There has been a certain amount of controversy waging on the News Shopper site about a
bus accident in Broadway. A Nissan Micra went up the back of a bus. Driver in
severe pain, passengers unharmed. As long term readers will know I have a friend
who earns his keep in the road safety and vehicle accident investigation arena. His
specialty is heavy goods vehicles including buses. He looks into many of the
high profile bus accidents and has got a few drivers off of manslaughter charges by
proving a police case cannot be true. Against the laws of physics etc. By the
same token some cases have been pushed in the reverse direction; so I referred
him to the News Shopper article. This came back by return…
I have just about stopped laughing about that bus driver’s claim! For most things, injury severity is broadly correlated with change in velocity so conservation of linear momentum is the name of the game. You would need to check the relevant masses but assuming for simplicity the Micra is one tonne and the bus is 15 tonnes (max for a two axle bus is 18 tonnes but I'm assuming not fully loaded), the Micra is travelling at 20 mile/hour when it hits the stationary bus and both then move off together after impact.
1000*8.94 + 15000*0 = 16000*V
V=0.56 m/s= 1.25 mile/hour
So the Micra changes from 20 mile/hour to 1·25 mile/h, a delta V of 18·75. The bus changes from 0 to 1·25, a delta V of 1·25. Now data would suggest low speed whiplash injury is not very sensitive to collision speed and buses are not necessarily very well equipped in terms of occupant protection but I think it might be quite hard to convince people that a change of 1·25 mile/hour was responsible for “severe pain” unless he had a pre-existing condition or something, especially given that nobody else involved was affected.
No I don’t understand it either but I guess the Micra’s insurer’s will be taking a close look at this. Maybe I could arrange a discount on a detailed technical report for the driver?
The News Shopper subsequently heavily censored the discussion on whether the bus driver was faking it while the passengers were entirely unharmed.