As part of the Warwick Tunnel Boring Team we are proud to announce our continued participation as finalists in Elon Musk’s 2024 Not-a-boring competition at The Boring Company in Austin, Texas. We shipped with us our tunnel boring machine (TBM) in a 20ft container from the UK to present our TBM with a focus on sustainability.
Extruded Concrete Lining: Innovation and Challenge
A key feature of our TBM is an extruded concrete lining, traditional methods include using pre-cast concrete segments brought into the tunnel or used in pipejacking or spraying shotcrete. However, the primary limitation of our design is a material limitation: during the 1.5m thrust phase of our TBM to achieve a digging rate of 1mm/s the concrete lining would need to cure rapidly. Withint 30 minutes it needs to support the soil overhead pressure, 16kN of force from the gripper pads and reaction shear forces from the cutterhead. This requirement drives the need for advanced mix design and curing technology.
Sustainability Through Water Recycling
Sustainability is a cornerstone of our TBM, a vortex system with flocculent recycles water from muck from the excavation process. Muck is a mixture of wet soil, mud, clay or sand and is considered waste. Discussion with the The Boring Company engineers revealed that their TBM had 80% less water usage, highlighting that the first step towards sustainability is material and resource reduction through design optimisation. While innovative the vortex filter system has some limitations, flocculent needs to be used meaning recycled water will contain flocculent which is not adequate for clay based soils.
Innovations in Muck Recycling
Updates: With my attendance at the British Tunneling Society (BTS) 2024 new solutions for muck recycling were showcased, particularly from China. 738km of new railway tunnels has opened for operation in 2024 as per the April 2025 ITA-AITES report, for reference in the planned journey of the HS2 23% will be underground and is 52.4km of tunnels. Containerised solutions to mechanically press muck into a sludge cake were shown, mechanically removing water.