SUSTAINABILITY | INSIGHT


Geotechnical and Geoenvironmental Engineering. The paper includes full details on the methodology and each case study is considered individually, along with additional analysis and discussion of the results.


CONCLUSION This article has provided an overview of research carried out to elucidate the embodied carbon of microtunnelling projects. The results demonstrate that the relative contribution of both shafts and tunnels to the overall embodied carbon is significant. The influence of different construction stages was


also explored, showing materials made up the majority of embodied carbon. In particular, the reinforced concrete pipes had high embodied carbon, owing to high-strength concrete and high steel content. This highlights the need for improved design methods for jacking pipes and, more broadly, advancements in materials technology. Onsite activities also made a significant contribution,


although this could be reduced by using mains electricity instead of diesel generators to power TBMs. The production method of steel used was explored,


demonstrating the importance of moving away from traditional basic oxygen furnace steel production worldwide. Comparisons were drawn to open-cut pipeline construction, suggesting microtunnelling is an environmentally prudent option. In addition, analyses were carried out on high-


level design optimisation, underlining the benefits of minimising the number of shafts. This highlights a key


Project dependent enabling works


Construction of launch/reception shafts Construction of the tunnel


Left, figure 5: Construction stages considered in embodied carbon analysis


Project dependent additional works


= considered in study


motivation for industry should be maximising drive lengths and utilising curved drives to achieve this.


ACKNOWLEDGEMENTS This research was enabled by enthusiastic support and input from Ward and Burke Construction Ltd., whose continued involvement with research at the universities of Oxford and Cambridge has been extremely fruitful for all parties. This work was also supported by the Royal Academy of Engineering under the Research Fellowship Scheme and the Engineering and Physical Sciences Research Council (Grant No. EP/T006900/1).


REFERENCES ● Alsadi, A. A., and Matthews, J. C. (2020). ‘Evaluation of carbon footprint of pipeline materials


during installation, operation, and disposal phases.’ Journal of Pipeline Systems Engineering and Practice, 11(2), https://doi.org/10.1061/(asce)ps.1949-1204.0000422.


● Chilana, L., Bhatt, A. H., Najafi, M., and Sattler, M. (2016). ‘Comparison of carbon footprints of steel versus concrete pipelines for water transmission.’ Journal of the Air & Waste Management Association, 66(5), 518-527. https://doi.org/10.1080/10962247.2016.1154487.


● Khan, L. R., and Tee, K. F. (2015). ‘Quantification and comparison of carbon emissions for flexible underground pipelines.’ Canadian Journal of Civil Engineering, 42(10), 728-736. https://doi. org/10.1139/cjce-2015-0156.


● Kyung, D., Kim, D., Yi, S., Choi, W., and Lee, W. (2017). ‘Estimation of greenhouse gas emissions from sewer pipeline system.’ Int J Life Cycle Assess, 22(12), 1901-1911. https://doi.org/10.1007/ s11367-017-1288-9.


● Lu, H., Matthews, J., and Iseley, T. (2020). ‘How does trenchless technology make pipeline construction greener? A comprehensive carbon footprint and energy consumption analysis.’ Journal of Cleaner Production, 261(2020). https://doi.org/10.1016/j.jclepro.2020.121215.


● Matar, M., Osman, H., Georgy, M., Abou-Zeid, A., and Elsaid, M. (2019). ‘Evaluating the environmental performance of pipeline construction using systems modelling.’ Construction Management and Economics, 38(8), 689-714. https://doi.org/10.1080/01446193.2019.1605185. ● Piratla, K. R., Ariaratnam, S. T., and Cohen, A. (2012). ‘Estimation of CO2


Emissions from the Life


Cycle of a Potable Water Pipeline Project.’ J. Manage. Eng., 28(1), 22-30. https://doi.org/10.1061/ (asce)me.1943-5479.0000069.


● Swallow, A. W., and Sheil, B. B. (2023). ‘Embodied Carbon Analysis of Microtunneling Using Recent Case Histories.’ J Geotech Geoenviron, 149(10). https://doi.org/10.1061/JGGEFK.GTENG-10989.


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