Train Derails in Lac Megantic Quebec, causes Massive Explosion

[Acevalefor]

Yeah, so a little research shows that all train brake systems require a charged system to release the brakes. Even vacuum brake systems work that way. The only way the brake systems can fail is if the valves between cars are closed which would then keep the system (on the cars with closed valves) open. This effectively turns off all brake control for the car with the closed valve. If it is closed when pressurized then he brakes will not apply. Conversely if the valve is closed when the system is not charged, the brakes downstream of the closed valve will remain on.

So if the train was stopped and the brakes were applied, i.e. the air pressure was released, the train would not have decided to take off on it's own. Even if power was lost and the air leaked out, if the brakes were applied as the conductor says they were then this would not have happened. There is something else going on that caused this train to take off without a conductor.

[Manako]

My mother used to work at CN, I was of the impression that there was a lot of procedure and checks for trains and their operations, they still use dead-man switches etc..

I guess MMA is considered a secondary tier of transportation so the current theory is that they were not used to handling more hazardous materials and may not have the same level of care in their operating procedures.
http://www.montrealgazette.com/news/...928/story.html

[Ratatapa]

Train conductor seems to have been fired and is no where to be found

The SQ is about to open a criminal offender

[Amiricle]

Man, if it's one dudes fault.....what a thing to live with.

[Stumblingdrunk]

Man, if it's one dudes fault.....what a thing to live with.

It will be so nice and convenient when we blame this all on one guy

[Ratatapa]

New video of the explosion



P.S that's not a Quebec accent but a french one



50 feared dead in Lac-Mégantic train derailment
Police meet with families, warn them to prepare for loss (and it's still far from beeing done)

[Byrthnoth]

I still don't think they have the brake situation right. Air brake systems are designed with fail-safe features in that the operating condition is normally open. If/when the brake system loses pressure and it drops below a certain threshold the brakes are closed and the vehicle stops. This type of brake system is used for many things including industrial electric/pneumatic motors, commercial ship engines, commercial truck/trailers, wind turbines, trains and probably many other applications. If there was a problem with the air system that allowed the train to operate on it's own, I really don't think it was the brake system. I just can't see any manufacturer building a brake system for a train that is not inherently fail-safe in it's design. Especially not when that very design has been the industry standard for over 100 years.

What provides the thousands of pounds of pressure required to hold the train still once the air pressure is gone? Inertia (at rest, stays at rest) works when it works, but the train wouldn't have run off if it was parked in a stable spot. Can they even make something with enough mechanical pressure to hold a loaded train still short of giving it square wheels?

You are talking about a 16 million pound object here.

[Acevalefor]

What provides the thousands of pounds of pressure required to hold the train still once the air pressure is gone? Inertia (at rest, stays at rest) works when it works, but the train wouldn't have run off if it was parked in a stable spot. Can they even make something with enough mechanical pressure to hold a loaded train still short of giving it square wheels?

You are talking about a 16 million pound object here.

Each wheel has its own brake. But even with each wheel on each car having a brake, It's still ~200,000 lbs. per car for a grain car and more for a liquid car. I know a tractor-trailer can, with the brakes set on the trailer (which means the air pressure was released), drag the trailer wheels without them rolling even with 60,000 lbs in the trailer. That's with pneumatic brakes on 2 axles. These train cars have brakes on 4 axles, 8 wheels. There are also cogs on the axle that are used as parking brakes. When the air pressure is released on the parking brake system which is separate from the active brakes, the cogs are blocked with a key on a rocker arm. If this system was not engaged there is a possibility that the train could have moved. It would not have been traveling 100km/h with a simple failure to set the park brake. There still would have been massive resistance from the active brakes.