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Spectacular derailment in Western Australia.


ben_issacs

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We would have to know the braking effort too, but anyway the outcome of the event tells us that it was not sufficient to hold the train on the grade.  Makes me wish I could remember physics class better 🙂, I did enjoy it.  Would 1 in 66 be 15 permil?

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The calculation for weight is as follows.

A 1 in 66 gradient is an actual angle of asin(1/66) or 0.868 degrees. (Assuming I understand railway gradient correctly, as the ratio of increase in height to distance along the rail, not horizontal distance.)

The component of the train's weight acting down the slope would be sin(0.868), or 1/66 again.

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Lots of unknowns here as well so it’s doing a lot of assumption to try to get any answer, and thus likely flawed.

 

jeff

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steffie, 

Train weight 42,500 tons, grade 1:66, divide 42,500 by 66, answer about 650 tons, which is the gravitational force pulling the train down the grade.

And this is the force which the handbrakes must resist to hold the train.

Anyrate, how many handbrakes were applied, and we can only speculate on this number, there weren't enough to hold the train.

We must await the full report for further details.

Regards, 

Bill, 

Melbourne.

 

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Also the combined frictional force of rolling resistance would add to brake side of the equation. Again unknowns.

 

jeff

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Folks, 

From Mark's shot of an iron ore car, they have roller bearing axle boxes, so rolling friction would be pretty low.

Regards, 

Bill, 

Melbourne.

 

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Folks, 

More info is now available on the ATSB web site, giving details of the action that the driver took, amongst other things,

But the final report looks to be still a long way off!

Regards, 

Bill, 

Melbourne.

 

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