FOI request detail

Wifi data

Request ID: FOI-2242-1617
Date published: 09 March 2017

You asked

I would like to make a Freedom of Information act request for the raw data and any materials that have been produced from the recent Wifi data collection on the tube - between 21st of November and 19th of December.

We answered

TfL Ref: FOI-2242-1617


Thank you for your request received by Transport for London (TfL) on 15 February 2017 asking for information about the WiFi data trial.


Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm we do hold the information you require.


Details of the trial and its objectives can be found in our press release at the following link:


However, please note that in accordance with TfL’s obligations under the Data Protection Act 1998 (DPA) we are not able to provide the raw data collected during the trial, as it is exempt from disclosure under section 40(2) of the FOI Act. This is because disclosure of this personal data would be a breach of the DPA, specifically the first principle of the DPA which requires all processing of personal data to be fair and lawful. It would not be fair to disclose this personal information when the individuals have no expectation it would be disclosed and TfL has not satisfied one of the conditions of Schedule 2 of the Data Protection Act which would make the processing ‘fair’.


Part of our controls to protect this data and prevent an individual being identified was that all MAC address information collected from wifi-enabled devices during the pilot was automatically pseudonymised and encrypted to prevent the identification of the original MAC address and associated device. The data is stored in an encrypted and segregated area of a secure network. The data collected during the pilot was not shared with any third parties or matched against any other data sets for the purpose of identifying or monitoring individuals.


Although the MAC address data has been pseudonymised, personal data as defined under the DPA is data which relate to a living individual who can be identified from the data, or from those data and other information which is in the possession of, or is likely to come into the possession of, the data controller. Given the possibility that the pseudonymised data could, if it was matched against other data sets, in certain circumstances enable the identification of an individual, it is personal data and therefore exempt from disclosure under section 40(2) of the FOI Act.


In terms of your request for the “materials that have been produced” after the trial, we are analysing the results of the pilot to see if we can plan and operate London’s transport more effectively for our customers, including providing better information and reducing congestion. We will publish the outcome of this analysis once this has been completed.


Therefore, in accordance with section 22 of the FOI Act we are not obliged to provide you with this information as it is intended for future publication.


The use of this exemption is subject to an assessment of the public interest in relation to the disclosure of the information concerned. We recognise that there is a public interest in openness and transparency but feel that, in this instance, the balance lies in favour of withholding the information to ensure that we’re able to collate and publish this information in accordance with the pre-determined schedule to ensure that the information is as widely available and accessible as possible.


If this is not the information you are looking for, or if you are unable to access it for some reason, please do not hesitate to contact me.


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


Lee Hill

Senior FOI Case Officer


FOI Case Management Team

General Counsel

Transport for London

Back to top

Want to make a request?

We'll email you the response within 20 working days.

We'll publish the response online without disclosing any personal information.