Broad gauge

Broad gauge railways use a track gauge (distance between the rails) greater than the standard gauge of 1,435 mm (4 ft 8 ¹⁄₂ in).

History

In Britain the Great Western Railway, designed by Isambard Kingdom Brunel, pioneered broad gauge in 1838 with a gauge of 7 ft ¹⁄₄ in (2,140 mm), and retained this gauge until 1892. Some harbours also used railways of this gauge for construction and maintenance. These included Portland Harbour and Holyhead Breakwater, which used a locomotive for working sidings. As it was not connected to the national network, this broad-gauge operation continued until the locomotive wore out in 1913.

The gauge initially proposed by Brunel was 7 ft (2,134 mm) exactly but this was soon increased by ¹⁄₄ in (6 mm) to get round clearance problems identified during early testing.

It became apparent that standardization on a single gauge throughout a rail transport system was advantageous. Rolling stock did not need to match the gauge exactly; a difference of a few millimetres could be coped with, so that interoperability on systems with gauges only slightly different was possible.