Streets how do you make em?

[Allegheny2-6-6-6]

I generally use .060" styrene sheet, cut to size and shape, and laid out to insure good fit, then spray painted concrete, or blacktop, then the lines are sprayed in. The finished sections are then permanently installed with water base contact cement, weathered, and the road shoulders built up.

I read some where perhaps in either MR or RMC about using styrene for streets but how do you cut it? It seems that every time I try and cut some of the .020 sheet styrene I have the cut edge never comes out sharp enough. Iuse a brand new #10 blade but the edge still doesn't look just right. I am contemplating using a large paper cutter that I have to see if I can get a more uniformed edge.