The motorway will be closed in both directions from 8pm on Christmas Eve (Wednesday 24 December 2025) until 4am on Sunday 4 January 2026 to enable the installation of a new underpass as part of the M27 Junction 10 improvement scheme which will create a new free-flowing, ‘all-moves’ junction whilst also enabling the delivery of new homes and jobs in the area.
A signed diversion route will be in place on the A27 throughout the closure.
Additional teams and specialist engineering equipment are preparing for the complex operation to slide a pre-constructed concrete structure – weighing around 8,500 tonnes – into position beneath the motorway. The innovative time-saving technique being used to create the underpass replaces what would otherwise have been many months of lane and speed restrictions, as well as overnight works.
Councillor Lulu Bowerman, Hampshire County Council’s Cabinet Member for Highways, said: “After months of meticulous planning, we are putting the final preparations in place for what will be a major and complex engineering operation. Once the M27 closes from 8pm on Christmas Eve, work will continue around the clock – 24 hours a day, seven days a week – to complete the job safely and as quickly as possible. The signed diversion route along the A27 will be very busy, so if you are heading out over the festive period, please plan ahead, check your route beforehand, and consider if you need to travel in this area at all. The work has been planned at a time when traffic levels are lower, but we appreciate it will cause inconvenience, and we thank everyone for their understanding in advance as we deliver these vital improvements.”
Andrew Jackson, National Highways Programme Manager, said: “We continue to work closely with Hampshire County Council to manage these works, and drivers may have already seen the advanced warning signs across our roads in the south-east. Traffic levels are much lower over the festive period but there will be significant delays, and so our advice is to plan your journeys carefully. These works allow us to accelerate this important scheme and stimulate economic growth across the region by supporting the building of up to 6,000 new homes and the creation of thousands of new jobs.”
Key travel advice for road users:
- The M27 will be closed completely, in both directions, between Junctions 9 and 11 from 8pm on 24 December to 4am on 4 January.
- A signed diversion route will be in place along the A27, which is expected to be busy every day. Drivers should anticipate severe delays, especially between 10am and 4pm. During the closure, it won't be possible to join the M27 eastbound or exit the M27 westbound at J10.
- Consider alternatives: public transport, travelling at quieter times, using different routes, or asking if your journey is essential.
- Drivers can exit the M27 westbound (from Portsmouth) at Junction 11 (Fareham) and eastbound (from Southampton) at Junction 9 (Whiteley), but there will be no entry westbound (to Southampton) at Junction 11 or eastbound (to Portsmouth) at Junction 9 during the closure.
Residents in Gosport and Portsmouth are reminded that the Gosport Ferry will run every day except Christmas Day, which could offer some travellers a helpful alternative.
The £100 million+ scheme is being delivered by Hampshire County Council, working closely with National Highways. It is fully funded by the Buckland Group, the developer of Welborne Garden Village, and by Homes England. The new underpass will connect Fareham with the Welborne Garden Village development, improving access to the M27 and supporting future growth in the area.
Over the closure period, a giant pre-constructed concrete structure - weighing approximately 8,500 tonnes (2.5 times heavier than HMS Victory) - will be slid 65 metres into a trench cut into the motorway embankment, from its current construction location on the north of the M27. The motorway will then be fully reconstructed above it (watch the short film showing the box slide process).
A series of complementary highways improvements on and around Junction 10 are being delivered by the County Council to support the development of Welborne Garden Village, which is due to provide up to 6,000 homes alongside schools and community services, just outside Fareham, and to provide better access to the M27. Under planning conditions for the Welborne development, no more than 1,160 new homes can be occupied until the new ‘all-moves’ Junction 10 on the M27 is completed and operational.
When open to traffic later in 2026, the underpass will provide four traffic lanes in each direction (two northbound and two southbound) connecting with westbound entry and exit slip roads. It will also accommodate a shared footway/cycling route connecting with Fareham Common to the south, and the Welborne Garden Village development to the north.
The two-year construction scheme is due to be open to traffic in winter 2026.
For full details or to subscribe to the scheme’s e-bulletin, visit: www.hants.gov.uk/M27-J10-xmas