HSR: High speed railway line. A high speed railway line, HSR, is specially built for high speed trains. Speeds were initially over 200 km/h (125 mph), but a new London to Birmingham link in the UK, given the go-ahead in January 2012, will see speeds of up to 400 km/h (250 mph). It was considered that above this speed it was not possible to see rail side signalling (IUR International Union of Railways standard). One of the main features of HSR is therefore to include a special signalling system to receive speed indications and other moment to moment information directly in the driver's cab.