FOI request detail

Traffic lights

Request ID: FOI-3591-2223
Date published: 26 April 2023

You asked

Dear Sir, Can you please provide me with a list of all the traffic lights maintained and managed by TFL

We answered

TfL Ref: 3591-2223
Thank you for your request received by Transport for London (TfL) on 29 March 2023 asking for information about traffic lights managed by Transport for London.
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. You asked for:
a list of all the traffic lights maintained and managed by TFL
We are responsible for all of London's 6,300 traffic lights. some of which are linked to safety cameras, for example, including those that enforce red light violations, red light and speed on green violations; and speeding offences.   
However, in accordance with the FOI Act, we are not obliged to supply you with the requested information as it is subject to a statutory exemption to the right of access to information under Section 31(1)(a) Law Enforcement, which relates to all aspects of the prevention and detection of crime.
Section 31 exemption has been applied as provision of this information could potentially identify where enforcement across the capital is in operation. The purpose of enforcement is to deter drivers from contravening restrictions and so is focused on those areas of greatest risk, where compliance is low and where other traffic management initiatives have been unsuccessful. Disclosing information which reveals each and every location of our traffic signals database could lead to a decrease in compliance with traffic restrictions and consequently increase unlawful driving.
When considering the prejudice test and taking into account any harm likely to arise if the requested information were put together with other information already published into the public domain (commonly known as the ‘mosaic effect’), we believe that by disclosing this information would enable others to build up a database of traffic light and enforcement camera locations, together with their functionality, and also attempt to predict when cameras may or may not be operational. 
Disclosure of this information to you has to be regarded as a disclosure to ‘the public at large’. We consider that the likelihood of prejudice is particularly high because there is a separate and well-established network of information available online which deliberately seeks to undermine legitimate enforcement of this nature. Hence, given the significant concerns we have that provision of this information would be likely to endanger the public and undermine the efficacy of managing our highways networks, we consider the exemption to be fully applicable in this instance.
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 the need for openness and transparency by public authorities, but in this instance feel that balance lies in favour of withholding the information to ensure that we’re able to continue to comply with our Network Management Duty, whilst ensuring the safety of all road users, and enforce traffic contraventions as and when they occur. With this in mind, we conclude that the overwhelming public interest falls in favour of maintaining this exemption.

If this is not the information you are looking for, or if you are unable to access it for any 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
Jasmine Howard
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London

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