Re: What about the buses?
We hope buses don't collide that often.
As to bus bunching, there is an explanation. If a bus is slightly delayed at one point there are, on average, a few more people to board (and subsequently alight) at the remaining stops. Each extra person boarding and alighting takes more time so the bus is more delayed. Those extra people would have been picked up by the next bus so it runs a little faster and catches up with the first bus. Apply in reverse for a bus running early, it catches up with the previous one hence bus companies instruct drivers not to get ahead of schedule.