M4 Smart Motorway


Highways England will begin upgrading the 32-mile stretch of motorway between junction three at Hayes, west London and junction 12 at Theale, Berkshire after the summer.

This will be the longest smart motorway project in England to date and the entire upgrade is set to take around three and a half years, completing in the Spring of 2022.

To minimise disruption to road users, the work is set to take place in stages. The first phase of these works will happen at junction eight and nine at Maidenhead in September, and is scheduled to be completed in May 2020.

At the same time, work will start on four bridges between junctions seven, eight and nine.

During this time, narrow lanes and reduced speed restrictions will be in place to create smooth and safe traffic flow; and noisier works will take place during the day to avoid disturbance. In addition, there will be temporary closures of the carriageway and slip roads at night on some occasions.

Advanced warning signs and clearly signed diversions will be in place in these instances.

Works east of junctions eight and nine will start next spring, information sessions in the area will happen in the New Year to ensure information is up to date closer to the works.

The reason behind this transformation to a smart motorway is because Highways England says the M4 is the main strategic route between London, the west of England and Wales; carrying on average 130,000 vehicles per day, because of this, it is prone to congestion, which will ease once the upgrade is completed.

Key features of a smart motorway include set speed limits to smooth traffic flows, converting the hard shoulder into an additional lane and the creation of highly visible emergency areas which will be no more than 1.6 miles apart. So if you are driving at 60mph you will pass one approximately once a minute.

To find out more about the M4 smart motorway project, including the work required how smart motorways operate and what to do if you break down on a smart motorway, download this guide:


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Downloadable File(s)

M4 Smart Motoryway Information exhibitions July 2018 leaflet M4 presentation Iver 27 November 2019 email size-min-compressed 1

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