Jointly Optimizing Cost, Service, and Environmental Performance in Demand-Responsive Transit Scheduling

ii ABSTRACT In certain types of fleet systems, the environmental impacts of fleet operation are, to some extent, a controllable function of vehicle routing and scheduling decisions. However, there has been little prior work that has considered environmental impacts in fleet vehicle routing and scheduling optimization, in particular, where the impacts were assessed systematically utilizing life-cycle impact assessment methodologies such as those described by the Society of Environmental Chemistry and Toxicology. In this paper, we present a methodology for the joint optimization of cost, service, and life-cycle environmental consequences in vehicle routing and scheduling, which we develop for a demand-responsive (paratransit or " Dial-a-Ride ") transit system. We demonstrate through simulation that, as a result of our methodology, it is possible to reduce environmental impacts substantially, while increasing operating costs and service delays only slightly.