NS train 34A derailed on the Horseshoe curve. It was a guaranteed derailment.
A ten minute calculation shows the head car will tip over every time.
A three unit consist of SD70ACes operating in notch 8 at 10 mph makes about 400,000# TE. (you can get the speed by timing the Virtual Railroading youtube video and TE = HP x 308/speed)
An 80' centerbeam car operating on a 9 degree curve has a portion of that force trying to tip the car over. 400,000# x sin(4) x 33/12 (coupler height) =76,700 lb-ft.
The weight of the car trying to keep the car upright = 62,000# (lt wt)/2 x 56"/2/12 (distance of car centerline to rail) = 72,300 lb-ft.
(https://www.bnsf.com/ship-with-bnsf/ways-of-shipping/equipment/pdf/73Centerbeam.pdf)
Over she goes!
Just plain stupid railroading.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmannd Over she goes! Just plain stupid railroading.
Thanks for the explanation.
On another thread participants have laid blame for the incident on various people. Who do you think is ultimately reponsible for the accident?
If the engine crew had pointed out the problem in Altoona, do you think it is probable that management would have over ruled them?
JPS1 oltmannd Over she goes! Just plain stupid railroading. Thanks for the explanation. On another thread participants have laid blame for the incident on various people. Who do you think is ultimately reponsible for the accident? If the engine crew had pointed out the problem in Altoona, do you think it is probable that management would have over rulled them?
If the engine crew had pointed out the problem in Altoona, do you think it is probable that management would have over rulled them?
I do not think it is probable that management would have overruled the train crew and commanded that they run the defective train. That's a fine narrative to show how stupid management is, but where is the proof that it actually happened?
The more likely scenario is that an error was made in the train makeup, and it just ran that way with nobody realizing the problem until it stringlined.
Bucky on this one I think you are correct. The simplest explanation is often the true one.
I ran some calculations for the tractive effort algorythm. It is pretty close for DC engines, but is way off (too low) for AC engines.
Caldreamer
Euclid JPS1 oltmannd Over she goes! Just plain stupid railroading. Thanks for the explanation. On another thread participants have laid blame for the incident on various people. Who do you think is ultimately reponsible for the accident? If the engine crew had pointed out the problem in Altoona, do you think it is probable that management would have over rulled them? I do not think it is probable that management would have overruled the train crew and commanded that they run the defective train. That's a fine narrative to show how stupid management is, but where is the proof that it actually happened? The more likely scenario is that an error was made in the train makeup, and it just ran that way with nobody realizing the problem until it stringlined.
If a train meets a railroad's established standards for train make up, they'll tell you to take it as is. Even if a train's make up meets the standard, there can be potential problems. Some people may see it, some don't. If there is minor deviations, they may give you initials of the okaying manager to take it as is. For us, that decision to deviate can't be made by a local manager. It has to come from someone higher up the food chain.
A lot of those managers aren't necessarily stupid, but it's becoming commonplace for them to have very limited, if any, real-world field experience. When all you have to go by is the "book", that's what you'll go by. Plus the fact, that they too, are under the gun to be more effecient and productive. Maybe more so because they can be replaced easier than agreement people.
Jeff
I know nothing about the physics and mathmatics of the problem. I simply looked at the picture and said "I bet I know what caused this!".
Thanks to Chris / CopCarSS for my avatar.
JPS1 oltmannd Over she goes! Just plain stupid railroading. Thanks for the explanation. On another thread participants have laid blame for the incident on various people. Who do you think is ultimately reponsible for the accident? If the engine crew had pointed out the problem in Altoona, do you think it is probable that management would have over ruled them?
There should be rules in the ETT and airbrake instructions on this kind of thing.
It's likely the train crew was apprehensive, asked the dispatcher who checked with the power desk, who checked the tonnage ratings for the consist and said "okay", so no helpers.
The churn and reduction of managment over the past decade or so has left the door open for lots of things like this.
I'm waiting for an improperly handled long DPU train to scatter over the landscape because of poor training/poor train consist/poor train handling. NS is moving outside it's envolope of experience in places with the new plan and I don't think there is much simulator training going on these days.
jeffhergertIf a train meets a railroad's established standards for train make up, they'll tell you to take it as is.
I think those "standards" in this case, have been lost. Nobody should be pulling a merchandise train up Horsehoe with 3 AC units in run 8 at 10 mph. It's a wonder they didn't pull a knuckle first.
Conrail had a tonnage limit for trains w/o helpers. NS apparently, has lost it.
oltmannd jeffhergert If a train meets a railroad's established standards for train make up, they'll tell you to take it as is. I think those "standards" in this case, have been lost. Nobody should be pulling a merchandise train up Horsehoe with 3 AC units in run 8 at 10 mph. It's a wonder they didn't pull a knuckle first. Conrail had a tonnage limit for trains w/o helpers. NS apparently, has lost it.
jeffhergert If a train meets a railroad's established standards for train make up, they'll tell you to take it as is.
I suspect PSR has eliminated it.
Never too old to have a happy childhood!
oltmanndA three unit consist of SD70ACes operating in notch 8 at 10 mph makes about 400,000# TE. (you can get the speed by timing the Virtual Railroading youtube video and TE = HP x 308/speed)
Actually, it was two 70aces and one 70m-2. Still a lot of TE, but a little less than 3 ACs.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
BaltACD:
You are correct. I checked and the only trailing tonnage restrictions over the Horsehoe Curve are for intermodal cars.
caldreamerBaltACD: You are correct. I checked and the only trailing tonnage restrictions over the Horsehoe Curve are for intermodal cars.
My understanding from acquaintances still employed by CSX are that a number for Train Handling Restrictions were eliminated by EHH with his implementation of PSR. CSX has paid the price several times.
Those restrictions were not just 'grabbed out of the air' - they were formulated after recurring incidents indicated that those things that were now being restricted had caused the prior derailments. Of course one of the first acts of PSR, as EHH implemented it on CSX, was to eliminate all institutional historical knowledge by terminating numerous (if not all) Operating Officials on most if not all territories.
day 1 in training we were told the rules were written in somebodys blood, true. also train restrictions usually are written after a accident such as derailments, srtinglining. i know of 1 good example, managment tried to eliminate a crew start, they put a fully loaded rail train ahead of 6000 trailing tons, on a major grade, the locomotives slipped on a greaser, a kunkle broke within the rail train, bad enough, managment had crew shove back to hitch train back together after nuckle changeout, crew did as ordered, laurl and hardey couldn't have done better, use your imignation what happened, new rule, no trailing tonage on loaded rail trains.
oltmanndAn 80' centerbeam car
.
caldreamer I ran some calculations for the tractive effort algorythm. It is pretty close for DC engines, but is way off (too low) for AC engines.
Why would the tractive effort of a DC locomotive be different than that of an AC locomotive?
BigJim oltmannd An 80' centerbeam car Can you prove to me that there was actually an EIGHTY FOOT centerbeam car in the consist? I've never seen one that long and I definately am not seeing one in the published videos.There was a stringline derailment like this years ago on the Hagerstown Dist. without any long cars involved. If I am not mistaken, it was due to an undesired emergency brake application back near the rear of the train.
oltmannd An 80' centerbeam car
Can you prove to me that there was actually an EIGHTY FOOT centerbeam car in the consist? I've never seen one that long and I definately am not seeing one in the published videos.There was a stringline derailment like this years ago on the Hagerstown Dist. without any long cars involved. If I am not mistaken, it was due to an undesired emergency brake application back near the rear of the train.
The UDE in the rear of the train exponentially increased the trailing tonnage by setting the brakes on the rear before the application could propagate to the head end.
JPS1 caldreamer I ran some calculations for the tractive effort algorythm. It is pretty close for DC engines, but is way off (too low) for AC engines. Why would the tractive effort of a DC locomotive be different than that of an AC locomotive?
The why's require the expertise of a electrical/mechanical engineer - that I am not. However, the AC's have a more effective wheelslip control set up than to DC's.
The reality is that DC's have less tractive effort than AC's of the same power and axle configuration. On CSX's Baltimore Belt Line grade (Howard Street Tunnel) a CW44AC is rated for 4900 tons, a CW40DC (EVO's) is rated 3600 tons (note CSX derated the 4400 HP the engines were purchased with to 4000 HP for fuel economy savings).
JPS1Why would the tractive effort of a DC locomotive be different than that of an AC locomotive?
Several reasons, the most important of which is that there can be essentially zero derating of the motors both right down to 'locked rotor' zero-speed operation and to avoid wheelslip above the 'microslipping' that gives best creep control. DC locomotives would require wildly more capable cooling arrangements, probably including sprayed coolant in the blown air, even to approximate what a good induction motor fed a properly-synthesized waveform can do.
The matter of adhesion limit is also a bit different, although I'll leave it up to Erik to make the electrical arguments comprehensible in English. DC motors typically 'cut power' in some way to accomplish creep control; AC drive can react in different ways that keep full nominal excitation strength active but keep wheelslip from propagating.
We can discuss the pros and cons of larger wheels if those aren't already known to you.
BaltACD ... note CSX derated the 4400 HP the engines were purchased with to 4000 HP for fuel economy savings
Interesting that NS seems to have done just the opposite. As I recall it, their dash-9-40W locomotives were delivered from GE with the 4000hp nominal rating 'for fuel savings', but with a simple override switch that would let them develop the 4400hp on demand; NS subsequently uprated quite a few of them between 2013 and 2015, but I believe kept the -40 designation on the cab to maintain the class distinction for parts and support.
Did CSX adopt the same electronics for their derating program as GE provided in the NS C40-9Ws, and can the derating be 'overridden' as easily if wanted?
The 73' centerbeam I found to use for my estimate is 80' over the pulling faces, which is what counts in this case.
zugmann oltmannd A three unit consist of SD70ACes operating in notch 8 at 10 mph makes about 400,000# TE. (you can get the speed by timing the Virtual Railroading youtube video and TE = HP x 308/speed) Actually, it was two 70aces and one 70m-2. Still a lot of TE, but a little less than 3 ACs.
oltmannd A three unit consist of SD70ACes operating in notch 8 at 10 mph makes about 400,000# TE. (you can get the speed by timing the Virtual Railroading youtube video and TE = HP x 308/speed)
I should have caught that. Actually my 10 mph speed estimate is probably off by more than the TE difference...
Well, it is and it isn't. It depends on how fast you are going, for the most part.
At 20 mph, there wouldn't be any difference. It's just force x speed = power since you are nowhere near the adhesion limit and thermal limit (DC only) of the propulsion system. The AC locomotive might give a bit more since it's electrical transmission system probably has less losses (I think...).
At low speeds, the AC unit can give you full HP down to lower speeds because it's adhesion is better (35% you can count on). Best you might get from DC is 27%. AC adjusts the frequency to match speed. DC has to react to slip by backing down main generator excitation which is slower due to the nature of the machine (inductive windings resist current change)
DC motors also have thermal limits which stop high TE levels from being produced for very long even when available adhesion is good.
Overmod BaltACD ... note CSX derated the 4400 HP the engines were purchased with to 4000 HP for fuel economy savings Interesting that NS seems to have done just the opposite. As I recall it, their dash-9-40W locomotives were delivered from GE with the 4000hp nominal rating 'for fuel savings', but with a simple override switch that would let them develop the 4400hp on demand; NS subsequently uprated quite a few of them between 2013 and 2015, but I believe kept the -40 designation on the cab to maintain the class distinction for parts and support. Did CSX adopt the same electronics for their derating program as GE provided in the NS C40-9Ws, and can the derating be 'overridden' as easily if wanted?
According to http://www.nsdash9.com/roster.html all of NS' Dash 9's were uprated to 4400 HP and reclassified as D9-44CW's between 10-2013 and 09-2014. However, not all of the units have had their external model designation lettering updated to reflect the internal changes. If I recall correctly, this was done during NS' 2014 meltdown in an effort to boost their system velocity numbers. NS uprated their DC GEVO fleet and reclassified them as ES44DC's at the same time.
My 2 cents on the AC versus DC.
The two chief advantages of an AC induction motor is a much more rugged rotor (conductors are uninsulated bars vs insulated wires) and inherent almost constant speed operation (DC series motor speed can increase dramatically with loss of load). The former is good for higher continuous tractive effort and the latter is good for better adhesion.
A further advantge of modern AC locomotives is indivdual control of the motors, so power reduction could be limited to the motor that is slipping as opposed to reducing power to the whole locomotive.
Response time of the DC series motor is limited by the inductance of the field winding limiting how fast the the motor current can be varied, a DC shunt motor (e.g. original AEM-7) can respond faster. Ultimate limit for response time for an AC motor is roughly the period of the highest frequency that will provide full power output of the motor.
Erik_MagThe two chief advantages of an AC induction motor is a much more rugged rotor (conductors are uninsulated bars vs insulated wires) and inherent almost constant speed operation (DC series motor speed can increase dramatically with loss of load). The former is good for higher continuous tractive effort and the latter is good for better adhesion.
All weather adhesion rating for AC units is around 35%. For DC units with computer based wheel creep control, about 27-28%. Non-wheel creep (Dash 2, 7 Series), 18-21%.
You want to dispatch trains on what you can count on, day in and day out.
oltmanndThe 73' centerbeam I found to use for my estimate is 80' over the pulling faces, which is what counts in this case.
BigJimCan you prove that even a 73' centerbeam was in the derailment?
They were definitely centerbeams, although the length could be debated.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
BigJimHas NS said anything about the cause of the derailment or are we to just take your word for it?
They haven't and probably won't say much. Your choice if you want to beleive what I've laid out or not.
You ever had a full tonnage train with three 4000 HP locomotives running in notch 8 at 10 mph on a 9 degree curve with an 80' empty head out? Where and when?
https://www.mrc-rail.com/project/centerbeam/
https://www.bnsf.com/ship-with-bnsf/ways-of-shipping/equipment/pdf/73Centerbeam.pdf
https://www.csx.com/index.cfm/customers/resources/equipment/railroad-equipment/
https://www.up.com/customers/all/equipment/descriptions/centerbeams/index.htm
Standard centerbeam cars are 73' between the bulkheads. A 73' centerbeam car is 80' 6-1/2" between pulling faces. There are 61' centerbeam cars still rolling around, but these are not the current standard.
Our community is FREE to join. To participate you must either login or register for an account.