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A comment on The Francis Scott Key Bridge in Baltimore, Maryland Has Collapsed. Parent comment

Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by master_crab on Tuesday March 26, 2024 @09:55AM (#39827860)
Also want to highlight this for another reason. At slow speeds rail and boats suffer from far less “moving” friction than road vehicles. So once off there is very little slowing them down vs cars and trucks that suffer from high rolling friction.
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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by theluketaylor on Tuesday March 26, 2024 @10:41AM (#39828529)
Grady Hillhouse of Practical Engineering recently did a great demo of this. He was able to pull his car in neutral and an empty train car on rails with roughly the same force.

https://www.youtube.com/watch?v=nGhBHrr5CYQ

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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by kamaal on Tuesday March 26, 2024 @12:02PM (#39829424)
One wonders how braking works on a train.
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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by master_crab on Tuesday March 26, 2024 @12:07PM (#39829482)
Mostly the same as it would work on a car with a brake shoe applied to the steel wheel.

The only major difference is that they often use a safety air brake system shared across an entire consist (train) that requires “charged” pressure (above atmosphere) to disengage the brake (although I think they have moved to an electronic system that now monitors air pressure in each car individually).

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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by singleshot_ on Tuesday March 26, 2024 @01:20PM (#39830400)
Semi trucks have air brakes that function very similarly. One air source for all brakes, pressure releases, brakes lock on failure.
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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by phyzome on Tuesday March 26, 2024 @03:51PM (#39832101)
I think it's actually in an earlier video, and he wasn't able to actually pull the train car due to track irregularity -- but according to calculations he should have been able to if there was a safe way to give it a bit of a nudge.
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Re:The Francis Scott Key Bridge in Baltimore, Maryland Has C... by theluketaylor on Tuesday March 26, 2024 @04:51PM (#39832697)
You're absolutely right; I posted the wrong link.

https://www.youtube.com/watch?v=tfA0ftgWI7U

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