BTS HARDING PRIZE COMPETITION 2025 | MECHANISED TUNNELLING


measure agreed within the TBM contract. The TBM completed this section without significant stoppages, demonstrating the effectiveness of the cutterhead and screw maintenance. The last 2km were completed in just under two


months, achieving the highest productivity rates of the entire project. The overall tunnelling on London Power Tunnels


Phase 2 was completed three weeks ahead of the original Clause 31 programme, with Package 2 finishing ahead of the contract date. The efficient TBM transition at Kidbrooke played a crucial role in mitigating risks on the longest tunnel drive of the project, ensuring uninterrupted progress toward Eltham. I fully immersed myself in the TBM transition at the


Kidbrooke intermediate shaft, choosing to be in the tunnel while much of the attention was on the west drive’s final breakthrough. This was an opportunity to develop my understanding of the TBM. To ensure a smooth ring build, I created a gasket-cutting plan for the miner and stayed late into the back shift after starting on the day shift, ensuring the work was done properly rather than relying on a handover. When the TBM was set to begin exiting the


replacement, tailskin brush replacement, and screw conveyor replacement, were critical in keeping the TBM moving forward. Getting the TBM through the shaft highlighted the


need for quick decision-making and adaptability on site. Good communication between the New Cross and Kidbrooke shaft sites was key to dealing with unexpected wear on components and keeping alignment on track during breakthrough. Using reinforced rings, temporary works, and support systems helped maintain tunnel stability and allowed the drive to continue smoothly. After the maintenance at Kidbrooke, TBM availability


for the remaining 4km drive to Eltham was the highest on the project, significantly exceeding the performance


intermediate shaft, and started breaking into the concrete wall, I was on the cutting wheel with a level, checking how close the top of the cutterhead was to the portal. Before this, my work as a shift engineer had been routine—steady mining and ring building. But real learning comes from challenges, not routine. I knew this was my chance to grow, so I stayed longer on shifts, and some miners stayed back with me. One shift, we were meant to finish at 3pm, but we


needed to build a ring in the shaft for temporary works. Two miners stayed with me until 5pm to get it done. When the hinge plate issue arose during shift handover, I caught it before it could damage the already worn screw. This experience pushed me in ways routine work


never could, giving me a deeper understanding of TBM operations and the confidence that I had made a real impact in delivering this critical phase of work.


Left:


Tunnel Engineer Sid Kaul (Author) at final shaft breakthrough, 4km away from Kidbrooke intermediate shaft


REFERENCES ● Kidbrooke: National Grid ET (no date). At: https://www.nationalgrid.com/electricity-


transmission/network-and-infrastructure/london-power-tunnels/in-your-area/kidbrooke


● Hakimian, R. (2024) ‘National Grid switches on first 2.5km circuit of £1bn London Power Tunnels 2,’ New Civil Engineer. At: https://www.newcivilengineer.com/latest/national-grid- switches-on-first-2-5km-circuit-of-1bn-london-power-tunnels-2-06-08-2024


● Hochtief-Murphy Joint Venture Ltd (2024). ‘Method Statement for TBM Transition Through Kidbrooke Shaft.’ Internal document, London Power Tunnels 2, Hochtief Murphy JV, London, March 2024. (Note: The referenced method statement is an internal document and is not publicly available.)


● Kundan, R., Daniele, S. and Martin, S. (2023). ‘Challenges of delivering 32.5km of major tunnelling infrastructure in South London (UK), and the influences of an innovative “Enterprise” project delivery model.’ Hochtief-Murphy JV, London


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