Insight: How a train ran away and devastated a Canadian town

Reuters ^ | Jul 8, 2013 10:06pm | P.J. Huffstutter and Richard Valdmanis

[thackney]

...The locomotive caught fire, so firefighters shut off the engine to stop the flames from spreading. That slowly disengaged the air brakes, and the driverless train carrying 72 cars of crude oil rolled downhill into the scenic lakeside town of Lac-Megantic, derailing, exploding and leveling the town center.

At least 13 people were killed and some 37 are still missing, according to Canadian police...

He secured the train at 11:25 p.m. on Friday, setting the air brakes and hand brakes, according to MMA. Burkhardt said the engineer set the brakes on all five locomotives at the front of the train, as well as brakes on a number of cars, in line with company policy. Four of the train's engines were switched off, but the front locomotive was left on to power the airbrakes. The engineer, who Burkhardt declined to name, then retired to a hotel in Lac-Megantic.

Soon after, things started to go wrong. Nantes Fire Chief Patrick Lambert said the fire department got a call about a blaze on one of the locomotives at 11:30 p.m. He said the fire was likely caused by a broken fuel or oil line.

Firefighters reached the scene within seven minutes.

"It was a good sized fire, but it was contained in the motor of the train," Lambert told Reuters. "By 12:12, the fire was completely out."

But as they extinguished the fire, the 12 volunteer firemen also switched off the locomotive, in line with their own protocols, to prevent fuel from circulating into the flames.

One of the many unknowns in the story is precisely what happened next.

Lambert said the fire department contacted the railway's regional office in Farnham, Quebec, and spoke to the dispatcher...

[Aqua225]

Trains are not different, their brakes go active as the brake line pressure falls.

However, it takes energy to activate those brakes. Each car’s braking system has a reserve tank that holds pressure to activate that car’s brakes. These do eventually leak down if not recharged from the locomotive. If line pressure had not recently been brought up (to unset the brakes at some point), these reserves would have failed here and there, causing the train to lose massive amounts of braking force.

Trains are often left alone. Railroads are private property and they have their own police. Generally, people don’t mess with trains because they don’t want to be arrested and prosecuted. Engines generally are left idling to keep their pure water coolant from freezing (pure water cools better than antifreeze mixture, but there is a freezing risk associated). Recent software for many engines now allow the ECM to cycle the engine on and off to keep the coolant from freezing, saving some fuel.

[Dalberg-Acton]

Same way on trains. Without air the brakes are applied. Not the way the article describes.

[informavoracious]

This is like the movie Unstoppable.

[freeandfreezing]

In trucks with air brakes, when the air pressure goes down the brakes come on automatically.

In air brake systems there are brakes which are spring loaded into the "stop" position, which are activated by loss of air pressure and are used as parking brakes, and brakes which are activated by pressure in order to move into the "stop" position.

It would seem that enough brakes would be of the spring loaded parking type to prevent motion of a train (or truck) with no air pressure present in the braking system, since this is a major safety feature of the systems. But apparently that wasn't the case in this situation, perhaps due to the grade where the train was parked or some other factor.

This accident is another example of how minor problems can compound into a disaster due to human error and ignorance.

[Aqua225]

Also, here is my theory of what happened:

(1) Sufficient braking force was available when all engines were idling while train was stopped.
(2) An engine caught on fire, and it may not have been the first or last engine in the locomotive line. Fire department put it out and shut down engine.
(3) Braking force was lost on the engine that caught fire, and possibly all the engines after.
(4) Having been sitting for a long time, the car brake reserves were depleted, and loss of a engine and airline problem on that engine caused the brakes to get applied, using the reserve in the car tanks.
(5) Loss of braking on one or more engines allowed the train to begin to roll.

Once rolling, there was no stopping it, since all the brakes necessary were no doubt not going to work whether a engineer was on board or not.

I would guess the chock solution is about the only thing that could have saved the train, other than if the firefighters or railroad had recognized what was about to happen and manually set the car brakes (the wheels on each that can force the car brakes on).

[Last Dakotan]

Worst ever reporting of a technical detail I've ever read.

That they went to print with the braking system explanation completely backward is a travesty of Journalism.

[Mycroft Holmes]

In trucks with air brakes, when the air pressure goes down the brakes come on automatically.

Evidently Trains are different.

I went to a talk long ago and far away about train brakes. I also recalled the brakes being actuated when the pressure went away.

It's a little more complicated than that. The brakes are actuated on a reduction in pressure, but the motive force for the application of the brakes comes from an air reservoir aboard each individual rail-car, not from a spring.

A procedure called "fanning the brakes" can deplete all of the reservoirs and cause total brake failure. Don't do that.

[katana]

I believe it was an attempt at sarcasm based on an SUV being, in the minds of Liberals, an evil and unstoppable piece of machinery with a mind of its own. Not my post ... just explaining what I think he meant. Sometimes people attempt levity to keep themselves from crying.

[Rage cat]

The reason for the difference between trucks and trains is a result of the amount of braking force required, and limits in practicality.

The size of the springs, the force they exert, and the breaking force required for trucks makes spring actuated air released brakes unworkable.

The size and force of the springs required for a train would make it impossible to assemble the braking system. And certain breaking systems just would not physically work.

An air, or fluid actuated system is the only viable ways to do it.

Since you want the system to apply on loss of air pressure (the line is broken), then you want a reservoir on each unit that is used to power the brakes. And a control line that will engage the brakes if the control pressure drops.

The onboard reservoir will supply breaking force long enough for the operator to correct the line problem, or apply hand breaks.

If the control line is disconnected, and the car is just left there, then the pressure will bleed down and the car will start rolling. It isn’t a mater of if, but just how long until it happens.

[C210N]

Yep, you nailed it...

levity to keep from going nutz what with all the other nutty things going on, covered in other threads, seemingly out of control

[wita]

Sounds logical, the SUV having “a mind of its own” another of the Rush Limbaugh theorem or would that be another insanity of the left.

[mandaladon]

Something very strange about this incident. Crude oil isn’t all that flammable. Burns like hell once it is started, but needs a real boost to get it going.

[saintgermaine]

I always was under the impression that it takes “Air pressure” to unlock those brakes. Or on the other hand if the air pressure goes down the brakes will lock up. The only scenario I can imagine is if the locomotive is removed that there is a way for the brake lines to remain sealed and a certain amount of pressure remains and keeps the brakes unlocked until the air finally bleeds off and the brakes lock up. It be interesting to hear an explanation from an engineer familiar with this process.

[q_an_a]

nice post...now “the rest of the story”

[canuck_conservative]

Though not proven at this point, there are background rumours that this incident may have been deliberate eco-sabotage by the anti-oil kooks.

Several groups in the US have already engaged in actions they use to stop the movement of North Dakota oil, and have not been shy about it - they call it “Fearless Summer”. An extremist group called 350 Maine set up a blockade 2 weeks ago - Maine is next door to Quebec.

Stay tuned.

[NonValueAdded]

See my post 9. Ruptured tank cars, a lake of crude comes in contact with red-hot steel wheels, combustion temps reached, sea of fire, intact tank cars start to boil, BLEVE, game over.

[thackney]

Thanks for that post on this thread.

[thackney]

Worst ever reporting of a technical detail I've ever read.

Sadly, this doesn't even make the top 20 for me.

[Rage cat]

Shesh……Some times, my brain is just not in full gear…..

“………. breaking force required for trains makes spring actuated air released brakes unworkable.”

And switch out “break” for “brake”

I guess that is why the site has post preview. I guess I should actually use it once in a while.

[Abathar]

"Don't the air brakes lock up when the air pressure in the system falls below a certain point? "

On a truck yes, but on something as long as a train if the airline failed in the back cars the engineer wouldn't know. It would destroy the wheels obviously, and if he ever went over a wood trestle bridge like that he would probably burn it down behind him.