With the gift-giving season almost upon us and increasing concerns about the environmental effects of all those deliveries and pickups, it is timely that researchers should turn their attention to the so-called Traveling Salesman Problem. Writing in a forthcoming issue of the Inderscience publication the International Journal of Logistics Systems and Management, researchers suggest a new approach to cutting journey times of courier services everywhere.
According to Chandra Sunil Kumar and T.T. Narendran of the Department of Management Studies, at IIT-Madras, in Chennai, India, the Traveling Salesman Problem, or to give it its modern name the Vehicle Routing Problem (VRP), is one of the biggest headaches for companies running delivery and pickup services - how to ensure the route taken by the couriers is not only as short as possible and so uses the least fuel but also ensures that all drop-offs and pick-ups are made in a timely manner. The efficiency of services involving express couriers, dial-a-ride systems, and partial-truck-load carriers might all be improved.
Narendran and colleagues have devised a computer model to investigate how companies might map out the optimum routes for their couriers.
In their model the researchers consider a single vehicle operating within a region. Each day, there are calls from customers, packages to deliver, and others to collect and deliver elsewhere. Static customer requests are those that are known in advance, while dynamic requests arise as the day progresses. The vehicle starts from the depot, moves to serve static customers according to a schedule of advance requests. As the day progresses, new requests come in and the dispatcher has to re-route to fulfill these new requests while minimizing the total distance traveled in accommodating advance bookings.
The vehicle then follows the latest determined route until a new dynamic request arrives. At that time, the vehicle is between the sta
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