On User Requirements and Operator Purposes in "Dial A Ride" Services

Demand Responsive Transport Systems (DRTS) were introduced for the first time in North America in the 1970’s as Paratransit services for elderly and handicapped passengers. They have recently been reconsidered, thanks to innovative technologies. They are usually adopted for low-demand areas or as night services in large cities or an addition to traditional transit service during peak hours. Unlike traditional transit services, DRTS are characterized by variable paths and timetables and they can operate door-to-door as well as stop-to-stop. Moreover, they can be classified according to how many origin and destination points there are and whether they deal only with advanced requests or also immediate requests. This work refers to a many-to-many service (customers have different points of origin and destination) and to advanced requests (all requests are received before the time of vehicle dispatch).