57 HS 125/APT J Cullin Dec 2018

HS 125 and the Advanced Passenger Train

At our meeting in December John Cullin described how in the 60’s British Rail set about developing high speed trains for the UK rail network. They recognised that for the longer distances there was an increase in competition from both air and road travel. Accordingly the British Rail Research Centre at Derby was given the task of developing a train which could travel at 150mph on existing track layouts using tilting carriages to reduce the centrifugal force effects.

The project to develop the so called Advance Passenger Train was to use the latest research and construction techniques with the propulsion being provided by gas turbines. However because of the number of technical problems which were encountered the project soon fell behind schedule and the BR Board decided that as a stop gap the relevant BR departments would develop a 125mph train powered by diesel engines using well tried current technology and production techniques.

In August 1970 the Board approved the sum of £800,000 for a project to design, construct and test the so called High Speed Train which was to run on existing lines with standard rolling stock. The prototype was completed by June 1972 and testing started on the East Coast Main Line in January 1973. A feature of the design was the provision of power cars, containing the diesel engines and associated generators, at both ends of the train with the carriages in between them, rather than having a single very heavy engine which might cause damage to the track and limit the routes available for the train. A design consultant was employed to help develop the shape of the front of the power car which included a full width windscreen to allow for double manning. During the design process it was decided that the usual buffers were not necessary and that a draw hook and other connections could be hidden behind a movable flap, thus providing a very clean appearance to the front of the train. After successful testing with runs reaching up to 140mph, fleet production began in 1974 with the first trains entering service on the Western Region in 1975. It was originally intended to produce 161 trains but this was later reduced to 95 with a few extra power cars. The ‘125’ HST has been one of the most successful and reliable class of train ever produced and has seen service throughout the UK.

However as electrification has spread throughout the network the ‘125’s are being gradually withdrawn, though at least 20 sets will be retained to work the West country routes.
The development of the sister train, the ‘150’ APT, was not nearly so successful, being beset by many technical problems which meant that by the early 1980’s it was still not ready to go into service even though experimental versions had reached over 150mph in testing. In December1981 it was decided to put 3 prototypes into regular service but although they ran successfully in some ways they also proved to be very unreliable and were withdrawn after about a year. The problems were eventually solved and the 3 prototypes were reintroduced into the regular service in 1984 and ran successfully until they were withdrawn in the winter of 1985/86.

Support for the project had collapsed and eventually the project was abandoned altogether. In spite of the APT’s troubled history some of the innovations in the design have greatly influenced the design of other trains throughout the world. For instance the carriage tilt system developed by BR is now incorporated in trains which are running today on the West Coast Main Line.