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 mph, only to be surpassed by the service prototype APT-P at 162.2 mph 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 The APTs were withdrawn from service to address these issues.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 Plans for a production version, APT-S, were abandoned, and the three APT-Ps ran for just over a year before being withdrawn again over the winter of 1985/6.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.
Background
British Rail Research Division
Following nationalisation of the UK's railways in 1948, British Railways, as it was then known, faced significant reductions in passenger numbers as the motor car rapidly became more popular through the 1950s and 60s. By 1970, passenger numbers were roughly half what they had been immediately prior to World War II. In an attempt to maintain a level of profitability, the government commissioned a report that resulted in the abandonment of many lines as part of the 1963 "Beeching Axe". In spite of this significant restructuring, the organisation was still built on lines that were pre-war, with routings dating into the 1800s. Maintaining the network created problems with derailments increasingly common.
In 1962, Dr. Sydney Jones was hired away from the weapons department at R.A.E. Farnborough with the eventual aim of having him take over as BR's research lead from Colin Ingles, who retired in 1964. Looking into the derailment problem, they found that much of the problem could be traced to a problem known as hunting oscillation. This was well known in the railway world, but tended to happen only at high speeds. On the BR network, especially on freight cars with worn wheels, it was being seen at speeds as low as 20 mph. Jones was convinced that hunting oscillation was an effect similar to the problem of aeroelastic flutter encountered in aerodynamics, and decided to hire someone from the aeronautics field to investigate it.
In October 1962, Alan Wickens was given the position. Wickens was a dynamics expert who had previously worked at
In service
Queasy rider
While the commissioning team continued to report, and solve, problems in the APT design, BR management was under increasing pressure from the press. By the early 1980s the project had been running for over a decade and the trains were still not in service. Private Eye lampooned it with a timetable proclaiming "The APT arriving at Platform 4 is fifteen years late".[12] Press pressure led to political pressure which led to management pressure, and the APT team was told to put the train into operation in spite of its ongoing problems.
On 7 December 1981 the press was invited aboard APT for its first official run from Glasgow to London, during which it set a schedule record at 4 hours 15 minutes. However, press reports focused on a distinct sickening sensation from the tilt system, and nicknamed APT the "queasy rider". They also reported that the stewardess, Marie Docherty, suggested the solution was to "just stand with your feet apart." A BR engineer suggested that the reporters were simply too drunk on BR's free alcohol. On its return trip from London the next day, one of the coaches became stuck in a rotated position when the tilt system failed, and this was heavily reported in the press.[4] Two days later, the temperature dipped and the water in the hydrokinetic brakes froze, forcing the train to end service in Crewe.[13]
Examination
The failure of the APT project saw extensive reporting in the 1980s, and has remained a topic of some discussion since then. Writers generally agree that the technical aspects of the design were largely solved by the time of their second service introduction, and put most of the blame for the delays on the shifting management structures and infighting within BR between APT and HST. There have also been concerns that carrying out development within BR was a major problem of its own, because this meant their industrial partners had no buy-in and their years of practical experience were being ignored.[5]
The development timeline is also a topic of considerable discussion. In comparison, the Canadian LRC train began development at the same time as APT, developed a unique active tilting system of its own, and entered production in the late 1970s. Like APT, LRC also faced teething problems that took some time before they were solved, and was subject to some press chiding over these failures. Unlike APT, LRC had no competition and management was in a hurry to remove the Turbo from service. The system was given the time it needed to mature with no serious possibility of cancellation.[17]
The slow pace of APT development has been blamed on the shoestring budget of £50 million over 15 years, although the press of the era dismissed this as too high.[5]
Legacy
Alan Williams[18] notes that work continued on a new variant, the APT-U (APT-Update). This was essentially APT-P with the tilt system made optional and the engines repositioned at either end of the train with power couplings running between them. That project was later retitled InterCity 225 (IC225), perhaps to distance it from the bad publicity surrounding the APT-P. The Mark 4 coach design that was introduced as part of the new IC225 sets for the East Coast Main Line electrification allowed the retrofitting of the tilt mechanism, although this was never implemented. The Class 91 locomotives that power the IC225s had design features "imported wholesale" from the APT-P power cars, including body- rather than bogie-mounted traction motors to reduce unsprung load, and having the transformer below rather than on top of the underframe to reduce the centre of gravity. Unlike the APT-P power cars, though, they were never intended to tilt.[19][20] In 1976 Fiat Ferroviaria built the ETR 401 trainset, a tilting train using an active system with 10 degrees of tilting that used gyroscopes to detect the corner in its early phases in order to have a more punctual and comfortable inclination: this is why the FIAT project has been successful since the '70s. In 1982 FIAT bought some APT patents that were used to improve their technology for the ETR 450 trainsets.[21]
APT today
The APT-E unit is now owned by the National Railway Museum and is on display at its Locomotion museum at Shildon in County Durham. An APT-P unit is now on display at Crewe Heritage Centre and can be seen from trains passing on the adjacent West Coast Main Line along with APT-P power car number 49006 which arrived in March 2018 after seven years at the Electric Railway Museum near Coventry.
During special events, the driving trailer 370003 offers a "tilt" experience which involves tilting the coach when it is static.
External links
References
- Bob Gwynne. Pacer: the bastard son of the APT The Railway Hub, 22 May 2020^
- Manfred Weigend. Handbuch Eisenbahninfrastruktur Springer Vieweg, 2013^
- Sam Wise. British Railways Research, the first hundred years Institute of Railway Studies, 2000, retrieved 8 February 2016^