If you try to place a vehicle from the current Demo Start Set of the Model Trains Simulator on a narrow gauge track in SCARM layout, you will see the Gauge mismatch message and nothing will be set on the track.

However, there is a fast and easy trick that can force SCARM to re-scale the whole track plan and to make it matching to the standard gauge, so the virtual rolling stock of the demo library to be able to run on the tracks.

The trick consists in attaching of same gauge model track that match to the standard gauge (1435 mm or 4 ft 8 ^1⁄2 in) in true scale ratio somewhere in the narrow gauge track plan. When SCARM find out joined tracks in mixed scales, it will offer re-scaling of the whole plan to one of the both scales. After re-scaling to the scale with standard gauge rail distance, you will be able to place the virtual rolling stock on the tracks and to simulate your layout in the Model Trains Simulator.

Example

As an example, let’s take the following plan from the Model Train Layouts & Track Plans database:

Bachmann G-scale Home Layout Design #1

This simple plan uses Bachmann G scale tracks with model gauge of 45mm and scale ratio of 1/22. Multiplying of 45 x 22 gives 990mm or near 1m which is equivalent to metre gauge in real scale. If you open that track plan in the Model Trains Simulator and then attempt to place some vehicle from the Demo Start Set, you will get the following message:

This is because the Demo Start Set library represents scaled models of prototypes in standard gauge.

And here comes the trick: Close MTS and select “Marklin-I” track library (scale 1/32) in the 2D editor of SCARM. The I scale has the same model track gauge of 45mm (like G scale), but is scaled at 1/32 which is near exactly the standard gauge in true scale (45 x 32 = 1440mm). Now attach a single short straight track from the Marklin-I library to the end of one of the sidings on the Bachmann G-scale layout – the tracks will join because they have the same model gauge of 45mm.

Now start MTS again. The simulator’s track plan verification routine will detect joined tracks in two different scales in the layout and will show the following message:

Here you can re-scale the whole layout – select the item “I (1/32)” in the Tracks scale drop-down list box and press Enter. Nothing will be changed in the visual representation of the plan, but all the tracks will be scaled to I scale at ratio 1/32. Now select a track, place desired virtual rolling stock on it and start the simulation.

Notes

• Re-scaling effectively changes the scale ratio of the tracks in the plan. It is used not only for correct scaling of the virtual rolling stock, but also for calculating of the model track distances and virtual train speeds. Re-scaling does not change the dimensions of the tracks nor affect the track plan size or geometry in any other way.

• If you have a track plan with several independent routes, you will need to attach the-different-scale track to each of these routes for full layout re-scaling.

• If you want to save the re-scaled track plan, it is recommended to do that under different file name and to keep your original project file in the original track scale.

• The verification for mixed scales and re-scaling works only when the option “Handling of joined tracks in mixed scales” is toggled in the settings (it should be checked by default).

• The current version of the simulator cannot work correctly with 3-rail mixed standard and narrow gauge tracks and turnouts, so the above trick can’t be of help for such layouts.

• True narrow gauge virtual rolling stock will come with some of the next editions of MTS.

See also
Model Trains Simulator – Starter Edition
What means the message “Gauge mismatch” in MTS