Variable gauge

[2] Similar systems for freight traffic are still in their infancy, as the higher axle weight increases the technological challenge.

[30] In 2009, at Roda de Barà near Tarragona, a Unichanger capable of handling four different VGA systems was under development.

Different systems have different limitations, for example, some can be used on carriages and wagons only and are unsuitable for motive power, while others require that rolling stock is unloaded before going through the gauge changer.

The Talgo RD GC changes gauge at a speed of 15 kilometres per hour (9.3 mph; 4.2 m/s) so a 100 m (328 ft) train takes only 24 seconds to convert.

Designs consist of a pair of running rails that gradually vary in width between the two gauges, combined with other rails and levers to perform the following steps, using Talgo RD as an example: In the Spanish Talgo-RD system, a constant spray of water is used to lubricate the metal surfaces, to reduce heat and wear.

A Talgo train with a locomotive can drive across a gauge change at 1 axle per second at a speed of about 10–15 km/h (6.2–9.3 mph).

[35] [36] A train (or an individual car) can be pushed halfway across the gauge-changer, uncoupled, and then (once far enough across) coupled to the new locomotive and pulled the rest of the way.

Break of Gauge stations were installed at Port Pirie, Peterborough and Albury; these were fairly manual in operation.

Five hundred vehicles were fitted with "adjustable gauge trucks" but following heavy day-in, day-out use the system proved unsatisfactory, particularly in cold and snowy weather.

The system used telescoping axles with wide hubs that allowed the wheels to be squeezed or stretched apart through a gauge-changer, after holding pins had been manually released.

[47] Train ferry traffic operated by SeaRail and arriving from Germany and Sweden by sea used bogie exchange facilities in the Port of Turku.

The "Gauge Change Train" is a project started in Japan in the 1990s to investigate the feasibility of producing an electric multiple unit (EMU) train capable of operating both the 1,435 mm (4 ft 8+1⁄2 in) Shinkansen high-speed network at 270–300 km/h (168–186 mph) and the original 1,067 mm (3 ft 6 in) network at 130–140 km/h (81–87 mph).

[52][53] The second-generation train, intended to run at a maximum speed of 270 km/h (168 mph), was test-run in various locations in Japan between 2006 and 2013.

[54] A third-generation train has been undergoing reliability trials since 2014 in preparation for potential introduction to service on the planned Kyushu Shinkansen extension to Nagasaki.

A gauge changing facility of the Polish SUW 2000 system is installed at Mockava north of the Lithuanian-Polish border.

On 14 December 2003 VGA passenger trains were introduced between Kraków (Poland) and Lviv (Ukraine) instead of bogie exchange.

In February 2004, RENFE placed orders for: There is also a 14.4 km (8.95 mi) circular test track in Spain.

[64][65] In VGA, the train is pulled through the "adjuster" at about 15 km/h (9.3 mph)[66] without any need to uncouple the wagons or disconnect (and test) the brake equipment.