Great Western Coffee Shop

"ppm"s are figures oft quoted as an indicator or performance.   But ...

* what are the targets that GWR are looking to achieve?

* how are they calculated?

* do they include Sundays?

* do they take account when a train's cancelled of the amount of disruption - i.e. if the next train after a cancelled one is in 30 minutes, does this have the same numeric negative as if the next one was 2 hours later, or indeed if it was the last train of the day that is cancelled?

* do they take into account stations skipped in the middle of the journey?

* do they take account of shortformed trains that are overcrowded as a result?

* do they take account of services flagged as "cancelled" but later re-instated?

And do they include services cancelled for part of the journey?

At some future date, isn't there going to be a change to measuring punctuality at every station on a route?  In which case, trains skipping stops or not completing the whole route can't really be disregarded.

‘All stops’ figures are now been recorded and published.  I should have a nice graph on the performance thread in a few days...  :)

A train that missed stops was always categorised as a ‘part cancellation’.

For PPM and CaSL see the ORR's "Passenger & Freight Rail Performance: Quality and Methodology Report (https://dataportal.orr.gov.uk/media/1235/performance-quality-report.pdf)". ORR publish these figures (and the freight one FDM) for the operators and for Network Rail. ORR assess and report on performance, and where this is poor they usually extract promises to do better (with explanations of how). That may cost the TOC or NR money, but only rarely to ORR threaten to demand direct payments.

The DfT's regular incentive payments, as defined in the franchise agreement, use cancellations (including part-route) and minutes lateness. Obviously these are related to PPM and CaSL, but not in an obvious manner. There is similar marking  scheme against benchmarks based on the National Rail Passenger Surveys scores, but that produces amounts of money the TOC has to put into improvements, or into the Customer and Communities Improvement Fund.

I have read that.    As I understand it - an example of PPM

Take the number of trains scheduled (over the 4 week period)  - say 476 on a sample line.  Cancel 48 of them,  and have a further 42 run 5 or more minutes late - leaving 386 trains running within 5 minutes of schedule. 386 out of 476 is 81% - an 81% PPM.

For PPM MAA - same thing but over a 52 week period. It can be equally and technically correctly calculated by averaging out the PPMs for 13  4-week periods where the level of service is unchanged for the whole period covered.

So ...
* Sundays ARE included
* A 6 minute delay has the same numeric effect as a cancellation
* No  effect on the numbers from the effect on passengers once at or beyond a 5 minute delay.

If a cancellation and a delay are 'costed' the same way, won't that mean there will sometimes be an even greater incentive for a ToC to turn a train around short of its destination to make up time?  And missing out Weston Super Mare can buy back easily 10 minutes.