Modeling travel choice problems in a multimodal elastic demand transportation network with park-and-ride trips

This paper presents a model formulation for modeling travel choices of commuters in a multimodal elastic demand transportation network with park-and-ride (P&R) trips. We assume that commuters can complete their journeys by three options: auto mode, walk-metro mode or auto-metro mode (i.e. the P&R mode). The proposed model simultaneously considers commuters' travel choices on travel mode, route/path and transfer point, as well as their parking choice behavior. The effects of elastic travel demand, together with passengers' discomfort in metro vehicles, are explicitly incorporated. The resultant problem can be formulated as an equivalent variational inequality problem, and is solved by a heuristic solution algorithm. Numerical results show that the introduction of P&R schemes could bring a positive, neutral or even negative social welfare increment, and its efficiency depends very much on the parking charging level and the number of parking spaces that are supplied at the P&R site and in the urban central area, as well as the metro dispatching frequency and fare.