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How do you model breaks in a routing problem?

I'm working on a vehicle routing problem where drivers must take breaks. How do I model whether a customer is visited before or after the break?

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By Meera Answered 1 month ago

You need precedence constraints with time variables. Define t_i as arrival time at node i. For a break node b, you want to enforce: if node v is visited before the break, then t_v < t_b. This is done with big-M constraints. Let y be a binary variable: 1 if break is before node v, 0 otherwise. Then:

  • t_v + M*(1-y)

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