What is the purpose of a dual gauge or multi-gauge track?

The purpose of a dual gauge or multi-gauge track on a model railway layout is to allow trains of different gauges (rail spacings) to run on the same section of track.

In the UK model railway context, this serves a couple of main purposes:

1. Modelling prototypical dual gauge trackwork - Some real railways in Britain had dual gauge track to allow both standard gauge and narrow gauge trains to operate over the same lines. Recreating this on a model layout adds realism and operational interest.

2. Allowing separate gauges to intermingle - A dual gauge section enables trains of different popular gauges like OO and O gauge to cross over and share certain sections of the layout. This maximises the variety of stock that can be run.

Common dual gauge combinations include:

- OO/O gauge - Allowing larger scale O gauge and smaller OO gauge to run together.
- OO/OO9 - OO representing standard gauge, OO9 for narrow gauge prototypes.
- OO/N gauge - The finer N scale trains running alongside OO gauge.

The dual/multi-gauge track has correctly spaced rails for each gauge, with the sleepers arranged to support both. Careful attention is required for reliable operation across gauges. But it allows enjoyment of different scales on one layout.