A4 between Theale and Newbury diversion route for the M4 between juncts 12 and 13
Case reference FOI2025/01974
Received 20 October 2025
Published 14 January 2026
Request
In accordance with the Freedom of Information Act, I request the following information:
1) Any policy or guidance relating to acceptable speed limits on roads that are used as diversion routes when a section of motorway is closed for any reason - and in particular short sections of streets in residential areas with proposed limits of 20mph.
2) Any instruction, guidance or advice given to West Berkshire Council on this matter in relation to the section of the A4 between Theale and Newbury (which is a diversion route for the M4 between junctions 12 and 13).
Response
The diversion route is a tactical diversion route identified as being suitable to accommodate motorway traffic.
National Highways applied to West Berkshire County Council to utilise the route as a diversion during the duration of motorway closures through an online booking portal used by highways agencies, local authorities and statutory undertakers call Street Manager. West Berkshire approved the diversion on 30 May 2025.
National Highways offers no guidance on acceptable speed limits to the local authority for a diversion route used on their network.
Diverted traffic is expected to adhere to the speed limits on the route as they would for any normal use by law and follow the official route by the provided signage.
Occasionally local authorities request additional signage to remind users of the speed limits on certain roads/routes due to their local knowledge of problem areas, however no such request was received for these works during the M4 closures.
Documents
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