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Petrochemical train explodes in Quebec's Lac-Megantic

A driverless train carrying light crude oil has exploded in a Canadian town, forcing the evacuation of 1,000 people...

Runaway train carrying Bakken crude to New Brunswick

Canadian train exploded after conductor parked it - railroad

Freight train derailment causes huge fire and evacuations in Canada

Train of 73 fuel-carrying rail cars was driverless when it derailed at 1am local time Saturday in Lac-Magéntic, in Quebec...

Train in Canadian derailment headed by Chicago rail veteran

Up to 60 feared dead in Canada railway inferno

Quebec train crash death toll rises to five as police search for more victims

the release of the train's brakes might be linked to how the locomotive was shut down...

Lac-Megantic train blast: PM Harper visits 'war zone'

Photos: http://www.spiq.ca/v2/ailleurs/2013_07_ ... index.html

Also a couple of good aerial shots at http://www.railroad.net/forums/viewtopi ... 4&start=75

Canada train crash death toll rises to five (video)

Canada train blast search for 40 missing in Lac-Megantic

Death toll in Canadian oil train disaster rises to 13

Canada train crash: fire fighters cut brakes due to engine fire

Airbrakes that would have prevented the Canada train disaster failed because they were powered by an engine that was shut down by firefighters as they dealt with a fire shortly before the calamity occurred...

Quebec locomotive inspected day before disaster, no problem seen

Quebec disaster death toll jumps to 13, some 37 still missing

Air brakes that would have prevented the disaster failed because they were powered by an engine that was shut down by firefighters as they dealt with a fire shortly before the calamity occurred, the head of the railway that operated the train said on Monday.

The train had been parked at a siding on a slope near the town of Nantes, which is 12 kilometers (8 miles) west of Lac-Megantic. The volunteer Nantes fire service was called out late on Friday night to deal with an engine fire on one of the train's locomotives.

Nantes Fire Chief Patrick Lambert told Reuters the crew had switched off the engine as they extinguished a "good-sized" blaze in the engine, probably caused by a fuel or oil line break in the engine.

The problem was that the engine had been left on by the train's engineer to maintain pressure in the air brakes...

Another video: http://www.youtube.com/watch?v=IoAP_j8XO1A

The problem was that the engine had been left on by the train's engineer to maintain pressure in the air brakes...

One does not want to speculate but this statement does not add up and was presumably made by someone who does not know how air brakes work. A loss of pressure in the train brake line would trigger a full brake application caused by the pressurised air stored in each vehicle's reservoir tanks. This is one of the "fail safe" features of the air brake system. To release the brakes will then require a repressurisation of the train brake pipe, whereupon the air reservoirs are also "topped up" again. Once the brake pipe is repressurised, the brakes will naturally "come off" and unless other action is taken, the consist would move if on a gradient. Certainly, maintaining pressure in the train brake pipe will cause the brakes to be off, not applied.

The system is not entirely foolproof though and perhaps a sequence of brake applications and partial releases was made at some stage, in effect "milking" and depleting the reservoirs, so the reservoirs were not fully up to pressure, although this seems unlikely with a standing train. If the train was to stand for any length of time without a responsible person present, enough handbrakes should have been applied and possibly even wheel scotches inserted.

I await a proper technical explanation with interest. Until then this is all speculation.

There is a good explanation of how air brakes work at: https://en.wikipedia.org/wiki/Railway_air_brake

Steve, I've been trying to follow this on Railroad.Net, where many knowledgeable north American railroad crew post, and I think most of them would agree with you. While the loco may well have been left running to recharge the reservoirs if they had been milked off, it had been running for at least an hour and would presumably have completed its task by the time it was switched off. Most railwaymen would then agree that it would take a long long time for the air to bleed off to an extent where enough brakes would release to allow the train to start running away. They speculate that whoever shut down the loco inadvertently released the train brakes (and probably the independent loco brake too) and on top of that not enough hand brakes had been applied to hold a train of that weight on that gradient. But, as you say, it is pure speculation until the investigation is completed.

Quebec train blast: police open criminal investigation as death toll rises

Quebec police... said investigators had "discovered elements" that gave rise to a criminal probe... but ruled out terrorism and said police were more likely exploring the possibility of criminal negligence...

Lac-Megantic train blast: Criminal inquiry under way

Investigators are focusing on whether the brakes were released as it was parked in a town several miles away...

Rail Industry Ignored Warnings that the Tank Cars Involved in Quebec Were Unsafe

It turns out that both US and Canadian regulators have been warning for years that the type of rail car involved in the fatal derailment and explosion in Quebec on 6th July is far more prone to rupturing in accidents than other models available...

Transport Canada says hand brakes must be tested on parked train

Quebec police open criminal probe after deadly train crash

Four questions about the Lac-Mégantic disaster

Quebec police boost list of disaster missing and dead to 60

Sixty dead or missing after Lac-Megantic train blast

Criminal investigation opened in deadly train crash (video)

I guess this is similar to the way SAPS here nearly always opens a homicide case each time there is a fatality in a motor accident. Unnatural deaths always require an investigation to determine whether any law has been broken and, if so, who was responsible.

Train firm chief believes engineer 'did something wrong'

Railway boss says sabotage not suspected in Quebec inferno

Canada train disaster: Blast missing 'probably dead'

The train operator's boss blamed a local engineer for the accident, saying he had probably failed to set a series of hand brakes....

Quebec train crash: families of 30 missing people told all presumed dead

"We think he applied some hand brakes, but the question is, did he apply enough of them?"... "He said he applied 11 hand brakes. We think that's not true. Initially we believed him, but now we don't."

Canada train disaster driver may have failed to set brakes

The engineer of a runaway oil cargo train that engulfed the centre of a small Quebec town in a fireball, killing at least 20 people, may have failed to set its handbrakes, according to the railway company’s boss...

Employee 'failed to properly set the brakes' on runaway train that hit Canadian town as the number of missing people jumps to 60 people and it is thought many VAPORIZED

[Typical Daily Mail but includes a lot of photos]

Deadly Quebec train crash to be fertile ground for lawsuits

Quebec's Lac-Mégantic oil train disaster not just tragedy, but corporate crime

At the root of the explosion is deregulation and an energy rush driving companies to take ever greater risks..