We're giving advance notice of the need to close the M4 motorway in Berkshire between junctions 10 (Winnersh) and 11 (Reading) from 9pm on the evening of Friday 18 September to 6am on Monday 21 September.
Why does a section of the M4 need to close?
In February 2026, a tree fell onto an electricity tower carrying a major part of our network in Winnersh. For the safety of everyone, and the preservation of power supplies to the wider area, the line was immediately switched off and the network re-routed. The tower was badly damaged; both it and the lines which were carried by it over the nearby M4 were quickly removed.
The work to restore the network back to its previous state is almost complete. Following months of design and site preparation, a replacement tower was installed in Winnersh in July 2026. This work can be seen in the timelapse footage below.
We now need to plan for the final stage of works, which involves running new high-voltage wires across the M4, and the only safe way to do this is to close part of the road to all traffic for a short period of time.
Why was this weekend chosen?
We know there’s no ideal time to close one of the South of England’s busiest roads, even if it’s only for a couple of days. By selecting the weekend of 19th-20th September, we’ve tried to avoid the main holiday season and significant summer events. But the need to restore the network back to its previous state is a pressing one, to ensure the reliability of electricity supplies for millions of customers.
The detailed work of running new wires between electricity towers is a delicate, precise task which relies in part on human sight. This rules out overnight working, and means the job is better done before the days become shorter, later in the autumn.
The closure has been planned in close co-operation with National Highways, and we're also communicating with the emergency services, and a wide range of local authorities, institutions and organisations whose day-to-day operations and planned activities may be affected by this essential closure.
I’m travelling in the area on this weekend – what can I do?
By informing people now of the need to close the route in several weeks’ time, we hope this gives them time to plan ahead. The main diversion route is going to be A329(M) and the B3270. There’s a likelihood all journey times in the area could be affected. The diversions signposted are only advisory, so it’s likely people with local knowledge may pursue their own alternative routes to avoid the very busy signposted diversion. Ourselves and National Highways expect all other roads in the area to be busier than normal, meaning extra time for journeys is strongly advised.
Will residents be affected?
We also need to close Hatch Farm Way in Winnersh over this weekend, as it runs beside the M4 at the point where the new wires are being suspended.
Jo Niven, SSEN Distribution’s Head of Capital, Maintenance and Inspection Investment says:
“The damage done to our network in Winnersh in February was extensive, and it’s important we return it to full operational health as soon as we can.
“Over the past few months, the design of this new stretch of network has been progressing at pace, and it’s now time to finish the job.
“Closure of the M4 between junctions 10 and 11 for the weekend of 19-20 September is the only safe, practical way to do this. By being open and honest now about the need for this closure, we want to ensure everyone who would be using the M4 along this stretch, as well as those who’ll be travelling on diversionary routes, is given ample time to plan around ahead.
“At this time, I’d like to thank everyone for their patience and understanding while we finalise preparations for this complex, final part of the project. I’d also like to apologise to residents in the area of Winnersh near to the affected electricity tower for the temporary disruption they faced back in February, and at certain points in the months since as we’ve worked to restore the network in this area."