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View Diary: More Mystery Surrounds Canadian Ghost Train: Where are the locomotives? (160 comments)

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  •  Multiple Single Points of Failure (6+ / 0-)

    The first rule (also 2nd through 50th rule) of engineering anything is:

    a) assume that everything can (and probably will) fail at sometime or another.
    b) design so that all failures fail to a condition that doesn't threaten human life (busted stuff is OK).
    c) If you can't do (b) establish defense in depth procedures (with redundancy) to handle as many of the remaining failure modes as technically possible.

    This doesn't protect against every eventuality, but it would have stopped at least 3 essential preconditions in the Lac Megantic train operation.

    1. The train was stopped on a downgrade. I'm sure that location was convenient for the engineer, but it put gravity on the wrong side of the equation. Why is any large, heavy train allowed to stop and be abandoned on a downgrade? Anywhere?

    2. There was only one engineer. Any human error by that one individual could occur with no hope of being caught by a co-worker. Of course, that makes him an easy target after the fact.

    3. The brakes require air pressure to work. Some old-time railway cars had huge springs that applied the brakes unless there was sufficient air pressure to force the brakes off. Losing air pressure actually brought a train to a halt. What justified the change? Lower rolling stock costs, I bet.

    If even one of these three failure points had been addressed, the conditions for the accident would not have existed. 50+ good people would still be alive.

    Maturity: Doing what you know is right - even though you were told to do it

    by grapes on Thu Jul 11, 2013 at 11:23:01 AM PDT

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