TfL Ref: 4985-1718

Thank you for your email received by us on 26 March 2018 asking for information about the A316 between Sunbury and Hanworth.

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:

Why is the A316 between Sunbury and Hanworth set at 50?

I can advise that just prior to Sunbury at Kempton Park, the A316 enters Surrey, which is outside of the Greater London Authority boundary and the A316 becomes a trunk road for which Highways England is responsible for. The A316 then becomes the M3 motorway at Sunbury itself, which is subject to national speed limits for motorway traffic.

As a result the 50mph stretch is in place at this location to act as a transition between the national speed limit on the M3 motorway and the 40mph speed limit when the A316 ceases to be elevated and changes name from Country Way to the Great Chertsey Road, just after the Apex Roundabout junction.

Without a transition from the national speed limit at the end of the M3 and the 40mph limit when the A316 ceases to be an elevated section, the Metropolitan Police Service would struggle to enforce a lower limit if there was an immediate reduction. This could also lead to unsafe driver behaviour such as sudden breaking. Safety cameras are in place along this stretch of the A316 to help to enforce this transition from national limit to 40mph.

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
Information Governance
Transport For London