OO gauge
The dominant model railway standard in the United Kingdom.
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OO gauge (also written as OO scale or 00 gauge) is the dominant standard for model railways in the United Kingdom, though it is almost entirely unknown elsewhere. It belongs to a family of 4 mm‑scale standards (4 mm representing 1 ft, or a ratio of 1:76.2) and is the only one produced by major manufacturers. The track gauge measures 16.5 mm, identical to that of HO scale (1:87), which in the model represents a prototype track gauge of 4 ft 1½ in—narrower than the real standard gauge of 4 ft 8½ in.
Origin
The origins of OO gauge trace back to 1921, when Bing launched “The Table Railway” running on 16.5 mm track and scaled at 4 mm to the foot. The first British prototype models appeared the following year. Initially all locomotives were clockwork, but electric power arrived in 1923.
The combination of a 4 mm‑scale model on HO‑gauge track (16.5 mm) arose because early clockwork mechanisms and electric motors were too large to fit inside HO‑scale models of British trains, which have a smaller loading gauge than their European and North American counterparts. Enlarging the model to 4 mm per foot while keeping the 3.5 mm‑per‑foot track gauge solved the space problem and also allowed room for external valve gear. This compromise means the HO track gauge of 16.5 mm represents 4 ft 1½ in at 4 mm scale—about 7 in too narrow, or roughly 2.33 mm in model terms.
Bing collapsed in 1932, but the Table Railway continued under the new Trix company, which adopted the emerging HO standard (half of French 0 gauge at 1:43.5 scale; European 0 scale is actually 1:45). In 1938, Meccano introduced its own OO range under the Hornby Dublo brand, cementing the combination of 4 mm scale and 16.5 mm gauge as the UK’s most popular model railway standard.
Meanwhile, in the United States, Lionel Corporation launched an OO range in 1938, followed by other manufacturers, but it never gained traction and production ceased by 1942 due to wartime steel restrictions. American OO used a 19 mm track gauge, equating to 4 ft 9 in—very close to standard gauge—but it was quickly overshadowed by the better‑proportioned HO scale. A small following of American OO still exists today.
OO today
OO remains the most popular scale for railway modelling in Great Britain, thanks to the wide availability of ready‑to‑run stock and starter sets.
Lore & Background
Double‑0 scale model railways were launched by Bing in 1921 as "The Table Railway", running on 16.5 mm track and scaled at 4 mm to the foot. In 1922 the first models of British prototypes appeared. Initially all locomotives were powered by clockwork; the first electric power appeared in 1923.
The combination of 4 mm scale and 16.5 mm gauge arose because early clockwork mechanisms and electric motors were difficult to fit within HO scale models of British trains, which have a smaller loading gauge than their European and North American counterparts. Enlarging the scale to 4 mm to the foot while keeping the 3.5 mm‑to‑the‑foot gauge track allowed more space for the external valve gear. The resulting HO track gauge of 16.5 mm represents 4 ft 1½ in at 4 mm scale, which is 7 in too narrow (approximately 2.33 mm too narrow in the model).
In 1932 Bing collapsed, but the Table Railway continued to be manufactured by the new Trix company. In 1938 the Meccano Company launched a new range of OO models under the trade name Hornby Dublo.
The combination of 4 mm scale and 16.5 mm gauge has remained the UK's most popular scale and gauge ever since. In the United States, Lionel Corporation introduced a range of OO models in 1938, but it did not prove popular and remained on the market only until 1942; Lionel OO used 19 mm track gauge, equating to 4 ft 9 in – very close to standard gauge. There is a small following of American OO scale today.
4 mm finescale standards
Since the 1960s, other gauges in the same scale have arisen – 18.2 mm (EM) and 18.83 mm (Scalefour) – reflecting the desire of some modellers for greater scale accuracy. OO is also used to represent Irish gauge, where it is a scale 13½ in too narrow. Though they run on the same track, OO and HO models of the same prototype do not sit well together because OO models are larger.
Reader's Guide
OO gauge remains the most popular scale for railway modelling in Great Britain due to a ready availability of ready‑to‑run stock and starter sets. Ready‑to‑run in the UK is dominated by Hornby Railways and Bachmann Branchline, with other sources including Dapol, Heljan, Peco, ViTrains, Rapido Trains UK, Accurascale, and formerly Lima, Tri‑ang Railways, and Mainline Railways. Other scales, with the possible exception of N, lack the variety and affordability of UK ready‑to‑run products. The gauge discrepancy is particularly noticeable when looking along the track, and because most proprietary track is designed for HO scale, sleeper size and spacing are underscale for OO.
These differences have led to the development of finescale standards such as EM gauge and P4 standards, though it is possible to model using OO to standards that fall just short of finescale. Many experienced modellers find the OO standard produces a "narrow gauge" appearance when the model is viewed head on. Greater accuracy is possible using EM gauge or the closer‑to‑exact‑scale P4 track, but ready‑to‑run point and crossing work is not available for those gauges (except for Peco EM turnouts from the EM Gauge Society), so trackwork must be constructed by the modeller. OO remains the entry point and the mainstream choice for British railway modelling.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: OO gauge (CC BY-SA 4.0).
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