"Bob Quintal" wrote in message
It will be interesting to get more details as the investigation continues.. I
was not fully familiar with the Westinghouse air brake system so I read up
on it:
http://en.wikipedia.org/wiki/Railway_air_brake
The individual car brakes should be applied automatically if the pressurein
the main brake line drops below a certain threshold, and each car has its
own reservoir of compressed air to exert maximum force on the brakes.
However, if the valve between, say, the engine and the cars is closed, the
system will be "fooled", as happened in the infamous accident in DC in 1953:
http://en.wikipedia.org/wiki/1953_Pennsylvania_Railroad_train_wreck
I think rail cars also have the old-fashioned manual parking brakes actuated
by a handwheel, which should have been used if the train was parked for any
length of time. But people are lazy and crews are sparse, so this was
probably not done. There are also wheel chocks that would have prevented
this.
Although sabotage and terrorism have been so far not suspected, this may
have been an attempt to push for the Keystone pipeline which would reduce
the rail transport of crude oil across Canada, to the less risky (for
Canada) of having it pumped across the US to refineries and ships in the
Gulf of Mexico where it will be taken to foreign customers. The benefits of
this pipeline to the US are minimal and temporary in the form of local jobs,
but the environmental impact of the inevitable oil spills could be
disastrous.
