National Highways is upgrading Junction 9 of the M3 to improve journeys for thousands of drivers every day and unlock economic benefits for the whole country.

Part of its transformation includes reconfiguring the roundabout to allow for the motorway to be increased from two lanes to four as it passes under the junction.

To do that, steel beams were installed earlier this year, and engineers have since been preparing the bridge deck surfaces and excavating the approaches that will connect to the new roundabout.

Now, a series of closures are needed so the project team can safely complete essential ‘tie-in’ works that cannot be carried out while traffic is using the roundabout.

This includes connecting new parts of the junction to the existing road network, with the new bridge on the north side of the roundabout and a new M3 southbound off slip both opening for the first time next week.

From 9pm on Friday 31 July, the roundabout, slip roads and several surrounding roads will all be closed until 6am on Monday 3 August, when the new bridge and off slip become operational.

The same applies for the weekends of 21–24 August and 11–14 September, though the main M3 carriageway will remain open throughout all three closures.

During each closure, stretches of the A34, A33, Easton Lane and A272 Spitfire Link will be closed.

The junction’s northbound entry slip road will stay closed from 9pm Friday 31 July all the way through until winter 2027.

Instead, drivers will be directed to join the M3 southbound at junction 9, travel to junction 11, then exit and re-enter the M3 northbound.

This is needed so the project team can safely build a new, dedicated A34 northbound link, which will provide a crucial route for freight travel from the ports to the Midlands and beyond.

A range of other work including drainage, earthworks, utilities, surfacing, and safety barrier works, will also be carried out.

Daniel Kittredge, National Highways Senior Project Manager, said:

“We are now moving onto the next phase of the project, and drivers travelling over the summer holidays may have to use the junction a little differently to how they’re used to.

“Winchester city centre and the main M3 carriageway very much remain open during these closures, but we’d urge anyone travelling in the area to plan their route carefully, particularly if their route involves one of the roads affected.”

The full list of areas closed over those three weekends is as follows:

• M3 junction 9 roundabout
• M3 junction 9 entry and exit slip roads both northbound and southbound
• A34 southbound from Bullington Cross
• A34 northbound to Three Maids Hill, also closing the A33 northbound
• A33 southbound from the Cart and Horses junction
• Easton Lane north and southbound at the Easton Lane roundabout
• A272 both northbound and southbound from the Spitfire roundabout (A31)

The M3 Junction 9 upgrade is essential to support the building of 2,000 new homes in Winchester, and will improve reliability for drivers – with peak time journeys set to be almost 30 per cent faster through the junction to the A272.

Between the M3 and A34, drivers will save more than 20 per cent of their overall journey time during peak hours.

The project will also provide a host of environmental benefits, including more than 22 acres of chalk grassland, as well as new routes for walkers, cyclists and horse riders.

Further information on the upcoming weekend closures, including diversion routes, can be found on the scheme’s dedicated webpage here.