As part of our passenger charter - Abellio Greater Anglia provides our passengers with 4 weekly updates on our performance.
These figures quote all trains arriving within 5 minutes of schedule regardless of service group, whereas the industry and Network Rail count long distance services as those arriving within 10 minutes of the time quoted in the public timetable. This gives rise to a small discrepancy when comparing our figures, which are more stringent, with those of the industry bodies.
What is PPM?
PPM, or Public Performance Measure, is the method that train companies use to measure and report the performance of train services at their final destination.
The PPM figure is calculated by counting the number of trains that arrive at their destination on time.
The following criteria can cause a train to be classified as a PPM failure:
- Arrived at its final destination greater than 4 minutes later than the advertised arrival time (or greater than 9 minutes for Intercity services)
- Did not run at all
- Did not complete its booked journey
- Did not call at all its booked stations
The measure of the lateness of trains is taken automatically from the signalling system. Some manual recording takes place in rural locations.
The number of trains that arrive on time is then divided against the number of trains scheduled to run that day to give the daily PPM measure.
On the occasions when there is a need to implement a temporary timetable, the daily PPM will, under certain circumstances, be measured against any amended timetable.
Greater Anglia collates the PPM figure on a daily, four- weekly and annual basis. When the PPM figure is quoted as a Moving Annual Average, or MAA, this is based on an average of the previous 13 four-weekly periods of data. The MAA, therefore, gives an accurate picture of how trains have performed over an annual or 52 week period. This will be applicable from 5 February 2013.
The PPM figure is collated for Greater Anglia train services as a whole and for the following routes:
Services to/from Liverpool Street or Stratford to/from Kings Lynn, Ely, Cambridge, Hertford East, Cheshunt, EnfieldTown or Chingford.
Services to/from Liverpool Street to Stansted Airport
Services to/from Liverpool Street to GideaPark, Shenfield, Southend Victoria and Southminster. Also includes the Romford to Upminster route.
Services to/from Liverpool Street to Chelmsford, Braintree, Colchester, Clacton, Walton on Naze, Harwich, Ipswich and Norwich. Also includes the Marks Tey to Sudbury route.
Services to/from Norwich to Cambridge, Sheringham, Cromer, Great Yarmouth and Lowestoft. Also services to/from Ipswich to Cambridge, Peterborough, Lowestoft and Felixstowe.