Simple Vehicle Routing Problem in Network Analyst

Discussion created by kokengek on May 18, 2010
Latest reply on May 24, 2010 by nan-esristaff
Hello All,

I'm using network analyst for the first time and am trying to solve a simple vehicle routing problem.

My problem is as follows: I have two sawmills and they both require "x" amount of orders (full truck loads of wood) each day. I have 2 trucks that start and end the day at a truck garage. These trucks can travel to 3 different wood storage locations where they can be loaded. The trucks then need to drop off a full load at one of the mills and return to a wood storage location for the next load.

In summary, a truck needs to 1) start at a garage, 2) drive to a wood storage location and load up fully, 3) drop a full load off at the mill, 4) return to a wood storage location and reload, 5) return to the mill and drop off a load....over and over again until the trucks have satisfied all the mill orders or exceeded their Max total time. I want to leave it up to the solver to decide what mills and wood storage locations each truck needs to go to throughout the day to satisfy the mills orders.

I've added the sawmills as orders, the truck garage and wood storage locations as depots, the wood storage locations as route renewal points, and my trucks as the routes.

My burning questions are: How do I tell the trucks that they need to go to a wood storage location to load and then return to a mill to fulfill an order? Does it have something to do with the sequencing? When I run the solver, the output says the trucks go straight to the sawmill and back without ever loading at a wood storage location.

Moreover, how do I specify how many truck loads (orders) the mills need each day? I tried setting the number of deliveries for each mill to 4 and the capacity of each route to 1....my thought process here was that a full truck load would be considered 1 and the mill needs 4 of these. However, I get errors saying that it violates capacity constraints.

I'd greatly appreciate any help or guidance.

Thank you,