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Protecting critical infrastructure through georesilient design: a case study from the A40 near Llanegwad

Event organised by ICE

27 November 2023

This event has now ended

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The UK’s critical infrastructure is at greater risk of deterioration and failure under a changing climate. To build resilience into the design of mitigation solutions, a thorough understanding of the historical role of site-specific processes, geomorphological and geological conditions and possible future climate scenarios is needed. This webinar will present a case study of an engineering scheme developed to protect a section of the A40 in Carmarthenshire from erosion by the River Towy. Due to rapid lateral erosion rates, it was estimated that with no intervention the A40 would be undercut within 10 to 15 years. Hence, a mitigation solution was proposed that would provide both protection from imminent risk of failure but also consider resilience to future risk under a changing climate.

To provide a resilient solution, an optioneering exercise was undertaken to identify the constraints, risks and uncertainties of a range of options. A phased process of acquiring, analysing and integrating site-specific information was undertaken to arrive at a design that would provide long-term resilience for the A40, through which the preferred solution of an anchored embedded sheet pile retaining wall was determined. This process included:

  • a desk study of historical mapping, aerial imagery and LiDAR to appraise the changes in the river planform over time,
  • consideration of the benefits and limitations of different approaches based on site constraints, river morphology and geological information, and
  • integrating all the information gathered through a geomorphological assessment of the options considering the future impact of climate change.

The steps taken in this approach will be outlined and discussed, from risk assessment and optioneering to design and construction, and will highlight the necessary multi-disciplinary, risk-based decision-making process that is required to develop resilient solutions.


Jack Blake

Jack Blake


principal geotechnical engineer

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Jack Blake

Jack is a principal geotechnical engineer for Atkins (member of SNC-Lavalin Group), with experience leading geotechnical schemes across the highways, rail, building and water sectors. He was the AtkinsRéalis designer on the project and co-author of the technical paper produced, published and presented at the BGA GeoResilience 2023 Conference.

The project is presented with thanks to contributors Atkins SNC-Lavalin; South Wales Trunk Road Agent (SWTRA); Welsh Government; Byland Engineering; Van Elle; Tarmac; Evans Pritchard; TerraDat; Malcolm Hughes.

For more information please contact:

Sara Horrell