Staff issues, including industrial action and problems with the train fleet are the other significant issues.
Delays are measured by what TfL call Lost Customer Hours (LCH). These are calculated by multiplying the delays in minutes by the number of passengers. TfL records all delays over 2 minutes. It uses the financial year from April to March and splits the year in 13 equal periods for performance measurement.
Data in the London Underground Performance Almanac for the last full year shows there was an average of 205,014 Lost Customer Hours per period on the Piccadilly Line.
The Piccadilly ranks in 4th place for the worst record on the network, but it has improved considerably in the past 10 years. It has reduced Lost Customer Hours by 69% in the pas 3 years compared to 2003/06.