How embracing engineering challenges unlocked the reduction in embedded carbon at the SSTC3 Soil Nailing project-Paper

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The paper describes the redesign and construction of a 250 m soil-nailed slope in Sunderland, England, which enabled a new highway excavation. The original proposal was a steel combi-pile wall supported by ground anchors. Aarsleff replaced it with a slope reinforced by hollow-bar soil nails and supported by geotextiles and steel mesh.<br /><br />The alternative used less material and had a shorter construction programme. The authors report an estimated 74% reduction in embedded carbon—around 2,000 tonnes of CO₂e—compared with the original design. Their conclusion gives estimated totals of 3,693 tonnes CO₂e for the wall and 1,058 tonnes for the soil-nailed solution.<br /><br />The lower-carbon design brought greater sensitivity to ground conditions and required careful management. The site contained variable made ground, buried structures and obstructions, asbestos-containing materials, and areas prone to erosion and water ingress. Construction teams addressed these issues through close engineering supervision, adapting nail locations, replacing unsuccessful installations, managing contaminated material safely, and improving drainage and erosion protection.<br /><br />The project demonstrates that lower-carbon geotechnical solutions can be viable even when they carry more ground-related risk than conventional designs. Achieving them depends on robust investigation and risk planning, responsive site management, and collaboration among designers, contractors, and the client. The authors argue that engineers should not dismiss sustainable alternatives because of uncertainty, but should commit appropriate resources to managing the challenges.

Keywords

soil-nailed slope

embedded carbon reduction

geotechnical engineering

hollow-bar soil nails

ground anchors

steel combi-pile wall

carbon footprint

sustainable construction

slope stabilization

Sunderland highway excavation