the bus jump!!!

Hello, I am italian but I study english in my school. When I enter in the bus (route Berlin - Spandau) the bus start jump. It is crazy!!! What do I have to do?

When the bus is jumping, you have too low frame rates.
Set down your graphic settings or load other presets (e.g. 2006) and see if the problem persists.
If not, turn up the settings the best possible until the bus jumps again