Modeling Impact of Transit Operator Fleet Size under various Market Regimes with Uncertainty in Network

A network-based model is proposed for investigating the impact of transit operator fleet size on a network with uncertainty under various market regimes. The market regimes concerned include monopoly, free competition, and oligopoly. In the proposed model, the transit operator aims to determine fleet size to optimize its objective function while accounting for transit passengers’ travel choice decisions that minimize their own perceived disutility of travel. To consider the uncertainty effects on transit networks, the proposed model incorporates the unreliability component of transit services into the passenger disutility function, which is mainly due to variations in in-vehicle travel time and the dwell time of transit vehicles at stops. A numerical example is used to illustrate the application of the proposed model. Numerical results show that transit service unreliability could significantly influence transit system performance and the travel choice behavior of transit passengers.