The westbound off-slip at M27 Junction 10 opens to traffic on 14 September, marking the first phase of a motorway upgrade expected to carry around 30,000 vehicles a day once fully complete.
The £100 million project was originally due to finish in winter 2026 but is opening ahead of schedule. Temporary speed limits and lane closures will remain on the M27 between Junctions 9 and 11 while safety testing and finishing work continue.
Eight minutes, one lane, live traffic
The new dual carriageway link road through the motorway underpass will initially operate with a single northbound lane. Landscaping and footway completion continue alongside live traffic, requiring restrictions on the site.
The motorway underpass, a 60-metre-long concrete box slide moved beneath the live motorway over Christmas, is installed. This major civil engineering element is complete, allowing the project to enter its operational phase.
Why phase the opening?
The junction currently permits only partial movements: a westbound off-slip and an eastbound on-slip. Full access from and to the M27 in both directions will follow in autumn 2026 with the eastbound and westbound on-slips.
Drivers cannot yet join or leave the motorway in every direction. Phased openings balance the need for early operational use with ongoing safety testing, technology commissioning and driver familiarisation with the new layout.
Supporting local growth
The improved junction links the A3222 directly to the motorway network, providing better access for Fareham, Wickham, Whiteley, Southampton and Portsmouth.
National Highways expects the upgrade to support Welborne Garden Village, delivering 6,000 new homes and thousands of jobs within the region.
Ongoing constraints on the M27
Despite the phased opening, temporary speed restrictions and lane closures remain in place until winter 2026. These measures aim to ensure safety during remaining work.
Hampshire County Council stresses the need for continued caution on and around the site while final tests and works proceed.
A pattern of phased handovers
M27 Junction 10’s partial opening reflects a broader trend in UK highway projects. Large schemes now often move from construction to use gradually, avoiding sudden changes for drivers.
This approach anticipates how junctions regulate motorway traffic, influence local route pressures and support expanding developments.
The nearby Junction 11 at Fareham also expects less congestion once full access at Junction 10 is achieved.
From 14 September, the M27 Junction 10 upgrade moves from building site to road use, step by step, with full operation expected by autumn 2026.
