ABSTRACT
The Chiltern Tunnels, part of HS2’s C1 lot, are the longest twin-bore railway tunnels since the Channel Tunnel. They were constructed over 33 months using two Herrenknecht Variable Density Tunnel Boring Machines (VD TBM). As part of this project, Bouygues Travaux Publics (BYTP) developed numerous safety innovations.
From the planning phase, safety was a priority. VD TBMs were chosen for their ground support capabilities, ensuring stability during excavations under complex geology, shallow groundcover and, sensitive aquifers. Inside the TBMs, BYTP developed ATLAS (Automatic Tunnel Lining Assembly System) and Krokodyl (a world first), greatly increasing operative safety. Krokodyl, a robotic arm, automates the retrieval of segment spacers, eliminating manual handling, working at height and, people-plant interfaces. ATLAS autonomously handles ring building, controlling the segment feeder and erector, under operator supervision, to install the tunnel lining and eliminates hazards associated with operatives entering the ring build area.
During tunnel dismantling, the KERN gantry (constructed by Kern Tunneltechnik), an adjustable height and width mobile platform, was introduced to remove the 2.5m diameter ventilation ducts and 12m long slurry pipes. It eliminates the need for MEWPs, HIAB lifts or any manual handling of the vent duct and pipes. Additionally, it allows vehicles to pass underneath to enable ongoing construction activities further up the tunnel.
BYTP’s Hazard & Rehearsal Academy enhances safety and has seen over 3000 delegates, improving the Reportable Injuries, Diseases and Dangerous Occurrences Regulations Accident Frequency Rate (RIDDOR AFR) from 0.16 to 0.09. The academy conveys the 5 major risks on site, including people-plant interface, working at height, stability, and allows lifting and rigging rehearsals. The Stop, Look, Assess & Manage (SLAM) initiative, championed by senior management, empowers operatives to halt unsafe activities.
An onsite occupational health team enhances well-being through health checkups, walk-in treatments and, emergency care. The Silent Voices initiative highlights the 507 annual suicides in construction, fostering awareness and discussion of mental health.
