The closure is needed to install a new dual carriageway underpass beneath the motorway - using an innovative time-saving engineering technique being used for the first time in Hampshire. 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).
The one-off closure of this section of the M27 to facilitate necessary improvements to a major component of the J10 improvement scheme, replaces what would otherwise have been many months of lane restrictions, speed limits, and overnight works. It has been timed to coincide with lower traffic levels over the holiday period.
Key information road users need to know during these works:
- The M27 will be closed completely, in both directions, between Junctions 9 (Whiteley) and 11 (Fareham), from 8pm, 24 December 2025 to 4am on Sunday 4 January 2026.
- There will be a signed diversion route along the A27, which is mostly two lanes in each direction, during the closure. This is expected to be busy, particularly between 10am and 4pm every day when drivers should be prepared for severe delays. Road users should plan their journey in advance and consider alternatives including public transport, travelling during less busy times, using different routes, or if their journey is really necessary.
- Drivers will be able to exit the M27 westbound at Junction 11 for Fareham and Gosport, and eastbound at Junction 9 for Whiteley and Park Gate. However, there will be no westbound entry to the M27 at Junction 11 for traffic heading towards Southampton or the A32 (Alton), and no eastbound entry at Junction 9 for traffic heading towards Portsmouth.
- For more information and updates visit www.hants.gov.uk/M27-J10-xmas
Councillor Lulu Bowerman, Cabinet Member for Highways at Hampshire County Council, said: “We will be using an innovative, time-saving engineering approach to accelerate delivery of this significant highway upgrade to avoid prolonged periods of work and disruption over many months. However, creating the new underpass is a major construction challenge which will require a full one-off closure of a section of the M27 to ensure it can be undertaken safely. Anyone planning to travel in the area over the Christmas and New Year period, especially those travelling to or from Southampton or Portsmouth, should factor the closure into their festive plans. This will cause disruption with severe delays possible at the busiest times, so we are urging people to plan ahead, consider if alternative travel arrangements can be made or if their journey is necessary. We thank everyone for their patience and understanding as we carry out this vital infrastructure improvement, which will bring long-term benefits to the region’s transport network alongside homes, jobs, and new services.”
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.
Andrew Jackson, National Highways Programme Manager, said: “We are working closely with Hampshire County Council to manage the impact of these works, which are being timed to coincide with lower traffic levels over the holiday period. This important scheme will 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. Local communities will soon benefit from a new underpass, new slip roads and a new dual carriageway that will provide a free-flowing, ‘all-ways’ junction onto the Strategic Road Network.”
Once complete, the new underpass under the M27 will carry four lanes of traffic - two in each direction - along with a shared walking and cycling route, improving connectivity between Fareham and the new Welborne Garden Village development.
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 development, more than 1,160 homes cannot be lived in until the new ‘all-moves’ Junction 10 on the M27 is completed and operational.
The two-year construction scheme is due to be open to traffic in winter 2026.