TfL Ref: FOI-0380-2425
Thank you for your clarified request received by us on 14 May 2023, asking for information about cycle trips and counting techniques.
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require.
We assume your request relates to the way we use cycle counts to produce our annual estimates of cycling (notably our headline ‘journeys’ metric as described in this press release).
Most of the answers to your questions are provided at cycling.data.tfl.gov.uk under “Active Travel Counts Programme” - notes titled 0 – Strategic active travel counts – release note and 0.5 – Strategic cycling estimates – methodology note.
I have also answered your revised questions in short below:
How does TfL define and record cycle trips? What makes a ’trip’? Is it between one counter to the next?
A trip is defined as a one-way movement between an origin and a destination for a single purpose (see footnote 1 on the methodology note linked above). As such, it does not relate to the counted flows directly. A trip is defined from the cycle user point of view, while the counts record ‘cycles’ going past an imaginary counting line on a link.
How does TfL ensure a single cyclist isn't counted multiple times across multiple counters?
This is not possible and also not necessary. It is expected that a single cycle user might go past multiple counters while making their trip. The way that this is typically dealt with in transport planning is by using volume metrics instead of raw counts, by assigning an assumed travelled distance to each count location and calculating kilometres travelled. This volume (in km) is an additive metric that solves the problem of double-counting. This is again explained in more detail in section 2 of the methodology note linked above.
How does TfL differentiate unique trips from multiple counts by the same cyclist?
As above.
What data management systems or algorithms does TfL use? Please provide an example of the technology used and its efficacy.
Details about the calculation methods are provided throughout the methodology note linked above. In terms of the technology used for counting specifically, section 1.2 of that same document explains that counts are either done based on video recordings or manually.
Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.
Yours sincerely
Eva Hextall
FOI Case Management Team
General Counsel
Transport for London
