Delivering Precision and Sustainability for HS2's Northolt Tunnel West
Pacadar UK has been a key partner in supporting the delivery of High Speed 2 (HS2), the UK's largest infrastructure project, by providing nearly 60,000 precast concrete tunnel ring segments for the Northolt Tunnel West. As one of the longest and most complex tunnels of the HS2 project, the Northolt Tunnel West required the highest standards of precision, efficiency, and safety—requirements that Pacadar UK met through its advanced production capabilities and robust logistical planning.
The production of the tunnel segments began in April 2022 at Pacadar's state-of-the-art factory in Kent, where a dedicated team set to work on manufacturing 59,129 segments, which formed 8,447 complete tunnel rings. Each tunnel ring consists of seven segments, and each segment weighs approximately seven tonnes. To meet the demanding project schedule, the factory maintained a consistent production rate of 130 segments per day. This was a remarkable feat, particularly when considering the complexity of the Northolt Tunnel West, which stretches beneath London’s busy urban landscape.
The precast tunnel segments serve a critical function as they form both the inner and outer linings of the tunnel. Once the tunnel boring machine (TBM) completes its excavation, the segments are fed through the back of the TBM and placed by an automatic segment erector. This advanced automated system improves safety significantly by minimising the need for engineers to work in confined underground spaces during the installation process. The accuracy and efficiency of this automated approach ensure the structural integrity of the tunnel, meeting the high standards required for a project of this scale.
Sustainability was at the forefront of Pacadar UK's operations on the HS2 project, not only in the production of high-quality precast concrete but also in the logistics of delivering the tunnel segments to the construction site. The company made a concerted effort to reduce the environmental impact of transportation by utilising rail freight to deliver the tunnel segments from the factory in Kent to the site in West Ruislip. This innovative solution meant that each freight train replaced 56 lorries, significantly reducing road congestion, fuel consumption, and carbon emissions. This approach aligned perfectly with HS2’s commitment to reducing its environmental impact and supporting sustainable transport practices.
The successful production of the tunnel segments was a major milestone, culminating in June 2024 when husband-and-wife team Saad and Loubna cast the final tunnel segment. This marked a moment of pride for the factory’s 180-strong workforce, who had worked tirelessly to deliver this critical component of the HS2 project. Beyond the Northolt Tunnel West, Pacadar UK continues to play a vital role in the overall success of HS2 by manufacturing precast concrete segments for other essential structures, including the Thame Valley Viaduct in Buckinghamshire and the Edgcote Viaduct in Northamptonshire.
Images credit - HS2