Maximum Grade for Regular Trains

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Maximum Grade for Regular Trains
Posted by rjemery on Friday, April 2, 2010 7:28 PM

I define here a "regular train" as one meeting no special requirements, a typical freight or Amtrak consist, with headend power no different than to be found anywhere else on North American railroads.  Helper power or slugs permitted.

1) What is the generally accepted maximum track grade on which such typical trains can operate?

2) Where is the steepest grade of any Class I road to be found?

3) For short haul or tourist trains, at what grade does cog rail and drive become necessary?
 

RJ Emery in NJ near ex-LV, PRR, RDG, CNJ & DL&W
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Posted by Paul_D_North_Jr on Friday, April 2, 2010 8:06 PM

1) For freights, I'd say about the standard maximum grade for the 19th century railroads - 2.2% or 110 feet per mile or so.  Steeper grades can be and are physically climbed, but the penalties in slower speeds and/ or reduced tonnage are so bad that they are not economic for the typical main line freight train of 100+ cars and 10,000+ tons, and hence not really practical. 

For Amtrak, the power/weight ratio is much higher, so I'd say up to 4% would be do-able - but again, only if absolutely necessary, and there is no other alternative.

Both of these are for grades long enough that the momentum of the train going into it will be largely used up, and it is up tp the pulling power of the locomotives to get up it.  For practical purposes, that would be a grade with a total rise of at least 200 ft. or so.  There were some Michigan logging railroads and maybe others that ran short grades in the 25% range, but those were by momentum - down one side of a shallow valley, race across it, and let the speed get the train to the top. 

2)  I believe it's Raton Pass, from which BNSF pulled off all or almost all of its through freights about 10 - 15 years ago, but which Amtrak still uses.  Per Al Krug's "Major Railroad Grades" webpage at - http://www.alkrug.vcn.com/rrfacts/grades.htm , the steepest Class I grade is Raton - which is why the figures I cite above for Amtrak are pretty close to Raton's - 3.5% WB for 6 miles, with a short 4%; he also mentions 3.3% EB for 7 miles.  He also includes 17 -19 miles of 3.3% on the ex-SP Siskiyou Line, and a few others over 3%, as you'll see.  Southern Rwy. had 4.7% on its Saluda grade, and the Northern Pacific has 4% at Lookout Pass, but both of those are out-of-service now, so I didn't count them. 

3)  Above 9 or 10 %, based on the performance of the Shays on the switchbacks at Cass Scenic RR on grades like that - 3 or 4 short passenger cars is about all each locomotive can get up those grades.

- Paul North. 

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by Modelcar on Friday, April 2, 2010 8:07 PM

rjemery

2) Where is the steepest grade of any Class I road to be found?

So many different answers found for this question....If you are interested in main line rail grades....and care to read about that subject....Check over on google or any good search engine:  Saluda, N C railroad grade.

Quentin

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Posted by diningcar on Friday, April 2, 2010 9:25 PM

So many variables:

How long is the grade - ruling or not?

Is it a momentum grade? Meaning excelleration is available from a a decending grade of significant distance that the acending grade can be overcome before reaching the place where gradient becomes a non factor, or a less significant factor.

is it a " one time grade " on a subdivision where helpers would not be required except for this one location (also see items above for their affect).

I am sure others will cite examples in addition to these. So these kinds of questions, while welcome because they permit further defination, do allow those with limited exposure to grasp the many complexities of railroad operations. 

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Posted by wabash1 on Saturday, April 3, 2010 4:54 AM

Paul_D_North_Jr

1) For freights, I'd say about the standard maximum grade for the 19th century railroads - 2.2% or 110 feet per mile or so.  Steeper grades can be and are physically climbed, but the penalties in slower speeds and/ or reduced tonnage are so bad that they are not economic for the typical main line freight train of 100+ cars and 10,000+ tons, and hence not really practical. 

For Amtrak, the power/weight ratio is much higher, so I'd say up to 4% would be do-able - but again, only if absolutely necessary, and there is no other alternative.

Both of these are for grades long enough that the momentum of the train going into it will be largely used up, and it is up tp the pulling power of the locomotives to get up it.  For practical purposes, that would be a grade with a total rise of at least 200 ft. or so.  There were some Michigan logging railroads and maybe others that ran short grades in the 25% range, but those were by momentum - down one side of a shallow valley, race across it, and let the speed get the train to the top. 

2)  I believe it's Raton Pass, from which BNSF pulled off all or almost all of its through freights about 10 - 15 years ago, but which Amtrak still uses.  Per Al Krug's "Major Railroad Grades" webpage at - http://www.alkrug.vcn.com/rrfacts/grades.htm , the steepest Class I grade is Raton - which is why the figures I cite above for Amtrak are pretty close to Raton's - 3.5% WB for 6 miles, with a short 4%; he also mentions 3.3% EB for 7 miles.  He also includes 17 -19 miles of 3.3% on the ex-SP Siskiyou Line, and a few others over 3%, as you'll see.  Southern Rwy. had 4.7% on its Saluda grade, and the Northern Pacific has 4% at Lookout Pass, but both of those are out-of-service now, so I didn't count them. 

3)  Above 9 or 10 %, based on the performance of the Shays on the switchbacks at Cass Scenic RR on grades like that - 3 or 4 short passenger cars is about all each locomotive can get up those grades.

- Paul North. 

Paul many years ago there was a film on the way engineers were to bring trains down saluda and every mans job for that pass. I am not sure if its on the net now but it be interesting to see what others might have thought of that film, in the film the engineer gives the throttle over to the roadforman or trainmaster and all retainers are set to either hold 20lbs or slow exhaust( i dont remeber which) and then they started down the hill with 4 big engines on the head end and 2 slaves in the middle they come down the grade and at one point there is measured lines and your train speed can not be above xxmph timed by track circuts and the crew,( the importance of check speedometers on engines) if you exceeded the limit even 1 mph it switched you to the run-a-way train ramp if your right on you get the green light and on down the grade you go. I was told they have used the ramp a few times I dont know myself.

Well being i brought it up can some of the west coast guys or maybe jeff on the bnsf do you have any grades out west where they have spacific train handling run-a-way ramps ? where they are?

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Posted by bubbajustin on Saturday, April 3, 2010 8:00 AM

What about the BNSF’s 3% on the Cajon Pass? I think the dispatcher tries to keep westbounds going around Sullivan’s Curve, and off the original 3%. The eastbounds are then given the 3% to run down.

Correct me if I’m wrong.

Justin

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Posted by rjemery on Saturday, April 3, 2010 8:46 AM

From reading the replies in this thread and from doing a little bit of additional research, it appears several places had or have grades of three percent.  Saluda, NC, is probably the steepest at 4.7 percent overall with one section 5.1 percent.

Looking at what it took to get over and down a five percent grade, I would say as a rule of thumb that was about the maximum that typical standard gauge trains could routinely handle.  Anything steeper begins to require special locomotives and smaller consists.

As for cog railways, they seem to be used for grades anywhere from eight percent to 25 percent.  Several cog systems are used for removal of ore and coal in underground mines.  Current cog systems can theoretically handle a 50 percent grade, but there are safety concerns with such a steep grade.  For grades above 30 percent, cable elevator systems come into play.

RJ Emery in NJ near ex-LV, PRR, RDG, CNJ & DL&W
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Posted by Modelcar on Saturday, April 3, 2010 1:39 PM

rjemery
Saluda, NC, is probably the steepest at 4.7 percent overall with one section 5.1 percent.

 

Yes, you are correct, Saluda did have recorded {at one location}, a 5.1%.

And....Standing at the entry up into Saluda....and looking down that grade, one really wonders how a steeper grade could be negotiated with any amount of tonnage.  Made me wonder how a 200 ton engine even made it.

Trivia:  I wonder if the Kudzu has completely taken over that section yet....?  It's been a while since it {RR}, has been active....What...back about 2001....?

Quentin

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Posted by PNWRMNM on Saturday, April 3, 2010 4:30 PM

Wabash,

I am unaware of any active line with runaway tracks still in service.  Saluda was the last to my knowledge.  The west slope of Tennessee Pass on the DRGW was 3% or better but to my knowledge never had a runaway track.

GN did at Wellington for at least part of the two mile tunnel era despite the fact that the grade was less than 2% and only about three miles long from Cascade.  There were none on the rest of the old line which was over 20 miles of 2.2% compensated descending from Wellington/Tye to Skykomish.

CPR had runaway tracks on the west side of Kicking Horse due to 4% or better grade.  They were eliminated when they put in the spiral tunnels on 2.2%, presumably compensated.

Except for Tenessee Pass, all of the existing transcontinental main lines are no worse than 2.2%, and some are much better.

Mac McCulloch

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Posted by Bruce Kelly on Saturday, April 3, 2010 5:46 PM

Justin, the 3% is on the west side of Cajon Pass, therefore it's mainly westbounds that use that track descending the hill, and eastbounds that stick with the 2.2% of the other lines when climbing. But adequately powered eastbounds can climb the 3%, and heavy tonnage westbounds are often sent down the 2.2%. With BNSF's new third main being on the 2.2% alignment, there's more opportunity to avoid the 3% when traffic levels allow it. It should be noted that 2.2% is not the maximum gradient on Main 1. Santa Fe and BNSF track charts show a short section of 2.82% for less than a quarter mile where Main 1 begins to separate from Main 3 (the 3% line, formerly Main 2) between the Cajon crossovers and Sullivan's Curve. I don't know if they were able to avoid the 2.82% when the new Main 2 was installed.

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Posted by timz on Saturday, April 3, 2010 6:35 PM

Bruce Kelly
Santa Fe and BNSF track charts show a short section of 2.82% for less than a quarter mile

Sounds like a typo, doesn't it? Seems like when they laid out the 1913 line it would have been easy enough to hold it to 2.2%, and the circa-1977 change lengthened the railroad so presumably didn't increase the grade. Does your chart show an elevation gain corresponding to 2.8% for the distance?

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Posted by Paul_D_North_Jr on Saturday, April 3, 2010 8:28 PM

That wouldn't be much of a 'delta' in the elevation: 1/4 mile x (2.82% - 2.2% = 0.62%; 0.62 x 52.8 ft. /mile = 37.2 ft./ mile) = about 8.2 ft. of an increase over that distance.  You'd think that would have been 'ironed out' over the years with the periodic resurfacings, etc.  But maybe not . . .

The ex-PRR/ CR/ now NS eastbound track No.1 at the top of the East Slope has a similar short and steep section.  Known as 'The Slide', it is about 1 mile of 2.36% as against 1.85% for the parallel westbound tracks 2 and 3 - mainly to provide about 25 or 30 ft. of clearance for the old 'Muleshoe' line to cross underneath it and join those other 2 tracks in a typical PRR 'flying junction' arrangement.  That steep section is still there, even though the Muleshoe was ripped out in the early 1980's, I believe.

- Paul North. 

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by timz on Saturday, April 3, 2010 8:52 PM

Looking at the SFe chart it doesn't look like a typo: a climb of 30.1 ft in something less than 1100 ft. If it exists it has only existed since the 1977-or-whenever-it-was change; it's mostly or all on the straight between the slight curve (total 1 degree) just above the Cajon X-overs and the big 6-deg curve that swings SWward up to what used to be Sullivan's Curve. (This is all from a pre-triple-track chart.) Anybody got any bright ideas why they would introduce it?

A 0.6% increase in grade would be fairly obvious to the naked eye on straight track, but with a curve at each end it won't be as easy to detect. With the naked eye, that is.

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Posted by erikem on Sunday, April 4, 2010 1:34 AM

wabash1

Paul many years ago there was a film on the way engineers were to bring trains down saluda and every mans job for that pass. I am not sure if its on the net now but it be interesting to see what others might have thought of that film, in the film the engineer gives the throttle over to the roadforman or trainmaster and all retainers are set to either hold 20lbs or slow exhaust( i dont remeber which) and then they started down the hill with 4 big engines on the head end and 2 slaves in the middle they come down the grade and at one point there is measured lines and your train speed can not be above xxmph timed by track circuts and the crew,( the importance of check speedometers on engines) if you exceeded the limit even 1 mph it switched you to the run-a-way train ramp if your right on you get the green light and on down the grade you go. I was told they have used the ramp a few times I dont know myself.

 

My recollection was that there was a simpler explanation for how the runaway tracks were set up on Saluda. Main point was that the switches were normally set to the runaway track, a train coming down the hill would pass a particular point on the track which would start a timer, after the allotted time had passed that corresponded to the maximum safe downgrade speed, the switch would align with the normal track and let the train descend further.

- Erik

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