> Easier to just build a second level road.

Lol wut? Easier to build a second level road than put a few gantries in to prevent vehicles over a particular height enter a road? I think not.

This bus isn't going to be used as a general bus that drives around the city. It's more likely going to be used down a single stretch of road, acting as a shuttle from one end to the other so people don't get stuck in traffic on it.