Making polygon roads into line roads is going to be difficult -- particularly if you want to preserve the turn restrictions that you need for routing (e.g. one way streets, no left turns, etc.).  

It would be better to start with a different road base.  I think OpenStreetMap will serve well for this kind of thing, though I haven't done routing with it myself.  I think I am seeing an extract of the DC metro area in shapefile format here:
specifically this:

I am not certain that it will serve, but I suspect it will.



On Jul 11, 2013, at 1:24 PM, David Masad wrote:

Hey guys,

This might end up being more of a GIS question than a MASON question, but I hope someone here has dealt with this before.

I'm working on a model involving agents moving along an urban road system. My test case was DC, and it turns out that the DC road data on the city's website ( has the roads as polygons rather than lines. Is there a good technique or tool for turning polygonal road data into a network of linestrings?