Western Railroad Discussion > BNSF Ditching HPT

"Effective October 2, 2023, Locomotive Horsepower values used in assigning locomotives and determining horsepower per ton (HPT) calculations will be changed. BNSF will now use tractive horsepower (THP) and tractive horsepower per ton (THPT) values."

Honestly I am glad to see the old and out dated HPT method go away.  UP did away with HPT over a decade ago.  It works well if you have a single or similar type of locomotive for the majority of your fleet however this is not case with BNSF.  Under the old HPT method a ES44C4, (4400HP) with only four traction motors, would have a higher tonnage rating that a SD70ACe (4300HP) with six traction motors, and a GP60 (3800HP) four axle, would have a higher tonnage rating than a SD40-2 (3000HP) six axle.  Now that's ridiculous.  A few years ago I saw a 14,000 ton ethanol train with a Dash 9 up front followed by a GP60M and another Dash 9 as a DP.  With a one percent ruling grade, the HPT may look fine at 0.9, however you better hope it doesn't rain.  With the new ET44ACH's and ES44ACH's starting to show up, it wouldn't surprise me if BNSF starts Increasing tonnages with AC locos system wide in the name of "fuel conservation".  Six years ago a 6000 ton Q train would run with 3 motors online and all notches. Now days that same Q train would would have to isolate a locomotive and would have a Notch 7 restriction.  With this new THP method for calculating train tonnage you could see that same Q train running with only a single ET44ACH.

They are finally realizing that a ES44C4 doesn't pull like a ES44AC?

Ted Curphey
Ontario, OR

This is all pretty funny. We as railfan could have told thme this years ago. You'd think that the fiasco 25 years
ago of putting GP60s on the 199 would been evidence that HP does not directly equate to TE.

Out 

So HPT may "work" for DC locomotives but not on AC locomotives. Does that sound somewhere near right?

PHall Wrote:
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> So HPT may "work" for DC locomotives but not on AC
> locomotives. Does that sound somewhere near right?

It depends upon what you're looking for.

If you want to get a target moderate-high speed (e.g. 60 mph) HPT/percent grade is the way to go. It even works for a target low speed (e.g.20 mph) HPT/percent grade is usually still the way to go.

If you want to know how much the engine will pull and the wheels still turn even if you need a chalk mark to tell - TE is the way to go.

TAW

callum_out Wrote:
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> This is all pretty funny. We as railfan could have
> told thme this years ago. You'd think that the
> fiasco 25 years
> ago of putting GP60s on the 199 would been
> evidence that HP does not directly equate to TE.

If I recall that was a problem with EMD's wheel slip system. Similar Class 500 GE's did just fine.

Or was there another fiasco which I missed?



Edited 1 time(s). Last edit at 10/02/23 18:06 by ts1457.

Nope, that was the one, happened when the 199 stalled in the rain while all the SF West Coast brass sat
atop the hill on the 3751 trip.

Out 

funnelfan Wrote:
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> They are finally realizing that a ES44C4 doesn't
> pull like a ES44AC?

The UP use a system of "Equivalent Powered Axles" and rates them less than a Dash-9.

C44/45AC = 12.1 epa
C44-9W = 11.5 epa
ES44C4 = 10.5 epa

-18_lbs

Their THPT formula said that three of the new AH's could pull a coal load over Palmer Lake. It stalled. Twice.

Posted from Android

Instead of lowering HP values on C4s and clapped out Dash9s they just raised the HP ratings for ACe and 44AC engines to claim they can pull more with less. Hopefully this won't last long.

Posted from iPhone

JerryShepardini Wrote:
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> Instead of lowering HP values on C4s and clapped
> out Dash9s they just raised the HP ratings for ACe
> and 44AC engines to claim they can pull more with
> less. Hopefully this won't last long.
>
> Posted from iPhone

i read the form C explanation as a excuse to run even less power or lower throttle restrictions. 

Make it up until failure. “AKA” fake it until you make it.

Pretty much sums up PSR.

Regards

Posted from iPhone

slug96 Wrote:
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> Their THPT formula said that three of the new AH's
> could pull a coal load over Palmer Lake. It
> stalled. Twice.
>
> Posted from Android

Wasn't one of the problems was that the units ran out of sand?

Pacific5th Wrote:
-------------------------------------------------------
> i read the form C explanation as a excuse to run
> even less power or lower throttle restrictions. 

Correct. Someone rearranged the metrics so it looks like they're saving money and get a big bonus.

PHall Wrote:
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> So HPT may "work" for DC locomotives but not on AC
> locomotives. Does that sound somewhere near right?

on the SP used the formula.. HPT 12000 total horsepower divided by 6000 tonage equals 2  times 12  24  divided by the grade 2 percent  equals 12mph  would give us the speed up Tehachapi..  with a GE you would minus 1 mph.. the new AC motors are roughly 1 1/2 times a DC.  Always used the comparison with the oil train. With DCs would take 5 units on the headend 6 unit helper to get up Vincent and Newhall hill.   When the ACs were new would take 2 ACs on the headend and 2 ACs on the rear to get up the hill..  The ACs would grind up the hill at 6 to 9 mph . 

PHall Wrote:
-------------------------------------------------------
> slug96 Wrote:
> --------------------------------------------------
> -----
> > Their THPT formula said that three of the new
> AH's
> > could pull a coal load over Palmer Lake. It
> > stalled. Twice.
> >
> > Posted from Android
>
> Wasn't one of the problems was that the units ran
> out of sand?

Yes. Then the next week they ran it again. They made sure it had sand this time. It stalled at the same place as it did the week before. Fire up the 2nd motor, still couldn't get it going. Had to back up to Spruce and get a running start at it.

There was a rough calc that it should take 550K of TE to get the train over the hill, well the new heavies should be capable
of 180K at 12 mph on good rail so if you follow the "promised" the 3 units should make it. Wel..........

Out 

Are all these calculations based off factory-new locomotives or are allowances made for a loco that's not pulling like it used to?

Chuck

 

RailDawg Wrote:
-------------------------------------------------------
> Are all these calculations based off factory-new
> locomotives or are allowances made for a loco
> that's not pulling like it used to?
>
> Chuck
>
>  

"Not pulling like it used to" is necessarily variable...no way to plan for it, so no the power bureau makes no such allowance, but we in the field are well aware that a clapped out locomotive can't pull what it once could. So when we stall and the dispatcher asks why we have to explain. 

I think it was a lot simpler in a pure DC world than it is now.  ATSF seemed to 'get it' with pouring on massive amounts of HP/ton to handle relatively shorter trains at track speed, the 199/991 in the 70's was typically 3 six-axle 3600HP F/FP45's or SD45-2's and around 18 piggyback flats and 90mph.   Fuel was cheaper then.   And you passed stuff on I40 across New Mexico.  And unless something went horribly wrong, no priority train every died on the road without somebody somewhere having a really bad day.

Now with AC, wheel slip, A1A truck again with sophisticated weight transfer, and all the 'stuff' monitoring it, it's a lot more complex.   But while I'm convinced AC does absolute miracles on low-speed TE without frying traction motors, you still have a lot of the same problems getting over the road without enough basic HP above the frame to get out of your own way.     The calculations are great, but a good experienced power desk that can make the call and a dispatcher that 'gets it' are better.    Limping upgrade at walking speed is better than stalling, but it's a really thin margin for error.



Edited 2 time(s). Last edit at 10/05/23 06:07 by randgust.