Modeling park-and-ride services in a multimodal transport network with elastic demand

With the rapid development of metro systems in large Asian cities, such as Hong Kong and Shanghai, China, local authorities are developing park-and-ride (P&R) schemes to encourage commuters to reach the cities' central areas by transferring from private cars to metro at stations with P&R facilities. A network equilibrium formulation can be used to model P&R services in a multimodal transportation network with elastic demand. It is assumed that commuters can complete their journeys by three options: auto mode, walk-metro mode, and P&R mode. The proposed model simultaneously considered 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, were explicitly incorporated. The resultant problem can be formulated as an equivalent variational inequality problem. Numerical results showed that the introduction of P&R schemes could bring a positive, neutral, or even negative social welfare increment, and its efficiency depends greatly on the parking charging level and the number of parking spaces supplied at the P&R site and in the urban central area, as well as the metro dispatching frequency and fare.