From: nilknocgeo@earthlink.net
"John Albert" wrote in message
news:53f621fb$0$20971$2c56edd9@usenetrocket.com...
>I downloaded the pdf format of the Lac Megantic report.
>
> It goes on for around 191 pages (in pdf format), but most of it is
> irrelevant as to answering the question, "why did the train move?"
>
> That answer can be found on page 23, in Table 1, "Locomotive event
> recorder information".
>
> Evidently, the engineman made a grave mistake in leaving his train the way
> he did. This mistake may not have been an intentional, but if he had done
> ONE MORE THING -- even though the number of hand brakes was insufficient
> to hold the train -- the train would not have moved within the time frame
> it did, even though there was no longer enough (or any) locomotive air
> pressure to keep the locomotive independent brakes applied.
>
> I will offer an explanation:
>
> Let's look closely at the FIRST TWO events in the event recorder timeline
> (p.23):
> 1. Brake pipe pressure is reduced to 82lbs to stop the train at Nantes
> using a service application.
> (Note: I believe at this point, the engineman applied some locomotive hand
> brakes, and car hand brakes, and then....
> 2. Brake pipe pressure increases to 94lbs -- train brakes are released.
> (Note: the engineman did this to [ostensibly] test the effectiveness of
> the engine brakes and train hand brakes with train air brakes released).
>
> The following is excerpted from the report, pages 1 and 2:
> [[ At around 2250, the train arrived at Nantes, was brought to a stop
> using the automatic brakes, and was parked for the night on a descending
> grade on the main track. The LE applied the independent brakes to the
> locomotive consist. He then began to apply the hand brakes on the
> locomotive consist and the buffer car (7 cars in total), and shut down the
> 4 trailing locomotives. Subsequently, the LE released the automatic brakes
> and conducted a hand brake effectiveness test without releasing the
> locomotive independent brakes. The LE then contacted the rail traffic
> controller (RTC) responsible for train movements between Farnham and
> Megantic Station (Megantic), who was located in MMA’s yard office in
> Farnham, to indicate that the train was secured.
> ...
> A taxi was called to transport the LE to a local hotel. ]]
>
> Critical factor that caused the disaster:
> AFTER CONDUCTING THE "RELEASE TEST" (even though it was not properly
> tested), THE ENGINEMAN LEFT THE AUTOMATIC AIR BRAKE (TRAIN AIR BRAKES) IN
> THE "RELEASE" POSITION.
> HE NEVER RE-APPLIED THE TRAIN AIR BRAKES USING THE AUTOMATIC BRAKE VALVE
> BEFORE HE LEFT THE TRAIN.
> (I will delve more into this below)
>
> What happened next (after lead locomotive had been shut down):
> Refer to page 23 again, and look at event 4:
> "Brake pipe pressure began to decrease, and continued to decrease at an
> average rate of 1psi per minute"
>
> Since there was no longer enough air supplied from the locomotive to
> replenish and maintain brake pipe pressure, it began to slowly "leak
> away".
>
> HOWEVER -- and this is VERY important -- the leak was "slow enough" so
> that the control valves on the cars did not move to the service position,
> which would re-apply brake cylinder pressure on the cars.
>
> How could this be?
> Because one of the first things I learned in air brake as an engineman was
> that a "service rate of reduction" is a movement of air in the brake pipe
> equivalent to 550 feet per second. (aside: emergency is a reduction rate
> of about 930 fps). The air pressure was reducing in the brake pipe, but at
> a slow rate, not sufficient to trigger the car control valves to move to
> the application position.
>
> The end result is that the brake pipe pressure slowly declined to the
> point where neither a service application OR an emergency application was
> possible -- in effect, the cars were sitting there with air pressure still
> in their main reservoirs, but it couldn't be directed to the brake
> cylinders because the control valves could no longer respond to the brake
> pipe.
>
> That's why the train "moved" -- because the train was left with the car
> air brakes released, and the slowly-leaking-down brake pipe effectively
> disabled any chance that they could re-apply.
>
> That's just about the end of the story. That's why the train actually
> began to move. What additional action might have changed this?
>
> Let's consider -- what if (before leaving), the engineman had RE-APPLIED
> the automatic brake valve to a 20lb reduction, leaving the train with the
> air brakes applied on the cars and the brake pipe at approximately 74lbs
> ??
>
> With the car control valves in the service position (and brake pipe at
> 74lbs), they would have REMAINED in the service position even as the brake
> pipe pressure began to drop away (after the engine failed and MR pressure
> was depleted). The control valves won't move to the "release" position
> unless there is an INCREASE in BP pressure of about 1.5-2.0 lbs. But with
> dead engines, that wouldn't have happened.
>
> The result would be that the brake pipe pressure might drop right down to
> 0, but the air brakes on the cars would have remained applied. A few cars
> might have had cylinder pressure "leak off", but even this would not
> change the position of the control valves (applied).
> There would have remained enough restraining force on the train to hold it
> still.
>
> But this didn't happen -- again, because once the engineman released the
> automatic air brakes, he never re-applied them before leaving the scene.
>
> The question is:
> Why didn't he re-apply them?
>
> Only he can answer that question.
> It may have been an oversight, completely unintentional. He might have
> been tired, anxious to get to the motel, and simply forgot.
> But again, a terrible mistake.
>
> Whenever I left a train standing with the locomotive attached and "live",
> I always put the service brake valve into the application position. On
> freight, it was also a good idea to move the brake valve handle to the
> "handle out" position, then remove the handle (you could do this on #26
> equipment) and "stow it away". This way, a trespasser couldn't put the
> brakes into release by moving the handle, because the handle wasn't even
> there. It was just good practice.
>
> Again, I can't understand why the engineman didn't re-apply the air,
> especially since the train was on a downgrade. In a situation like that,
> you want "all the brakes you have" against the grade -- if not "full
> service" on the train, at least a good-size reduction in addition to the
> hand brakes.
>
> I read a few pages earlier in the report regarding the state of the train
> air brakes, and how they were to be left with equipment left standing. As
> presented in the report, this seems ambiguous.
>
> About the only relevant info I could find regarding leaving a train with
> the air brakes applied (as well as hand brakes) are here:
>
> ....a CN rule (p. 22):
> [[ Trains with locomotives attached with at least 1 locomotive running can
> be left on the main track with only 1 locomotive hand brake applied,
> provided that there is brake continuity throughout the train, the
> automatic air brakes are fully applied and the independent brakes are
> applied. ]]
>
> ....From CN special instructions (also on p. 22):
> [[ The automatic air brakes must not be solely relied upon to secure
> equipment against undesired movement. ]]
> (NOTE that it says "solely relied upon", but that does not exclude the use
> of the automatic air brake to supplement hand brakes)
>
> I don't know whether there were any instructions similar to these in MMA
> operating rules and special instructions.
>
> I didn't see anything from what I read (and admittedly I didn't read the
> ENTIRE report) that said that, under MMA operating rules and instructions,
> a train should be left unattended with BOTH hand AND air brakes applied.
>
> BUT -- as someone who worked on the railroad for 32 years, it was just a
> good idea to leave a train standing with air applied, if air was
> available. Just "one more thing" to protect the train against movement.
>
> I KNOW the rules say that one should never depend solely upon air brakes
> to secure a train left standing. You put on hand brakes and used the air
> brakes, too.
>
> Those who have read this far may repeat the mantra, "if there had been
> enough hand brakes the train wouldn't have moved". Of course -- that was
> known from day one, there was no need for a 191-page report for anybody to
> understand that.
>
> Of course there weren't enough hand brakes.
>
> BUT -- if the engineman had only taken that "one extra step" of
> re-applying his air brakes after releasing them -- this wouldn't have
> happened.
>
> I can't speculate as to whether his failure to do this represents
> negligence on the engineman's part, because (as above) I didn't see
> anything that might have required him to leave the train with air brakes
> as well as hand brakes applied. He may not have been required by the
> operating rules and instructions to do so. It may have been left to his
> discretion.
>
> HOWEVER -- if the engineman had re-applied the air brakes that night, the
> train wouldn't have moved and there wouldn't have been a disaster.
>
> That's my take on it, and I'm standing by it.
Great analysis. But who, then, is "responsible?" Who knows?!!
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