Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Built an HO triple curve mainline test track with 2” centers—surprising results

3932 views
22 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Friday, October 15, 2021 3:51 PM

Mike,

Just responded.

Rich

Alton Junction

  • Member since
    February 2015
  • From: Ludington, MI
  • 1,862 posts
Posted by Water Level Route on Friday, October 15, 2021 11:17 AM

richhotrain

 

 
Water Level Route
 

I had a blast for years running trains on 18" radius curves.  

 

 

Mike, is your PM feature working?

 

Rich

 

Not if you just sent me one.  I just tried sending you a message titled "MRR Forums".  Maybe it will work.

Mike

  • Member since
    January 2009
  • From: Maryland
  • 12,897 posts
Posted by ATLANTIC CENTRAL on Friday, October 15, 2021 11:06 AM

PRR8259

It's great that it worked for the small-ish rolling stock he tested.

2" centers are a bad idea for big mainline freight cars and big modern diesels.  i routinely have 86' boxcars and 89' flatcars/autoracks, and they like more distance between the tracks for good operation.

Where i slipped and got closer to 2" track spacing they did sideswipe.

John

 

When it comes to freight rolling stock, I guess "small-ish" depends a lot on what year it is in your imaginary little world? But my curves are big-ish, so it does not effect me. My EM1 will pass 85' passenger cars at 2" centers on 36"/38" concentric curves with no issues.

That loco is the biggest overhang in my fleet.

Sheldon

    

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Friday, October 15, 2021 10:17 AM

Water Level Route
 

I had a blast for years running trains on 18" radius curves.  

Mike, is your PM feature working?

Rich

Alton Junction

  • Member since
    March 2016
  • 1,553 posts
Posted by PRR8259 on Friday, October 15, 2021 9:44 AM

It's great that it worked for the small-ish rolling stock he tested.

2" centers are a bad idea for big mainline freight cars and big modern diesels.  i routinely have 86' boxcars and 89' flatcars/autoracks, and they like more distance between the tracks for good operation.

Where i slipped and got closer to 2" track spacing they did sideswipe.

John

  • Member since
    February 2015
  • From: Ludington, MI
  • 1,862 posts
Posted by Water Level Route on Thursday, October 14, 2021 8:07 PM

Mister Mikado
I might end up with a toy train layout look but since I love just running trains, so be it. -Rob

And I bet you'll have fun doing it.  I had a blast for years running trains on 18" radius curves. Glad to hear your plan is going to work for you.  Enjoy!

Mike

  • Member since
    September 2010
  • 400 posts
Posted by Mister Mikado on Thursday, October 14, 2021 6:14 PM

riogrande5761

Two inch centers on 18/20/22 inch curves sounds like a bad idea.  I guess the OP got lucky with his rolling stock but it would be interesting to hear how it goes in the future.  Especially with passenger cars or other rolling stock not yet tested.  Personally I would not choose the danger; even on my 32" + radius curves, I'm generally leaving 2 1/2 inch centers on curves.  In my yard, yes, 2 inch centers on the straight sections.

 

 

Thanks for your input, Rio Grande.  Those 72 foot Athearn passengers will be my longest, so I'm all set.  Anything longer would look even more silly anyway--even the cut-down Athearns' hangover is pushing it.  But due to space restrictions I don't have the luxury of prototypical curves so 22" is my max.  I might end up with a toy train layout look but since I love just running trains, so be it. -Rob

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Thursday, October 14, 2021 2:03 PM

As I have contributed a number of times to threads dealing with this matter, I have one item that is 'too wide' and one that is 'too high'.  The too high is my Trix GG1 with pantograph extended.  The too wide is my Rivarossi H-8 2-6-6-6.  In fact, that one loc is also too low in a way (driver's side injector overflow will snag on low shrubs and things lineside, especially along curves). 

Used to be the model came with two cabs, one with an extended roof extension that covers the sliding footplate between tender and cab. I damaged mine, so it has the lesser overhang.  Good thing because, on curves under about 30", that thing's gonna snag something, a tunnel portal, a passing item of rolling stock, a pole set too close.  It's articulated front end helps, but it's still a beefy beast whose front end also cuts a wide swath.  So, while others might be fine on reasonably wide curves with a fraction over 2" separation, I need something closer to 2.75".

  • Member since
    January 2009
  • From: Maryland
  • 12,897 posts
Posted by ATLANTIC CENTRAL on Thursday, October 14, 2021 11:53 AM

At my minimum of 36" radius, and given my self imposed restrictions on long rigid steam locos, 2" track centers have always worked fine for me.

Sheldon

    

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Thursday, October 14, 2021 11:04 AM

I can verify that with 2 3/8" track spacing a 2-8-8-4 will contact 85' passenger cars on 24" and 26 3/8" curves.

I know this by actual experimentation like Mr. Mikado did.

-Kevin

Living the dream.

  • Member since
    July 2006
  • From: North Dakota
  • 9,592 posts
Posted by BroadwayLion on Thursday, October 14, 2021 9:57 AM

LION wanted > 24" centers.

Him cut the table with 24" curves so that each track laid would be wider than that.

Him assumed 26", 28", 30" and 32". (Him runs four track main lions.)

 

Well that didn't work the way I planned: I ended up with sharper curves than watt was intended. Still, with 50' subway cars these curves offer no problems, even with all ten trains running at once.

 

Yeah... Right... Like I can really get up there these days.

Gotta put an elevator in that building.

ROAR

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Thursday, October 14, 2021 9:13 AM

DSchmitt

 

 
Mister Mikado
my longest passenger cars, Athearn 70 footers, and even my gs64 and gg1 and 2 10 2 Santa Fe and E8s ever touched or got touched by another car.

 

What would happen if you had 85' cars?

 

 

For a passenger car, the overhang on the inside of the 22" curve would increase by .17".

Lots of 85' cars won't work on 22", 20" 18".

 

Ed

  • Member since
    February 2015
  • From: Ludington, MI
  • 1,862 posts
Posted by Water Level Route on Thursday, October 14, 2021 9:12 AM

Lastspikemike
Luck had nothing to do with it. Testing is what worked.

You're saying he didn't get lucky that he did not have equipment that wouldn't pass his test?  That would seem to suggest that any equipment would work on curve spacing of that dimension if you just test it first.

Mike

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Thursday, October 14, 2021 9:05 AM

Lastspikemike

Luck had nothing to do with it. Testing is what worked.

Isn't the NMRA recommended minimum spacing something like 2 1/16" anyway?

 

 

No.

 

Ed

  • Member since
    June 2007
  • 8,892 posts
Posted by riogrande5761 on Thursday, October 14, 2021 6:04 AM

DSchmitt
 
Mister Mikado
my longest passenger cars, Athearn 70 footers, and even my gs64 and gg1 and 2 10 2 Santa Fe and E8s ever touched or got touched by another car.

 

What would happen if you had 85' cars? 

Two inch centers on 18/20/22 inch curves sounds like a bad idea.  I guess the OP got lucky with his rolling stock but it would be interesting to hear how it goes in the future.  Especially with passenger cars or other rolling stock not yet tested.  Personally I would not choose the danger; even on my 32" + radius curves, I'm generally leaving 2 1/2 inch centers on curves.  In my yard, yes, 2 inch centers on the straight sections.

Rio Grande.  The Action Road  - Focus 1977-1983

  • Member since
    September 2003
  • From: California - moved to North Carolina 2018
  • 4,422 posts
Posted by DSchmitt on Thursday, October 14, 2021 1:29 AM

Mister Mikado
my longest passenger cars, Athearn 70 footers, and even my gs64 and gg1 and 2 10 2 Santa Fe and E8s ever touched or got touched by another car.

What would happen if you had 85' cars?

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

I don't have a leg to stand on.

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Wednesday, October 13, 2021 10:39 PM

Mister Mikado
I built a test track on a tabletop board and rolled all my longest cars and engines through in every combination.  I expected many sideswipes but was shocked to discover that none of my longest passenger cars, Athearn 70 footers, and even my gs64 and gg1 and 2 10 2 Santa Fe and E8s ever touched or got touched by another car.

This is great news.

A simple experiment is always the best.

-Kevin

Living the dream.

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Wednesday, October 13, 2021 7:50 PM

Let's not let the passenger car off the hook, here.  It was using up 1/4" of the clearance itself.

Since rolling stock is about 1 1/2" wide, 2" centers leaves 1/2" clearance.  Passenger cars hang "inwards" an extra quarter inch on that 32" curve.  So if your equipment on the inside curve does the same "outwards", you hit.

 

Ed

  • Member since
    May 2002
  • From: Massachusetts
  • 2,899 posts
Posted by Paul3 on Wednesday, October 13, 2021 7:09 PM

On my old layout, I had 30" inside curves and 32" outside curves.  I experimented with my 85' passenger cars (longest cars) and my engine roster.  Turns out that the worst offender was my brass NH 2-10-2 on the inside track.  The cab overhang would scrape a passenger car going the other way on the outside track.  All I had to do was widen the track spacing on the curves by 1/8" and I was all set.

  • Member since
    December 2002
  • From: US
  • 39 posts
Posted by fisherdm on Wednesday, October 13, 2021 5:39 PM

Lastspikemike

That implies that closer track centres would work for parallel tangent tracks....closer to prototype in fact. 

I laid my (HO) staging yard with tracks at 1 3/4" on center. The tighter spacing allowed me to get 6 tracks onto an 11 inch shelf. Since only one train comes or goes at a time, there's no sideswipe issues at the entrance. Removing and replacing rolling stock isn't quite as easy, but I use a rerailing ramp for that. No problems with the equipment contacting each other.

Dan

  • Member since
    September 2010
  • 400 posts
Built an HO triple curve mainline test track with 2” centers—surprising results
Posted by Mister Mikado on Wednesday, October 13, 2021 2:12 PM

Hi all, my HO layout plan called for an 18" radius mainline with 20.25" r and 22.5" mainlines built out beyond that with flex track, following the 2.25" minimum rule.  But then I decided to go with 22" snap track leaving me with no choice but run a 20" r flex track in between if I wanted 3 train operation.  I worried about where the three mainlines curved in one spot so I built a test track on a tabletop board and rolled all my longest cars and engines through in every combination.  I expected many sideswipes but was shocked to discover that none of my longest passenger cars, Athearn 70 footers, and even my gs64 and gg1 and 2 10 2 Santa Fe and E8s ever touched or got touched by another car. Closest they got was 1/8" inch apart and that's good enough for me.  Made my day!  -Rob

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!