BANK STATION UPGRADE | TECHNICAL


to the opening is not readily accessible or the space to install opening support is limited. Where existing assets are not well aligned, reinforcement is also better able to adapt and doesn’t require shims, etc.


● Connections to existing tunnels are still an area of significant unknowns, where levels of conservatism can be overlain, potentially reducing efficiency and creating other risks. Assuming full over burden loads on the new openings typically results in heavy/large steel beams, which pose significant health and safety risks during construction, but limited data exist to justify moving away from this approach. Strain gauges were installed on the opening beams of one of the largest openings in the Northern Line platform to share knowledge for future projects. More projects should install strain gauges to understand opening frame behaviour and loading from the cut segments. While they won’t necessarily help the project you are on, a data set is needed to allow future optimisation.


● There is a balance to be struck between constructability and carbon savings. Practical minimum thicknesses for cast secondary linings may limit the potential to optimise these secondary linings but can still result in lower CO2


solution when taking into account lower wastage


values, rebound, not requiring additional regulating layers and even the potential to avoid cladding. Tools to quickly compare options need to be standardised across the industry to allow decision making and reporting on a fair basis.


than a sprayed


BSCU won multiple awards over the project’s lifetime, but most significantly for many involved in the project, a number of those recognised the importance of the behaviours of the team. This includes winning the NCE Tunnelling Team of the Year, twice, and the BGA’s Fleming award, which emphasises teamwork. Many of the improvements in design and innovations discussed above were the direct result of the open lines of communication available between the client, design and construction teams. Co-location is most definitely a part of this success, but equally important was the mentality and approach from all involved. In complex upgrades, having asset owners that understand their assets and are well resourced to manage risk in-house, as well as having mature standards that maintain requirements without inhibiting innovation, are as crucial as knowledgeable construction and design teams. On BSCU we were lucky to have all these things and hope that future projects are as fortunate as we were.


REFERENCES ● Anthony, C., Kumpfmüller, S., Feiersinger, A. and Ares, J. (2020) Improving safety through design at London Underground’s


Bank station capacity upgrade. Proceedings of the Institution of Civil Engineers – Civil Engineering 173(5): 41–47, https:// doi.org/10.1680/jcien.19.00022.


● Barker, C.A., Kechavarzi, C., Xu, X. and Nasekhian, A. (2020) Fibre Optic Monitoring of Existing Under Ream Piles for Tunnelling Interception, British Geotechnical Association (BGA) Piling 2020 Conference, Durham, 15-16 September 2020.


● BSI (2004) BS EN 1992-1-1:2004: Eurocode 2: Design of concrete structures – Part 1-1: General rules and rules for buildings. BSI, London, UK.


● Dimmock R. (2022), Steps forward in SCL sustainable tunnels. Tunnels and Tunnelling International, BTS Talk (T&TI August 2022, pp47-52).


● Jensen, C. (2015) Bank Station capacity upgrade, 2015. Ice.org.uk, 5 November. See https://www.ice.org.uk/engineering- resources/case-studies/bank-station-capacity-upgrade-2015/ (accessed 25/07/2022).


● Kumpfmueller, S., Nasekhian, A. and Dryden, P. (2022) Uphill excavation of an escalator barrel between operational underground platforms. Proceedings of the Institution of Civil Engineers – Civil Engineering 175(4): 175–183, https://doi. org/10.1680/jcien.21.00042


● Nasekhian, A., Onisie-Moldovan, A., Ares, J., Kelly, D. and Dryden, P. (2020) Sprayed concrete lining versus traditional hand-mining at Bank station upgrade, Proceedings of the Institution of Civil Engineers – Civil Engineering 173 (3): 127-135, https://doi.org/10.1680/jcien.19.00028


● Nasekhian, A., Anthony, C., Haig, B., Dewhirst, M., Ares, A. and Barker, C. (2021) Tunnelling in Urban Areas and Pile Interception Challenges – A Case Study: Bank Station Upgrade Project (BSCU), 10th International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, Cambridge, UK.


● Nasekhian, A. and Feiersinger, A. (2019) Sprayed concrete lining optimisation at Bank – a combined lining approach. Tunnels and Tunnelling International (T&TI April 2019, pp27–32)


● Nasekhian, A., Ng, Z., Savage, G., Macknight, S. (2023) Hybrid SCL and Handmined Shaft – A Case Study from the Bank Station Upgrade Project, World Tunneling Congress (WTC) 2023, Athens.


● Norrish, A. (2023) Tunnel and Tunnelling International, interview, link: https://www.tunnelsonline.info/features/ alison-norrish-interview-10815344/


● Pamsl, A. and Nasekhian, A. (2023). FEA meets construction: Sprayed concrete lined tunnels connecting existing subsurface assets at London Underground’s Bank Station. Proceedings 10th NUMGE 2023 10th European Conference on Numerical Methods in Geotechnical Engineering, Zdravković, L., Konte, S., Taborda, DMG and Tsiampousi, A. (eds)


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