Works were completed to the Thorneyfields Lane Bridge as the final phase of a multi structure package. Planned Works involved concrete deck repairs, re waterproofing of the deck, removal of pedestrian parapets, vehicular restraining systems and degraded string courses replacing them with a vehicular parapet on newly cast string courses.

To avoid any total closures of the M6 and therefore mitigating disruption and delay to the public it was proposed to use the innovative designed Mabey Cantilever Scaffold (Mass 50) System following best practice learning from other similar schemes within Area 9.

The system was constructed into modular sections off network, lifted into place over the verge and then pulled into place all at night under lane closures with the encapsulation installed simultaneously and the final waterproofing installed (in preparation for Hydro-demolition) using a combination of police rolling blocks and utilisation of the existing Traffic Management installed for the Smart Motorways project.

In the Early stages of the project it was discovered that the As Built information provided by the Statutory Utilities companies was in-accurate, specifically the 300mm water main was actually a 450mm reservoir main that was hung from the deck within the service bay using a bespoke hanger solution.

To avoid the water main having to go onto an expensive bypass, a bespoke live monitoring and alerting vibration monitoring system was installed, works methodology was revised using alternative tooling to ensure that the stringent vibration limits set by the asset owner was not exceeded and through detailed surveys and extensive reactive redesign an alternative solution to replacing one of the two string courses was devised while maintaining the utility in its existing location and mitigating the risk of pipe failure and flooding of the M6.

Limiting vibration during construction resulted in the re-planning and execution of bespoke work methodology the concrete verges had to be saw cut into small sections, separated from the deck waterproofing with the use of a steel wedges and removed from site with mechanical assistance, larger sections on the area with falsework were wire cut to mitigate vibration, and hoisted using the falsework onto a beam runner which enabled them to be guided away from the work area mitigating manual handling.

Through collaboration with the Smart Motorway Project on the M6 below, information regarding the vibration monitoring was shared resulting in their construction techniques being adjusted to ensure the third-party asset was not adversely affected.

Shortly after the project started, the condition of the stringcourse plinth was noted to be in a much more deteriorated condition, with spawling and cracking far more extensive than recorded. Emergency teams were mobilised to remove the loose material and encapsulate the remaining stringcourse in Stainless steel mesh to ensure the M6 remained operational with no increased risk of debris falling during construction.

During Hydro demolition of the existing string course the remaining deck slab broke up exposing the pre-tensioned deck beams, surveys of these beams highlighted unexpected cracks that required immediate reactive works. An approved design solution consisting of localised concrete repairs and resin injection was deployed to rectify the defects. Product selection and input from specialist sub-contractors managed by the site team facilitated the repairs to be completed in poor climatic conditions.


  • Client: Kier Highways Area 9
  • Date: March 2018 to August 2019
  • Value: £2,111,669