Simulation of requests in demand responsive transport systems
In a demand responsive transport system (DRTS), vehicles follow routes and timetables automatically scheduled by a travel dispatch centre to match the trip requests and to associate as many users as possible to the same vehicle, while guaranteeing the quality standards in terms of pickup/delivery time and travel duration. How efficient the system is in combining user requests on vehicles depends on the dispersion of travel demand, both space-wise and time-wise. This study describes and analyses a trips simulation method that aims at generating users' requests by recreating an actual demand structure of a study area divided into zones. It has been assumed that trip requests are sampled looking at specific features, such as the ability of attracting and generating trips assigned to the zones of the area, the information on minimum distance for trips and the time profile of the requests. Travel requests are then processed by a trip-planning tool, in order to assess the resources needed for the service operations (number of vehicles, travel times). The demand scenarios explored show the influence of the assumed criteria on the random minimum distance for DRTS trips, both on the characteristics of the generated demand and on the consequent trip-plans.
