What Makes for "Bulletproof" Trackwork?

Model Railroader Layouts and layout building
1

Over the years there has been a steady reference in these forums to “bulletproof” trackwork. Often accompanied by justifiable pride that it has been achieved. But let me ask this question: Just what constitutes that description? Obviously, bulletproof means trackwork that is never itself responsible for derailments and other operational problems. I may be missing something from the definition here, but if so, please weigh in.

But what I’m really asking for is a list of goofs, mistakes, and imperfections that can pop up in the process of both design and installation - and have to be corrected after the fact. If you wish, please include a tip or two on how to avoid them. I’m not looking for things as obvious as insufficient radii for the length of motive power and rolling stock to be used later - I’d think that’s a no-brainer from the start. Let’s just make that first on the list and get to the rest of them.

Thanks!

John

2

  1. Rails are not separated accurately. That is, they are out of gauge;

  2. One rail dips or rises such that they are not at the same height measured at any one point along the centerline;

  3. Both rails rise or dip concomittantly, but it’s too much for the wheels and suspension of the items meant to roll over them;

  4. The joints are not carefully assembled. There is a large gap on the outer rail of a tight curve, or the joint(s) are kinked sufficiently that there is too great a resulting radius at that joint. Or, one rail is outside of/above/below the joiner by mistake;

  5. At some point along the general arc of a curve, the radius is sufficiently short over a sufficiently long arc that one truck or an entire wheelbase of a steamer, as examples, cannot safely negotiate the curve at that sharpest point, and there’ll be a derailment, or possibly just a stall if the speed is slow and the rails pinch and bind the flanges. Or, with longer cars, or passenger cars with diaphragms, the sharpness of the curve will cause derailments when the couplers cannot swing in azimuth sufficiently or the diaphragms impinge;

  6. Turnouts are the wrong diversion angle for the rolling stock’s ability to run through them railed, or turnouts’ approaches and exits have kinks at their joints with external rail segments;

  7. S-curves, caused by turnouts too sharp or set too close to one another, or caused by sinuous geometry on regular non-turnout rails;

  8. Improperly prepared roadbed, especially under turnouts, or at vertical curves into and out of grades; and

  9. Super-elevation along curves inexpertly fashioned that causes derailments, almost always along the outer raised rail, and usually due to inconsistent grade. A dip on the outside rails of curves, but also super-elevated curves, will almost always result in a derailment.

3

Gidday John, having built all my benchwork and tracklaying in a club environment, my definition of “Bullet proof trackwork” is “Track that the most moronic reckless club member can run his prized piece of garbage locomotive at Warp Factor 9 without it derailing”.

As with everything in life, to do well there must first be a good foundation, hence don’t expect good trackwork if the bench work is rubbish, not that that means that the timber has to be of first grade dimensional quality, though, of course, it helps. All the trackwork done at the club has been with predominately Peco Code 100 Flextrack, with some GT Italy Code 100, laid directly on the MDF road bed / bench work, so I can’t comment on any brands or codes of track or other road bed materials.

I draw the track centre and use a homemade radius bar to draw the curves.

I’m old fashioned in that I use track nails, for the reason, especially in laying the curves I may find that I have to remove the nails to relieve any “Oops” that I’ve inadvertently built in!! Also, I should

4

These first two replies cover the universe of issues so well that I am not sure what else there is to add. So, here is what I will do. Without referring back to the first two replies, I will summarize all of my issues in failing to achieve bullet proof track.

  1. Curves. You gotta solder all of the rail joiners before installing a curved section of track to avoid kinks.

  2. One Rail Higher Than The Other. This is especially a problem on curves.

  3. Humps and Valleys. Any dip or rise in the track from level will often cause derailments.

  4. Rails Out Of Gauge. This most often occurs on curves where too many ties are removed to accomodate soldered rail joiners. But, it can also occur on straight sections of track. Nailing down track can also cause rails to be out of gauge if the nails are driven to deep.

  5. Lack of Easements. All curves should begin and end with an easement.

  6. One Rail Higher or Lower Than The Other. This occurs at rail joints and is caused by rail joiners that slip and cause the adjoining rail to be higher or lower.

  7. Flex Track Meets Turnout. Improper joining results in a kink.

Hope this helps.

Rich

5

I built a rather large HO scale layout using code 100 atlas flextrack with PECO and Shinohara switches including double slips and 3 ways. I ran mostly 4 axle geeps and yard engines and found the track to be pretty much “bullet proof”

Then–I started putting some of my older brass steam and a couple of later Chinese 4-8-2 and 2-10-2 locos on the layout. Then I had to re-define “bullet proof”. It no longer applied to my trackwork.

Test your trackwork as you lay it with the longest wheelbase, rigid frame engine you intend to run if possible. Then you will know what “bullet proof” means.

grizlump (grouchy German)

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That’s a good point. Run that longest wheelbase, rigid frame engine at the highest possible speed around the entire mainline three times. Then turn the loco around and run it three times in the opposite direction at the highest possible speed.

Rich

7

Good morning

I think the Bear hit the nail right on the head in his statement of providing a good foundation.

Even our childhood story books gave us life long lessons when our brains where still developing.

That’s why the third little pig had much more success building his house on solid ground out of brick. Unlike the first little pig that built his house out of straw on the sand. We won’t even mention the second little pig as he had the right idea but Cut Corners, No pun intended[(-D] The big bad wolf representing when your locomotive “Huffs and He Puffs” but he falls off the tracks[(-D]

A good foundation IS the key factor for everything else to go well for anything. As long as the sub roadbed bench work transitions gradually for all factors involved. Then taking the time to make sure the track work on top of it can do the same. If subtle transitions are made everywhere there is one, there should be no problems.

Much like the artist Monet orchestrated his beatiful flow of color in his paintings. He subtly transformed one color into the next. You can see this up close as the color contrast looks somewhat blurry, but standing back at a distance from his work it has distinct definition. The reason why he was, and remains such a famous artist to this day.

[:)]TF

8

The nature of a railway means you don’t need to be that careful building one. Where you build it matters a lot.

As long as the sub base is mostly flat and mostly level railways work well even if not fastened down at all. Prototype railways just rest on the ground.

Dips or humps are a nuisance if they are severe enough to uncouple cars. You will find those dips or humps are in the sub roadbed.

Accidental superelevation, tilted track, should be avoided but it has to get pretty bad before cars will derail. Again, this superelevation cannot be achieved unless you tilt the subroadbed.

Track just resting on the layout surface works just fine or no train set could be any fun.

So, #1 on the requirements list is to aim for flowing track alignment. The remainder of the items mentioned actually make very little difference.

9

Yes, good trackwork starts with a good base - subroadbed. Geometry needs to be very good with curves the longest equipment can handle, easements on curves and grade changes. I also check subroadbed for dips and rises using a nice straight piece of lumber to get rid of those before track goes down.

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Ironically, perhaps, bulletproof track might be getting harder to accomplish now that more modelers are attempting to replicate (following the lead of our British counterparts) the exact look of prototype rail and track, and closer to prototype or even exact Proto87 wheels and flanges: rail joints every 39 feet (staggered so they are never across from each other), slight dips at each joint, the irregularity of very light rail on very poorly maintained roadbed, that sort of thing.

Dave Nelson

11

I won’t repeat all the good points listed above but will add one of my own.

Curved turnouts need to be securely fastened to the roadbed. I have always let turnouts float making sure the track leading up to them was stuck down solidly and I never had an issue. With a curved turnout that is not well secured a big steamer will torque it when it hits it at speed and will pop out.

I use various larger steel levels on the rails to check for dips. I use this level on the track to make sure the rails are even along the way. It has fine pencil lines on it so when I am doing superelevation I can check for consistency.

I have a long straight stretch that has a bit of an undulating dip in it. I thought it looked so cool when a thirty car freight rolls through it I didn’t fix it.

Trackside Treasure: Springtime in Belleville, April 2015

12

And for these reasons I still put performance above appearance regarding track, trucks and couplers.

Others are welcome to do what works for them, but I build on a firm foundation with good civil engineering principles applied to the roadbed.

None of the physics of real life scales down to our models, they have their own dynamics which must be accommodated for reliable operation.

To that end:

Code 83 rail is small enough

NMRA Standards are good

Original regular head Kadee couplers only

Code 110 wheelsets only, equalized trucks were practical

Something close to NMRA car weight recommended practice

Easements a must have

Large curves, in my case 36" minimum on the mainline.

No cork, no foam, homasote or wood roadbed for all trackwork.

My typical train is 35-45 cars, longer trains are possible, 100 cars can easily be done.

Sheldon

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About the only thing I don’t see covered are the NO NOs of which I did one of the worst you can do. Do not put a turnout at an elevation transition!!!

I thought if the track was perfect to and from the turnout and at the same level it would work. Well it did with all my biggie locomotives and rolling stock but when I bought a pair of six wheel truck Proto 2000 PA-1s they would derail every time through the diversion. All my biggies worked fine as well as my Athearn six wheel truck diesels and my Proto 2000 E7s but not the Proto 2000 PA-1s.

The fix was to move the turnout 18” away from the transition.

Mel

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

I’m beginning to realize that aging is not for wimps.

14

[tup] +1

I learned “bulletproof” trackwork building from a group of true masters in the Scale Rails of Southwest Florida club back in the 1980s.

These guys proved to me that derailment free operation was possible, and since then, that is all I will allow.

Any derailments on my layout are almost always equipment problems.

People say I overbuild and put too much effort into foundation, structure, and framing. I think all this is critically important to achieve bulletproof track.

I won’t go into construction processes because people have already covered that very well.

Working off of Sheldon’s list:

Code 83 rail is small enough. I also use code 70 and code 55 rail in some places for visual effect.

NMRA Standards are good. Yes they are. The NMRA track gauge is the first pass/fail trackwork confirmation.

Original regular head Kadee couplers only. Same here.

Code 110 wheelsets only. Same here.

Equalized trucks where practical. Yes. I use striclty ONLY Kadee trucks and wheels on all freight cars.

Something close to NMRA car weight. My system for weighting cars is “something close” to NMRA recommended practice.

Easements a must have Large curves, in my case 36" minimum on the mainline. I don’t have room for this in all locations.

No cork, no foam, homasote or wood roadbed for all trackwork. I do use cork. I might use foam in locations if the plan makes it easier.

My typical train is 35-45 cars, longer trains are possible, 100 cars can easily be done. My maximum

15

The only thing I can add is that, despite all of our efforts, trackwork will likely have imperfections after the intial nail down. Especially if you have limited experience in this.

I intentially designed my layout with zero elevations because of the grief it causes, especially for switching and steam locos (that I run 99% of the time). I also took a lot of care when building the benchwork and I made sure all of my curves were of 22" minimum in radius. Despite all of these efforts, I still had a few imperfections that some of my finicky engines found for me. I also let the trackwork “sit” for a few years to see how stable it was, and fix any imperfections my rolling stock may find. I found a few within the first 6 months. After 3 years, I think I finally found all the gremlins and scenery building is planned for this summer. Lessons learned: take great care when tracklaying; test with a finicky engine; don’t rush the scenery and ballast work until all the gremlins are found.

Simon

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You can’t do it once and expect it to be perfect. Sometimes, you have to tear up a section and rebuild it. Sometimes, a minor lift under one tie will correct a small vertical kink. Sometimes, it runs derailment-free for years but then you get a new engine or a long car and you’re in trouble again. Understand that this happens.

That’s why I put down track and roadbed, and then start working on other things, structures, scenery, signals, rolling stock kits. My track was fastened down but not ballasted for years, and I had chances to fix the track along the way. On the whole layout, I only had two trouble spots, one caused by unreliable Atlas snap-switches and the other by a vertical kink I didn’t recognize until after the track was ballasted.

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Also… very important… Do not push the limits of your trackwork!

On the most recent STRATTON AND GILLETTE railroad built in my spare bedroom, I had zero derailments. However, my largest locomotives were a USRA 0-8-0, and a GP-7. All freight cars were 40 foot maximum. No passenger cars. Hidden curves were 18 inch radius with no transitions, and yes, there were “S” curves.

If I had tried to run 4-8-2s, SD-40s, PA-1s, or passenger equipment, I am sure problems would have happened.

-Kevin

18

This has been well covered above. My first thought was a curved turnout that was not flat. One problem with that was a 4-8-2 where leading and trailing trucks did not do well.

I also had some avoidable problems when I installed flawed components. One was a turnout with an internally dead rail due to a bad internal jumper. Easily cured by adding an additional feeder but it never occured to me to check before installing. Similarly, I installed three Atlas code 87 90-degree crossings (vintage 2011) that had clearance issues (I forget the details) that I had to fix with a bit of filing of the plastic so the wheel flanges made it through easily. If I had been aware, I would have installed different crossings.

Along those lines, some turnouts have shorting issues where wheels bridge to the opposite polarity rail. While fixable with a bit of nail polish, knowing the quirks of given turnouts in advance might even, at the extreme, result in a different turnout choice. The gotcha here would be a knowledge gap as opposed to a technique error.

19

Kevlar crossties?

20

In 60 years of trains, 20 years at a large club, 10 years at the museum. The biggest goof is to not have the track, roadbed, and the benchwork it sits on in a controlled environment. Control the temp. Control the humidity. Any expansion and contraction due to either of these environmental issues can make havoc of the most carefully laid trackwork.

There is always a bigger or better bullet.