vehicle Manufacturers Association. The T3DRS:V1 version consolidated all vehicle combinations into one program with improved input/output format, a new closed-loop path-following steering option, optional side-to-side differences on all paired components, a simplified tandem axle suspension model, and more versatility in the choice of output information. The program has been validated against analytical models, predecessor simulation programs and vehicle test data acquired separately by the Texas Transportation Institute and the Highway Safety Research Institute. The simulation program has achieved operational status on FHWA computer facilities and a training seminar was held to introduce users to the program.
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