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Modern Train Length

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Modern Train Length
Posted by NILE on Friday, March 26, 2021 2:50 PM

What are the limitations on train length?  I thought at one point, 115 cars was the limited due to air loss or quality of brakes.  I realize that brakes have improved over the years and with DPU locomotives provides more air sources in the middle of end of a train.

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Posted by dehusman on Friday, March 26, 2021 3:00 PM

Over 9000-10000 ft the EOTD can have trouble communicating with the head end.

Even before DP we ran trains over 115 cars so that's not a barrier.

Longest run is about 18,000 ft in the US, maybe longer in Australia.  14,000 ft is pretty common in the western US.

A bigger barrier is tonnage.  You can't exceed the drawbar strength so that limits train size on grades.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by peahrens on Friday, March 26, 2021 3:30 PM

dehusman
Longest run is about 18,000 ft in the US, maybe longer in Australia.

That's only 207' in HO, about 400 40' cars (if 45' long).  Glad I have a 5 x 9 layout because I would have to start building lots more freight cars.  I wonder how many locos I would need on the train, even with no grade.  If 25 (what is typical?) cars per loco on the flat, that would require 16.  

Paul

Modeling HO with a transition era UP bent

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Posted by selector on Friday, March 26, 2021 3:39 PM

...or two PCM Y6b's. Cool

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Posted by NHTX on Friday, March 26, 2021 3:43 PM

     Another limiting factor is the length of passing sidings.  Many railroads are lengthening them or replacing them with double or triple main tracks.  Passing siding length?  Sounds like a model railroad problem, doesn't it?

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Posted by gregc on Friday, March 26, 2021 3:47 PM

NHTX
Another limiting factor is the length of passing sidings

only if both trains exceed the siding length

greg - Philadelphia & Reading / Reading

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Posted by ndbprr on Friday, March 26, 2021 5:32 PM

And you need to take in account any hills.  Every railroad has a table that says how much power it takes to ascend the biggest grade. In railroad speak it is calledthe ruling grade. Train length can be shorter when the route is hilly. It is hard to control a train when some of it stretched going uphill while some of it is going down hill and pushing.

DrW
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Posted by DrW on Friday, March 26, 2021 6:51 PM

dehusman

Longest run is about 18,000 ft in the US, maybe longer in Australia.  14,000 ft is pretty common in the western US.

Actually, the longest trains in Australia in regular operation, transporting iron ore from the Pilbara/Hamersley Range to the coast, are "only" about 9,000 ft long, because the loaded iron ore cars are so heavy (nearly 30,000 t for a 9,000 ft train). The record run in 2001 was more than triple this size, 682 cars with a total weight of nearly 100,000 t, powered by 8 distributed GE AC6000CW locomotives.

Of course, when these trains are loaded they do not have to climb; it is either flat or slightly downhill (~ 2,000 ft in 300 miles).

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Posted by caldreamer on Friday, March 26, 2021 9:21 PM

One 2-6-6-6 Allegheney could handle a train like that.

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Posted by NHTX on Saturday, March 27, 2021 12:12 AM

     Even one train exceeding siding length can completely screw up a single track piece of railroad.  Back in 1985, Southern Pacific ran an AVLAT (AVondale-Los Angeles Trailers) totaling 0 loads, 115 empty 89'4" flats, plus caboose.  This monstrosity was pulled by three units equalling 9000-10000 HP.  I don't know what the consist leaving New Orleans or Houston was BUT, that's what they left San Antonio with.

      The Espee west of San Antonio is not a mountain railroad until you get to Paisano Pass, just west of Alpine TX.  It is a piece of railroad that does seem to always be cresting and dropping over changes in elevation continuously.  The longest passing tracks between San Antonio and El Paso were at Amistad, MP 391.4 (from Houston) 10,345 ft, Comstock, MP 413.4, 10,649 ft, and Sierra Blanca, MP 736.9, 10,425 ft.  This point is made because at approximately 11,000 feet in length, this AVLAT producing zero dollars in revenue was causing EVERY opposing movement to have to stop between the switches, so it could occupy both switches of even the longest sidings simultaneously!

     This fiasco came to a rapid resolution when it broke in two, and went into emergency, for the third and final time in the 171.1 miles between San Antonio and Del Rio, the first crew change to the west.  The crew was ordered to drop enough cars to get them under 8000 feet in length which would fit all the sidings to El Paso, at Johnstone, a passing track just east of Del Rio, and proceed  with a more managable train.

     Why did this happen?  It is one of those occurences that no one ever attaches names to--just like the night a certain dispatcher wound up with two 9000 foot trains staring at each other at an 8300 foot siding.  Anyone for a saw-by?  On a single track piece of railroad, in my estimation, siding length is the limiting factor in train length.  You can pile on the horsepower to move incredible tonnage but, space is finite, and an overly long train gums up the works.

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Posted by dehusman on Saturday, March 27, 2021 8:24 AM

peahrens
I wonder how many locos I would need on the train, even with no grade.  If 25 (what is typical?) cars per loco on the flat, that would require 16.  

On the 18,000 ft train there were 4 sets of three, one set on the point, one on the rear and one at each of the 6000 ft points.  The train was all empty containers going to the west coast from Dallas.  12 engines total.  I was told it handled (acceleration and stopping), like a 6000 ft train.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by John-NYBW on Saturday, March 27, 2021 8:43 AM

Even with my large basement (28x48) layout, I have found that a 25 car HO train dwarfs the layout. Even a with a large layout with multiple towns (I have three on my mainline) there is not that much distance between them. In addition my steepest grade is partially on a curve and that creates a lot of stress and derailments. I had designed the layout for 25 car trains but I now try to limit freights to 15-20 cars. Very short by prototype standards but they look very long on a model railroad. 

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Posted by Lastspikemike on Saturday, March 27, 2021 9:33 AM

John-NYBW

Even with my large basement (28x48) layout, I have found that a 25 car HO train dwarfs the layout. Even a with a large layout with multiple towns (I have three on my mainline) there is not that much distance between them. In addition my steepest grade is partially on a curve and that creates a lot of stress and derailments. I had designed the layout for 25 car trains but I now try to limit freights to 15-20 cars. Very short by prototype standards but they look very long on a model railroad. 

 

This is the fundamental challenge presented by model railroading. Can you evoke the long train passing through the landscape or is that just not possible?

I've acquired a Rapido Canadian with an ABA FP9 consist and ten cars. I did so because I couldn't resist it as a collectible,  but after considering the question of actually running the train I have my doubts. That's a long train even from the 50's.

 We have run a simulacrum of this train using four P1K C Liners in ABBA consist and eight cars. Sometimes we add a silver reefer or two at the head end to simulate express baggage boxcars. That's a long train on 22' x10'. We have built three parallel long passing sidings into the outside edge of our main yard, one of which is technically main line but any one of the three is suitable for mainline speeds. These are each approximately 10' long. Hmmm  three FP9 plus ten passenger cars. Is that more than 10'?

Freight trains started to get very long very soon after MU diesels made it practical. Current era trains cannot be represented even approximately and even in N scale unless the layout is ginormous. 

Also, the comment above about the effect of inserting MU consists at intervals along a very long train neatly complements another thread about where and how many pushers might be inserted and why there.

Alyth Yard

Canada

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Posted by dehusman on Saturday, March 27, 2021 10:50 AM

Part of the model train length issue is perspective.  Is the viewer a stationary observer or is the viewer the engineer moving along with the train?  If you are a stationary observer then a smaller train will look smaller, if you are the engineer then the smaller train doesn't necessarily look smaller.  The other aspect is whether or not you can see the whole train.  If the track is curved or going through scenery where buildings, trees or land forms block the view of the the entire train, then the train looks longer. 

If you can't see both ends, then you mind can't tell how long the train is.

Dave H. Painted side goes up. My website : wnbranch.com

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