Progress on HS2's Longest Green Tunnel Construction

The construction of HS2’s longest green tunnel, located near Greatworth in West Northamptonshire, has reached a significant milestone with the recent realignment of the B4525 road. This development allows for the next phase of excavations on the 2.7-kilometer tunnel, which is being constructed using a 'cut-and-cover' technique. This method involves placing soil back on top of the tunnel to help it blend into the surrounding landscape. Engineers have successfully assembled the first kilometer of the structure, which features an 'M' shape with separate sections for northbound and southbound trains.

Construction Resumed on HS2’s Longest Green TunnelNext stage of construction begins at HS2’s longest green tunnelWork moves forward on HS2’s longest green tunnel

To enhance the construction process, several improvements have been implemented. The delivery of steel reinforcing bars has been optimized by using a 'roll mat' system, allowing for quicker installation. Additionally, the assembly of the five concrete segments that form each section of the tunnel has been streamlined, with a focus on reducing waiting times and increasing accuracy. The introduction of prefabricated reinforcing cages and changes in concrete delivery methods have also contributed to a doubling of the installation rate for tunnel segments at both the Greatworth and Chipping Warden sites.

Next stage of construction begins at HS2’s longest green tunnelConstruction Resumed on HS2’s Longest Green TunnelWork moves forward on HS2’s longest green tunnel

Chris Barrett, a senior engineer with EKFB, emphasized the importance of these improvements, stating that they have allowed for accelerated installation and the reopening of roads, which facilitates further community connectivity.

Next stage of construction begins at HS2’s longest green tunnel

Once completed, the Greatworth tunnel is expected to protect the rural landscape and minimize disruption for local residents. HS2 Ltd’s Project Manager, Sam Arrowsmith, expressed satisfaction with the progress made, acknowledging the lessons learned from the Chipping Warden tunnel that have significantly increased productivity. He noted, “This major milestone means that we can keep local traffic moving while we deliver the next stage of the Greatworth green tunnel.”

Work moves forward on HS2’s longest green tunnelNext stage of construction begins at HS2’s longest green tunnelConstruction Resumed on HS2’s Longest Green Tunnel

The HS2 project aims to improve travel between the UK’s two largest cities, London and Birmingham, while also freeing up capacity on the existing West Coast Main Line for additional freight and local services. However, challenges remain, as some civil engineering aspects of the project are reportedly behind schedule. In response, HS2 Ltd’s chief executive, Mark Wild, is leading a comprehensive reset of the program to ensure efficient delivery at a reasonable cost.

Next stage of construction begins at HS2’s longest green tunnel

• “This major milestone means that we can keep local traffic moving while we deliver the next stage of the Greatworth green tunnel.” — Sam Arrowsmith, Project Manager, HS2 Ltd.

Next stage of construction begins at HS2’s longest green tunnel

• “EKFB’s senior engineer, Chris Barrett, said: “Implementing the construction improvements and learnings from the Chipping Warden tunnel has allowed us to accelerate the unit installation of the Greatworth tunnel.” — Chris Barrett, Senior Engineer, EKFB.

Next stage of construction begins at HS2’s longest green tunnel

The ongoing construction of HS2’s longest green tunnel reflects significant advancements in engineering and project management, with a focus on minimizing environmental impact and enhancing community connectivity. As the project progresses, the lessons learned from previous phases will continue to inform future construction efforts.

Next stage of construction begins at HS2’s longest green tunnel