Textured walls, a vehicle

I've textured the walls and added some traffic:

Also the three lanes is more claustrophobic than I expected, I might need to widen the road to five lanes or so to allow the kind of weaving gameplay I'm hoping to implement, but I'll leave that until I have some element of gameplay implemented to test with.

For now I'll add some different vehicles and work on their collision system, and then get to implementing the player vehicle