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Old 07-19-2013, 07:36 AM   #46
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Re: Train derails. Blows up half a ****ing town in Quebec

I'm confused then about why they leave one engine running? Seems like a pretty big inefficiency in a company that was clearly all about cutting costs wherever it could.

Edit: I don't mean to come off like I'm doubting you. I'll take real experience over the media any time - I'm just curious to figure out how it actually works.
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Old 07-19-2013, 11:35 AM   #47
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Re: Train derails. Blows up half a ****ing town in Quebec

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I'm confused then about why they leave one engine running? Seems like a pretty big inefficiency in a company that was clearly all about cutting costs wherever it could...
In North America, the kinda diesel engines used are a PITA to start, and they run without anti-freeze. For these reasons, they are designed to, and SOP calls for them, to be kept running 24/7. Also, a time consuming safety test is required on start-up, which takes twice as long with the one man crew.
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Old 07-19-2013, 11:56 AM   #48
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Re: Train derails. Blows up half a ****ing town in Quebec

Except the report is that 4 engines were turned off and only 1 was kept on. If its more efficient to keep them running I'd assume they would all be left on.
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Old 07-19-2013, 12:27 PM   #49
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Re: Train derails. Blows up half a ****ing town in Quebec

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Except the report is that 4 engines were turned off and only 1 was kept on. If its more efficient to keep them running I'd assume they would all be left on.
I didn't see that, TYVM! Newer engines are indeed designed to be turned off. If only one was left running it would have been left running primarily to keep the brake air-pressure line charged.
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Old 07-19-2013, 12:59 PM   #50
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Re: Train derails. Blows up half a ****ing town in Quebec

MD - Ok? I'm not sure what your point was then.

Edit: MD - I read your post as "I didn't say that" and not "I didn't see that". So I think I'm on the same page as you now.

Anyway - I found the following image that explains the brake situation pretty well to me (and it seems like the media reports are probably correct).


Last edited by jjshabado; 07-19-2013 at 01:04 PM.
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Old 07-19-2013, 05:29 PM   #51
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Re: Train derails. Blows up half a ****ing town in Quebec

The explanation of the brakes in a stable state is misleading.As you can see from the diagram there is no method for air to pass from the brake line to the brake cylinder whilst it is like this so whether the loco is running or not doesn't matter.
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Old 07-19-2013, 05:30 PM   #52
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Re: Train derails. Blows up half a ****ing town in Quebec

The first two recommendations from the TSB are for more stringent handbrake regulations and for better procedures for securing driving cabs.
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Old 07-19-2013, 07:06 PM   #53
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The explanation of the brakes in a stable state is misleading.As you can see from the diagram there is no method for air to pass from the brake line to the brake cylinder whilst it is like this so whether the loco is running or not doesn't matter.
Everything I've read, including some train forums, talk about air bleeding off over time. Although some people think someone might have triggered something in the engine that empties the air pressure.
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Old 07-19-2013, 07:26 PM   #54
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Re: Train derails. Blows up half a ****ing town in Quebec

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Everything I've read, including some train forums, talk about air bleeding off over time. Although some people think someone might have triggered something in the engine that empties the air pressure.
Yeah the air bleeds off from the brake cylinder over time, but that has nothing to do with the loco running or not.

The other thing is that you shouldn't be depending on the air brakes to hold the train anyway so if they were they weren't operating safely who/whatever caused the air brakes to release.Our procedure for stowing a train is you put on the required number of handbrakes, then you release the train and loco brakes and apply power.If you can move the train you have to put on more handbrakes.You then apply the air brake and shut the loco down.The air brakes are a bonus not a necessity to hold the train in place.

With the TSB recommending changes to securing cabs on stowed trains , it will be interesting to see if that was because someone did something in there at the time of the fire or whether it just noted that the companies procedures didn't include this as they were looking at them.
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Old 07-19-2013, 09:12 PM   #55
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Yeah the air bleeds off from the brake cylinder over time, but that has nothing to do with the loco running or not.
Sure it does. If the loco is running its actively maintaining the pressure in the line. That seems to be stated in many different places do in inclined to believe it.


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The other thing is that you shouldn't be depending on the air brakes to hold the train anyway so if they were they weren't operating safely who/whatever caused the air brakes to release.Our procedure for stowing a train is you put on the required number of handbrakes, then you release the train and loco brakes and apply power.If you can move the train you have to put on more handbrakes.
I was surprised when I read this in other places too. Seems a bit flawed since you really don't know your margin of safety with this method - you just know that you have enough holding power.

Seems like after you can't move the train you should apply another 10% (or whatever) hand brakes to make sure you have a margin of error in holding power.

Someone pointed out that it's possible (although unlikely) that the engineer did this procedure but ended up with just barely enough stopping power at that time. During the fire the train could have been shifted or changed in some way that now there wasnt quite enough holding power.

It'll be interesting to see if the blank box type device can or does show if the engineer performed the braking test you described.
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Old 07-19-2013, 09:58 PM   #56
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Re: Train derails. Blows up half a ****ing town in Quebec

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Sure it does. If the loco is running its actively maintaining the pressure in the line. That seems to be stated in many different places do in inclined to believe it.




I was surprised when I read this in other places too. Seems a bit flawed since you really don't know your margin of safety with this method - you just know that you have enough holding power.

Seems like after you can't move the train you should apply another 10% (or whatever) hand brakes to make sure you have a margin of error in holding power.

Someone pointed out that it's possible (although unlikely) that the engineer did this procedure but ended up with just barely enough stopping power at that time. During the fire the train could have been shifted or changed in some way that now there wasnt quite enough holding power.

It'll be interesting to see if the blank box type device can or does show if the engineer performed the braking test you described.
Look at the brake diagrams you posted and see what happens when you either add or remove air from the brake pipe and you will see that potentially adding air by having the loco running isn't going to keep the brakes on.

With regard to checking if you have enough handbrakes on I believe that the force of the loco/s trying to pull it is greater than the other forces that the train will be subject to ( gravity etc.) so the margin for error is built into the test.You then add loco handbrakes and wheel chocks on top of that and then train is going to stay where you put it.

The black box should show whether a test like this was done and also if any alterations were made to the control settings afterwards.
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Old 07-19-2013, 10:12 PM   #57
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Look at the brake diagrams you posted and see what happens when you either add or remove air from the brake pipe and you will see that potentially adding air by having the loco running isn't going to keep the brakes on.
The engine isn't adding pressure it's maintaining it (so effectively only adding air to counteract whatever leaks out) . That's why the diagram says to maintain static pressure you need the engine on.

I'm not trying to be difficult but literally everything I have read says the same thing.
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Old 07-19-2013, 10:58 PM   #58
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Re: Train derails. Blows up half a ****ing town in Quebec

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The engine isn't adding pressure it's maintaining it (so effectively only adding air to counteract whatever leaks out) . That's why the diagram says to maintain static pressure you need the engine on.

I'm not trying to be difficult but literally everything I have read says the same thing.
The air produced maintains the brake pipe pressure at whatever it is set for, if you don't have that because the loco is turned off the pressure in the brake pipe will reduce due to leaks and if you look at the diagrams reducing the brake pipe pressure leads to the brakes applying.

Last edited by andyhop; 07-19-2013 at 11:27 PM.
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Old 07-19-2013, 11:52 PM   #59
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Re: Train derails. Blows up half a ****ing town in Quebec

Maybe I have found an answer to the confusion

An American driver was suggesting that it is possible for the loco brakes to bleed off after the engine was shut down as these unlike the wagons do use main reservoir air to directly maintain their effectiveness and for some reason tend to leak more than wagon brake cylinders,I guess that that is a possibility if the driver didn't follow or the company didn't have safe procedures in place.

So instead of having enough handbrakes applied to hold the train he had enough handbrakes whilst the loco brakes were on fully to hold the train.Turn off the train and a bit of leakage from the loco brakes releasing them slightly could have been enough to let it roll.The loco handbrakes would either have to have not been applied or the train was so finely balanced that having one bogie on each loco with brakes on rather than all of them was enough to set things in motion.

A bit like the chance that someone moved the brake handles when shutting the train down ,applying enough handbrakes and testing you have done so would have prevented this becoming a problem.
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Old 07-25-2013, 04:59 PM   #60
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Re: Train derails. Blows up half a ****ing town in Quebec

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Meh, that would require being able to foresee human error.
Yeah, then the human error would be in the HR department.

Or something something, CEO's fault.

Last edited by Hardball47; 07-25-2013 at 05:04 PM.
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