Just to add to this: buses are so bad that you actually will have less pollution if all the bus riders just get cars and drive themselves. This isn't true if the bus is a nice coach and all its seats are full, and it's driving all these people from one place to another fairly distant place, but for city buses it absolutely is because of their low-speed, herky-jerky operation and the fact that they're rarely full and frequently mostly empty.

Buses are crap in the US. Try a bus in Geneva; they are a wonder of cleanliness and efficiency.

No, they're not. They might be better if they're electric (but we have those here in the US too in some places, like NYC), but they'll never be efficient. The only efficient system is an automated personal rapid transit system which can move people between arbitrary points without any stops in between. Only something like SkyTran can do that. As long as you have to stop and pick up other riders in-between, or have to stop for traffic lights, you'll never get an efficient trip.