Dual Gauge - Gauge Conversion

Gauge Conversion

The complications and difficulties outlined show how important it is to ensure that railway gauges are standardised in the first place, if at all possible. If a railway operator seeks to convert from one gauge to another, then it helps if a dual-gauge intermediate step can be done (this has often been practised in the past).

If the gauge is to be reduced, then the sleepers can continue to protrude from the side of the rails. If the gauge is to be increased, then the sleepers used for narrow gauge may be too short, and some at least of these 'short' sleepers will have to be replaced with longer ones. Alternatively the rails may be too light for the loads imposed by broader-gauge railcars. Such potential problems can rule out dual-gauge as a feasible option. Another issue is affixing the rails to the sleepers (spikes, nails or bolts are used). If existing sleepers are wooden, extra holes can be drilled without problems. If the existing sleepers are concrete, then drilling extra holes is impractical, and the whole sleeper has to be replaced, unless extra boltholes are already allowed for.

The embankment could need widening too. It is possible that viaducts and tunnels are too narrow and too low. This could cost a lot and need the closing of the line for a year or two.

During the conversion of the Melbourne-Adelaide railway in Australia from 5 ft 3 in (1,600 mm) to 4 ft 8 1⁄₂ in (1,435 mm), dual gauge with heavy rails was not possible as the rail footings were too wide. A special gauge-convertible sleeper with a reversible chair for the Pandrol clip allowed a two-week conversion process.

In the Adelaide metropolitan area, broad-gauge timber sleepers are being replaced with gauge-convertible concrete sleepers. On June 5, 2008, the South Australian Government announced that the Metropolitan Network would be converted to standard gauge (1435 mm) in 2012.

Dual-gauge lines in Java were regauged from 4 ft 8 1⁄₂ in (1,435 mm) to 3 ft 6 in (1,067 mm) (Cape gauge) during the Japanese administration in 1942-1943. Regauging occurred only on the relatively short Brumbung-Kedungjati-Gundih main line and the Kedungjati-Ambarawa branch line, as the rest of the line was already dual-gauge (some only recently dual-gauged).