M25 DBFO widening J27-30, one of the fastest highway construction programmes

M25 widening

M25 widening


Steve Chewins

Steve Chewins

Highways Operations Director
T: +44 7946 484 825
Ramboll. Andy Bell.

Andy Bell

Highways Director
T: +44 7501 495 204

Section 4 of the M25 DBFO for the Highways Agency (now Highways England) involved widening 25.8 km of dual 3-lane motorway to dual 4-lanes within the existing highway boundary, whist maintaining dual 3-lane operation. Design included upgraded junctions, controlled motorway infrastructure and overall improvements to the environmental, operational safety and maintenance provisions of the motorway.

An outstanding scheme

The application of innovation and continuous improvement to the delivery of design solutions to major linear transport infrastructure have been notable over time and have been critical in minimising disruption and providing safe, economic solutions timely to meet the needs of the travelling public. At a widening rate of 1.8km per month across this 39 month programme, the widening of the M25 between junctions 16-23 and 27-30, was one of the fastest motorway widening construction projects – being completed ahead of the target date, the start of the 2012 London Olympics.


The M25 Widening used CEEQUAL to drive improvement in the sustainable delivery of this £1bn major infrastructure project. Initially CEEQUAL was used as a tool to benchmark the sustainability of the project, and then to drive and monitor improvement as opportunities became clear. The contract comprised seven individual Whole Project Assessments, all achieving ‘Excellent’ award ratings. CEEQUAL scores were all in the 90's (the highest score being 92.5%) to the high end of "excellent" and the highest score in its highways category (further details here.) Achievements:
  • Outstanding project management led to savings of 100,000 tCO2e and £37.5 million across the project
  • Identifying (and using) external suppliers of recycled materials to reduce carbon emissions
  • Increasing CEEQUAL Assessment scores by 12% from first assessment to last.


Ramboll, with joint venture partner WSP, was primarily responsible for designing the upgrade of Junctions 27 to 30 (Section 4) to dual four-lane. We also provided gantry design for the whole of Junctions 16 to 23 (Section 1). A Skanska / Balfour Beatty joint venture acted as contractor for the works while the operating consortium for this Design Build Finance and Operate (DBFO) scheme was Connect Plus.

In addition to the main widening works our other design tasks on Section 4 included: creating slope retention solutions for the widened carriageway; incorporating a concrete step barrier in the central reserve; widening existing structures including crossing railways; replacing substandard bridge parapets; and upgrading drainage and attenuation.

Ramboll’s environmental engineers and scientists were responsible for the section’s environmental management and design, and also produced a whole life carbon report which was commissioned separately from the main contract.

Ramboll Highways Director Andy Bell said: "This is an outstanding scheme which has been delivered on time, to budget and contributes to accessibility and transport choices. Our design and site teams played a significant part in ensuring the M25 DBFO’s completion well before the target date."


Ramboll and WSP have collaborated and worked with Contractors on major highway design for over 40 years and have been at the forefront of motorway widening since the first design and build contract on the M25 between junctions 8 and 10 in 1997. Collaboration has continued with ECI contacts for widening the M1 between junctions 6a and 10 and between junctions 25 and 28 and the M25 between junctions 12 and 15. The M25 DBFO Section 4 was the most recent for this relationship bringing the total length of widened motorway to over 100 km. Thorough records were maintained throughout design development and consultation, and Design Input Statements were used to record design decisions and the reasons leading to their use. Services for the M25 DBFO included independent checking of structures on Section 1 of the project, including modifications to a major viaduct, and the design of sign and signal gantries for Sections 1, 2, 3 and 5.


  • Detailed design and specifications for highways and structures
  • Design of controlled motorway infrastructure
  • Environmental design improvements
  • CEEQUAL and Carbon assessments

Novel techniques/Innovation

  • 3-Dimensional modelling for clash detection
  • Development of innovative slip-formed L-shaped retaining walls
  • Innovative one-way system and signalised junction from the construction compound onto a motorway junction

Added value

  • Scheme delivered 2 months early and £55m (15%) under budget. Significant confidence gained in early delivery of this key element of infrastructure for the 2012 Olympics
  • Sustainable environmental design solutions recognised by “excellent” CEEQUAL scores
  • Continuous improvement and value engineering by phased delivery of design with lessons learned workshops before starting each phase
  • Value engineering such as avoiding existing bridge strengthening and removing the need for permanent structures in the central reserve

Requirements satisfied

  • Production of high quality, safe, affordable and environmentally acceptable designs
  • Continuous improvement and innovative design solutions
  • Develop / apply earlier phase designs
  • Use of Building Information Modelling (BIM) and electronic document system
  • Consideration of Operator requirements
  • Design for construction and interfacing with operational infrastructure
  • Production of robust cost and risk estimates
  • Value management and value engineering
  • Development of specifications and standards
  • Collaborative working
  • Designing for interface / integration issues
  • Design representatives and quality assurance teams co-located with Client and Contractor
  • Liaison with stakeholders & other 3rd parties


  • All three sub-sections between Junctions 27 and 30 received ‘excellent’ Client and Outline Design Awards from CEEQUAL – the Civil Engineering Environmental Quality Assessment & Awards Scheme (further details here.)
  • The entire project team’s belief in high environmental and technical standards was recognised with an ICE East of England Exceptional Merit Award for Sustainability, and a Merit Award for Technical Excellence and Innovation, for Junctions 16 to 23 and Junctions 27 to 30.
  • The success of the scheme received further recognition with the Chartered Institution of Highways and Transportation (CIHT) Major Project Award 2013:"The team faced one of the biggest challenges in widening one of the busiest motorways in Europe to four lanes, with a deadline determined by the London 2012 Olympic Games. The judges were impressed with the health and safety ROSPA award and the excellent CEEQUAL award among others. Despite the difficult conditions cost savings of 18% were achieved and the quickest road widening rate of 1.8km per month." – CIHT Judging Panel.
  • ICE East of England Merit Award exceptional merit award for physical achievement 2011

Related articles

Ramboll achieves CEEQUAL ‘Excellent’ for M25 DBFO Section 4b; junctions 28-29

Working for the Highways Agency’s contractor Skanska Balfour Beatty (SBB) Ramboll and design JV partner WSP, along with the client, have secured an interim ‘Excellent’ rating.


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