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Why could narrow gauge have tighter curves?

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Why could narrow gauge have tighter curves?
Posted by hgodling on Sunday, December 8, 2019 12:03 PM

One of the typical rationale for narrow gauge is that it could handle tighter curves. However, it is much harder to find rationale for that. 

The only real benifit I can determine is a reduction in flange contact (wheel climbing derailment) 

The narrow gauge also used smaller equipment, but that doesn't seem like a reason to change gauge. You could just smaller equipment at lower speeds on standard gauge. 

 

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Posted by BigDaddy on Tuesday, December 10, 2019 12:21 PM

I disagree with your premise.  Britain settled on a standard gauge in 1846, but at the time, there was also a Broad gauge of 7'

The US didn't settle on a gauge until 1886.  It wasn't a matter of changing gauge, in the US, it was pick a gauge.

Smaller cars meant lighter rail, less expense all the way around.  It was about the money not about the radius of the curves.

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Posted by RR_Mel on Tuesday, December 10, 2019 12:44 PM

The SP built a logging railroad for logging in the southern New Mexico mountains in 1900 and used narrow gauge rails with standard gauge width.  Some of the curves were very tight but most were very large radius.
 
They went with light rail because they weren’t using heavy equipment.  The heaviest locomotives were four truck Shays that climbed the 4.2% to 6% mountain grades, all standard gauge with light weight rails.
 
 
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Posted by selector on Tuesday, December 10, 2019 3:27 PM

hgodling

One of the typical rationale for narrow gauge is that it could handle tighter curves. However, it is much harder to find rationale for that. 

The only real benifit I can determine is a reduction in flange contact (wheel climbing derailment) 

The narrow gauge also used smaller equipment, but that doesn't seem like a reason to change gauge. You could just smaller equipment at lower speeds on standard gauge. 

 

 

Because the gauge loading was somewhat smaller, you didn't have to clear the same width of right-of-way as you would have done for standard and wider gauges.  This saves a TON of money.  Your crossties can be shorter....even more money saved.  With more slender gauge loading, you can have sharper curves to get around things you'd rather not displace or dig around, and it helps to obviate tunneling.  Even more money saved.

Of course, your rolling stock and locomotives are also smaller, on average, which reduces material costs and erection costs, including finishes.

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Posted by dknelson on Tuesday, December 10, 2019 4:08 PM

hgodling

One of the typical rationale for narrow gauge is that it could handle tighter curves. However, it is much harder to find rationale for that. 

The only real benifit I can determine is a reduction in flange contact (wheel climbing derailment) 

The narrow gauge also used smaller equipment, but that doesn't seem like a reason to change gauge. You could just smaller equipment at lower speeds on standard gauge. 

 

The real thing is that the narrow gauge ROW was so much cheaper to build in many ways - rail was lighter, ties were smaller, tunnels and bridges were smaller and less heavily engineered.  Cuts and fills were less important - just let the little trains rise and fall with the land.  Sharper curves were just part of the advantage.  Smaller drivers on steam locos meant slower speeds and shorter rigid wheelbases, hence tighter curves were possible.  More to the point, a railroad could be built where curves would have to be too tight to be practical for standard gauge.  The Tweetsie and the Colorado lines are examples.  

John Armstrong in his book Creative Model Railroad Design, Ch. 2 "Layout Design as Influenced by Scale and Gauge," made the case for modeling the Maine 2 foot gauge in a very large scale, 7/16" scale.  He has an interesting illustration that imagines if two locomotives used the same gauge of track: a C&O Allegheny 2-6-6-6 and a Sandy River 2-6-2.  Obviously the scales of the two engines are vastly different.  But when equalized for gauge the Sandy River 2 foot gauge dwarfs the Allegheny in width and height.  The point is once the narrow gauge dictated the physical plant, you in essence got a lot of bulk in your trains on a proportional basis.  Perhaps I am not making his argument very clearly for him - get the book and read the chapter.

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Posted by dehusman on Tuesday, December 10, 2019 4:26 PM

The premise of narrow gauge was that it would use cheaper track, have less dirt work, use cheaper equipment, etc.

Unfortunately it didn't turn out that way.  It actually didn't save them a ton of money on the right of way.  Turns out the labor and production costs were almost the same.  The cost to cast a car wheel were virtually the same, except a smaller amount of iron was used.  Then there was the added cost of reduced capacity and having to transload all the shipments.  Post Civil War when a "national" rail system came about, that put the narrow gauge lines at a competitive disadvantage.

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Posted by Overmod on Tuesday, December 10, 2019 8:24 PM

Look at all these answers, with not a one of them addressing the question 'why can narrow-gauge trains negotiate tighter curves'.  

There are technical reasons, including a proportional miniaturization of the wheel-rail interactions for rigid wheelsets on the inner and outer radii.  I don't think I can describe the physics and math without putting everybody to sleep, so leave it up to someone like dhusman to do it in proper English.

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Posted by BigDaddy on Tuesday, December 10, 2019 8:45 PM

Overmod
Look at all these answers, with not a one of them addressing the question 'why can narrow-gauge trains negotiate tighter curves'.

That, indeed, is the title of the thread but the OP clearly states a case that the only purpose for narrow gauge was to negotiate tighter curves.   That is not true.

We don't agonize over the math and physics when someone asks about running their sd 40's with 85' passenger cars over 15" radius in HO.  Swinging couplers gearboxes or truck mounted couplers exist in the model world.

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Posted by Overmod on Tuesday, December 10, 2019 9:07 PM

BigDaddy
That, indeed, is the title of the thread but the OP clearly states a case that the only purpose for narrow gauge was to negotiate tighter curves.   That is not true.

Certainly not true.  In fact, there is a gauge ... somewhere between metre and Cape gauge ... where it becomes possible to run trains just as well in any significant respect as on standard gauge, right up to about 100mph (as on test in Queensland, for example), where the civil can accommodate it.  SAR steam is proof of this all by itself.

Arguably metre gauge might qualify too (cf. the GELSA locomotives in particular) but that's just a smidge too narrow for what we normally recognize as full-size equipment.

I agree with you that the OP is a little confused in the conclusions he seems to be drawing from narrow-gauge equipment being able to negotiate tighter radii.  But part of the answer is inherent in rail/wheel and truck geometry, not just in shorter equipment or lower speed or guided couplings.  I'd encourage the OP to revise the thread title if it is not, in fact, the precise thing he wants an answer to.

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Posted by hgodling on Tuesday, December 10, 2019 10:56 PM

I think the title was the only clear part of my post. 

 

Maybe a little more explanation will help. The tighter curves were certainly not a primary reason for the prototype, but from my perspective it seems like one of the few benefits that would translate to the model scale. I think we can all agree there is no cost benefit to HOn3. 

 

 I am in the process of planning my layout. It will be a freelance, but the primary prototypes that have caught my interest are ones like The White Pass and Yukon Route or The Newfoundland railway. These Pike's were narrow gauge for other reasons, but supposedly the gauge benefited their very tight curves. I am in the process of trying to decide whether to stick with HO (I have some equipment) or change to HOn3. I am trying to determine if there is a tangible benefit at model scale for the narrow gauge that will outweigh the headache I see in switching gauge. 

 

I was trying to stick to a more narrow topic of the curve radius and address the other issues later in another post. 

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Posted by Overmod on Tuesday, December 10, 2019 11:10 PM

In my opinion no, the benefits of model narrow gauge don't justify changing.  Most of the observed advantages involve things like wheel wear, weight, and clearance that apply in the real world but not at HO scale.

Others with more experience may differ.

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Posted by Jetrock on Wednesday, December 11, 2019 1:25 AM

hgodling

 I am in the process of planning my layout. It will be a freelance, but the primary prototypes that have caught my interest are ones like The White Pass and Yukon Route or The Newfoundland railway. These Pike's were narrow gauge for other reasons, but supposedly the gauge benefited their very tight curves. I am in the process of trying to decide whether to stick with HO (I have some equipment) or change to HOn3. I am trying to determine if there is a tangible benefit at model scale for the narrow gauge that will outweigh the headache I see in switching gauge. 

Okay, I think several of us (myself included) read the OP and assumed you were asking about the advantages of narrow gauge vs. standard gauge in prototype railroading, but what you really meant was advantages of narrow vs. standard in model railroading? Heck, that's a very good question!

 

The considerations are different: modeling an obscure/rare prototype (such as narrow gauge) can be more challenging, requiring the willingness to scratchbuild, hunt around for the rare examples of your subset of the hobby available, and often pay more money since there aren't as many products mass-produced for what you're modeling. But if you really have an interest in narrow gauge, enjoy the challenge of doing your own building, research, and finding just the right bit, it can be more rewarding--and there's the added fun of your own pike being "different" instead of just another copy of the same pike we've seen a hundred times.

 

When I got back into the hobby, I was very interested in narrow gauge, in part because I have always had a preference for small locomotives, funky quaint equipment, and obscure short lines. I also had a soft spot for a particular prototype, the Arcata & Mad River Railroad, a "bastard gauge" (3'6") logging line in northern California. But before long my interest started to wane, as I realized that HOn3 equipment was very hard to find, there were basically no models of the locos I wanted to run, and even HOn3 wasn't quite accurate to the prototype I modeled with its weird gauge--was I going to have to compromise on gauge, or scratchbuild every piece of equipment, from track to locomotives? Now, I enjoy the modeling aspect of the hobby a lot, especially kitbashing and scratchbuilding structures, but at the time I didn't have much confidence in my modeling skill.

 

I considered modeling another prototype, and toyed with HOn30, having grown up enjoying photos of the Carrabassett & Dead River RR in Model Railroader, but after some experimenting, decided I wasn't satisfied with how well HOn30 locomotives ran, and of course I'd still have to kitbash or scratchbuild a lot.

 

And in the meantime, I discovered yet another obscure subset of model railroading, electric interurbans, which engrossed me more than narrow gauge! Now, I think traction is probably a smaller subset of the hobby than narrow gauge, and most of the models built of traction prototypes are spectacularly rare, mostly expensive brass, and ran about as well as Tyco toy train sets. But I'm absolutely fascinated with the subject, found another prototype railroad that tickled my fancy, and it ran on standard gauge, so everything except the locomotives themselves was available at the local hobby shop. And traction often operates on curves sharp enough to give the most steely-nerved narrow gauge engineer the heebie-jeebies!

 

So, the answer is, is narrow gauge worth it even if the curves aren't as sharp as on traction layouts? If you're fascinated with Southwestern mining railroads or New England logging lines, European industrial and port lines, love the charm of small steam and geared locomotives, and/or enjoy being part of a small fraternity in a relatively obscure hobby, then yes, absolutely, narrow gauge is worth pursuing! But if your only criterion is being able to have sharper curves, then maybe narrow gauge isn't for you.

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Posted by trwroute on Wednesday, December 11, 2019 7:14 AM

Overmod

Look at all these answers, with not a one of them addressing the question 'why can narrow-gauge trains negotiate tighter curves'.  

There are technical reasons, including a proportional miniaturization of the wheel-rail interactions for rigid wheelsets on the inner and outer radii.  I don't think I can describe the physics and math without putting everybody to sleep, so leave it up to someone like dhusman to do it in proper English.

 

 
And yet, you didn't answer the question either.  You just deferred it to someone else...

Chuck - Modeling in HO scale and anything narrow gauge

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Posted by freeway3 on Wednesday, December 11, 2019 8:06 AM

hgodling
The tighter curves were certainly not a primary reason for the prototype, but from my perspective it seems like one of the few benefits that would translate to the model scale.

I have nothing to add to the math and physics re: the prototype, but find the discussion interesting.

Regarding "advantages" to narrow gauge MODELING vs. standard gauge, as an avid HO modeler, life issues forced me to downsize my living space a couple of years ago. This caused me to dismantle my HO standard gauge RR, set in the ubiquitous eastern US in the transition era. But I didn't lose my desire to start another RR.

It quickly became apparent that I could not have what I wanted in an HO standard gauge RR in my new space, mainly because of issues with track radius. I always felt N scale too small for my liking, but then began researching HOn3. I loved the fact that this equipment could both run well and LOOK GOOD on tighter radii relative to standard gauge, but still used HO scale structures, vehicles and figures. And it gave me the opportunity to research and model a completely different era and locale. I'm enjoying it!

Ed

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Posted by ATLANTIC CENTRAL on Wednesday, December 11, 2019 8:59 AM

hgodling

I think the title was the only clear part of my post. 

 

Maybe a little more explanation will help. The tighter curves were certainly not a primary reason for the prototype, but from my perspective it seems like one of the few benefits that would translate to the model scale. I think we can all agree there is no cost benefit to HOn3. 

 

 I am in the process of planning my layout. It will be a freelance, but the primary prototypes that have caught my interest are ones like The White Pass and Yukon Route or The Newfoundland railway. These Pike's were narrow gauge for other reasons, but supposedly the gauge benefited their very tight curves. I am in the process of trying to decide whether to stick with HO (I have some equipment) or change to HOn3. I am trying to determine if there is a tangible benefit at model scale for the narrow gauge that will outweigh the headache I see in switching gauge. 

 

I was trying to stick to a more narrow topic of the curve radius and address the other issues later in another post. 

 

I have always found it better to ask the "real" question directly, rather than trying to sneak up on it........

If you like short line back woods kind of railroading, and you have some decent model building skills, narrow gauge can be fun and can pack more railroading into less space.

Otherwise stay with standard gauge.

Sheldon

    

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Posted by ROBERT PETRICK on Wednesday, December 11, 2019 9:42 AM

Overmod

Look at all these answers, with not a one of them addressing the question 'why can narrow-gauge trains negotiate tighter curves'.  

There are technical reasons, including a proportional miniaturization of the wheel-rail interactions for rigid wheelsets on the inner and outer radii.  I don't think I can describe the physics and math without putting everybody to sleep, so leave it up to someone like dhusman to do it in proper English.

+1

When going around a curve, the outside rail is a teeny bit longer than the inside rail and so the outer wheel has to go a teeny bit faster than the inside wheel. Solid axles do not allow this. Automobiles solved the problem with differentials.

The shorter the gauge the smaller the difference in the lengths of the inside and outside rails, and the better a solid axle could function.

Has very little effect in the 1:1 world; even less in the 1:87 world.

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Posted by wjstix on Wednesday, December 11, 2019 11:18 AM

I think there's a greater advantage to narrow gauge when contemplating a change to a larger scale. For example, in O scale standard gauge, curves are normally 5' or 6' radius; roughly equivalent to 30" to 36" radius HO std gauge curves. However, O narrow gauge equipment can take much sharper curves. I believe most if not all of Bachmann's On30 equipment can take curves down to 18" radius for example.

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Posted by IRONROOSTER on Friday, December 13, 2019 12:13 AM

One big model railroading advantage to using narrow gauge can be to save money.  On3 is fairly expensive, but On30 uses HO track and can use HO trucks and locomotive drive trains with a new super structure.  I know that Bachmann has On30 stuff, but it has also gotten quite expensive. And ME has On30 track also expensive.  But using HO Atlas track, HO trucks, etc. you can with a little scratchbuilding save money, and have an O scale layout.  And with On30 you can follow either 3 ft or 2 ft prototypes.

You can also use HO track, etc. for Sn42 narrow gauge to save money in S scale.  Again following a 3 ft gauge protoype.

Paul

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Posted by Overmod on Friday, December 13, 2019 12:53 AM

trwroute
And yet, you didn't answer the question either more.  You just deferred it to someone else...

I just framed it more correctly so people would stop answering questions the OP didn't seem to have asked.  Believe me, I'd happily answer the thing in detail if someone hadn't done better ... or for that matter if the OP hadn't fairly quickly established what his real concern was (which need not involve things like invocation of physics and engineering issues  that, as I think I did note, matter conparatively little in a model context.  (If you model in something like N finescale, which apparently is a thing even though I have trouble imagining how it runs, then you might need to know...)

Sometimes a discussion is better answered by a refinement or redirection than by a dissertation on something ultimately peripheral.  As I thought was the case here.

Anyone who feels left out of a fire hose drink on curve guiding, feel free to PM me.

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Posted by xboxtravis7992 on Friday, December 13, 2019 3:36 PM

Narrow gauge being shorter and smaller definetly allowed for tighter clearances and smaller structures along the right of way to. My best illustration of it in principle, abusing Train Simulator to plop a UP Challenger & Big Boy double header... onto Wales's narrow gauge Corris Railway. In the entire space needed to fit just one Challenger locomotive, the Corris Railway can fit their entire regular trains into that space!

As for why it fits the tighter curves, the shorter axle definately helps. It probably reduces the torque/moment to an extent on the inner wheel in a curve. 

 

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Posted by Overmod on Saturday, December 14, 2019 10:02 PM

For a fun solution, consider the original Thorold system in "Railways on Turnpike Roads" just after the Civil War.  This is a bit like a Brennan gyroscopic setup without the gyroscopes.  Lay a rail or pipe as if it were the 'curb' of a road.  Balance the locomotive and cars of the train on this, using double-flanged wheels, like a ground-running version of a Lartigue monorail (or the bottom half of a Boynton bicycle railroad train).  Then add an outrigger wheel with some form of primary suspension (perhaps a pneumatic tyre or rubber chevron springs) that has about 5% of the weight of the car resting on it, just enough to preclude the wheel tipping on curves or slight asymmetrical loading.  Most of the benefits of steel-on-steel low friction, essentially zero curve drag ... presumably there would be arrangements to swap the outrigger between sides, or duplicate it and perhaps fold-stow it on the 'off' side if you want bidirectional operation turning the train on a loop or table.  This uses even a fairly primitive road surface as the 'other' rail so your developed ROW cost is limited to a strip less than a foot wide, which can follow relatively sharp curves and gradient transitions.

W.J Ewing improved this to private ROWs by using a narrow graded or paved path for the 'outrigger' wheels, which doesn't have to match the alignment standards for the rail.  You can see an example (although one with decidedly 'cultural' elements of engineering) in the Patiala Monorail system.  MUCH less fixed cost than even a poorly engineered, lined, and surfaced narrow-gauge railway!

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Posted by dehusman on Sunday, December 15, 2019 10:18 AM

Smaller engines and smaller trucks have shorter rigid wheelbases so they can negoiate sharper curves more easily.

Wheels rigidly mounted on axles require one wheel to slip when going around a curve.  The sharper the curve the greater difference there is between the radius of the inside rail and the outside rail, between the distance the outside wheel has to travel and the inside wheel has to travel.  With a narrower guage you can have a tighter radius with the same difference in travel.

That is one answer to your question but does nothing to solve your problem.  

 

Other than just liking the smaller equipment or operations or location, the benefits are mostly due to smaller equipment allows tighter radius for the above reasons and the shorter cars allow the same car count in a shorter space.  A 10 car train of 30 ft narrow guage cars is less than half the length of a 10 car train of 60 ft modern standard guage cars.

Having said that you can get nearly the same effect by backdating to 1890's standard gauge or modeling an  industrial line (particularly street trackage) in standard gauge.  If you model 1925 in a dockside area, you can use 0-4-0 switchers, 30, 36 and 40 ft cars and 18", 15" and even 12" radius.

I would say only change to HOn3 if you like HOn3.  If you don't want to change everything choose a scenario with tight radius and small cars and model standard gauge.

I really liked the EBT, but I am modeling 1900-1905 Reading.  I get many of the small car benefits but use standard HO components as far as trucks and track.

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Posted by dknelson on Sunday, December 15, 2019 12:18 PM

dehusman
I would say only change to HOn3 if you like HOn3. If you don't want to change everything choose a scenario with tight radius and small cars and model standard gauge.

At Trainfest in Milwaukee this November I was chatting with someone who is an avid HOn3 modeler and has been for some years.  He was mentioning to me that he could not imagine anyone becoming a beginner in HOn3 at this time unless and until Blackstone starts importing locomotives again, even at the shockingly high pricing that the Blackstone website says they were quoted for their K 36 and K 28 models.  He, like, some other HOn3 modelers in the area, basically put their older brass HOn3 on the shelf when Blackstone came around and finds it hard to imagine going back to brass, which tended to be very finicky.  He's glad he has the Blackstone locos that he does but is rather doubtful about the immediate future of HOn3 for new entrants.

Dave Nelson

 

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Posted by BMMECNYC on Monday, December 16, 2019 4:56 PM

Edit:

Just realized that Im completely off topic here... 

To bring it back on topic for at least part of the reply.   In addition to what others have said, many of the smaller D&RG consolidations had blind drivers on the second and third driving wheels, which allowed them to accomodate very tight curvature.  Additionally, these wheels where actually somewhat wider than the standard driving wheel.

Ive just started in HOn3.  Ive managed to aquire a non-working K-27 made by Blackstone (2006 run with motor issues) and have replacement parts.  All other locomotives are brass.  Unpainted lightly used Hon3 brass is actually less expensive than Blackstone, even after adding a sound decoder, but be prepared to tinker with things to get them running smoothly.   Most of my rolling stock is Blackstone with a few Labelle, Durango Press and Rail Line (I think, little blue box) kits thrown in.

My primary reason for switching to narrow guage is nearly everything runs on a 16.5" radius.  Everything I've tested to date will negotiate 18" radius.  The railroad(s) Im modeling had what works out to 18"-24" radius curves and up to 5% grades.   I probably won't go for 5%, but the curves being tight is very attractive for my relatively narrow layout space.

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