Vehicle Routing Problem Help

534
5
08-12-2010 12:00 PM
Highlighted
New Contributor
Hello,

I'm currently attempting to solve a Vehicle Routing Problem and I have a reoccurring issue.  Here are the basics:

I have 100 orders that need to be serviced by 5 vehicles.  There is one depot that they originate from and end at.  The addresses for the orders and the depot have been geocoded and entered into the ArcGIS accordingly.

I have gone through the tutorials step by step and gone through each setting to make sure it is set to what I'm looking for.

Now for the problem ... when I click "Solve" I get a network of routes that is nowhere near optimized.  The routes themselves scatter areas that don't even have Order locations near them.

Is there something I am blatantly missing?  As I'm typing this, I notice that the Orders themselves do not have lat/long coordinates attached after I load them into orders.  Is there a step I am missing?

I appreciate any help that you may be able to give me!
Tags (2)
Reply
0 Kudos
5 Replies
Highlighted
Esri Regular Contributor
From your description it sounds like the orders are not located where they should be. This can happen if you had previously located them on another network and saved them and re-loaded to a new network. That is, network location fields get populated and used next time when you use Load Locations (you can choose use geometry option to avoid this problem).

The way to fix this is to right-click the orders in the NA Window and choose "Recalculate Location Fields" All option. You can do the same with the Depot and then re-solve.

Regards,
Jay Sandhu
Reply
0 Kudos
Highlighted
New Contributor
Hi Jay,

Thanks for the response.

I initially used the Geometry Option when loading my orders.  I believe that they are linked correctly, as when I run the "New Route" option, it gives me an optimized version to get from A-Z.

When I attempt to use the VRP, however, even using 1 "Van", it appears to randomly go all over the map.

I'm curious if my settings in regard to the Impedance and Capacities is throwing it off.  It appears to start at the main depot and end there (as I thought maybe it was only going to one order at a time and returning to the depot).

In order to use the VRP, do I need to have a "Minutes" Impedance established in the Attributes Section of the network dataset?  If so, how do I go about establishing that?  Currently I have a Length Attribute Established by Meters with the evaluators for From->To and To->From as Field and Shape.  Do I need to do something similar for Minutes and if so, how do I configure it correctly?

If I'm not being completely clear, I apologize.  I'm a student learning this software and probably know just enough to be dangerous.  I'm happy to provide any additional information if you need it.

Thanks again for your help.
Reply
0 Kudos
Highlighted
New Contributor
For those who may be running into a similar situation ...

I believe the problem occurred because the Tiger Line files I have been using do not specifically have a section for Time Impedance.  In order to establish the Time Impedance to properly calculate a VPR, I had to do the following:

In the Attributed Section of the Network Dataset, I created a new Attribute called "DriveTime".  For the From-To and To-From Edges, I set the Type to Field and created a custom value by pushing F12.  In there, I created the following formula:


((Shape)/25)*60

Shape=Miles
25 = Average MPH
60 = Convert to minutes

This calculated the appropriate minutes between each stop.

From there, I was able to use the VRP.

I can't say for certain that the results I am getting are 100% optimized, but it is a very good start.

Hope this helps anyone who may be running into a similar situation.
Reply
0 Kudos
Highlighted
Esri Regular Contributor
You do need a time attribute for using VRP. The formual you used is fine but you need to qualify it for the various types of road times (not just use 25 MPH for all roads). But let me ask you a question: any reason why you are using Tiger data? Why not use the streetmap data that comes with ArcGIS on the data and maps dvd. It will be better than Tiger and has a time attribute built in.
Regards,
Jay Sandhu
Reply
0 Kudos
Highlighted
New Contributor
Hi Jay,

I was using Tiger Lines as I thought that was the most complete road network data I could find.  Now that you have made me aware of Streetmap Data, I will most definitely start working with that to see if it can meet the needs of what I'm trying to accomplish.

Thank you for the suggestion and your help thus far!
Reply
0 Kudos