M25/A3: Junction 10 improvement project takes huge strides forward

The Clearmount bridge – a bridleway offering safe passage for pedestrians, cyclists and horse-riders over the motorway – was jacked into place last weekend (November 2-3) having been constructed off-site during the summer.

Construction began back in August 2024 and the 450 tonne steel and concrete structure was positioned alongside the M25 for two months until the abutments on either side of the motorway were constructed.

Meanwhile, work has also now been completed on the Wisley Lane bridge which will open to traffic on Monday (November 11), and marks one of the scheme’s first large- scale accomplishments.

Daniel Kittredge, National Highways Senior Project Manager, said: “The opening of the Clearmount and Wisley Lane bridges are significant milestones for the M25 Junction 10 project, which will help reduce congestion, create a smoother flow of traffic and provide safer journeys for thousands every day.

“The original Clearmount bridge was demolished during the first full weekend closure of the M25 in March as it was not long enough to span the new slip roads.

“This new bridge will be wider and provide an improved way for people to navigate over the M25 by foot, bike or horseback.”

Last weekend, the 61m long Clearmount bridge was jacked up to its maximum height and placed on self-propelled modular transporters (SPMT).

The SPMTs then carefully slid the bridge onto the carriageway and moved it sideways 300 metres along the M25 and into place, with the road reopening to traffic more than two hours ahead of schedule once it was safely installed.

This was the first time this method of transporting an already constructed bridge into place on the M25 has been used – meaning a full weekend closure of the M25 was not required. The bridge will be opened at a later date.

Meanwhile, the opening of the Wisley Lane bridge will see the existing access both off and onto the A3 at the old Wisley Lane permanently closed with the new access to Wisley Lane via the newly constructed Wisley Lane Bridge in use from next week.

From Monday, this stretch of road will also provide access to the RHS Garden Wisley for customers wanting to access the gardens using the new Wisley Lane. From the A3 southbound off slip road, take the first turning on the left between the A3 slip road exit and Ockham Lane North (B2039), then onto and across the new Wisley Bridge, following the brown signs. For those travelling northbound on the A3, access to Wisley will be via the M25 junction 10 gyratory to turnaround and travel southbound along the new route.

As part of recent work at the junction, National Highways closed the slip roads of the M25 and the A3 over two weekends in October. These closures allowed for the implementation of jet lanes which carry traffic through the junction and help avoid traffic signals.

Drivers are urged to take care through the junction as the configuration has changed. This will be the position until further new bridges are installed in 2025 with two further full weekend closures of the M25 due to take place.

The M25 Junction 10 improvement project will also see changes to the gyratory and work to install further bridges, including the green bridge at Cockcrow, as well as some gantries. Heathland will now also be restored and new trees and woodland will be planted in other areas as part of the scheme’s pledge to make environmental improvements.

The Wisley interchange, used by many drivers from Hampshire travelling north, is one of the busiest junctions in the UK.