G Scale

G Scale (or G gauge) refers to a larger scale train size that is usually 1:24 in scale, and the actual track gauge measurement is 45mm (or about 1 3/4 inches).

We currently have two G Scale train layouts running at the museum.

One layout, which truly can be called our “garden” train, is operating out front, providing a unique way for our curators to stage this layout with all sorts of unique details and environments.  Almost all scenery dressing this layout is set in place before each open house and removed immediately after. Of course, Tucson’s outdoor temps pose a challenge for those operating these trains and the folks viewing them.  If early fall or late spring temps rise much above 90 degrees, you may find this exhibit closed.

Inside the museum our overhead G scale trains circle and cross above the museum floor.  The indoor G scale layout has seven trains and two trolleys. The trolleys and three trains are always moving above and around visitors throughout their visit.

Image Gallery

Click on one of the images below to get a larger view!


G scale was introduced by Ernst Paul Lehmann Patentwerk under the brand name LGB and was intended for indoor and outdoor use. Lehman Patentwerk, founded in 1881, started producing LGB in 1968. The remains of the company were bought by Märklin and production of certain items continues.

The G name comes from the German word groß meaning “big”. More recently some people have come to interpret it as standing for “garden scale”.

G gauge track has a spacing of 45 mm between the railheads (tracks) (c.f. 44.45 mm for 1 gauge , but that does not determine the scale to which the models are built because, to maintain a constant track width when real-life counterparts have a variety of railroad gauges, the scale has to vary. The most common full-scale practice uses a spacing of 4 ft 8 1⁄2 in (1,435 mm) standard gauge, whereas some narrow-gauge railways (serving mines, etc.) have rails only 3 ft (914 mm) apart. Although often built with standard-sized doors, a narrow-gauge train is in most other respects smaller than its standard-gauge counterpart: its cars are generally narrower and shorter, allowing them to navigate more sharply curved and lighter built tracks.

Model trains are built to represent a real train of standard or narrow gauge. For example HO scale (3.5 mm to 1 foot) (and also, although inaccurately, double-O/OO at 4 mm to 1 foot) models all use 16.5 mm gauge track to represent standard gauge trains while a narrower-gauge track such as 9 mm N gauge is used to represent real narrow gauge.

G model railways depart from this and always use the same gauge with the trains instead built in different sizes depending on whether they are intended to represent standard-gauge or narrow-gauge trains. Because of this it might be more correct to speak of “G gauge” rather than “G scale” since the consistent aspect is the gauge, 45 mm (1.772 in), but the term “G scale” (or “scale IIm”) is used when 1:22.5 is used.