page_title: Advanced Passenger Train
section_title: Service testing
hierarchical_section_title: Advanced Passenger Train / Background / Service testing
caption_attribution_description: April 1983
context_page_description: The Advanced Passenger Train was a tilting high speed train developed by British Rail during the 1970s and early 1980s, for use on the West Coast Main Line. 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, only to be bested by the service prototype APT-P at 162.2 miles per hour in December 1979, a record that stood for 23 years.
  Development of the service prototypes dragged on, and by the late 1970s the design had been under construction for a decade and the trains were still not ready for service. The election of Margaret Thatcher brought matters to a head and she alluded to funding cuts for the project. 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. The result was a media circus when every problem large or small received front-page coverage and the entire project derided as an example of BR's incompetence.
context_section_description: Although APT-P used much of the technology developed on the APT-E, construction of the first APT-P was delayed several times. The first power car was delivered from the Derby locomotive works in June 1977, and the first passenger cars on 7 June 1978, a year late. The first complete train was not ready until May 1979. It entered testing soon after, and set the UK speed record at 162.2 miles per hour (261.0 km/h) in December 1979, a record that stood for 23 years. Two additional examples were delivered, each with minor changes, one in late 1979, and the last in 1980. Initially proposed in the 1960s, and given the go-ahead in the early 1970s, the design was now significantly late.
  Long delays in the production of the prototype meant that the brake units had to be stored for an extended period before being installed. The change from oil to water-glycol mix required the cylinders to be covered internally with an anti-corrosion coating, which broke down during storage. In testing the cylinders repeatedly failed, and the loss of pressure caused the train to take nearly as long to slow from 25 mph to a standstill as it did to slow from 125 mph to 25 mph. During commissioning, because of this and other development issues, every axle on the trains was modified and exchanged.
  The compressed air systems that actuated the brakes and powered the doors and other moving parts was another source of problems. The air piping would normally be run in such a way that there were natural low points where water condensing out of the air would collect and could be removed. On APT these runs were tortuous, and resulted in numerous points where the water would collect, and in cold weather, freeze. The commissioning team found a Westinghouse designed solution that would eliminate the water being produced by the compressors, but the design team would not accept the solution. They stated that the problem would not occur with a full train formation, as opposed to the shorter formation used in commissioning.
  Finally, it was only discovered at the APT-P commissioning stage that parts of the WCML had been built in such a way that, if two APT-P trains with their tilt systems failed and the carriages stuck in the inward tilted position met, they would strike one another. The railway had not been built with tilting trains in mind, and the dynamic envelopes were too small for a tilted APT. The effect was not seen with conventional trains since, without tilt, their movements stayed well within the dynamic envelope.
  Adding to the problems, in 1980 another reorganisation resulted in the disbanding of the APT team, leaving responsibility for the project spread across several divisions.
caption: An APT-P at Carlisle in 1983
exif: {"Image ImageWidth": "2404", "Image ImageLength": "1620", "Image Make": "Plustek", "Image Model": "OpticFilm 7200", "Image Orientation": "Horizontal (normal)", "Image XResolution": "1800", "Image YResolution": "1800", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 6.0 Windows", "Image DateTime": "2010:07:26 00:53:46", "Image ExifOffset": "244", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "414", "Thumbnail JPEGInterchangeFormatLength": "6549", "EXIF DateTimeDigitized": "2010:07:25 23:54:48", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "2404", "EXIF ExifImageLength": "1620"}