The Study On Vehicle Routing Problem With Simultaneous Pickup And Delivery In City Road Network

With the development of logistics industry, it becomes a crucial issue how to reducethe cost of logistics distribution. So the study of logistics distribution route which iscalled VRP has attracted great attention, while the traditional distribution care more onthe simply pickup or delivery, this kind of distribution doesn’t use the vehicle loadingspace sufficiently. The vehicle routing problem with simultaneous pickup and delivery(VRPSPD) allow the service of pickup and delivery happen at the same time, so we canreduce the cost of distribution by serve one customer only once. And the distributionactivities often accomplished in the city road network, and the traffic conditioninfluence the distribution routes’ choice, with these consideration, this paper selects theVRPSPD in the city road network as the research subject.This paper introduces the problem’s research background and the significance atfirst, then analyses and review the research status at home and abroad. Also wedetailedly introduced the thought of simultaneous pickup and delivery, the inscapes andforms of the VRP, furthermore, we conclude and sketch up the solving method for VRP,such as accurate algorithm, traditional heuristic algorithm and modern heuristicalgorithm.In the city road network, the traffic speed of road segments is different with thetime changing, that is the road network has the time varying character, affected by this,the shortest distance route in road network is not the shortest route in transit time, so weput forward the calculation method for the time varying shortest path problem at thebasis of shortest path problem. Then, set a mathematical model for the traditionalVRPSPD with the shortest distance and minimum vehicle number as the optimizationgoal in the road network without consider the traffic speed influence, and another modelfor the time varying VRPSPD aim at find the route with shortest transit time andminimum vehicle number.This paper select and use a effective coding scheme which can reflect the numberof distribution vehicle in the coding, and then by combine the character of thesimultaneous pickup and delivery structure the fitness function, and programming inmatlab to solve the problems. At last,by designing a example and solving it withgenetic algorithm proves the model and algorithm is feasible, the result shows that theroute find by time varying VRPSPD model has more short transit time, and it suit the reality more well.