City Street Playmat ?

[Trooper]

Yeah great if you want to be covered in tar and bitumen, roofing felt is a no no.

The stuff I use has no tar on it and is easy to use. Some of the grain stuff comes off but its not messy I assure you.

[jeffteaches]

I bought a black sheet and bleached it down to a dirty gray.

I'm printing world works roads on regular paper and gluing it to craft felt with rubber cement. Except for the amount of ink it uses from my printer, I am well pleased...

Someday, when I'm not commuting every weekend to see my better half, I will post pictures.

[mattblackgod]

Mine is a grey sheet with the roads painted on it in a grid system.

[joroas]

Dave Bickley has a sheet of MDF painted dark grey and using Ainsty kerbs and footpaths to allow his painted buildings to slot into place.  This does mean that it is pretty static and buildings cannot easily relocate.
You could, instead, base your buildings with footpaths, kerbs and alleys to create different blocks on a prepainted board.