jonnhrr wrote:CHTT1 wrote:The Illini/Saluki run with seven to eight coaches, mainly to allow them to operate at full speed over grade crossings. Shorter trains would have to slow down at each grade crossing since CN, unlike every other North American railroad, can't time its gates to accommodate shorter trains.
I don't understand that. The gates should be triggered to lower when the loco or cab car enters the track circuit before the crossing, and raise when the last car clears. Should have nothing to do with train length. Otherwise how would you mix even 7 car Amtraks and 100 car freights?
Jon
I believe it has to do with speed.
A freight train travelling at say 30 miles an hour that triggers the gate .5 miles away will take 1 minute to get there.
A passenger train travelling at say 60 miles an hour will get to the same gate in 30 seconds.
I think the goal is to get the gate to trigger in a similar amount of train in each case. (otherwise drivers used to freight trains will start to assume they always have the longer time).
So my guess is the axle number is so it can do some math and calculate how fast the train is going and how long to wait (or not wait) before triggering the gates.
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