Naples sTreeT

An American switching layout in TT

Having spent a good few years building, operating and exhibiting my American HO scale switching layout, Yorkford, PA, in 2017 I decided it was time for a change. I still like American trains, and being a fan of TT from my British 3mm scale modelling years, I was pleasantly surprised to find that a small amount of 1:120 scale American TT was available, in both kit and ready-to-run form. Interestingly, it is produced in Europe.

So having sold my HO layout and a good amount of stock, I ordered a few American TT items and started designing a new layout.

The Layout at a Glance

Name: Naples Street

Style: Micro switching layout

Scale: TT 1:120

Minimum Radius: 15in.

Size: 48 x 11 inches plus 20-inch fiddle yard

Benchwork: Birch ply on softwood battens

Prototype: North American

Height: 38in.

Era: Conrail, 1976-1999

Roadbed: Cork

Track: Peco HOm with Peco and handbuilt turnouts

Backdrop: Painted plywood

Scenery: Mostly scratchbuilt structures with proprietary vehicles, figures and vegetation

Control: Roco Multimaus DCC

The Setting

The small industrial park straddling Naples Street in the imaginary town of Sorrento, Illinois, is served by a branch of Conrail in the last quarter of the twentieth century. A mixed bag of rolling stock makes an appearance, moved around by a selection of small switchers.

There is a mix of boxcars from different eras and to justify this I have imagined that short boxcars with roofwalks weren’t phased out in the 1970s but lasted over a decade longer.


Track Plan

The track plan is very simple – four sidings off a central run-round loop, each with room for two or three freight cars. The layout measures 48 inches by 11, and the fiddle yard adds another 20. Originally the scenic section was 40 inches long but after the first couple of shows highlighted that one of the spurs was too short for effectively switching the team track, I added another 8 inches. The backscene, lighting frame and covering case had to be extended as well as the baseboard, and a few buildings had to be repositioned.

Track and Wiring

Track is Peco HOm, left over from my 3mm modelling days. The ties (sleepers) are a bit on the chunky side for TT but look reasonable covered in paint and ballasted. The gaps between the ties would be too wide for a mainline but are fine for a set of industrial sidings.

The turnouts are a combination of Peco and hand-built with radii varying between 15in. and 20in. They all have live frogs, and like the track, are mostly left over from previous layouts. The exceptions are two turnouts I built myself, and which, much to my surprise, work without problems.

All turnouts have their switchblades electrically bonded to the adjacent stock rail, the hand-built ones by design, the Peco ones through modification. This means that all frogs need to be electrically isolated from the switchblades and that their polarity needs switching according to which way the points are set. This is done by using under-baseboard pushrods, each of which works a microswitch as the points are changed. The pushrods run from front to back of the layout so the points can be changed from either side, depending on whether the layout is being operated at home or at a show.

An electrical interface board sits underneath the layout. This is a piece of plywood to which are screwed a set of terminal blocks for the various inputs and outputs, as well as the timer that controls the smoking chimney. It is covered with a piece of acrylic sheet.

                 Upside-down view of turnout switching mechanism               Interface board showing inputs, outputs and timer
                                                                                                                                                 for smoking chimney

Locos and Stock

Two of the locos are near-identical EMD switchers, an SW8 and an SW1200, one lettered for SOO and the other for Conrail. They are made by Czech company MTB and were supplied by Zeuke in Holland. They come with an NEM 651 DCC socket, which enabled me to easily fit a Zimo MX622N decoder in each. They both run very smoothly.

The other two locos to date are both Lionel 1:120 scale Big Rugged Trains GP9 display models which I obtained cheaply from the US and motorised using a variety of parts.

I have added sound to one of the converted Lionel models by fitting a Zimo MX648 decoder with a sugarcube speaker.

Sound for the other three locos comes from two MRC under-baseboard diesel sounders, which produce the right sound for EMD equipment. A bit of a compromise, but it works well enough.

Stock is mostly ready to run with the addition of a handful of kit-built freight cars from Lok-n-Roll and Siggis in Germany, and a 3D printed gondola from Shapeways courtesy of TT Nut.

The German kits come complete with trucks and wheelsets and just need couplers. Lok-n-Roll supplied these, and also wheelsets and couplers for the Shapeways gondola. I also bought some Shapeways brake wheels from Bone Valley Scale Models.

Couplers are either Micro Trains 1016s or Kadee 713s or 714s, the difference in these last two being in the colour – rust or black. They are for HOn3 but are also perfect for TT. They work well but are fiddly to assemble and need much patience; the springs used are even smaller than those for HO, and do not come ready fitted. Luckily a few spares are included! The Micro Trains couplers come ready assembled.

Kadee have now introduced the 705, a ready-assembled coupler.


Buildings and Scenery

Like the stock, American TT buildings are in short supply. A couple of card kits are available from Zeuke (a station building and a small warehouse), and you may be able to get away with HO or N scale kits from the likes of Walthers or Pikestuff, as these are sometimes close enough to 1:120 scale to be acceptable. The most crucial factor is probably door height – if it’s around 16.5 or 17mm, or you can make it so, it will do.

Short of finding what you want, one alternative is to buy TT scale plastic kits from European companies like Auhagen and convert them to something a bit more American. Another way is to download printable kits in PDF format from one of the many suppliers and print them out onto paper at the right scale.

Or you can scratch-build. Scratchbuilding is not that much harder than cutting out and assembling a downloaded printable kit. Embossed plastic sheet and corrugated paper give a more 3-D look than flat prints, and you also have the advantage that you can make something exactly to suit the space you have and which is based on any prototype you can take or download pictures of.

Most of the buildings on Naples Street were made from a combination of embossed plastic brick sheet, plastic strip, card and corrugated paper, painted with various brands of acrylic and enamel modelling paints, and weathered with pastels. Some of them are loosely based on photos of actual buildings in Illinois. Some are detailed with left-over HO windows and doors from Walthers. The personnel doors and some of the factory windows were designed using Microsoft Excel.

Clara’s Diner and the small workmen’s hut are 3mm scale resin castings. They are not prototypically American but I like to think they more or less blend in.

The oil tank outside Napoli Distribution is one of two from a Ratio N scale kit.

Backscene and lighting

The backscene is made from 5mm ply, screwed into the back and sides of the baseboard, and covered with poster paint to give the effect of streaky cloud against a blue sky.

The lighting is a self-adhesive LED strip fixed to a removable wooden frame attached to the layout’s side panels.

Road vehicles

Three of the road vehicles are via Shapeways: a Ford Thunderbird and a Ford Ranchero from Madaboutcars and a Mack truck from Stony Smith Designs.

All the US autos which Madaboutcars featured on the Shapeways website came in pairs but when I explained I only wanted two, both different, they changed the design to accommodate me. The world of 3D printing has been a revelation.

The Ford CL-9000 cab and the 1970 Chevrolet Malibu are both ready-assembled from RailTT in the Ukraine.

The dishevelled static trailer is an HO card kit from Clever Models printed out at a reduced scale for TT.


The figures are from the Preiser range, both painted and unpainted. As the setting is industrial there are plenty blokes around wearing serious clothing. There is no call for passengers around here but Clara’s Diner attracts a few non-railway customers from nearby because the food is so good.

Other details

The chimney at Can-Freeze Food Company was made from rolled-up paper and contains a Seuthe 117 smoke unit wired to a timer (a Velleman kit), enabling spectators to make it smoke for a pre-set time by pressing a button on the front of the layout.

On cold days the workers at Napoli Distribution like to keep warm by gathering round a glowing brazier in the yard.

The smoke unit is powered from the DCC track circuit and the timer from a regulated 12V adaptor which also powers the LED strip and the glowing brazier.


Industries and Operation

On Naples Street there are six industries to switch. I generally treat these as all having one spot each, though some have room for more. The industries are arranged either side of a central run-round loop, the first three to the left on facing point spurs and the second three to the right on trailing point spurs, as seen by a loco driver entering the area from the fiddle yard via a gap in the side panel behind Napoli Distribution (4).

The industries receive and ship goods as follows.




Car type

1.     Can-Freeze Food Company

Empty bottles & cans; cardboard packaging; fresh and processed foods; fuel oil

Frozen, canned and packaged foods

Boxcar; reefer; tank car

2.      Will’s Print Shop

Paper; ink; chemicals

Printed matter; waste paper and chemicals


3.      Sorrento Engineering

Engineering components; steel rods; sheet metal; fuel oil

Engineering finished goods

Boxcar; gondola; flat car; tank car

4.      Napoli Distribution

Dry goods; consumer goods; fuel oil

Boxcar; tank car

5.      Team Track

Sand; gravel; chemicals; corn syrup


Hopper; tank car

6.      Big Baddy Scrap

Scrap metal


The run-round loop can accommodate three short cars (40ft or less) or two 50ft or longer cars.

The lead track at front left into the team track/scrap dealer can accommodate three short or two long cars plus the loco. Likewise the fiddle yard, although an extra car can be squeezed in by using the hidden track behind Napoli distribution.

There are no uncoupling magnets on the layout. Uncoupling is done using the Kadee uncoupling stick. It is inserted into the gap where the couplers overlap and twisted slightly clockwise.

There are various ways to approach switching, some of which can be combined:

  • Pull all cars to be removed first, then return to the fiddle yard to form a new train of cars to spot or
  • Pull and spot together, an industry or two at a time.
  • Use of the run-round loop can largely be avoided by switching all facing point spurs first then all trailing point spurs on the next ‘trip’, or vice versa. Cars to facing point spurs will need to be shoved, and cars to trailing point spurs will need to be pulled beyond the turnouts and then shoved by reversing the loco’s direction.
  • For each spot, the manoeuvre can be started by coupling the car to be spotted to the car to be removed, if any, and then pulling both away, or by first parking the car to be spotted on a spare bit of track before first removing the car already spotted and coupling it up to the new car before spotting. Either way will involve the same number of switching moves.

To avoid too many complications, there are no industries on a switching lead.

For the actual switching, I don't use car cards or waybills. I have written a switchlist generator program which generates a series of switching trips based on the demands of the industries. It features multiple spots per industry, optional off-spots, and variable intensity of operations. It produces switching moves in list format or in a basic car card/waybill style.

In this example I would:

  • make up a train of the three cars to be shoved to the first three industries in trip 1 as these are all on facing point spurs. I would order the cars as in the list with the first one furthest from the loco.
  • spot the oil tank car at Can-Freeze.
  • back up slightly and spot the newsprint boxcar at Will’s.
  • back up, move to the next siding and spot the boxcar of engineering components at Sorrento.
  • make up another train of the two cars for Big Baddy and the team track, this time pulling them to the spur at the far end of the layout, then backing up and shoving the cars to their spots on the team track/scrapyard spur.

I would then proceed similarly for trips 2 and 3, this time picking up the empties too. These all need to be removed back to the fiddle yard except for the oil tank car in trip 2, which is still part full and needs to go from Can-Freeze to Napoli Distribution, involving a run-round move.

Where Big Baddy and the team track both have cars to be spotted and removed in the same trip, the operation has to be completed in two steps as the switching lead does not have room to hold four cars plus the loco. In other words the car at the team track is removed first and parked, followed by the car at Big Baddy, then the two new cars are spotted.

Sometimes a car at Will’s which is not yet ready to be removed may need to be moved from its spot temporarily and then returned after Can-Freeze has been switched. The same applies to the team track and Big Baddy.

Here are a few ‘advanced’ rules to use, where practical, to make switching a bit more challenging:

  • Avoid blocking the road.
  • The ‘open’ cars have removable loads to make switching a bit more realistic. The loads should be added and removed as necessary. Most of them can be lifted with the load removing magnet.
  • Tankers containing flammable liquids should not be coupled next to the loco or to each other.
  • Very long cars should not be coupled to very short cars. On Naples Street, this means in practice that the 60ft hi-cube should not be coupled to any car 40ft or less in length.

Click here for instructions on downloading and using the Switcher program. I am contactable on should anyone have comments or queries on its use.

Resources for US TT

American TT is rare – even in America – and products can be hard to get hold of. Locomotives are particularly in short supply. However, here are some links I found useful to get me going.

ttnut – an invaluable forum with a truly international character, where you will find answers to most of your TT questions, including a few ways to assemble a loco.

Zeuke-TT - Dutch-based suppliers of a small range of locos, freight cars and buildings.

Lok-n-Roll - German-based suppliers and manufacturers of a small range of locos, freight cars and accessories.

RailTT - a supplier of road vehicles from various eras, based in the Ukraine. Orders can be placed via

Siggis – a German supplier of US freight car kits.

Shapeways have a variety of TT scale road vehicles and loco and freight car body shells from designers such as Madaboutcars, TT Nut and Stony Smith Designs.

Gaugemaster – UK-based suppliers of Preiser TT figures.

Auhagen produce TT scale buildings and scenic items, some suitable or adaptable for US outline.

Sebnitz stock Tillig components for European TT, e.g. truck parts, some of which are suitable for US locos and stock.

Other Links

Here are some other stockists of TT items which I have not used as yet.

Art&Detail - a German supplier of a limited range of US freight car kits, loco kits and components.

Tillig and Kuehn – German suppliers of 12mm gauge track, probably more prototypical for TT than Peco HOm.

TT-West – a US-based supplier of a limited range of decals and kits.

Muellerradsatz – a German supplier of 12mm gauge wheelsets suitable for US freight cars.

Various printable kit suppliers e.g. 3DK, Clever Models and, whose kits can be downloaded and printed at 1:120 scale.


In its June 2016 issue, 'Model Railroader' magazine carried an article entitled ‘What became of TT scale?’. It started off ‘TT scale has disappeared from our consciousness’ and disappointingly, it made no mention of any of today’s small suppliers. While it will most likely always be a niche scale, I hope that a visit to the forum will reassure readers that American TT is alive, and that my small layout helps to bring it back into the consciousness!


Rod Shaw, 2020

Videos: video 1  video 2

Other layouts:
Briargate - British 3mm Scale      Lightwood - Continental TT
Ecclesford - British 3mm Scale      Yorkford, PA - US HO

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