Case Studies

M6 Junctions 21a-26 Launch and Reception Pits

Project: M6 Junctions 21a-26
Launch and reception pits
Employer: Highways England
Contractor: Costain
Contract: NEC 3 Option B Subcontract
Project Value: £1.1 Million
Duration: 8 months

Kilkern excavated launch and reception pits in preparation for direction drilling along an 11 mile length of the M6 motorway in Lancashire.

Principal contractor Costain appointed Kilkern to carry out the work on the M6 Smart motorway project in Lancashire. The team had to tackle varying ground and geological conditions at 45 separate locations. Successfully deploying multiple solutions has paved the way for the installation of new services beneath the motorway.

The works involved excavating down to a suitable level and creating a working platform and ramp to facilitate access for the directional drilling equipment. New ducting was installed below the live motorway with reinstatements carried out as soon as possible to maintain the stability of the existing ground. Where possible the excavation was stepped or ramped but at various locations temporary works installations where necessary due to the limited room available or the proximity of existing structures.

Key metrics

  • 45 pairs of launch and reception pits
  • 24,000mᶾ of excavation
  • 5000m of new ducting
  • 45,000 tonnes of backfill
  • 170 mass concrete blocks
  • 190 night shifts
  • 19,500 man hours

Project Challenges

The challenging ground conditions over the considerable length of the site meant that the Kilkern team were actively involved with the Costain temporary works design team to advise on the possible delivery solutions. Our teams experience guided the design by promoting cost effective solutions and installation methodology which could be safety installed adjacent to a live motorway.

At many locations the presence of a shallow rock head precluded the use of traditional sheet piles to retain the existing ground. The Kilkern team recommended a mass gravity retaining wall solution using readily available large concrete blocks. These could be installed safely and quickly meaning the project programme and the follow-on construction activities were unaffected.

At most locations the quickest and most cost-effective solution was to step or batter the sides of the large excavations. This required moving and then replacing large quantities of material requiring a large number of wagon movements. The original plan was for all this material to be moved to and from the main project compound. In order to reduce these plant movements, the Kilkern site team actively researched suitable temporary laydown areas as close to the working area as possible. This helped reduce the time taken to carry out the works, as well as delivering the environmental benefits of reduced fuel use and carbon emissions.

Even with this the Kilkern team needed to plan and coordinate a large volume of plant and vehicle movements in and out of the traffic management at each working location. The Kilkern team planned for the sequential access and egress of resources for the multiple activities and set up personnel exclusion zones to separate operatives from plant.

The works were carried out during night shifts which can lead to more challenging visibility, so the Kilkern team promoted the use of driver aids to assist the works. Our experienced plant operators used the latest in GPS 3d modelling technology to excavate the launch pits as the information displayed in the operators cab gave more clarity on the works required. All of our operators received extended training on the equipment and this commitment to embracing innovative technology delivered benefits in improved programme durations and improved the skills of our team.

Project Success

The project was successfully completed in September 2022 and was executed accident free and ahead of the original project timescales. Our teams experience assisted in identifying the best solution at each location and our flexible working approach proved beneficial when planning the best locations to deploy the workforce and deliver efficient progress.

Our team’s commitment to always be positive, work collaboratively with our clients and actively find a way to overcome challenges in a safe manner contributed to the success of the project.

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