Minimum track radius for storage siding

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Minimum track radius for storage siding
Posted by rluke on Thursday, May 31, 2018 8:09 AM

What would be the minimum radius for a curve on a storage siding?  Siding would be used for 85 ft. coaches and would include a turnout and a "S' curve.  I know that curves are not normally expressed as a radius but that's how I have to draw them with my CAD system.  Don't worry - I am not doing the final plans - just seeing what fits for now.-   thanks

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Posted by Overmod on Thursday, May 31, 2018 10:02 AM

A few considerations before the professionals pile on:

A critical thing may be the permitted lateral swing of the draft gear on the reverse of the S curve: there will be a hard limit in swing under buff/compression, and another for recoupling should the pin be pulled and knuckles separated under lateral load.  At least theoretically you've got the ability to pull using a chain or heavy cable between knuckles should the swing be insufficient and derailments threaten; it's more difficult to arrange a shove under those conditions.

Do NOT have one end of the S curve, even if spiraled, immediately abut the end of the reverse curve.  I'd put at least one full carlength between the two, and I suspect more is better.

Watch your vertical curvature and any small pinch points in gauge or curvature that may develop in settlement after the track is laid.  This may be difficult to keep on top of, 'practically' but it is easy to forget and the consequences can bite you just when you least need biting.

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Posted by tree68 on Thursday, May 31, 2018 11:11 AM

That S curve thing is what will complicate your curvature requirements.  You may be looking at some pretty high numbered switches, too.

I found a conversion site that might help you if you find numbers in degrees: https://www.easycalculation.com/engineering/civil/railroad-curve-calculator.php

Your best bet here on the forum will be Mudchicken.

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Posted by mudchicken on Thursday, May 31, 2018 11:43 AM

(1) You had better have at least 85-100 feet of tangent between those reversed curves in that storage track. Long cars with trucks reversed in both directions is a capital bozo no-no. (You will be popping trucks and wheelsets over the rails or possibly rolling the rail over.)

(2) The old rule was 12 degree 30 minute (459.28 feet) with exceptions up to 15 degrees, but that was before 89 Ft flatcars, shelf couplers and locomotives with limited throw drawbars (GE's are really bad! as in they suck-especially the fiberglass bricks masquerading as passenger engines)... Ten degree curves (573.69 ft) are about the acceptible limit now.

If a common carrier railroad is going to switch this stuff, you had better study their industry track standards carefully. Don't be surprised if your redline plans look like a mass casualty event after railroad review - Most civil engineers can highway, but they can't railroad worth a nickel. (Unless you have special versions of MicroStation, your software can't railroad either. ) Watch your clearances too!

Turnouts are dependent on the railroad (whose standard are you using?)...You would be smart to use a #10 or # 11 turnout  (equivilent degree of curve 6d 05'14"/941.69' or 5d 01'50"/1139.32' respectively)....and don't start curving behind the frog until you are off the long ties.

Happy brain damage!

(betcha discover you have a whole lot less room than you thought)

 

...and what are you coming out of? (PDN, DC and I know where we can "cheat", but only if we have to. Minimizing consequences is a really good thing with track layout....Jeff, Zugs, LC, EdB,LARG et al can all probably tell you horror stories about bypassed knuckes and other switching horror stories in extreme track geometry)

 

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by VOLKER LANDWEHR on Thursday, May 31, 2018 11:56 AM

Perhaps a look at the CSX Standard Specification for the Design and Construction of Private Sidetracks may help: https://www.csx.com/index.cfm/library/files/customers/industrial-development/site-design-guidelines-and-specifications/

Table 2 on page 14 shows the main requirements. Minimum length between two reverse curves is 100 ft.

I must admit that I haven't searched the standard for any railcar limitations.

Each railroad has its own specifications.
Regards, Volker

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Posted by mudchicken on Thursday, May 31, 2018 12:10 PM

Volker - You would be surprised how many civil engineers and surveyors get lit up by railroads when they submit plans and proposals and think they understood the industry sidetrack minimum standards. (wish I had the red ink concession on some that I see with what I do.) 

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by rdamon on Thursday, May 31, 2018 1:02 PM

Interesting line in the CSX link ...

While a maximum curvature of 10º (radius of 573.69’) is highly recommended, under no circumstance without written approval of the Assistant Vice President Engineering - Design and Construction, will the degree of curvature for the track exceed 12º (radius of 478.34’).

 

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Posted by rluke on Thursday, May 31, 2018 1:35 PM

This is some good information and yes I am finding out how much room it is going to take and it's better to find out now if the track will not fit.  One advantage is that this track will be within our yard limits so no host railroad special requirements to consider. I am going to take some time to digest all of this. - thanks thanks thanks

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Posted by VOLKER LANDWEHR on Thursday, May 31, 2018 1:37 PM

mudchicken
Volker - You would be surprised how many civil engineers and surveyors get lit up by railroads when they submit plans and proposals and think they understood the industry sidetrack minimum standards. (wish I had the red ink concession on some that I see with what I do.)

I do not pretend that I understand the standard. I stumbled across them sometime ago when searching for something else.

I thought they might provide some information to check what fits into the OP's space.
Regards, Volker

As said before I haven't checked them for any limitations

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Posted by mudchicken on Thursday, May 31, 2018 1:55 PM

rdamon

Interesting line in the CSX link ...

While a maximum curvature of 10º (radius of 573.69’) is highly recommended, under no circumstance without written approval of the Assistant Vice President Engineering - Design and Construction, will the degree of curvature for the track exceed 12º (radius of 478.34’).

 

 

A lot of this evolves out of practical experience - the question in the end for special cases is "is it worth the extra hassle?" ....

When I was roadmaster in LA for ATSf, the engine facility at Hobart was designed to service only end cab switchers. #6 1/2 Turnouts were OK* for that and it fit in the limited space. Then AMTRAK happened. Then First Street roundhouse and engine facility were given to AMTRAK.  All engine servicing moved to Hobart. Warts and all, Hobart muddled along with SD-40-2s and SD45s plus the bigger GE c30-7s and C36-7s squeeking through those tiny 6-1/2 turnouts and ties soaked with spilled diesel fuel.  Along come the third generation diesels and all hell breaks loose (and I become aware of how limited coupler/drawbar throw gets and derailments with rolled over rail gets to be a regular event and gage rods everywhere Ick!Ick!Ick!) - funny how the EMD and GE technical services people vanish overnight from Hobart..except when it's one of their test sets with dynamometer car attached with beaucoup extra wiring spaghetti attached between units on the ground Mischief)....Ah, The bad old days. (Amtrak at First Street started having similar issues)

 

(*) no room for a #8 or #10 turnout.Sigh... talk about outgrowing a facility! and the Supt. did not want to see cause of derailment: Limited drawbar throw/ rolled over rail. (much less the delay and extra hostelers needed while one of the engine facility leads was out of service.)

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by mvlandsw on Thursday, May 31, 2018 9:03 PM

   The B&O Pittsburgh & Western subdivision now being run by the Allegheny Valley RR has a 14 degree curve on the main track. We didn't have any problems running long heavy trains through it. Amtrak also used the track for a time.

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Posted by Paul_D_North_Jr on Thursday, May 31, 2018 9:16 PM

rluke
. . . One advantage is that this track will be within our yard limits so no host railroad special requirements to consider. I am going to take some time to digest all of this. - thanks thanks thanks 

The restrictions/ limits are from physics and the resulting geometry, not just host railroad special requirements, which are based on their experiences.  The derailed equipment is not going to care whether the paint on the loco and cars is Santa Fe, Amtrak, or yours. 

"+1" to everything mudchicken said about the practical standards - better than I could. 

- PDN. 

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by BaltACD on Thursday, May 31, 2018 10:33 PM

mvlandsw
   The B&O Pittsburgh & Western subdivision now being run by the Allegheny Valley RR has a 14 degree curve on the main track. We didn't have any problems running long heavy trains through it. Amtrak also used the track for a time.

B&O and Chessie for a number of years had restrictions on Hi-Cube Covered hoppers 4750 cuft and greater.  If a train containing them could not exceed 25 MPH it had to reduce speed to no more than 10 MPH when operating through curves of 6 degrees or greater.  The P&W up Bakerstown Hill became at 10 MPH railroad.

The restriction was a function of the rocking coupled with 39 foot rail joints.  Since the railroad has been relaid with welded rail and all the low joints have been surfaced out - the restriction was removed before the P&W was sold jointly to the AVL and B&P.

         

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Posted by rluke on Saturday, June 02, 2018 8:57 AM

I am just starting to digest all of this good information.  I should have put more details about the purpose of the storage track in my original post.  The proposed track will be used for 4 or 5 coaches that will be taken out of service. They are currently taking up space on our acitve sidings. -  We may be able to push them in one at a time.  -  thanks again

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Posted by mudchicken on Saturday, June 02, 2018 10:51 AM

Watch your long car - short car combinations...

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by cx500 on Sunday, June 03, 2018 12:16 AM

If I recall correctly, turning loops at a couple of Canadian passenger facilities had a degree of curvature about 16 degrees.  Possibly the entry and exit had at least a short easement.  You most definitely don't want a reverse curve without at least a car length of tangent between them.

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Posted by BaltACD on Sunday, June 03, 2018 8:51 AM

rluke
I am just starting to digest all of this good information.  I should have put more details about the purpose of the storage track in my original post.  The proposed track will be used for 4 or 5 coaches that will be taken out of service. They are currently taking up space on our acitve sidings. -  We may be able to push them in one at a time.  -  thanks again

Coupled long cars on tight curves create tremendous leverage against the track structure - the leverage to roll the rail over and derail the movement.

         

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Posted by Paul_D_North_Jr on Sunday, June 03, 2018 10:20 AM

mudchicken
Watch your long car - short car combinations... 

Empty/light cars are more prone to derailment from train forces - esp. pushing - than loaded/ heavy ones, too.  

Just for fun, after this past Christmas I took some photos from directly above of the 'long' Lionel aluminum passenger cars, with 1 on a tangent and 1 fully in a curve (roughly a 60 ft. long car on a 72' radius curve!).  The couplers met at the P.C. (P.T.) - the spot where the curve ends and the straight track begins.  Although (because?) the couplers are truck-mounted, the angle between them was extreme.  Even if they had been frame-mounted, the angle and displacement between the carbodies was also extreme.  For comparison, I then took photos with both cars in the curve.  In that symmetrical condition, the couplers pointed at each other - still at an angle, but nowhere near the displacement that was seen at the curve/tangent point.  None of this is news to those of us in the business, but for the 30 minutes or so it took it was the best illustration I've seen of the condition.  (Credit to the late John H. Armstrong for his explanantions and diagrams, too - https://kalmbachhobbystore.com/product/book/12148 ).- PDN. 

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by rluke on Monday, June 04, 2018 9:25 PM

Mudchicken

  One of the coaches is shorter than the rest.  What should we be looking for when it's paired with a longer coach ?   thanks

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Posted by mudchicken on Tuesday, June 05, 2018 7:38 AM

Ideally it oughtta be first in and last out, had better not be too light in a shoving situation against heavier cars. (or it's gonna go up and over the curve rail)...some are worse than others (like cabeese) depending on coupler/drawbar throw binding in curves, especially  reverse curves causiing L/V force issues like what PDN was saying.

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by tree68 on Tuesday, June 05, 2018 1:00 PM

Our baggage car (used as an "open air" car) is about 10 or so feet shorter than our coaches.  I don't recall that we've ever had any issues with it.

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Posted by BaltACD on Tuesday, June 05, 2018 1:33 PM

tree68
Our baggage car (used as an "open air" car) is about 10 or so feet shorter than our coaches.  I don't recall that we've ever had any issues with it.

Are you dealing with curvature near the maximum amount of curvature that the equipment can be operated on?

         

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Posted by mudchicken on Tuesday, June 05, 2018 1:34 PM

Wouldn't be as big an issue as say an 85' coach and a 35' caboose in compression.

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by SD70Dude on Tuesday, June 05, 2018 2:52 PM

Long car-short car combinations are bad in freight trains too, and there are restrictions on how they may be marshalled in a train in relation to each other.

I cringe whenever I see a baby tank car or sand hopper coupled to a autorack.

Greetings from Alberta

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Posted by BaltACD on Tuesday, June 05, 2018 2:56 PM

SD70Dude
Long car-short car combinations are bad in freight trains too, and there are restrictions on how they may be marshalled in a train in relation to each other.

I cringe whenever I see a baby tank car or sand hopper coupled to a autorack.

Long cars make a hell of a lever at the coupling - short car not a much of a lever.

         

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Posted by tree68 on Tuesday, June 05, 2018 5:16 PM

BaltACD
Are you dealing with curvature near the maximum amount of curvature that the equipment can be operated on?

Don't know the specs on either - just noting that we've never had a problem that I know of in the yard or on the line.  The caboose we occasionally haul around can be a pain, though - it's a little B&M caboose.  

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Posted by dpeltier on Thursday, June 07, 2018 10:24 PM

If you can get access to the AREA / AREMA _Manual of Railway Engineering_ from any time after 1984, look in Chapter 5 section 3. There's more than half a page on reverse curves in yard tracks, with some pretty specific guidance. It might be a little bit aggressive for long passenger cars.

Dan

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Posted by rluke on Monday, June 11, 2018 9:41 PM

Still digesting all of this. Lot of things to consider.  Thanks for all of the great information.

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Posted by mudchicken on Monday, June 11, 2018 10:07 PM

Happy brain damage .... I hope, if this is what I think it is, you have some idea of what trackwork you get to start with is coming from. (Ex B&O/Valley Railway?) 

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by erikem on Tuesday, June 12, 2018 12:51 AM

dpeltier

If you can get access to the AREA / AREMA _Manual of Railway Engineering_ from any time after 1984, look in Chapter 5 section 3.

Obnoxiously minor nit pick here... In my 1995 edition, the info is in Chapter 5 part 3 - more specifically page 5-3-12.1 - good find. There are some more comments on yard and industrial tracks in Chapter 5 part 4.

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