Why do road accidents happen and where do they happen?

Sometimes the aliens shoot nasty beams that make our cars/buses/bicycles/trucks/trains/unicycles swerve and occaisionally hit something. This is also the answer to you second question. We can predict the exact time and place of these beams by folllowing the moon each night with your middle finger. The leprechauns will see this as a signal and bring you a coded "Accident Beam Forecast" for the week. Take this to your local cornershop and give it to the owner whispering the passWord (which the leprechauns should tell you). The owner will then perform a tap dance and provide you with the exact time and place of the upcoming accidents. Use this to avoid those areas. Accidents are dangerous. Good luck on your quest