In the derivation of common travel demand models, it is customarily claimed that the main assumptions are based on micro economic theory. However, the author investigates whether they are made mainly to justify existing models. The economic implications of the assumptions are not fully discussed. In some cases this results in models with characteristics that are questionable in the light of economic theory. In other cases theoretically possible but restrictive characteristics are given in advance rather than determined in the estimation process. The intercity travel demand model proposed in this study starts from the general assumption that travel demand can be derived from the more basic demand for visits to other cities. Then, necessary conditions for various demand elasticities are formulated and the consequences for the mathematical specification of the model discussed. Finally the model is estimated on Swedish data of intercity travel volumes for the period 1990- 1994. (Author/publisher).
Abstract