Abstract
For many years a great amount of knowledge has been built up with regard to car traffic in a unimodal traffic model in the region of Noord-Brabant. To use this information in a simultaneous traffic model in the best way, a special method has been applied to estimate a bimodal gravity model. The method makes use of a car and a transit O/D-matrix. This paper contains the theoretical as well as the practical derivation for a regional model.