Summary + Thesis + Support #3

Designed to optimize performance while maintaining safety standards during underground excavation, Herrenknecht’s Multimode (MM) Tunnel Boring Machine (TBM) is a state-of-the-art piece of engineering. The MM TBM can operate on various geological conditions, including soft ground, heterogenous ground and rock formations (Herrenknecht, n.d., Multimode TBM). Two key features are its modular structure and integrated systems which includes Earth Pressure Balance, Open-face and Slurry TBM modes (Herrenknecht, n.d., Multimode TBM). The functions of these features allow clients to modify components when facing complex geological conditions. Additionally, the integrated system enables these changes can be made in a relatively short time and at a lower cost (Herrenknecht, n.d., Multimode TBM, One basic idea two concepts section, para. 4).

Herrenknecht’s MM TBM revolutionizes tunnel construction through enhanced efficiency and adaptability to diverse geological conditions. However, challenges such as high costs and operational complexities must be addressed to maximise its long-term accessibility and sustainability in global infrastructure projects.

Herrenknecht MM TBMs improves efficiency and cost-effectiveness by eliminating the need for multiple machines, reducing downtime and optimising excavation across varying geological conditions due their integrated system. For example, in the Klang Valley MRT Project, with Herrenknecht MM TBM’s integrated system, they were able to combine the advantages of Earth Pressure Balance (EPB) and slurry mode with only minor modifications. This combination was used to prevent loss or leak by being able to control the density of the medium. Hence, this enhances efficiency in excavation work and diminishes costs for having several TBMs as it simplifies the tunnelling work. (Chapman et al., 2017, p. 157). In contrast, Underground Infrastructure Technologies (UIGTEC) TBMs, do not have a single TBM that is as efficient as Herrenknecht’s MM TBM when faced with challenging geology that usually requires more than different types of TBM (Underground Infrastructure Technologies, n.d., Product Catalog). By offering a versatile integrated system, Herrenknecht MM TBM enhances efficiency, productivity and minimises procurement, making it the ideal solution where speed and precision are essential, ensuring optimal performance.

Herrenknecht MM TBMs offer superior adaptability, allowing seamless transitions between different geological conditions due to its modular feature. A Herrenknecht multimode machine was used in Paris to tunnel through various geology such as clay, limestone and three different groundwater levels (Chapman et al., 2017, p. 157). In contrast, each UIGTEC TBMs mainly depends on the geological conditions of the project (Underground Infrastructure Technologies, n.d., Product Catalog). This means that, unlike Herrenknecht MM TBM, UIGTEC does not offer a TBM capable of adapting to different geological conditions. Hence, Herrenknecht MM TBM provides unmatched flexibility and reliability, making it the top choice for complex infrastructure that span multiple conditions.

High procurement costs and the requirement of specialized operators are some challenges facing the Herrenknecht TBMs. Herrenknecht TBMs typically cost between US$5 million to US$30 million USD, depending on the machine’s specifications (Charter Capital, 2022, Tunnel Boring Machine Cost section).  In some large-scale projects, such as BART Silicon Valley Phase 2 Project, a Herrenknecht TBM was procured for US$76million (Valley Transportation Authority, 2023, para 1). The high level of automation and specialized training for operators, increases labour costs (Herrenknecht, n.d., Utility Tunnelling Customer Training). Conversely, the traditional drilling and blasting method is cost-effective for smaller tunnelling projects. However, despite its lower initial cost, it poses greater risks, including environmental damage, slower excavation rates and higher labour requirements, making it unsuitable for large-scale urban projects. While the initial purchase of Herrenknecht TBMs is expensive, the long-term cost is justified by their efficiency, safety, precision and reduced operational costs in large-scale projects.

With the introduction of Herrenknecht MM TBMs, tunnelling technology is forever changed in the spheres of safety, efficiency, and adaptability to different geo-conditions. Although they have high operational costs and specific requirements, they are still the most preferred option for large scale infrastructure projects across the globe. With the changes in the world of technology like the increase in automation and more advanced AI driven excavation, modular TBM designs are anticipated to improve. As this happens, Herrenknecht TBMs are projected to lead the industry in sustainability, infrastructure expenditure, and global automation.

References:
Herrenknecht. (n.d.). Product detail: Multimode TBM. https://www.herrenknecht.com/en/products/productdetail/multi-mode-tbm/

Chapman, D., Metje, N., Stark, A. (2017). Introduction to Tunnel Construction. CRC Press. https://www-taylorfrancis-com.singaporetech.remotexs.co/books/mono/10.1201/9781315120164/introduction-tunnel-construction-david-chapman-nicole-metje-alfred-stark

Underground Infrastructure Technologies, n.d., Product Catalog. https://ugitec.co.jp/en/products/product-catalog/

Charter Capital. (2022, November 15). How Much Does a Tunnel Boring Machine Cost. https://charteraz.com/2022/11/15/how-much-does-a-tunnel-boring-machine-cost/

Valley Transportation Authority. (2023, November 6). VTA Purchases the Tunnel Boring Machine for the BSVII Project. https://www.vta.org/blog/vta-purchases-tunnel-boring-machine-bsvii-project

Herrenknecht. (n.d.), Utility Tunnelling Customer Training. https://www.herrenknecht.com/en/services/transportation-and-jobsite-assembly/utility-tunnelling-customer-training/