From: j.albert@snet.net

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.

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