Corsham Box Tunnel

Civil Engineering, Earthworks & Drainage

Brief Description

CML were awarded the contract initially in October 2019, to clear vegetation on the approach to Box Tunnel. An additional phase was awarded in October 2020 to remove overhanging rock situated above the retaining walls. A further three phases of work, between June 2021 and September 2021 were awarded. As the cutting is a designated SSSI (Site of Specific Scientific Interest), collaboration between all stakeholders was key.

Overview of work completed

Isambard Kingdom Brunel designed the 1.8 mile long railway box tunnel on the Great Western mainline between Bath and Chippenham. At its completion in 1841 it was the longest tunnel in the world, with 4000 men tunnelling from both ends.

CML were awarded the contract initially in October 2019, to clear vegetation on the approach to Box Tunnel. A further phase was awarded in October 2020 to remove overhanging rock situated above the retaining walls. CML were awarded a further three phases of work, between June 2021 and September 2021, an advantage of already being on site and having developed a firm relationship with the key stakeholders including Natural England and local landowners.

The site is located within the Corsham Railway Cutting SSSI designated area. Close liaison with Natural England was undertaken to develop the required granted Assent to initiate the works.

Scope of Works

Phase 3 (June 2021 – September 2021)

  • Design and implementation of permanent works for remainder of the Down Side cutting slope
  • Installation of 8,400m2 High Tensile Geobrugg TECCO G65/3 mesh
  • 216 anchors installed

Phase 4 (September 2021 – December 2021)

  • 204 repairs of defects over 800LM of the Up side cutting face and retaining walls
  • Ecological mitigation measures for Lesser Horse Shoe Bats in the tunnel running adjacent to Box Tunnel

Phase 5 (September 2021 – December 2021)

  • Removal of 10,500m2 of vegetation and undertake scaling works to the Up side in conjunction with Phase 4

Minimising disruption to the railway

Our priority as a team was to ensure we put passengers first and minimise disruption to trains also identifying key landowners to gain access to site. Our close relationship with Natural England was maintained throughout all phases and facilitated a speedier response to work requests from Network Rail.

Benefits to the local community and railway users

Having the team established on site has made it possible to be able to consistently provide high quality and aesthetically pleasing repairs to the improved approach to Box Tunnel. Railway users will be able to enjoy a better experience now they can see the whole structure on its approach. The Landowners have a better appreciation of what is on their doorstep and understand the importance of gaining access. The local community of railway users will benefit from the improved look of the approach, and should be proud of their local heritage.

Successes

Outstanding teamwork gets results

Our Client, fellow subcontractors and stakeholders successfully implemented a truly collaborative team environment to allow each phase to be delivered safely and offer value for money

High productivity levels

Due to the collaboration and good working relationship with stakeholders, productivity and safety standards has remained high

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