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 contained 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.
APT-E in the RTC sidings between tests in the summer of 1972
Driving controls of the Advanced Passenger Train (APT-P) at Crewe Heritage Centre.
Superelevation was applied to portions of the BR network, although the angle was limited. Here, an InterCity 225, based on APT technology, rounds a canted turn on the East Coast Main Line.
In contrast to APT, HST was a huge success.
A tilting train is a train that has a mechanism enabling increased speed on regular rail tracks. As a train rounds a curve at speed, objects inside the train experience centrifugal force. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest, and standing passengers to lose their balance, or in such excessive speeds, could even cause the train to derail. Tilting trains are designed to counteract this by tilting the carriages towards the inside of the curve, thus compensating for the g-force. The train may be constructed such that inertial forces cause the tilting, or it may have a computer-controlled powered mechanism.
A Japanese KiHa 283 series tilting DMU, which can tilt up to 8° (6° in normal operation)
A ČD Class 680 Pendolino train in July 2006
A Swiss SBB RABDe 500 on the Hauenstein railway line in May 2007
An ICE T (DB class 411) leaves a curve, showing cars tilted to different degrees.