M4: Speed Limits
(asked on 25th May 2023) - View Source
Question to the Department for Transport:
To ask the Secretary of State for Transport, for what reasons the M4 speed limit is 60mph between Junctions 3 and 4 on the westbound carriageway.
This question was answered on 5th June 2023
This section of the M4 has dangerous air quality, above the legal limit for nitrogen dioxide of 40µg/m³. The speed restriction is in place to help address that. It is expected to improve in time, which will, in due course, allow the restriction to be removed.