I wonder what's your trouble about understand something already written, Seahawk...
If Sajmon, who's the track author, said that's not possible, it means that's not possible... Got it now?
For "tiny", he means that the system of the minimum number of roads and intersections necessary to have only the AI cop cars to work is really tiny. It's a lot smaller than a car wheel, for comparing... A similar thing has been done with the MM2 conversion of Archipelago map, but in that case, it was for the purpose to get working AI opponent cars for one of its races.
Also, you can well see that all the roads of National Road map are properly modeled and textured, and so, they're PKG objects; roads with traffic are blocks part of the PSDL terrain, instead, and they're always made in an apposite way, about modeling and texturing, which is somehow semi-automatic (meaning that you model them in a certain way and assign them some materials with textures, and then, MM2 City Toolkit and the game engine will do the rest with finalizing the road modeling and mapping the textures).