Request ID: FOI-0942-2122 Date published: 23 August 2021
You asked
F/on from FOI-0712
I am a little bit surprised that there is no data on this, as how does TFL measure performance of their service.
What data does TFL hold that one can use as a proxy to measure performance of the trains to and from Chesham?
We answered
Our ref: FOI-0942-2122/GH
Thank you for your request received by Transport for London (TfL) on 1 August 2021 asking for information about cancelled or significantly delayed trains to/from Chesham.
Your request has been considered under the requirements of the Freedom of Information Act 2000 and our information access policy.
Unfortunately we do not hold the information you require. Prior to the pandemic, branch reports for the Metropolitan line were produced, but these were based on Amersham and Uxbridge (not Chesham). Outside of that we measure our proxy at Finchley Road which only reflects the frequency of the Metropolitan line service in the core.
As previously advised, we hoped we could answer your request using information from the signalling system to provide arrivals/departures data, but the data feed for Chesham is unfortunately unreliable. We hope to resolve this problem in the future when the signalling is upgraded.
Therefore the only information we can provide is would be a report on all northbound trains for Chalfont & Latimer. We have run this report, and found that sometimes the “Passenger Destination” field shows the destination, sometimes it does not. For the period 01/01/16 – 31/07/21 there are almost 170,000 rows in total, as there is an entry for every train, and the file is therefore very large. If you would like us to provide you with this report, please let me know.
I am sorry that we do not currently hold the requested information in a way which enables us to more readily answer your request.
If you are not satisfied with this response please see the attached information sheet for details of your right to appeal.
Yours sincerely
Graham Hurt
FOI Case Officer FOI Case Management Team General Counsel Transport for London
