The NTSB says the lack of alignment control couplers on two yard engines being handled in a long train played a role in a derailment in Alabama in 2023: https://www.trains.com/trn/news-reviews ... n-alabama/

https://www.ntsb.gov/investigations/Acc ... IR2409.pdf

I can only predict that it will be even more difficult, if not impossible, to move preserved diesels lacking alignment control couplers on Class Is in the future, unless you agree to a special "hospital train" movement.

Not just the lack of alignment control but also running the heavy cars on the rear resulting in excessive slack run-in. And, the inspector totally wiffed it on the bogus stop blocks. Those switchers shouldn't have been in the consist even if put in the consist correctly.

But you're right to worry about NS totally banning non-alignment control equipment.

To save everyone else the trouble of searching:

RMEX 6 was a former IC/ICG Paducah Rebuild GP10; RMEX 8 was a former IC/ICG Paducah GP11, originally a UP GP9B. Both had been in use for short line switching.

Didn't we have another thread on this same incident?

viewtopic.php?f=1&t=47301

My carrier still has some 4-axle yard engines without alignment control couplers and we are allowed to move one or two NACC units on the head end, subject to restrictions on trailing tonnage and DB use.

Sometimes our deadheading yard engines get marshalled in the middle of the locomotive consist instead of behind all the working units.

Thank you!

The locomotives had "stop blocks", blocks of metal welded into the coupler pocket to restrict lateral movement(i.e. swing).

The engines in question should not have been coupled together. NS rules state they should have had a spacer with alignment control between them.

There are some other 'interesting' details in the report.

Something I found interesting from an 'implied conspiracy theory' standpoint is that the 'inspector' who signed off on the movement not only claimed he knew nothing about alignment-control couplers (or kludges to limit alignment movement) but filled out the necessary report incorrectly (he checked two boxes with mutually incompatible sense). Much was made of the NS 'chain of control' not picking up on problems with the written documentation. Quietly swept under the rug (I haven't carefully gone through the NTSB docket yet) was the craft of the inspector.

The 'heavy block' on the end was apparently massively heavier than reported. The report cites "65" which I interpret as six full five-well sets, double-stacked, and one five-car well. single-stacked. Placed on the rear of a consist including, if I remember correctly, 11 cars with long-travel underframes.

Run-in in simulation was a fairly sharp 225,000lb. I got the impression that there was a sort of perfect storm/holes aligning in the cheese, with heavy dynamic as the rear of the train came off the summit, with the power entering a sharp curve just as the run-in jammed the defective alignment-control blocks sideways. The resulting shock either rolled a rail or induced the initial derailment.

Heavy damage was reported to the draft gear of the GP10 and 11 -- again, there appeared to be some question as to whether this was pre-existing damage of some sort, which to me points the finger back at the 'inspector'.

Overmod-glad to see you posting here again. I learn a lot from your posts!

What was in the paper is in agreement with what I've been told and after witnessing the aftermath of a hard shove - same principle. Alignment control have compressive rubber cushion blocks back beside the pin that that keep the coupler from slamming into the sides of the pocket. Stop blocks just make a hard limit to how far the coupler swings. That hard slamming and shove into the side of the pocket or stop block skews the car/loco. Put enough tons of force into that and you can pop a car or loco right off the track over the high rail.

Not to mention that management likes long, heavy trains and doesn't like the expense of replacing brake shoes and/or wheels. Hence, DB first always, then brakes if there's an uh-oh.