Editing Advanced Passenger Train (section)

===Service testing===
[[File:Carlisle InterCity APT.jpg|thumb|An APT-P at {{rws|Carlisle}} in 1983]]

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.{{sfn|Wickens|1988}} It entered testing soon after, and set the UK speed record at {{convert|162.2|mph}} in December 1979,{{sfn|Wickens|1988}} a record that stood until beaten by a Class 373 [[British Rail Class 373|Eurostar]] in July 2003.<ref>{{cite news |last1=Clark |first1=Andrew |title=208mph Eurostar sets UK record - and we're starting to catch the French |url=https://www.theguardian.com/uk/2003/jul/31/transport.world |access-date=20 December 2022 |work=The Guardian |date=31 July 2003}}</ref> 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.{{sfn|Wickens|1988}}

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&nbsp;mph to a standstill as it did to slow from 125&nbsp;mph to 25&nbsp;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 [[Loading gauge|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.{{sfn|Wickens|1988}}