Freedom of Information request - A41 Broadfields avenue traffic lights
Request ID: FOI-0671-2324 Date published: 27 June 2023
You asked
Dear Transport for London,
The Traffic lights at the intersection between Broadfields Avenue and the A41, usually has 4 phases.
1) Broadfields Avenue
2) A41 Eastbound including right turns
3) A41 Eastbound and Westbound with no right turns
4) A41 Westbound including right turns.
Often the first phase of the light is skipped, causing traffic to back up on Broadfields Avenue and in the local area, and I had a few questions regarding this:
1) Please can you share copies of all policies and procedures regarding these traffic lights.
2) Is this behaviour of the traffic light intentional?
3) How long has this behaviour been in place for?
4) Does this behaviour vary when there is heavy traffic on the A41 (ie detected through sensors or cameras), or is it programmed to occur at specific times regardless of traffic levels, and when are these times?
5) Are there cameras or sensors on Broadfields avenue which feed traffic levels into the traffic lights?
We answered
Our ref: FOI-0671-2324/GH
Thank you for your request received by Transport for London (TfL) on 2 June 2023 asking for information about A41 Broadfields avenue traffic lights.
Your request has been considered under the requirements of the Freedom of Information Act 2000 and our information access policy. I can confirm that we do hold the information you require.
1) Please can you share copies of all policies and procedures regarding these traffic lights. The design documents for traffic signal controlled facilities are as follows: National Guidance Traffic Signs Manual chapter 6 – by the Department for Transport Transport for London has its own design guidance which is based on the National guidance which are attached: SQA 643 – Signalised Junctions SQA 644 – Stand Alone Crossings SQA 645 – Traffic Signal Timings Please note: these documents are based on the previous DfT guidance which has all been replaced by TSM chapter 6, and hence we are in the process of being updated so the references are still to the old DfT documents.
2) Is this behaviour of the traffic light intentional? The operation of Broadfield Avenue north and southbound will only activate and receive a green signal when a vehicle demand is present on either approach. On occasions that there is no vehicle demand on either approach these arms will not receive a green signal with the time reallocated to other approaches.
3) How long has this behaviour been in place for? The last major change to the operation of these signals was in 2015 when the site started to be controlled by the central computer system. Our records indicates that since coming onto the computer system, the Broadfield Avenue approaches has only been called when a vehicle demand is present during normal operation. However, it is possible there have been occasions when the normal operation has been overridden during works or events, which makes these approaches occur without the need for a vehicle demand.
4) Does this behaviour vary when there is heavy traffic on the A41 (ie detected through sensors or cameras), or is it programmed to occur at specific times regardless of traffic levels, and when are these times? The site operate a standard order for all time periods. 1. A41 Edgware Road east and west bound without right turns 2. A41 Edgware Road westbound with right turn 3. Broadfield Avenue north and southbound 4. A41 Edgware Road eastbound with right turn In this setup, the Broadfield Avenue approaches appearing is dependent on vehicle demand during all time periods. This does not change dependent on vehicle demand
5) Are there cameras or sensors on Broadfields avenue which feed traffic levels into the traffic lights? Yes, the site operates a dynamic traffic control system known as SCOOT. This system uses sensors in the ground to measure vehicle volumes on each approach and adjusts green times for each approach based on this information.
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.
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
