Scale, Gauge, and Track Geometry Information
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 of model 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 represented as 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 more commonly 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 produced in a "lower" readily available gauge with broader ties in order to conform to scale. For instance, Scale 1 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 Gauges in use today, Standard/Wide, TT, Z and T less commonly so.
Gauge (5) | Gauge width | Scale | (UK mm/ft) | Ratio |
2 Standard/Wide (1) | 54 mm / 2 1/8 inches | 2 | 1:22.5 or 1:27 or 1:28 | |
G (2) | 45 mm/ 1 3/4 inches | 2 | 1:22.5 or 1:27 or 1:28 | |
1 | 45 mm/ 1 3/4 inches | 1 | 10 | 1:32 or 1:30 |
0 | 32 mm/ 1 1/4 inches | 0 | 7 | 1:48 or 1:43.5 or 1:45 |
0n30 | 16.5 mm | 0 | 7 | 1:48 or 1:43.5 or 1:45 |
S | 24 mm/ 7/8 inch | S | 4.7 | 1:64 or 1:65 (Europe) |
H0 | 16.5 mm | H0 | 1:87 | |
H0n30, H0e (3) | 9 mm | H0/00 | 1:87 (1:76 Europe) | |
00 (UK) (4) | 16.5 mm | 00 | 4 | 1:76 |
TT | 12 mm | TT | 3 | 1:120 or 1:101.6 (UK) |
N | 9 mm | N | 2 | 1:160 or 1:148 (UK) |
Z | 6.5 mm | Z | 1.4 | 1:220 |
T | 3 mm | T | 1:450 |
Notes:
(1) In North America, the equivalent of Europe's Gauge 2 was "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 was also Gauge 3 and Gauge 4 in Europe:
Gauge | Gauge width (6) | Principal Manufacturers | ||
2A | 67 mm | Schönner | ||
3 | 65 mm | Carette, Plank | ||
3 | 67 mm | Bassett-Lowke, Bing, Carette | ||
3 | 75 mm | Gamages, Märklin, Schönner | ||
4 | 75 mm | Bassett-Lowke, Bing | ||
4 | 85 mm | Schönner |
(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-above table is of necessity an approximation and summary of the principal known makes.
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 firms such 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 “set track" 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: The tables below have been constructed empirically, and are to 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
Manufacturer | Straight – clockwork (cw) Length inches | Straight – electric (el) Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Ives, American Flyer, Lionel, Dorfan |
| 14 |
| 8 ~ 44 |
Gauge 2
Manufacturer | Straight – clockwork Length inches | Straight – electric Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Märklin | 14 |
| 12 ~ 54 |
|
Gauge 1
Manufacturer | Straight – clockwork Length inches | Straight – electric Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Märklin | 14 | 14 | 8 ~ 34 16 ~ 68 | 8 ~ 34 16 ~ 68 |
Bing |
| 14 |
| 8 ~ 38 |
Carette |
|
|
| 8 ~ 34 |
Ives |
| 13 ¾ |
|
|
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.
Manufacturer | Straight – cw Length inches | Straight – el Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Hafner | 8 ¾ 9 ½ 10 ¼ |
| 8 ~ 25 |
|
Am Flyer early | 10 |
| 8 ~ 24 | 8 ~ 24 |
Am Flyer later | 10 ¼ | 10 | 8 ~ 30 | 8 ~ 30 12 ~ 38 |
Ives | 10 | 10 | 8 ~ 25 | 8 ~ 27 |
Lionel |
| 10 |
| 8~31 16~54 16~72 |
Lionel T |
| 15 |
| 16 ~ 72 |
Dorfan |
| 10 |
| 8 ~ 28 |
Märklin | 10 | 10 ¼ | 8 ~ 28 | 8 ~ 28 12 ~ 48 |
Bing | 10 ¼ | 10 ¼ | 8 ~ 25 | 6 ~ 18 ½ |
Bub |
| 10 ¼ |
| 8 ~ 28 |
Hornby Meccano S. | 10 ¼ |
| 4 ~ 18 6 ~ 24 |
|
Hornby Hornby S. | 10 ¼ | 10 ¼ | 6 ~ 24 12 ~ 48 | 6 ~ 24 12 ~ 48 |
Hornby Steel |
| 10 ¼ |
| 10 ~ 36 |
Paya |
|
|
| 16 ~ 72 |
Bassett-Lowke |
|
| 12 ~ 48 |
|
Gauge 027
Manufacturer | Straight – clockwork Length inches | Straight – electric Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Marx | 8 ¾ | 8 ¾ | 8 ~ 27 | 8 ~ 27 8 ~ 42 |
Lionel |
| 8 ¾ |
| 8 ~ 27 |
Hornby M | 10 ¼ | 10 ¼ | 4 ~ 18 6 ~24 | 4 ~ 18 6 ~24 |
Gauge 00 (early table top, 28mm gauge)
Manufacturer | Straight – cw Length inches | Straight – el Length inches | Curved – cw. Pieces to form a circle + ~ diameter inches | Curved – el. Pieces to form a circle + ~ diameter inches |
Bing |
|
|
| 4 ~ 16 ½ |
Successive Track Series
Some manufacturers have brought out successive series of tracks:
Lionel 0 [traditional tinplate {compatible with Hornby Series}, Super 0 and Fastrack];
Hornby Gauge 0 [Meccano and Hornby Series];
Trix 00 [bakelite, fibre base, plastic base];
Triang-Rovex/Hornby 00 [Standard, Series 3, Super 4, System 6];
Märklin H0 [M track, K track, C track];
Triang-Rovex TT [Type A and Type B].
Several H0 makes such as Fleischmann [Profi], Roco, Bachmann [EZ track], Lifelike and Atlas offer track with pre-molded track bases.
Code
Where encountered in describing model railway (as opposed to toy train) track, "Code" refers to the height of the rail. For instance "Code 100" is rail 0.100 of an inch high, and has been the traditional standard in H0 Scale. H0 fine-scale variations are Peco and Atlas Code 83 (0.083) and Shinohara Code 70 (0.070). N scale has been traditionally Code 80, but Code 55 and Code 40 are now on the market.
"G" and "F" Scales
G Scale started out as a generic description of narrow gauge Scale 2 (1:27 or 1:28, technically Gauge 2n) trains; as opposed to Scale 1 (1:32) trains, both running on a 45mm gauge (Gauge 1) track. (The difference in scale [where it is being observed] is or should be readily noticed in the size of the track ties as between that made, for example, by LGB for Scale 2, and that by Märklin-Maxi for Scale 1.)
There has been a real resurgence in popularity of Gauge 1 for "large" trains, and some real confusion has been created by popularly referring to both the true Scale 1 trains and all the variety of narrow-gauge scale trains running on 45mm track, as "G scale". The emergence of F Scale that seeks to define an exact modelling ratio of 1:20.32 (or 15mm to the foot) for one specifically-defined scale of narrow gauge trains running on 45mm (Gauge 1) track, identified as Fn3 Scale; is a step to refine the labelling of this generic conglomeration of "large scale" trains on 45mm track. Confusing? Yes - there are as many as six or seven scales ranging from 1:32 to 1:13.7 using 45mm gauge track.
Note: the meaning of "G" has been variously ascribed to "Garden"; or "Grosse [Bahnen]" as in German for "large [trains]"). The "F" of F Scale stands for Fifteen mm to the foot, and other refining scales for trains using 45mm track are sure to emerge.
Miscellaneous re Track and Track Formations:
:
1. Track bases and/or ties. These are tinplate, bakelite, plastic, rubber compound, milled wood or fibre according to age, gauge size and manufacturer. The rails themselves are usually tinplate, brass, steel, steel alloy, nickel silver.
2. Turnout operation. Pre-WWII turnouts are mostly hand-operated (exceptions are Lionel and Märklin), post-war turnouts and slips may be hand- or electrically-operated, and hand-operated formaitons are commonly convertible by means of an add-on switch machine by various manufacturers.
3. Frog number. Today's model railway turnouts are usually referred to as a # 4, 5, 6, 8, 10 and so forth (known as the frog number). The frog number of a turnout is an expression of the degree of the diverging route's radius sharpness. For instance, in HO scale, the converging inside rails of a #6 turnout where they meet (at the "frog") measure 6 inches from the frog to the toe of the turnout. In N scale, the equivalent for a #4 turnout is approximately 2.2 inches, for a #6, 3.27 inches, and for a #8, 4.36 inches.
A #4 turnout is therefore "sharper" (has a tighter radius) than a #6; a #6 is "sharper" than a #8; and a #8 is "sharper" than a #10.
4. Turnout anatomy. The "toe" of a turnout is where the rails of the turnout diverge (the switchstand end!).
The "heel" of a turnout is the other end of the turnout where the two tracks have diverged.
TRACK-types
cog rail
sectional track
flex-track
dual track
hand-laid track
embedded (light rail transit) track
TURNOUTS, CROSSINGS AND SLIPS
right-hand and left-hand straight turnouts/switches/points (referred to elsewhere as turnouts)
bifurcation (where in a dual gauge track, the narrow gauge track diverges from the standard gauge track.
crossing, 90, 60, 45, 30, 25, 22 1/2 , 19, 15, 12 1/2, 10°, H0/N crossing
crossing, double, 90° embedded (light rail transit)
crossover (a connecting track between two parallel tracks)
curved turnout
double-junction turnout
double-slip
dual gauge
parallel turnout - Y formation (e.g., Hornby O Gauge)
parallel turnout - left or right hand (e.g., Fleischmann O Gauge)
railshift (where on a dual-gauge track, the narrow gauge shifts position from one common running-rail to the other.
scissors (double) crossover
scissors (double) crossover with centre through-track
single-slip
three-way turnout
wye formation
Y turnout
OTHER
bridge and ramps
buffer or bumper stops
dead-end uncoupler track
derail (catchpoints)
level (grade) crossing (with or without gates)
mail pick-up and drop track (travelling post office)
re-rail track
reverse/brake track
rheostat track
signal track
terminal connector track
track clips
transfer table
turntable
uncoupling track