On a November morning in 1994, Peter Conlo0n got a call that there had been a derailment on the Southern Pacific's Tennessee Pass in the Rocky Mountains of central Colorado. Peter takes us to the scene of the wreck in the aftermath of a disaster caused by brake failure.

http://thetracksidephotographer.com/202 ... ssee-pass/


Edd Fuller, Editor
The Trackside Photographer
http://thetracksidephotographer.com/

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I also was under the impression that retainers were set on every car in the train at the summit before descending, and then changed back at Minturn before heading west, a nuisance but necessary.

As reference regarding Tennessee Pass, Retainers and braking. The first attached file is from the Special Instruction from 2 years after the incident in SP Central Region TT No. 1 (1996). Not sure if the incident influenced these instructions or if they were in place at the time.

The second attached is from DRGW TT No. 8 (1988) which is one of the last DRGW ETT prior to SP. These instructions are certainly not as specific as those by SP.

The few times I saw trains come over the top of Tennessee Pass, they did not not stop. Whether they did a running brake test, I do not know. How effective doing a running test as your train is draped over the top of the hill is debateable. By the time one put a 10 lb set on the train, felt it drag down, released it, watched the air recover on the head end device, waited for the train to recharge, then went after the air again, you might already be in trouble.

Notice the rule regarding retainers on La Veta Pass, which was later run by yours truly while working for the San Luis & Rio Grande: Retainers on all loaded cars. No exceptions.

I always found it interesting that La Veta and Tennessee Pass both had 3% grades, but La Veta had more intense precautions.

Couldn't the running test be done before tipping over? One of our special instructions on the Lakes Division on the WP&YR is to make a running test before descending Fraser Hill at Meadows. It's about a mile of fairly level track before dropping down a 4% into some sharp curves.

It can be difficult (but not impossible) to do a running brake test at some locations where the grade abruptly transitions from going uphill to downhill with no flatter section in between. I've never been to Tennessee Pass and have never seen a track profile of that line so I can't say if this would be a concern there.

The line I spent the first decade of my career on has several such locations where you abruptly tip over a hill to start down a grade of 2% or worse. My practice in winter was to set the automatic while still going uphill or tipping over (depending on how cold and snowy it was) and then transition to dynamics as the train crested the hill, while doing around 5 mph below the speed limit, maybe slower. As I bunched the train up I would sneak a bit more air off to counteract the potential for an unintentional release, as the leakage and airflow would normally be lower on a bunched train vs a stretched one.

The worst location was the Cardinal River coal mine, whose spur has a 3% grade which goes to exactly one train length from the end of the track. So it was physically impossible to do a running brake test or warm them up in winter before descending that grade. The standard procedure there was to set a minimum application while you were stopped after loading the train, and then release the independent and start pulling. Needing low throttle to start the train meant it would brake normally, if it rolled away without any throttle you knew you would need more air than usual (needing a 14 to 16 PSI reduction from a 90 PSI charge was considered normal on that hill). After a January 2018 runaway we started doing a walking brake test and applying handbrakes on cars that would not set up before descending that grade.

https://www.tsb.gc.ca/eng/rapports-repo ... e0007.html

Around 1980 a different part of our line had a very similar runaway to the one the OP's link describes. Our rock quarry loads their train themselves using their own air supply to roll it downhill one car length at a time, and they use air brake antifreeze in their system. On this day they had for whatever reason used a substandard type of antifreeze, but did not notice as one of our famed Chinooks was blowing in and warming up the quarry site. The train behaved normally as it departed they quarry but soon entered a zone of colder air as it approached one of the aforementioned 2% grades, causing the "antifreeze" to solidify. When the engineer took air nothing happened, the train ran away and everything derailed except for the power, first car and caboose. No one was killed but they were all pretty shaken up.