Purpose of black box beneath speed limit sign
Request ID: FOI-1166-1920
Date published: 12 August 2019
You asked
Along the A1 Lyttelton Rd, just East of the junction with Blandford Close, there are a set of signs either side of the road to show a change of speed limit from 30 - 40 mph and vice versa.
Recently, black boxes with padlocks have been mounted just below each of these signs facing oncoming traffic on either side of the road.
Please see this link for a photo:
https://ibb.co/album/esq6aa
I request the following information in regards to the described boxes:
1. What are these boxes? If they are a commercially sold product, what are they called?
2. What is the purpose of these boxes?
3. If information is collected by these boxes, what information is collected?
4. When were these boxes installed?
5. Who installed these boxes?
6. If these boxes are not permanent, when will they be removed?
We answered
Our ref: FOI-1166-1920/GH
Thank you for your request received by Transport for London (TfL) on 19 July 2019 asking for information about black boxes beneath speed limit signs.
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.
We believe that the black boxes you are referring to are traffic survey equipment recording vehicle counts, vehicle type and vehicle speeds, such as these:
http://www.ca-traffic.com/en/ca-solutions/counters-classifiers-(temporary)/radar-recorder/
Traffic surveys are usually conducted by external survey companies, that company could be running the traffic survey for TfL, London Borough of Barnet, a consultancy or any other organisation that has commissioned the survey. The survey company should have requested permission from the highway authority (TfL) to place the equipment on our network, but on this occasion we have been unable to find any record relating to this location.
We therefore went out to the site to try to find out who installed the boxes but found they have now been removed.
We therefore do not have the answers to the specific questions you have raised.
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
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