Vehicle routing problem

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A figure illustrating the vehicle routing problem

The vehicle routing problem (VRP) is a combinatorial optimization and integer programming problem seeking to service a number of customers with a fleet of vehicles. Proposed by Dantzig and Ramser in 1959,[1] VRP is an important problem in the fields of transportation, distribution and logistics. Often the context is that of delivering goods located at a central depot to customers who have placed orders for such goods. Implicit is the goal of minimizing the cost of distributing the goods. Many methods have been developed for searching for good solutions to the problem, but for all but the smallest problems, finding global minimum for the cost function is computationally complex.

Overview

Several variations and specializations of the vehicle routing problem exist:

  • Vehicle Routing Problem with Pickup and Delivery (VRPPD): A number of goods need to be moved from certain pickup locations to other delivery locations. The goal is to find optimal routes for a fleet of vehicles to visit the pickup and drop-off locations.
  • Vehicle Routing Problem with LIFO: Similar to the VRPPD, except an additional restriction is placed on the loading of the vehicles: at any delivery location, the item being delivered must be the item most recently picked up. This scheme reduces the loading and unloading times at delivery locations because there is no need to temporarily unload items other than the ones that should be dropped off.
  • Vehicle Routing Problem with Time Windows (VRPTW): The delivery locations have time windows within which the deliveries (or visits) must be made. In computational complexity theory, this problem is known to be NP-hard.[2]
  • Capacitated Vehicle Routing Problem (with or without Time Windows): CVRP or CVRPTW. The vehicles have limited carrying capacity of the goods that must be delivered.
  • Vehicle Routing Problem with Multiple Trips (VRPMT): The vehicles can do more than one route.

Several software vendors have built software products to solve the various VRP problems. Numerous articles are available for more detail on their research and results.

Although VRP is related to the Job Shop Scheduling Problem, the two problems are typically solved using different techniques.[3]

Free software for solving VRP

Name
(alphabetically)		 License API language Brief info
jspritopen source Java lightweight, java based, open source toolkit for solving VRPs. link
Open-VRP Lisp Open-VRP for Lisp, hosted on Github. link
OptaPlannerApache LicenseJava Open Source Java constraint solver (optaplanner.org) with VRP examples.
vrphlibraryopen source Home page of open source VRPH software. link
vroomopen source Open source libraries for the VRP and dynamic VRP link

See also

References

  1. ↑ Dantzig, George Bernard; Ramser, John Hubert (October 1959). "The Truck Dispatching Problem". Management Science 6 (1): 80–91. 
  2. ↑ Beck, Prosser, Selensky, 2003; p.2 left
  3. ↑ Beck, J.C.; Prosser, P.; Selensky, E. (2003). "Vehicle routing and job shop scheduling: What’s the difference". Proceedings of the 13th International Conference on Artificial Intelligence Planning and Scheduling. 

Further reading

External links

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