Travelling salesman problem with time windows

Pesant, G. Savelsbergh, M. Discrete Optim. Wang, X. Personalised recommendations. Cite paper How to cite? ENW EndNote. Buy options.

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Question feed. Stack Overflow works best with JavaScript enabled. Accept all cookies Customize settings. We present the same instance proposed by Dumas et al. Here is the content of the file n20w The first line contains the number of nodes, including the depot. The n20w The following 21 lines represent the distance matrix. This distance typically represents the travel time between nodes and , plus the service time at node.

The distance matrix is not necessarily symmetrical. The last 21 lines represent the time windows earliest, latest for each node, one per line. The first node is the depot. We present exactly the same instance as above. Here is the file n20w As you can see, the authors are not really optimistic about solving instances with more than nodes!

You might think that the translation from this second format to the first one is obvious. It is not! The objective value is the sum of the costs of the arcs and not the time spent to travel which is in this case. IsFeasibleSolution returns true if the submitted solution is feasible and false otherwise. To test this solution, we construct the tour node by node. First, if we have to wait. If not, the method returns false. If all the due times are respected, the method returns true.

As you can see, the recorded objective value in the solution file is while the value of the computed objective value is This is because the distance matrix computed is different from the actual one really used to compute the objective value of the solution. We refer again the reader to the remark on Travel-time Computation from Jeffrey Ohlmann and Barrett Thomas cited above.

Now both the given objective value and the computed one are equal. Note that the total travel time is a bit longer: for a total distance of The ServiceTime method only makes sense when an instance is given in the da Silva-Urrutia format. To model the time windows in the RT, we use Dimension s, i.

At a given node to , the accumulated time is the travel cost of the arc from, to plus the time to service the node to. This way, you can load solution files and test them with the bool IsFeasibleSolution method briefly seen above.