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Ain't Built For Speed

There are other things that could use a bit of hurrying, like medical fitness for duty standards and the National Transportation Safety Board, but those two have proven themselves so resistant to urgings, proddings, cris du coeur, that they've almost worn me down. Almost.

Oh...and then there's love. The Supremes said you can't hurry love. They're probably right, but that doesn't prevent anyone from falling into it, love, at a rate of acceleration greater than that reached when bungie jumping, which, bungie jumping, seems to be an appropriate metaphor for what falling in love does to your head, your stomach, and the loose coins you forgot to remove from your pockets.

So the NTSB released its report on the August 2, 2017 derailment of CSX train Q38831 at Hyndman Borough, Pennsylvania. Three years and four months... after the event. You can't hurry love.

Now the report concludes that the derailment was caused by a flange-climb in a curve with a descending grade. The probability of the flange-climb was increased by: the make-up of the train of 178 cars, where 36 of the 42 head cars in the consist were empties, followed by a block of 44 loads, with the rear 92 cars carrying 79 loads.

Swallow hard and whisper, "train make-up."

The flange-climb was facilitated by the CSX practice of authorizing train crews to apply hand brakes to the freight cars before descending in order to control acceleration.

This train's crew made use of that authorizationn and traversed, or attempted to traverse this "one of the steepest grades in the CSX system" (page 15). So we have 120 loads, 58 empties, with empties clustered at the head end, on a curve of 8+ degrees on a grade with 33 hand brakes applied to the first 40 cars in the consist.

Does this sound like a recipe for disaster? I'd say it's a Michelin-starred recipe for disaster.

What's missing here? Built up tread, generated by sliding the wheels due to the hand brake application, with the metal migrating into the throat of the flange, change the contact angle between wheel flange and gage face of the railroad? Not missing for long, that's for sure. Built up tread was found on the initial car to derail and I'll bet it was present on every car that had a hand brake applied.

How about curve wear to the gage face of the high rail in the curve? Bullseye, Catnip! Strip my gears and call me shiftless. The secret ingredient to turn this melange of mistakes into an award winning wreck, curve wear to the high rail in the curve. Sure enough, there was curve wear.

Now I have never heard of a railroad authorizing, as a part of regular, daily operations, the application of hand brakes to control the speed of a train on the main track when air and dynamic braking is available. And I hope I never hear it again.

I've heard of the use of retainers. Never had to use them myself, flatlander that I am, but I've heard from the experience of others that retainers should be used judiciously, wisely, and with limitations-- like selecting "slow direct" rather than high pressure retain; like not "bunching" the set retainers in one section of the train, thereby increasing in-train forces; like releasing the retainers as soon as possible on the cars where activated, and if a second application was necessary, selecting different cars in order to avoid.......built up metal. All of that makes sense to me, but I already told you, I'm a flatlander.

Can I indulge in just a few remarks about hand brakes and certain practices on certain railroads?

Sure I can.

So first, WTF? What is going on? I mean, it appears that (some) Canadians have never considered using handbrakes to secure a train awaiting a crew on the main track, even when the train has obvious problems with the air brakes. And here, CSX allows train crews to apply hand brakes to assist the retarding efforts of the train's air and dynamic brakes when a train is moving? Are you looking to pull the train apart, derail it, stringline the cars around curve?

Is it just me? Did, as Ripley asked, IQs drop sharply while I was away? Does anyone remember standing there as your road train started to pull out of the yard, checking for stuck handbrakes? Remember being eaten alive by mosquitos in summer or frost forming on the inside of your forehead in winter while you did this? I do.

NTSB makes a determination for the cause of the derailment:

...the probable cause of the accident was the inappropriate use of hand brakes on empty rail cars to control the train speed and the placement of blocks of empty rail cars at the front of the train consist, leading to elevated longitudinal forces and increased lateral forces at the wheel-rail interface at the curve in the rail

That sounds reasonable, but here's the thing. When we're talking about longitudinal and lateral forces, elevated and increased longitudinal and lateral forces, we're talking quantities, quantifiable values. We're talking thresholds. We're talking about measurements that predict the violation of safe operating thresholds.

We have to see and know the numbers to know what the limits are and to determine minimum safe operating standards.

This is the "data driven" approach that FRA has adopted, establishing minimum safe operating standards based on the analysis of conditions and forces present in actual train movement.

This also might be, in my opinion, why our industry has been so reluctant to adopt the "risk reduction" or "system safety" approaches that don't provide hard operating limits.

I don't think "minimum safe operating standards" are sufficient by themselves, for the operating officers of a railroad, but I do think these standards are necessary requirements to be established by the railroads' regulator.

We have to know what we are capturing in our operating conditions in order to establish new methods for assessing the risks, and we can't do that without having certain universal standards.

NTSB in its post accident analysis states:

The NTSB Office of Research and Engineering conducted a study of the train forces leading up to the derailment. Calculations were made using the force required for the recorded motion distributed between the cars based on the recorded tractive effort and brake pipe pressure with normal brake behavior, with hand brakes added.

The ratio of lateral to vertical force (L/V) is an important contributor to derailment.

OK, so where is the study? Where are those calculations? Those calculations are not in the NTSB's docket of evidence for this investigation, and those items are critical. In fact, I would call them "vital"-- just as important as the accident report itself.

The ratio of lateral to vertical force is indeed an "important contributor to derailment" and that ratio needs to be presented and explained.

Well sure, L/V, the famous Nadal's limit, can get complicated as our studies of wheel-rail interface get more thorough, but the ratio, and its variables can be explained, even to someone of my non-engineering background. Just remember to not be frightened by all the symbols and equations. That's just vocabulary, a means of indentifying the various forces.

There are a number of simulation programs that will do the calculating for you, and even provide an animation of the wheel set movement in response to the changing lateral, vertical and longitudinal forces. There's NUCARS®, VAMPIRE®, GENSYS, Universal Mechanism, to name a few.

TTCI did that for Metro-North in 2008, using NUCARS.

You can instrument the track and the vehicles and record the forces in real time. Strain gauges cost more than a dime a dozen but not that much more. FRA and the Volpe Institute were more than generous with time and effort and connected us with Susan Kristoff back in 199? She oversaw the instrumentation of our test site and developed the application that turned the data into intelligible L/V ratios sorted by time, direction, axle and wheel numbers.

Alas, NTSB doesn't provide the numbers and that's a problem if we're going to press forward with the issue of train make-up and the segregation of cars in trains by weight, loaded vs. empty, in addition to blocking cars by destination. What, where, and when are excessive forces being generated? How can I abate them, other than by running trains carrying exclusively empty or loaded cars, or exclusively loaded cars on the head end and empty cars on the rear?

I'm not sure that I disagree or don't disagree with NTSB's determination of cause. NTSB missed something, something critical and obvious to even the casual observer. NTSB says in its study:

Calculations were made using the force required for the recorded motion distributed between the cars based on the recorded tractive effort and brake pipe pressure with normal brake behavior with handbrakes added.

Normal brake behavior? There was no normal brake behavior. On page 12 of the Mechanical Group Factual Report included in the docket of evidence, we find this:

The evening of August 3, 2017, a Class 1 Brake Test and Mechanical Inspection was conducted at the CSX yard in Cumberland MD of the leading (east end) 31 cars of train Q38831 that did not derail. Investigators observed 13 defective/non-complying air brake conditions according to 49CFR 232.103(f3). Eleven of the cars did not apply brake cylinder pressure or did not maintain brake cylinder pressure after applied.(underline added)

Really? Really. So really, NTSB's study of forces under conditions where the brakes are operating properly is.....not applicable? Irrelevant? Non-determining? Eleven out of the 31 head cars did not have properly functioning air brakes? Maybe that might have generated some excessive in-train forces? Ya think?

NTSB made three recommendations to CSX concerning the make up trains, train handling, etc. It omitted a fourth that should have been first. Make sure the damn air brakes work. Maybe your crews won't be tempted to use hand brakes.

David Schanoes

December 12, 2020

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dmschanoes@ten90solutions.com