Suburban Demand Responsive Transit Service With Rental Vehicles

Demand responsive transit (DRT) services in suburban regions serve residents as the complements of the public transportation. Since suburban DRT service usually faces demand fluctuation in some special situations, such as terrible weather, DRT operators have recourse to temporal rental vehicles to satisfy all requests. There are two types of rental contracts. In the first case, the costs of rental vehicles are similar to the costs of owned vehicles, and the multi-trip vehicle routing problem is studied. In the second case, the costs of outbound trips are not covered by DRT companies, and the open vehicle routes are introduced. In this paper, a mixed integer linear programming formulation is proposed to model the route optimization problem of the suburban DRT service, in which the number of rental vehicles and two classes of routes should be decided simultaneously. To solve the proposed model, a branch-and-price algorithm is designed, which has two pricing subproblems to generate two classes of routes, respectively. From the results of experiments, it can be found that the service sequence is introduced, when open routes are involved. Renting vehicles can help DRT companies save operational costs even in daily operations.