Diversion Issues in Real-Time Vehicle Dispatching

Abstract

Recent technological advances in communication systems now allow the exploitation of realtime information for dynamic vehicle routing and scheduling. It is possible, in particular, to consider diverting a vehicle away from its current destination in response toIn the past few years, there has been a rapid growth in communication and information technologies (e.g., global positioning satellites, cellular phones, geographic information systems, geosynchronous satellite-based systems, etc.). These recent advances afford opportunities for using real-time information to enhance the performance of decision systems in the area of vehicle routing. According to the fraction of requests that are known in advance, vehicle routing problems may be classified as static or dynamic. In the static case, all data are known before the routes are constructed and do not change afterward (e.g., location of transportation requests, demand, etc.). However, in the dynamic case, all or a fraction of all requests are revealed as the routes are executed. Hence, dispatchers are forced to react to events that occur in real time, such as new service requests, unexpected delays, accidents, etc. Numerous examples of dynamic vehicle routing and dispatching problems may be found in practice, like ambulance or police services, courier services, diala-ride problems (e.g., transportation-on-demand for the handicapped) and many others.Due to the new information technologies mentioned above, real-time information is now available at lower costs. This explains the new interest that dynamic vehicle routing problems have gained recently. However, there is still a lack of methodologies that can efficiently solve dynamic vehicle routing problems through a judicious integration of realtime information.In dynamic vehicle routing problems, one potential use of real-time information is to divert a vehicle away from its current destination to serve a request that just occurred in the vicinity of its current position. In this work, we propose an approach for the dynamic assignment of new requests, which includes diversion, and we examine different ways of implementing it. An empirical evaluation is performed within the tabu search heuristic reported in GENDREAU et al. (1996b).The problem considered is motivated from a courier service application found in the local operations of long-distance shipping services, where the mail is collected at different customers' locations and brought back to a central office for further processing and shipping. This problem belongs to the class of pick up (or delivery) only problems where a set of requests must be transported to (or from) a central depot. The goal is to design a set of minimum cost routes, originating and ending at the central depot, to satisfy the transportation requests. In a dynamic context, each new request is inserted in real time in the current set of planned routes, where a planned route is the sequence of requests that have been assigned to a vehicle but have not been serviced yet.The paper is organized a...

Waiting Strategies for Dynamic Vehicle Routing

“…Once a customer of a vehicle has been served, the best solution found up to now is used to determine the next stop for the particular vehicle and all other current solutions are updated correspondingly. Based on the same tabu search heuristic, in a subsequent paper, Ichoua, Gendreau, and Potvin (2000) examine the benefit of allowing a vehicle to change its destination while under way from one scheduled customer to the next in order to service a newly arrived customer. Empirical tests show a reduction in the number of unserved customers and in the combined objective function addressing the distance traveled and the total lateness, if diversion is allowed.…”

The vehicle rescheduling problem: Model and algorithms

“…Recent surveys on dynamic VRP can be found in [19,20,28]. Tabu search [23], genetic algorithm [21], assignment, and insertion-based heuristics [17], approximate dynamic programming [31], and nearest-vehicle based heuristic [16] have been proposed to consider online requests and uncertain travel time in the dynamic VRP problem. Yang et al [34] have developed a general framework for the dynamic vehicle routing problem in which new requests can arrive during operations.…”

“…Since vehicle breakdowns have not been explicitly considered in train rescheduling [11,26], dynamic VSP [22], or dynamic VRP [16,17,21,23,31,34], most of results available are not directly applicable to our problem. Although aircraft breakdown is considered in some studies of airline operations recovery, most of the available algorithms [8,25,29,32] involve a small number of trips and aircrafts.…”

An Auction-Based Dispatching Method for an Electronic Brokerage of Truckload Vehicles

“…Madsen et al (1995) suggested a heuristic algorithm for a dial-a-ride problem, which is one example of a dynamic vehicle-routing problem. Ichoua et al (2000) addressed a real-time vehicle-dispatching problem with a diversion possibility in which diverting a vehicle away from its current destination in response to a new customer request is allowed. Fischer et al (1996) suggested a multi-agent approach for solving transportation problems.…”