Request ID: FOI-0238-2425 Date published: 17 May 2024
You asked
• Where Transport for London receives a request from a law enforcement agency for information associated with a MAC address (a MAC address which the law enforcement agency supplies to TfL), are you able to provide information relating to the movements of the associated device or any other metadata associated with that MAC address?
• If TfL is able to provide such information, can you confirm how many requests have been received for this information or similar from law enforcement over the last 3 calendar years, divided by year and month.
• Documents on any information-sharing agreement in place between Transport for London and the Metropolitan Police relating to TfL’s Wi-Fi data collection.
We answered
Our Ref: FOI-0238-2425
Thank you for your request received on 22 April 2024 asking for information about data collection. Your request has been considered in accordance with the requirements of the Freedom of Information (FOI) Act and our information access policy. I can confirm that we hold some of the information you require. You asked: . Where Transport for London receives a request from a law enforcement agency for information associated with a MAC address (a MAC address which the law enforcement agency supplies to TfL), are you able to provide information relating to the movements of the associated device or any other metadata associated with that MAC address? . If TfL is able to provide such information, can you confirm how many requests have been received for this information or similar from law enforcement over the last 3 calendar years, divided by year and month. We treat our customers’ privacy extremely seriously and have detailed information about how we collect data on our website, including how we pseudonymise MAC addresses to prevent identification: https://tfl.gov.uk/corporate/privacy-and-cookies/wi-fi-data-collection The original MAC address is only used by WiFi access points to allow a user to connect to the free WiFi on the TfL network. Authenticated connections are sent in near real time to a central database where they are combined with location data, but the pseudonymisation process described on our website happens before data is stored in this database. Each access point handles this separately and does not store the data after it has been sent. As a result there is no database in TfL that contains both the original MAC address and the device's location within our network, nor any other metadata generated. This process was designed precisely to prevent tracking a specific individual using the MAC address for their device. . Documents on any information-sharing agreement in place between Transport for London and the Metropolitan Police relating to TfL’s Wi-Fi data collection. We do not hold this information as we do not have an information sharing agreement with the Metropolitan Police for Wi-Fi data collection. If this is not the information you are looking for please do not hesitate to contact me. Please see the attached information sheet for details of your right to appeal.
Yours sincerely
Gemma Jacob Senior FOI Case Officer FOI Case Management Team General Counsel Transport for London
