Silvertown Tunnel opens: Ayesa’s Engineering played a major role in the delivery of this London landmark

Ayesa played a pivotal role in making this international project a success, cementing its reputation as a leader in complex underground engineering.

Ayesa’s ground engineering contributed to the design of the innovative ‘peanut’ shaft — the first of its kind in the UK, and a standout example of cutting-edge tunnelling techniques

The recently inaugurated Silvertown Tunnel beneath London’s River Thames stands as one of Europe’s most significant infrastructure projects — not only due to its scale with an investment exceeding €1 billion, but also for its technical innovation and environmental achievements. Ayesa has made its mark on this modern engineering megaproject as one of the lead underground structural designers for the Riverlinx CJV consortium.

Ayesa’s Geotechnical impact

In this new 1.4 km double-bore underground tunnel, Ayesa was responsible for designing critical elements, including temporary embedded walls to enable excavation and the construction of permanent works, as well as TBM operations. Ayesa also designed permanent structures such as retaining walls, cut and covers, and portals. Additionally, Ayesa oversaw damage assessment, instrumentation, and monitoring.

Facing Challenges with Collaboration & Innovation

The project involved a significant geotechnical challenge, as it was built beneath the bed of the River Thames with a vertical gradient of 4%, meaning the tunnel rises 4 meters for every 100 meters horizontally. The tunnel boring machine used was the largest ever operated in the UK, with a cutting face diameter of 11.91 meters.

A Series of “Firsts”

One of Ayesa’s most notable contributions was its collaboration on the design of the innovative “peanut” shaft. This “peanut-shaped” shaft design was groundbreaking due to its unique approach requiring no traditional anchoring systems. Typically, tunnel shafts are circular or rectangular and require heavy-duty anchors to stabilize the structure during construction, a process that can be costly and time-consuming. The Riverlinx Construction Joint Venture (CJV) won the Innovation in Design award at the NCE Tunnelling Awards 2023, for its “Secant Bored Pile Peanut Shaft” design and construction on the Silvertown Tunnel project. This pioneering technique utilized temporary secant pile walls as a screen — a first for the UK.

Another groundbreaking innovation was the use of a nitrogen skate system to rotate the tunnel boring machine (TBM) 180 degrees within a specially constructed rotation chamber. This system allowed the 1,400-tonne TBM to be repositioned efficiently and safely, eliminating the need for a lengthy dismantling and reassembly process. This method, which had never been used before in the UK, showcased remarkable efficiency and cost-effectiveness, setting a new precedent for large-scale TBM rotations.

The project also faced additional challenges, including lockdowns during the COVID-19 pandemic. Ayesa effectively coordinated international teams — from Madrid and London — to ensure continuity and efficiency, keeping the programme on schedule. During the lockdown, Ayesa’s collaboration with ground engineering lead, COWI, optimized workflows and reduced costs and review times. This coordination was recognized with a nomination for the Ground Engineering Geotechnical Team of the Year 2022 award.

Together with COWI, Ayesa conducted rigorous technical analyses, damage assessments, and mitigation proposals for ground movements caused by excavations and drainage works, especially under sensitive infrastructures like the DLR viaducts.

One of the leading engineering projects of the last century in Great Britain

Now operational, the Silvertown Tunnel will significantly reduce traffic congestion and pollution, improving the quality of life for Londoners. The tunnel is also expected to stimulate economic growth by improving access to key commercial and residential areas, supporting business, tourism, and investment in East London.

By diverting traffic from overground roads, it will ease pressure on surface-level streets, improving pedestrian safety and reducing noise in local neighborhoods. Furthermore, the tunnel supports sustainability efforts, contributing to the reduction of greenhouse gas emissions over time.

The project has received numerous awards, highlighting Ayesa’s role in delivering exceptional engineering solutions. Its technical and innovative work has been key to this international success, positioning the company as a leader in complex underground engineering.