A freight train's emergency brake is applied at 40 MPH. How long does it take to stop?

Originally published at: https://boingboing.net/2019/11/26/a-freight-trains-emergency-b.html

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Put regenerative braking on every wheel!

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23 car lengths by my count. So more than 1000’ to stop

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Math checks out.

A rail car is about 53 feet. Conveniently this means 100 cars is just about equal to 1 mile. In case you were wondering how long that train was that made you 15 minutes late for work.

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Possibly longer than you think:

And for a more humorous take on the thing:

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He always had trouble thinking three-dimensionally…

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Not possible, because the freight cars don’t have any motors.

Eelctronically-controlled brakes can be used to shorten the response time. Every car in the train would brake simultaneously.

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Exactly. Basically all modern electric locomotives or EMUs use regenerative breaking. Another advantage of railway electrification.

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The brakes on freight cars have to do several things.
They have to operate reliably with minimal maintenance, even after long periods of time sitting idle outside in the hot deserts of the Southwest, or through the cold Canadian winter. They have to come on automatically if they are separated from the locomotive. Which in turn means that the power to operate them has to be stored somehow in the car itself. They have to be relatively inexpensive, because there are many more cars than locomotives. They have to be standardized across almost the entire North American railway system, because a railway car may travel over several different railroads before reaching its destination.

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Looks staged

ECP brakes are air brakes, and there is still a continuous brake line running down the train, so if a car became separated the brakes would be applied automatically because of the loss of air pressure.

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Americans rhyme “math” and “wrath”? I did not know that.

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I didn’t mean to imply that improvements couldn’t be made or that ECPs wouldn’t work. I was just trying to point out a few of the design issues involved.

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The Wikipedia article I linked to is focused on ECP braking systems developed for North American freight trains.

Man, I miss the glory days of The Simpsons. Stopped watching sometime around season 9…

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Yep. And we also say math and not maths.

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And then somebody steals your methylamine

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