High-speed rail
High-speed rail is a type of rail transport that operates significantly faster than traditional rail traffic, using an integrated system of specialized rolling stock and dedicated tracks. While there is no single standard that applies worldwide, new lines in excess of and existing lines in excess of are widely considered to be high-speed, with some extending the definition to include lower speeds in areas for which these speeds still represent significant improvements. The first such system began operations in Japan in 1964 and was widely known as the bullet train. High-speed trains normally operate on standard gauge tracks of continuously welded rail on grade-separated right-of-way that incorporates a large turning radius in its design.
High-speed rail in Europe
Britain has a history of high-speed rail, starting with early high-speed steam systems: examples of engines are GWR 3700 Class 3440 City of Truro and the steam-record holder LNER Class A4 4468 Mallard. Later, high-speed diesel and electric services were introduced, using upgraded main lines, mainly the Great Western Main Line (GWML) and East Coast Mainline.
The InterCity 125, otherwise known as the "High-Speed Train" (HST), was launched in 1976 with a service speed of and provided the first high-speed rail services in Britain. The HST was diesel-powered, and the GWML was the first to be modified for the new service. Because the GWML had been built mostly straight, often with four tracks and with a distance of 1 mile (about 1.6 km) between distant signal and main signal, it allowed trains to run at with relatively moderate infrastructure investments, compared to other countries in Europe. The Intercity 125 had proven the economic case for high-speed rail, and British Rail was keen to explore further advances.