You don't have to hand draw streets, you can get a street texture and when you create your terrain in MED just use the select tool and texture the parts that you want.

You could find some street textures here just search for street or something and click on sort by lower prices you will get some free stuff.

They also have some really good architecture there aka alot of city building and such, pretty good site for models.

Hope that helped if not sorry lol.