10 King William Street is a nine-storey commercial development located above the new Bank London Underground Station entrance on Cannon Street in the City of London. The site is bounded by King William Street to the north, Cannon Street to the south, Nicholas Lane to the east and Abchurch Lane to the west.
The development comprises a single building delivering Grade A office space, alongside ground-level retail including a café, with a partial basement extending to the west of the station box.
We were engaged to deliver structural and civil engineering services for the over-station development, building on our involvement in the Bank Station Capacity Upgrade. The station box, which we previously delivered with provisions for over-station development, forms a fundamental part of the structural solution, supporting the new building at lower levels and defining the interface conditions across the site.
Integrating with the Bank Station Upgrade
A defining aspect of the scheme is its direct integration with the newly constructed station entrance, with the station box supporting the superstructure and its roof forming the Level 01 floor. We developed the structural design to work within the constraints of this pre-existing infrastructure, carefully managing load transfer, movement and interface behaviour between the commercial development and the station.
Our prior involvement in the station upgrade enabled us to understand the embedded provisions for over-station development and apply this knowledge to the evolving design. As the scheme progressed, we worked closely with the wider team to ensure that the structural demands of the building remained compatible with the capacity and performance of the underlying station structure.
Foundations and Subsurface Constraints
The site sits above a complex network of tunnels and shafts associated with Bank Station, significantly constraining foundation design. In response, we supported the development of a raft foundation solution beneath the basement and lower levels, avoiding the risks associated with installing piles in such a sensitive environment.
This approach required careful coordination of load distribution across the site, as well as consideration of the interaction between the raft, the station box and surrounding underground infrastructure.
Structural Strategy and Floorplate Efficiency
We developed a structural strategy centred around a centrally positioned core, providing overall stability while enabling efficient, long-span office floorplates. Steel framing extends from the core to maximise column-free space across the site, including over the station box, supporting the delivery of flexible and highly lettable commercial floors.
The structural design facilitates the integration of building services within the floor depth, reducing overall floor build-up and supporting the architectural intent for clean, efficient internal spaces. This approach also contributes to material efficiency by optimising spans and reducing the need for additional structural elements.
Responding to Evolving Design Requirements
As the over-station development evolved, an additional storey was introduced, pushing the limits of the existing station interface loading provisions. We undertook detailed assessment of load paths and interface conditions to ensure that the revised scheme could be safely accommodated without compromising the performance of the underlying infrastructure.
The constrained footprint at lower levels, with the station box occupying a significant portion of the site, required us to carefully coordinate the structural arrangement to maximise usable floor area while maintaining compliance with the established interface constraints.
Infrastructure Protection and Coordination
Given the proximity to and integration with a live Underground station, we fulfilled an infrastructure protection role, working closely with Transport for London to safeguard the operation, safety and long-term integrity of the station and surrounding assets.
Our role involved ongoing coordination, assessment of structural impacts and verification that the proposed works remained within acceptable limits, ensuring that the development could be delivered without adverse effects on critical transport infrastructure.
Sustainability and Structural Efficiency
The project set ambitious sustainability targets, including a structural embodied carbon limit of 600 kgCO₂/m² for the overall building. We contributed to achieving this through the development of an efficient structural scheme, including long-span solutions with Westok beams that reduce material use and a coordinated approach to integrating services within the structural depth.
By enabling development above existing transport infrastructure, the scheme also supports a more efficient use of land in a highly constrained urban environment, contributing to the City of London’s wider sustainability objectives.