The busiest section of motorway in Europe lies to the west of London on the M25 orbital, close to Heathrow airport and between the strategically important M3 and M4 motorways.
In a flagship scheme for the Highways Agency, WSP, in a joint venture with Gifford & Partners (GWSP), provided engineering design, design project management and construction certification services to widen the M25 from four to five and six lanes in both directions over a distance of 11 km.
GWSP was also responsible for the design and supervision of a new spur road and free flow interchange from the M25 to Heathrow Airport’s new Terminal 5 building. This included 8 km of new link roads and five new major bridges, including a viaduct across the M25 and an environmentally and aesthetically sensitive bridge over the River Colne.
The project demonstrates a range of innovative road widening techniques:
- Unique retaining wall design and construction process
- Complex geometry to fit the widened road into tight width constraints
- Use of recycled materials including granular fill from the demolition of old Wembley Stadium
Environmental benefits for road users and the adjoining local communities:
- Environmentally sensitive lighting
- Low noise surfacing
- Acoustically absorbent environmental barriers
- Landscaping including the planting of hundreds of semi-mature trees
The Highways Agency stipulated that there should be minimal disruption to road users. GWSP and Balfour Beatty achieved this through exemplary traffic management and vehicle recovery systems, maintaining four lanes of traffic in each direction during daytime hours, setting up a dedicated public information helpline and providing a reception, refreshments and crèche area for stranded motorists.
“The successful and timely completion of the M25 widening has highlighted the skills of the professional team as well as demonstrating a range of innovative road widening techniques which pave the way for future motorway widening.”
Peter Anderson, Project Director for Balfour Beatty Civil Engineering Ltd (Contractor)
Project information
Client: Balfour Beatty Civil Engineering Ltd for the Highways Agency and Heathrow Airport Limited (BAA)
Size: N/A
Value: £148M
Status: M25 Junctions 12-15 widening completed November 2005, Heathrow Spur ongoing