| Sn3½ | |
| Scale: | to |
| Ratio: | 1:64 |
In rail transport modelling, Sn3½ is a scale/gauge combination derived from S scale to represent narrow gauge track by using gauge track (the same as HO gauge). The scale is .
Sn3½ is popular in South Africa, Australia (particularly Western Australia,[1] Queensland[2] and Tasmania[3] where narrow gauge systems exist) and New Zealand.[4]
Sn3½ is very rarely or never used for modelling in other countries with 3 foot 6 (1067mm) gauge railways such as in Japan, Taiwan, and Indonesia
As track scales down to 16.5 mm at 1:64, modelers use HO gauge track (which represents standard gauge at 1:87 scale) on Sn3½ layouts.[5]
See also: New Zealand Model Railway Guild. Sn3½ is the primary scale for modeling New Zealand's narrow gauge 3 ft 6 in railways. The majority of rolling stock available, are white-metal kits, making them considerably more expensive and heavier than other scales and countries. Many of these kits are highly detailed. Buildings are generally hand-made, and track (HO gauge track) can either be purchased or hand laid with sleepers and rail. Alternatives for modeling New Zealand railways is 1:120 or TT scale, known as NZ120, as it is a cheaper option. HOn3½ gauge, HO scale with 12mm gauge, is also increasing in popularity.
Sm gauge is also defined by the German NEM 10 standard,[6] representing Continental European metre gauge.