Author Topic: Tehachapi Derailment  (Read 1356 times)

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John

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Tehachapi Derailment
« on: January 22, 2023, 04:50:23 PM »
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« Last Edit: January 23, 2023, 04:18:55 PM by John »

lock4244

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Re: Tehachapi Derailmet
« Reply #1 on: January 22, 2023, 05:44:35 PM »
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Interesting that it's stack cars involved in the derailment on what is nominally a general freight.

nkalanaga

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Re: Tehachapi Derailmet
« Reply #2 on: January 23, 2023, 01:06:00 AM »
+1
Unusual, but not unheard of.  I've seen a few stack cars in general freights on NS south of Kenova, WV.
N Kalanaga
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Chris333

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Re: Tehachapi Derailmet
« Reply #3 on: January 23, 2023, 03:52:34 PM »
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This one seems to be right in the middle of it:


Ed Kapuscinski

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Re: Tehachapi Derailment
« Reply #4 on: January 23, 2023, 04:33:41 PM »
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Interesting that it's stack cars involved in the derailment on what is nominally a general freight.

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John

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Re: Tehachapi Derailment
« Reply #5 on: January 23, 2023, 04:50:52 PM »
+1
Welcome to PSR

The author of the video was a signal maintainer on that stretch for many years, dating back to SP days - He states several times that he didn't see any more derailments now than in the past .. granted its anecdotal, but unless one of us digs up the records, I'd give him some credence

mu26aeh

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Re: Tehachapi Derailment
« Reply #6 on: January 23, 2023, 05:54:34 PM »
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He made mention that the train had stalled and was backing down the hill when the derailment happened.  I'm wondering if those containers were empty/light and acted as the empty centerbeams that stringline.  There were DPUs on the end.  Everything gets bunched up and the lighter cars buckle in the middle of the train

John

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Re: Tehachapi Derailment
« Reply #7 on: January 23, 2023, 06:51:46 PM »
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He made mention that the train had stalled and was backing down the hill when the derailment happened.  I'm wondering if those containers were empty/light and acted as the empty centerbeams that stringline.  There were DPUs on the end.  Everything gets bunched up and the lighter cars buckle in the middle of the train

Possible..

ednadolski

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Re: Tehachapi Derailment
« Reply #8 on: January 23, 2023, 07:26:24 PM »
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I'm wondering if those containers were empty/light and acted as the empty centerbeams that stringline.  There were DPUs on the end.  Everything gets bunched up and the lighter cars buckle in the middle of the train


I thought he said there was a broken rail...?

lock4244

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Re: Tehachapi Derailment
« Reply #9 on: January 23, 2023, 11:46:51 PM »
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He made mention that the train had stalled and was backing down the hill when the derailment happened.  I'm wondering if those containers were empty/light and acted as the empty centerbeams that stringline.  There were DPUs on the end.  Everything gets bunched up and the lighter cars buckle in the middle of the train

That's what I was intimating with my earlier comment. Intermodal cars tend to be rather light when empty relative to other equipment types, and even if carrying cans, those cans can themselves be empty or lightly loaded. My experience observing CN is that when mixing intermodal and general freight, they tend to place the intermodal behind the general freight equipment, including placing the DP between the carload and cans. CN 305 is a good example between Montreal and Toronto as it would often carry 121's (Halifax - Toronto cans) Montreal lift if 121 was running heavy (you know, over 2 miles long) and they'd always put the cans on the tail and always after the DP. Another favorite was filling EB intermodals from western Canada to Montreal with a slug of grain loads, and again these wre always placed up front behind the power, then cans after.

I also recall that after at least one incident, SOO Line banned placing empty pig flats anywhere near the front of a train. An accident investigation revealed that during an emergency brake application they found that empty 89's flats had a tendency to lift off the rails if there was too much tonnage behind them.

The above Tehachapi derailment involved stack cars, so my first thought is they may be the culprits in this accident.

lock4244

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Re: Tehachapi Derailment
« Reply #10 on: January 23, 2023, 11:48:51 PM »
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Welcome to PSR

Possibly poor marshalling... which is likely related to PSR and the need to do more with less thinking.

Tristan Ashcroft

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Re: Tehachapi Derailment
« Reply #11 on: January 25, 2023, 08:52:15 PM »
+1
I feel like at some point, "Derailment on Tehachapi" will just be one of the pinned threads...

Hawghead

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Re: Tehachapi Derailment
« Reply #12 on: January 27, 2023, 02:53:01 PM »
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The problem you have here is that if the train didn't have enough power to pull it up the hill, it sure didn't have enough dynamics to hold it backing down the hill.  That leaves using air to bring it down.  Add to this the fact that when the train stalled the engineer set the train brakes to hold the train on the hill.  Now to back it down the hill you have to release the brakes and use dynamics to control the speed (hopefully) until you pump the train line back up enough to once again set the brakes.  Then as the brakes start to set up you would have to, using asynchronous mode, transition the uphill engines to power while leaving the downhill engines in dynamics and have to balance the amount of power in each set of engines so as to maintain control of the train speed and also control the draft and buff forces in the train.  That is a pretty tricky assignment for a really good engineer that thoroughly understands the dynamics of train handling with DPUs.  Unfortunately more and more of our engineers are becoming less and less skilled due to poor training and being forced to rely on "Energy Management Systems" like LEADER and TRIP OPTIMIZER for the newer engineers and eroding skills through lack of use for our older experienced engineers.  The right and safe thing to do in this situation is for helpers to have been brought to the head end and help pull the train up the grade, or if that wasn't an option, to tie the train down, split it and double the hill.

DISCLAIMER:  This is speculation on my part as I don't know the profile of the train, what power it had or where it was placed in the train, the experience of the crew and I don't have knowledge of the territory or the operating rules and/or special instructions for that territory.

Scott 
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nkalanaga

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Re: Tehachapi Derailment
« Reply #13 on: January 28, 2023, 02:21:42 AM »
+1
Or, apply hand brakes to hold the train until the air was pumped up.  But with no brakemen today, that wouldn't be too practical.
N Kalanaga
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John

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Re: Tehachapi Derailment
« Reply #14 on: January 28, 2023, 05:53:56 AM »
+1
Or, apply hand brakes to hold the train until the air was pumped up.  But with no brakemen today, that wouldn't be too practical.

From reading everything you pro's put put there - its obvious there are a lot of physics/dynamics involved (and a lot of gut instinct from what you guys have posted) in handling a heavy train under normal conditions.  Since most of those forces are known, do the railroad traffic management computers / managers take into account those factors when they (automated?) build the train manifest for weight, grade, pulling power of the engines, etc?

The airlines have a lot of support systems that can calculate flight parameters (fuel,wind, weight, time to destination, etc) as an example. 

Some of you have mentioned the management software on the engines - I'm guessing its not there yet?

Also, whats the cost to cleanup a wreck like that vs the added "efficiency" from maxing out the train?  In the IT world, we do a Business Impact Analysis then both quantitative and qualitative assessments - for example - I choose not to buy a malware program that costs $1000 for my 100 computers. Assume that it's 100% effective.  If I have 1 incident per month, and it takes the system admin 1 hour per machine to restore it, you can quickly see that it's worth while to spend the $$$



Just curious
« Last Edit: January 28, 2023, 06:06:47 AM by John »