Causes
Network Rail delays due to infrastructure faults cause about 39% of delays, train operating companies 28%, weather, trespass, vandalism, cable theft and fatalities 20%, other train operating companies (mostly other passenger trains) 13%.History
Prior to PPM's introduction in 2000, there were a variety of punctuality measures. For example, in 1957 Gerry Fiennes published an analysis showing thatCriticisms
* PPM doesn't measure strict punctuality − whether a train arrived strictly on time − but has an inbuilt margin for lateness. This means that a train can be 'on time' according to PPM, but still late enough for passengers to miss their connections. It also means there can be, or appear to be, a difference between the rail industry's perception of what is success, and that of passengers. * PPM doesn't reflect passenger experience, as no weight is given to the number of passengers on each train − a late night service with few passengers on is counted the same as a rush hour service. Therefore, according to PPM, a near-empty train which arrives 6 minutes late is worse than a fully loaded commuter train which arrives 4 minutes late. As busier rush hour trains are more likely to be delayed than off peak trains, PPM scores are likely to be higher than what most passengers experience. * As only the time at the terminating station is recorded, a train could have been late at some of its intermediate stations, affecting passengers alighting at those stops, and this would not be a PPM fail. This is particularly the case for timetables with 'backloading', or 'padding', which is when extra minutes are built into the final leg of the journey as 'catch-up' time. While time at the terminus is important for morning commuter trains into a city, when most passengers alight at the terminus, for inter-city trains, cross-country trains, and evening commuter trains out of a city, it is irrelevant to most passengers, who will alight at different points along the journey. * PPM doesn't measure the ''quality'' of the service provided: **It makes no judgement whether customer demand is met by the level of service provision, for example whether departure times match customer journey times, how many people have to stand, or whether people are able to board the first train that departs. **If minutes are added to a timetabled journey due to repeated lateness, then the service will deteriorate, but PPM will improve. **If a different type or size train is run than originally scheduled, then this doesn't count as a PPM fail. Therefore if a train is run with fewer carriages than normal, meaning that some passengers are unable to board who would normally be able to do so, the train can still be a PPM success. * PPM is measured against the planned timetable as agreed between theReferences
{{Reflist Transport policy in the United Kingdom Department for Transport