A major motorway on England's south coast will be shut down for more than ten days over the festive period to allow engineers to slide a colossal pre-built underpass into position.
Motorway Shutdown and Engineering Feat
The M27 will be closed between junctions nine and 11 from 8pm on Christmas Eve until 4am on 4 January 2026. This lengthy closure is essential for a critical phase of the £100 million upgrade to junction 10 near Fareham in Hampshire.
During the shutdown, a ready-made concrete underpass, weighing a staggering 8,500 tonnes, will be installed. To put that into perspective, the structure is two and a half times heavier than the historic warship HMS Victory.
The Sliding Operation and Project Goals
The pre-constructed box will be carefully slid 65 metres into a prepared trench cut into the motorway embankment. Once the underpass is in place, the carriageway above will be reconstructed before the motorway reopens.
This engineering work is part of creating an "all-moves" junction, designed to significantly increase capacity. The upgrade is primarily to accommodate future traffic from the huge Welborne Garden Village development, which promises up to 6,000 new homes alongside schools and community facilities.
Travel Warnings and Official Comments
Officials have warned that the signed diversion route along the A27 is expected to be extremely busy. Motorists are being strongly advised to plan ahead and consider whether travel in the area is necessary during the closure.
Lulu Bowerman, Hampshire County Council's cabinet member for highways, stated: "After months of meticulous planning, we are putting the final preparations in place for what will be a major and complex engineering operation." She confirmed that once the closure begins, work will continue 24 hours a day, seven days a week to complete the task as swiftly and safely as possible.
Bowerman acknowledged the inevitable inconvenience, adding that the work was timed for when traffic flows are traditionally lower, and thanked the public for their understanding in advance.
Andrew Jackson, National Highways programme manager, emphasised the broader benefits, saying the works "allow us to accelerate this important scheme and stimulate economic growth across the region."
The M27 is a key route along the south coast, running between Cadnam and Cosham in Hampshire and connecting the major port cities of Portsmouth and Southampton.
