Charles Cooper's Railway Pages - Scale, Gauge, and Track Geometry Information (2024)

Preamble:
Scale and Gauge
Scale is the proportion of the model to the prototype. (The prototype standard gauge is 1,435 mm or 4ft 8.5in.) Scale is usually represented as a ratio, e.g. 1:87, so that 1 inch ofmodel represents 87 inches of the prototype. Scale is also sometimes expressed as millimetres to the foot, e.g. 4 mm scale, meaning that 1ft of prototype is representedas 4 millimetres of model.
Gauge is the width between the rails, measured from inside edge to inside edge, or from centre-top to centre-top of rail.
In the Toy Train age, there was not a rigid correlation between Gauge and Scale. Unless there was a rigid adherence to Scale, trains of that age were morecommonly referred to by "Gauge".
Manufactured "narrow-gauge" track, (i.e., representing a prototype track of less than the 4ft 8.5in prototype standard gauge width (not to be confused with Lionel's toy train"Standard Gauge") is usually producedin a "lower" readily available gauge with broader ties in order to conform to scale.For instance,Scale1 narrow gauge would be represented by a Gauge 0 track with larger ties that conforms to Scale 1, than that of Gauge 0 track. Common prototype narrow gauges are 3ft, 3ft 6 in, and 1m.

A summary Table of Scales and Gauges
Scales and Gaugesin usetoday, Standard/Wide, TT, Z and T less commonly so.

Notes:
(1) In North America, the equivalent of Europe'sGauge 2was "Standard" (Lionel) or "Wide" Gauge (Ives, American Flyer, Dorfan)
(2) The popular so-called "G Scale" trains were originally European-style narrow gauge equipment to a scale/ratio of 1:22.5, running on 45 mm track, but this designation now commonly refers to both Scale 2 narrow gauge and Scale 1 trains, although Scale 1 trains should more prototypically run on Scale 1 track. Strictly speaking, there is no such thing as "G Scale", only a range of variously-scaled narrow gauge trains running on 45mm track. Among them is the emerging F Scale with a ratio of 1:20.32, or 15mm to the foot, its narrow gauge designated as Fn3 Scale.
(3) There is also still a following for H0n3 (i.e., 36" prototypical narrow gauge), with a gauge width of 10.5 mm.
(4) In the UK, there is a substantial following for EM (18 mm) Gauge as a correct-to-scale track for the 00 scale ratio of 1:76.
(5) While Gauge 2 is generally considered to be the beginning of the Toy Train Age, there wasalso Gauge 3 and Gauge 4 in Europe:

(6) Originally, track width was measured from rail centre to rail centre, but eventually from inside to inside track edge. This resulted in some confusion, and the immediately-abovetable is of necessity an approximation andsummary of the principal knownmakes.

Important Note: The relationship between scale and gauge was the most significant defining distinction between the toy train era and its evolution into "railway modelling" or "model railways" that took centre-stage after WWII. The "toy train" era, that is to say the age of mostly tinplate-manufactured toy trains in all gauges produced before WWII (other than the beginnings of model trains produced and marketed by emerging specialty firmssuch as Bassett-Lowke in the UK),did not concern itself with the niceties of scale - its products were really defined only by gauge. The first efforts in the non-specialty market to start to define scale came with the advent of Märklin and Hornby-Dublo 00 trains in the 1930s. References to scale below in the larger gauges are therefore generally qualified as "Modern Day".

Track geometry

“Track geometry” may be defined as the design and dimension of track pieces required to obtain any one of the earliest favourite layout designs of the toy train era, namely a circle, a figure-8, or an oval (curved-end rectangle).

The concept of track geometry evolved from its simplest and earliest application: the number of curved track pieces required to form a circle around a Christmas tree – to the sophisticated devolution to the “defined"or “settrack" Gauge 00/H0 era by WWII, with “tracklaying plans” for far more ambitious and complicated layouts. As scales and gauges became smaller in the post-WWII era, the required track dimensions became very precise, but the post-WWII introduction of flexible track made “tracklaying” plans obsolete for those scales and gauges now available in “flextrack”.

Returning to the toy tinplate train era, major manufacturers improved their track designs over time with more track formations and increased radii options. Significant retooling occurred with the introduction of electric trains, powered with a centre third rail. A further major change occurred with the introduction of a cheaper Gauge 0 range marketed by Marx and Lionel as 027, and by Hornby as M.

Dimensions between manufacturers were surprisingly similar, but straight track lengths varied within and between manufacturers up to half-an-inch, but the larger layouts were able to absorb these variations. On the other hand curved rail designs varied extensively between manufacturer both as to time frames and options within time frames.

So overall there was a relative standard of uniformity that allowed for the ability to mix trackwork designs – up to a point. There remained differences, chiefly in radii, tie design, camber and the provision of track pins (either the 3-0 or the 2-1 system) that forbade complete adaptation. Track pin differences could be overcome with a pair of pliers, and if short sections needed to be created that were not obtainable ready-made, a small hacksaw and a file could be relied upon to accomplish the necessary fitting.

Early toy train manufacturers often collaborated with each other (e.g., Bing, Bub and Carette) in the design of track, or would contract with a manufacturer, usually Bing, for the production of track. The Hornby Series design was somewhat influenced by Lionel 0.

Typically, quoted diameters of track circles vary from inside-to-inside rail to centre to centre to outside-to outside rail. Those shown here are centre to centre, or as defined by the manufacturer.

Note: Thetables below havebeen constructed empirically, and areto some extent anecdotal based on observation.It is therefore partial. Blanks mean either not made or not known. Early catalogues would undoubtedly supplement or confirm the information provided here.

Standard/Wide Gauge

Gauge 2

Gauge 1

Gauge 0

The advent of Gauge 0 saw an explosion of track types and designs, both within and between manufacturers. Gauge 0 had started to appear before WWI with simple clockwork circles, and rapidly expanded with the proliferation of electric trains post-WWI.

Gauge 027

Gauge 00 (early table top, 28mm gauge)