M25 Junction 25, National Highways Regional Delivery

The M25 Junction 25 carries both regional and national importance connecting the M25 with the A10. Carrying up to 6,300 vehicles per hour at peak times the junction and its A10 southbound approach experienced regular congestion and delays.

We worked in collaboration with our client National Highways and design partner SWECO to successfully deliver a major junction upgrade increasing traffic capacity, improving average speeds, shortening journey times and providing better local air quality.

The new junction layout provides extra lanes on the roundabout, widens the A10 southbound and M25 approaches and provides a free flow left turn from the M25 eastbound to the A10 northbound. A new at-grade Non-Motorised User route with toucan crossings enables more convenient and direct north/south movements whilst addressing safety concerns at the existing subways. Through the detailed design stage we were able to optimise the construction methodology, saving a month of night-time closures on the slip roads and addressing significant health and safety risks associated with working in close proximity to the Holmesdale tunnel.