M27 closed between junctions 9 and 11 for major junction 10 revamp with drivers warned to expect "severe delays" - diversion details

Drivers are being advised to plan ahead to avoid severe delays this Christmas and New Year with the motorway closed completely in both directions between Junctions 9 (Whiteley) and 11 (Fareham), since last night (December 24) until 4am on January 4 2026.

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 northern side of the M27 .

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The box slide, which has been visible to drivers passing along the M27 with it being constructed next to the carriageway, will create a new dual carriageway beneath the motorway as part of the £100 million plus scheme led by Hampshire County Council, with the motorway then fully reconstructed above it.

It is part of the ongoing works to upgrade the junction which will create entry and exit points in both directions of the M27, along with a shared walking and cycling route, and a new bridleway improving connections between Fareham and the new 6,000-home Welborne Garden Village development.

A series of complementary highways improvements on and around Junction 10 are being carried out to support the development of Welborne Garden Village next to Knowle village, which is due to provide up to 6,000 homes alongside schools and community services, 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.

The council has previously said the one-off closure of this section of the M27, replaces what would otherwise have been many months of lane restrictions, speed limits, and overnight works and that it has been timed to coincide with lower traffic levels over the holiday period.

There is 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.

The council urged road users to plan their journey in over the next week and a half and consider alternatives including public transport, travelling during less busy times, using different routes, or if their journey is really necessary.

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.”

HERE MORE FROM LULU BOWERMAN HERE

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Key information

• Drivers will be able to exit the M27 westbound at Junction 11 for Fareham and Gosport, and 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.
• When complete the scheme the new-look junction will be ‘all ways’ fully functioning in both directions with three new slip roads being created, with the A32 sliproad towards Portsmouth being retained
• The new dual carriageway running underneath the motorway will have four roundabouts, to link the sliproads to the existing road network, forming the 'free flowing link'
• Hampshire County Council has appointed VolkerFitzpatrick as the lead contractor which is carrying out the work
• Staff will be working round-the-clock over the festive period - including on Christmas Day
• Welborne Garden Village includes proposals for up to 6,000 homes, employment space, schools, and community facilities
• Planning approval for Welborne was conditional on significant infrastructure improvements, particularly to the M27 at J10 and the A32
• The completed two-year construction scheme is due to be open to traffic in winter 2026

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Hampshire County Council has been working closely with National Highways on the project which is being fully funded by the Buckland Group, the developer of Welborne Garden Village, and by Homes England.

Andrew Jackson, National Highways Programme Manager, said: “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.”

It has been advertising the closure across the wider road network, including on the M25 and M4, in a bid to help reduce the impact, and will be keeping the rest of the M27 as open as possible, with the impact of other traffic schemes.

For more information and updates visit www.hants.gov.uk/M27-J10-xmas

Box slide facts

• The pioneering use of a timesaving ‘box slide’ engineering operation – a first for Hampshire
• It is one of only a handful of box slide operations undertaken in the UK
• Dimensions - 60m long, 25m wide and 10m in height (1m thick) = length equivalent to six double decker buses.
• Weight: 8500 tonnes = 2.5 x HMS Victory
• Slide distance: 65m = about two-thirds the length of a football pitch
• Before the sliding operation, 24,000m3 of material - which could fill around 10 Olympic size swimming pools - will be excavated from the existing embankment to accommodate the new underpass, before the existing M27 road section above is reconstructed and reopened to traffic.