Nova is the £400m first phase of a mixed-use development by Land Securities in the heart of Victoria between Buckingham Palace Road, Bressenden Place and Victoria Street. It comprises two commercial buildings of 13 and 17 storeys (total 46,000m2 office area), a 13-storey high-end residential building (170 apartments) and ground level retail. There is a four-level basement with two primary levels (B1 intermediate and B2 raft) and two mezzanines, B1M and B2M.
The development interfaces with substantial improvements to Victoria Station (VSU) and LUL passenger facilities, significant Thames Water sewer assets and Victoria Palace Theatre. Provision is made for future Cross Rail 2 lines running along adjacent Buckingham Palace Road and pedestrian link to Victoria Station, under and through the Nova basement. Robert Bird Group (London) was appointed by Land Securities as structural and civil design engineers, and then novated to the D&B contractor, Mace, to complete the design documentation and provide construction engineering services.
Key technical challenges
Challenges included mitigation of risk in respect to third party assets and infrastructure, whilst minimising overall construction time to maximise commercial viability. Another challenge was future-proofing for new infrastructure and later development. The design process began with a detailed review of the overall site, the phasing possibilities and interfaces, the technical parameters regarding third party assets and adjacent infrastructure, building massing, impact of existing piled foundations and suitable foundation type. This review highlighted the sensitivity to ground movement of buried infrastructure, particularly LUL and VSU assets and vertical displacement of the sewers, taking into account the load history over the entire demolition, excavation and construction process.
RBG worked closely with the relevant authorities to understand the effect of ground movement and developed an early proposal for partial top-down basement excavation combined with a jump-start technique for the six slip-formed concrete cores, columns and floors.
The construction materials and methods are fundamental inputs to the structural design for any project. However, when a top-down method is adopted this heavily influences the design of various elements, particularly the basement columns and slabs. They are required to perform functions during the early stages of construction that are unique to the methodology. Adding an early start to the core construction adds another layer of complexity to the structural design. The top-down / jump-start approach had several advantages, including:
- Programme efficiency and flexibility building up whilst digging down.
- Significant overall saving on construction time (over conventional top down approach)
- Basement excavation direction prioritised to enable the concrete framed residential building to be completed early to suit the extensive fit-out period and early marketing.
- Early establishment of construction access route, reducing traffic disruption on adjacent ‘red route’ roads
- Minimised retaining wall movements, important for adjacent assets and LUL/ VSU works.
- Controlled application of load (confinement pressure) on the WDS Sewer below the site.
- Elimination of temporary works, through incorporation into permanent works design.
Commercial & Retail
Robert Bird Group Services:
Structural & Construction Engineering