Advanced Passenger Train

The Advanced Passenger Train (APT) was a tilting high speed train developed by British Rail during the 1970s and early 1980s, for use on the West Coast Main Line (WCML). The WCML contains many curves, and the APT pioneered the concept of active tilting to address these, a feature that has since been copied on designs around the world. The experimental APT-E achieved a new British railway speed record on 10 August 1975 when it reached 152.3 miles per hour (245.1 km/h), only to be surpassed by the service prototype APT-P at 162.2 miles per hour (261.0 km/h) in December 1979.

Development of the service prototypes progressed slowly, and by the late 1970s the design had been under construction for a decade and the trains were still not ready for service. Facing the possibility of cancellation, BR management decided to put the prototypes into service, with the first runs along the London–Glasgow route taking place in December 1981. They proved to have a number of problems and this led to a press backlash when any problem, no matter how small, was excuse to heap scorn on the program. It was referred to in the press as the "queasy rider" and "Accident Prone Train". The APTs were withdrawn from service to address these issues.

The problems were solved and the trains quietly reintroduced in 1984 with much greater success. By this time the competing High Speed Train, powered by a conventional diesel engine and lacking the APT's tilt and performance, had gone through development and testing at a rapid rate and was now forming the backbone of BR's passenger service. All support for the APT project collapsed as anyone in authority distanced themselves from what was still derided as a failure. Plans for a production version, APT-S, were abandoned, and the three APT-Ps ran for just over a year before being withdrawn again over the winter of 1985/6. Two of the three sets were broken up, and parts of the third sent to the National Railway Museum where it joined the APT-E.

Despite the challenges faced by the APT, its design was highly influential and directly inspired other high-speed trains, such as the Pendolino. The extensive work on electrification carried out alongside the APT was used effectively in later non-tilting designs, including the British Rail Class 91. The APT’s tilting system was reintroduced on the West Coast Main Line with the British Rail Class 390, which was based on the Fiat Ferroviaria tilting train design and built by Alstom. However, certain features introduced by the APT, such as the hydrokinetic braking system, have not been widely adopted.