An Incident Report re String Lining.
http://www.tsb.gc.ca/eng/rapports-reports/rail/2015/r15v0003/r15v0003.asp
Stoney Creek Bridge.
SECOND Arch added later to accommodate heavier power.
http://static.panoramio.com/photos/large/19972692.jpg
Another Stoney Creek Bridge Tadanac, B.C.
https://kootenaymodelrailway.files.wordpress.com/2012/09/img_4003.jpg
Thank You.
Wow!
The more you read this report, the more things jump out at you. In a way, this is an even more dramatic concatenation of small decisions into ultimately inevitable disaster than Lac Megantic. (Again, a couple of the more fascinating aspects being a RTC making really bad decisions, and insufficient training or policy.)
Note the very small changes in so many things that would have solved this “before it happened” – and the understating of the forces involved. (I will take a risk here, and note that a good derailment detector with notice to the train crew would have identified the stringlining while still going uphill with the 24th traction motor cut out.)
Something that isn’t identified in the report is precisely what happened after the train started backing down. I read between the lines a bit to speculate that the resistance of the stringlined derailed cars exceeded the gravitational potential of the train behind the derailment point, and the crew applied backing power to get the reverse move started more briskly down to wherever they were going to start their ‘run’ on the grade, but in the picture I see, the well cars appear to be still visibly stringlined. Is there a picture of the point at which the air line actually parted?
Reading this, I was not impressed with fobbing off notification of TrAM violations on the crew, when so clearly providing both the relevant information and a computer program to analyze it to the RTC environments is so simple and straightforward. (The business with converted AEIs further confirms this to someone with knowledge of data harmonization.)
I also note – trusting it will not be abused – that the track across the bridge is indicated as being on rolled plates with flexible securement (I take this to be Pandrol fixation on wood ties, as at Fabyan Bridge) and no rail anchors. I am n
It sounds to me as if there was a fatigue problem when writing this report. There is no indication that this string lining occurred as the train was pulling up the grade. So where did the tensile force come from that caused the string lining?
From the report:
“While operating past Fraine towards Stoney Creek, train 199 continued to lose speed as it climbed the grade. At 0505, the train crew advised the RTC that they were at Mile 76.6 and that train speed was now at 1 mph owing to the steep grade. Shortly thereafter, the train came to a stop on a 8.75-degree right-hand curve, with the head end of the train at the west-end bridge abutment of the Stoney Creek Bridge. To continue up the grade, it was decided to cut in the 24th driving axle. After an unsuccessful attempt to pull the train up the hill, the RTC issued train 199 a Rule 577. Train 199 was therefore authorized to back up (that is, down the hill) until it was on a tangent track where the grade was not as steep. The train would then make another attempt at cresting the grade.
As the train was backing up, an undesired emergency brake application occurred. Once the train came to a full stop, the conductor exited the locomotive to inspect the train. It was determined that 6 platforms from 2 empty intermodal flat cars had derailed on the Stoney Creek Bridge. The crew advised the RTC of the situation. There were no injuries, and no dangerous goods were involved.”
This description s
How would you recover the equipment in that location? I don’t see how you could get any heavy equipment to it. I was also thinking “just cut 'em loose” and let them fall, but it’s my understanding that you can’t release couplers if they are under tension, and if you were able to release them, you’d have to release both ends simultaneously to keep them from pulling more cars down. Maybe I’m thinking about this too much.
The report does not specifically identify when the cars stringlined. I wonder if they had already derailed when the train stalled, then the air line finally broke as the back-up move added to their displacement.
If the train was still on the grade, the tensile force exists whether the train is moving forward or backward. At these low speeds, the tensile forces are essentially the same if the train is not accelerating, and could go to zero only if the train was in free-fall.
Anthony V.
I can see that there would be a high tensile force if a train were standing on a grade with the automatic brake released and holding the train with just the independent brake. I wonder if that alone has ever caused a string line derailment. I always associate the excessive force that causes a string line derailment as being caused by the pull of the locomotive against just the inertia of the cars during accelertion; or by pulling against the resistance of a rising grade.
But if this derailment was caused by the gravitational tensile pull of the train, I don’t clearly see what circumstances led to that outcome. In backing down the grade, the train would have to be restrained by braking. Automatic brakes would apply to all cars, so fundamentally, there would be no tensile stress.
However, if they were restraining the descending train with dynamic brakes, then there would be considerable tension in the train, particularly if the dynamic brake force were increased at any point during roll back do
The report clearly says that the stringlining occurred pulling uphill, likely BEFORE the 24th traction motor was cut back in. They hypothesize that the train stoppage was actually caused by the increased resistance of the stringlined cars, not the steeper grade. I did not see any discussion of how long the train was in the process of ‘pushing back’ before the unexpected brake application, or what the actual failure that caused this application was; both are moot given the issue.
It might be interesting to go back retrospectively and consider whether any aspect of the flexible rail securement system might have contributed to this incident.
I think maybe the U.D.E. caused the derailment… the train was stopped and the brakes were released so that it could start backing down the grade. The Engineer started backing the headend engines before the brakes on the rear cars were fully released so the train started to bunch. Then the rear cars started moving as the brake releasing drop in pressure reached them. Because there is no “gradual release” of train brakes and the rear cars are on a downgrade they are rolling free. Some car toward the head end dynamites and causes loss of brake pipe pressure, re-applying the brakes on the cars, but the propagation delay along the train line causes the cars at the head end to stop, but the cars at the rear are still rolling free and have enough momentem and weight to string-line the empty well-cars on the curve.
[quote user=“Euclid”]
AnthonyV
Euclid
It sounds to me as if there was a fatigue problem when writing this report. There is no indication that this string lining occurred as the train was pulling up the grade. So where did the tensile force come from that caused the string lining?
If the train was still on the grade, the tensile force exists whether the train is moving forward or backward. At these low speeds, the tensile forces are essentially the same if the train is not accelerating, and could go to zero only if the train was in free-fall.
Anthony V.
I can see that there would be a high tensile force if a train were standing on a grade with the automatic brake released and holding the train with just the independent brake. I wonder if that alone has ever caused a string line derailment. I always associate the excessive force that causes a string line derailment as being caused by the pull of the locomotive against just the inertia of the cars during accelertion; or by pulling against the resistance of a rising grade.
But if this derailment was caused by the gravitational tensile pull of the train, I don’t clearly see what circumstances led to that outcome. In backing down the grade, the train would have to be restrained by braking. Automatic brakes would apply to all cars, so fundamentally, there would be no tensile stress. <
Okay, I see the clarification under the section called “The Accident”. The train string lined just before stalling while pulling up grade. The air stayed connected, so they did not realise they were on the ground. Then upon reversing to back down the grade, the string lined, derailed cars apparently jacknifed and parted the air line, thus causing the “Emergency” application, which they refer to as an undesired emergency application. Then the conductor went back and found the derailment.
So it was actually a derailment that occurred in two separate stages. One stage was string lining going up the grade, and the other was jacknifing while backing into the derailed string lined cars while attempting to back down the grade for another run at it with the 24th traction motor cut back in.
No, because I see no indication of jackknifed cars at all, and even a little tension release would likely cause some of the well cars in the illustration to fall.
I got a pretty good laugh out of the TSB working their ‘angled coupler’ logic for a bunch of articulated well cars, the antithesis of long cushioned-underframe draft gear angularity… might be interesting to conduct a modeling of the mechanics of stringline derailment on the leading vs. trailing wheels (larger diameter) of the intermediate articulated three-piece trucks in these well car sets.
So much has changed since the ‘Good’ Old Days.
Thank You.
The ‘old ways’ are unknown today, not forgotten they aren’t even known.
What is meant by “cut in the 24th driving axle”?
Thanks.
Anthony V.
Individual traction motors on locomotives can be removed from electrical loading by the crew when necessary to comply with rules. Restoring a traction motor to loading that had previously been cut out would be considered having it ‘cut in’ again.
It’s in the report. In order not to exceed permissible ‘pull’ on the train, the engine crew derated the consist by cutting out one traction motor, hence the ‘23 axles’ going up the grade. When the train stalled, the crew was given authorization to cut that additional motor back in to try to get the train moving.
Thanks guys.
Yes, it is in the report. I don’t have any idea how I missed it.
Anthony V.
I was only referring to jacknifing to the extent that it took to part an air hose. But I see your point that upon shoving back, a car may have just dropped out of the string and fell, which caused an air hose to part. However, the string lining happened with the cars under tension. When the train then stalled, what would the engineer do with the brakes at that point? Could he hold the train with just the idependent brakes or would he set the automatic?
If he set the automatic, I would expect the backup move to begin by releasing the automatic, which would maintain the tension of the stall. But I suppose the cars ahead of the string line would release and shove back into the string lined cars with buff force.
Considering that possiblity, it is hard to imagine how those cars can be hanging in mid air like they are.
If the train stalled on it’s own, the engineer ‘should have’ felt gravity start to pull the train back down the grade if all brakes were released at the time of the stall. If the train didn’t respond much to gravity that would be an indication that part of the train was off the rails and did not have a normal response to gravity.
Once the engineer decided the train was stalled (whether it was moving or not), upon reducing power the train brake should have been applied with a service application, while the crew (and their superiors) decided what the next actions would be. Had the decision been to double the grade, the Conductor would begin walking back along the train to determine and/or identify where the cut was going to be made and to apply sufficient hand brakes on the portion of the train that was going to be the 2nd movement so that it would stay where it was.