A Lagrangian heuristic for the urgency vehicle routing problem

For solving the vehicle routing disruption problem which is caused by vehicles breakdown or traffic accidents in the logistic distribution system, an urgency vehicle scheduling scheme is established based on the theory of disruption management. According to the characteristics of the problem, Lagrangian relaxation approach is applied to simplify and divide the problem into two parts. The column generation and saving approach method are used respectively to obtain the solution, and then the subgradient optimization method is used to iterate to get the Lagrangian multiplier, therefore the initial solution for the original problem is obtained. In Order to solve the infeasibility problem caused by Lagrangian relaxation operation, an insertation algorithm is adopted. In the end of the paper, the feasibility and effectivity of the algorithm giving by the paper are verified by compared with an example.