Not sure but since this thread has come up again, yesterday on the boing someone posted some pics of cracked glass panels that looked (to me) exactly like road systems in a dense city and as I looked at them I thought of this thread. So... if you can replicate this effect then you can get a road map network.

http://www.boingboing.net/2010/08/26...zing.html#more

Also, there was some thread about a free vector map of the world which would have lots of real roads in a network to use unless your specifically looking to generate them.

Oh... and welcome btw !