A 3D geological model, referred to as the Project Stratigraphic Model, has been developed for Crossrail 2, a proposed £30 bn railway linking Surrey and Hertfordshire via 27 km long tunnels through London. The British Geological Survey 1:50 000 scale 3D model of the London Basin was adopted as the initial baseline. Over 1000 boreholes were collated, together with information from existing publications, such as tunnel face excavation records, to review and develop the Project Stratigraphic Model. Digital tools such as ArcGIS and Leapfrog Works facilitated the efficient development, interrogation and dissemination of the c. 40 km2 model and helped to communicate geological uncertainty. The Project Stratigraphic Model was a key tool in identifying geological hazards along the route, designing the vertical alignment, informing early design decisions for the proposed structures and estimating third-party building foundation depths for obstruction risk assessments. Further refinement of the model will continue into future design and construction stages, including the addition of project-specific ground investigation, geotechnical parameters and construction data, and will provide an invaluable geotechnical risk management tool for the project.

Thematic collection: This article is part of the Ground models in engineering geology and hydrogeology collection available at: https://www.lyellcollection.org/cc/Ground-models-in-engineering-geology-and-hydrogeology

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