Wisley Interchange/Improvement Project

The M25 Junction 10 Improvement Project is an on-going major road scheme which aims to improve capacity at the Wisley Interchange between the M25 and the A3. The scheme also includes widening to the M25 and significant changes to the A3, including two adjacent Grade Separated Junctions.

In 2016, Highways England announced a plan for a comprehensive upgrade to the Wisley Interchange. A Public Consulation was announced in December 2016, containing two possible options:

• Option 9 - Two Semi-direct connectors from the A3 to the M25, and additional free-flow left turns
• Option 14 - Enlargement of the existing 3-level-stack roundabout to accommodate more traffic using extra lanes. Free flow left turns are also provided.

An addition option was rejected before consultation, but was still shown in the document:

• Option 16 - Cyclic interchange providing free-flow movements in every direction

• 

  2016 Current Layout

• 

  Option 9

• 

  Option 14

• 

  Option 16

Option 14 was selected as the preferred option to reduce congestion, and improvements to the A3 are also included.

During 2019, plans were submitted to the Planning Inspectorate, who made their suggestion in 2020 on whether the application should go ahead. By Summer 2022, the decision was made to give the scheme a green light, and construction started in Spring 2023. Works are due to be completed by Summer 2025.

The scheme

Although the scheme is named after one junction, most of the works don't actually involve the junction.

M25 / A3 Interchange - Wisley Interchange

The interchange will retain is existing design, however completely rebuilt and enlarged to increase capacity. The Circulatory carriageway will be widened to 4 lanes throughout, and enlarged to increase throughput. In order to achieve this, both of the existing bridges over the M25 carrying the circulatory carriageway will be demolished and new ones built, in a slightly different location. Each corner of the roundabout will also include dedicated free-flow left turn lanes, essentially removing half of the traffic from the roundabout, leaving it only for right turning traffic (and those rejoining/u-turning). Due to the enlarged circulatory carriageway, many of the slip roads will have rebuilt further away, including all of the M25 slip roads, except Clockwise on-slip. Every Entry to the circulatory carriageway will be under signal control.

Ockham Park Junction

Ockham Park Junction is the next junction on the A3 to the South-West. It will have some of its arms signalised, which also benefits the A3 cycle route, by allowing cyclists to cross the road at a traffic signal controlled crossing. A small exit slip for cyclists is also included prior to the junction. The junction will also gain a new arm, Wisley Lane (Diversion)

Wisley Lane Diversion

Before the scheme, Wisley Lane connected to the A3 using a LILO and an axillary carriageway, this is being removed and instead Wisley Lane will be connected to Ockham Park Junction to the South-West. This is achieved by building a new 1.5km long road, including a bridge over the A3 to replace a previous footbridge.

A3 (South-West of M25)

The A3 between the M25 slip roads & Ockham Park Junction is being widened to 4 lanes, from the existing 3 lanes with a 2 lane drop at the M25, and a 1 lane drop at Ockham Park. The existing direct access to Wisley Lane & Elm Lane are to be closed, along with a private access located on the North-Eastbound off-slip. Two direct access will remain however, these are Old Lane which will remain a LILO, but with longer merge & diverge lanes and the other is Mill Lane which remains full access located on the Ockham North-Eastbound On-slip. The Existing cycle track/footway will also be removed as part of this widening, which is replaced with a different route. 7 New gantries will be installed, and other refurbished / removed.

A3 (North-East of M25)

The A3 between the M25 slip roads & Painshill Junction is being widened to 4 lanes, from the existing 3 lanes with a 2 lane drop at the M25, and a 1 lane drop at Painshill Junction. All direct accesses are being closed up by relocating their access onto service roads. The Southernly side access road is accessed by a LILO on the South-West On-slip at Painshill Junction, whilst the Northern access is from a new service road from either Seven Hills Road, or Redhill Road. The existing cycle routes on either side of the A3 will be removed to allow for widening, cycle routes will be replaced further away from the road. 5 New gantries will be installed, and other refurbished / removed.

Painshill Junction & A245

Pains hill junction will have minor changes made. The junction is already fully signalised, but changes are to be made on the A3 North-Westbound off-slip to provide a free-flow (with Toucan Crossing) slip onto the A245. The A245 will also be widened Heading West, to three lanes & with a new shared cycle/footway located parallel to the carriageway. The A245 & B365 junction will also have some changes, such as additional lanes & a free flow left turn. Old Byefleet Road will also have its access changed from the A245, onto Seven Hills Road.

M25

The M25 will be widened through the junction to 4 running lanes (ALR) from the existing 3 lanes, removing the lane drop. One ERA will be provided on each carriageway. The M25 will also be widened at the diverge / merge points to 6 lanes (4 through, 2 aux.), this will require moving of the central reserve. 5 New gantries will be installed along the M25, many others will be refurbished or removed.

NMU Routes

NMU Routes, including cycle routes are being replaced & new ones added. Whilst, they aren't as direct as the previous ones, they will be much nicer as they don't run directly beside a pseudo-motorway. Two bridges over the A3 at near Wisley will be removed. The one at Wisley lane is replaced by the Wisley Lane Diversion Bridge, and the one at Ockham Common will be replaced by a larger green-bridge. Over the M25 there is only 1 existing bridge on the Northern side. This will be replaced as well, but another bridge will be added South of the Junction on the M25. Over the A3 to the North-East there are currently no bridges - one new bridge will be added new Redhill Road.

Links

National Highways

• Public Consultation Document  December 2016 (archive.org)

Roads.org.uk

• We Need to talk about Wisley  April 2024 (archive.org)

legislation.gov.uk

• The M25 Junction 10/A3 Wisley Interchange Development Consent Order 2022

• The M25 Junction 10/A3 Wisley Interchange Development Consent (Correction) Order 2023 - This Order corrects correctable errors in the M25 Junction 10/A3 Wisley Interchange Development Consent Order 2022 (S.I. 2022/549), a development consent order made under the Planning Act 2008 (c. 29), following a request under paragraph 1(5)(a) of Schedule 4 to that Act.