M25 J10: Upcoming road layout change on A3 from 7 May

Published: 06 May 2025

Update from National HIghways: 

We are writing to let you know about an upcoming change in road layout and speed restrictions on the A3.

From 5.30am on Wednesday 7 May 2025 until the end of the year, a contraflow system will be in operation on the northbound A3 between Ockham Park roundabout and the M25 Junction 10. This is to enable us to safely carry out the carriageway widening of the southbound A3 between junction 10 and Ockham Park roundabout.

Use of a contraflow means that we can maintain three-lanes running in both directions. On the northbound carriageway, there will be three lanes for northbound traffic and one lane for southbound traffic. On the southbound carriageway, there will be two running lanes for southbound traffic.

Northbound traffic

The contraflow layout for northbound traffic is now in operation and the speed restriction between Ockham Park roundabout and just after the M25 exit has been reduced from 50mph to 30mph due to the narrow lanes.

The following change in lane layout is also now in effect for northbound traffic:

• The inside lane is for traffic wishing to join the M25 in either direction
• The middle lane is for all traffic wishing to remain on the A3
• The outside lane is for all non-HGV traffic wishing to remain on the A3. HGVs are not permitted to use the outside lane due to width restrictions.

Southbound traffic

Once the contraflow is in operation on Wednesday 7 May, the speed restriction for southbound traffic, including within the contraflow, will remain at 50mph and the following layout will apply:

After the M25 junction 10 exit slip:

• The inside lane (lane 1) will be all traffic. If you’re an HGV driver or you wish to exit the A3 at the Ockham Park roundabout (e.g., to visit RHS Wisley or Ripley) you must use the inside lane. Traffic entering the contraflow from lane 2 won’t be able to exit at Ockham.
• The outside lane (lane 2) will cross over into the contraflow lane on the northbound carriageway. HGVs are not permitted within the contraflow due to width restrictions. Traffic within the contraflow will not be able to exit the A3 at the Ockham Park Roundabout.
• If you’re joining the southbound A3 from the M25, you will join the carriageway as normal.