33 Piccadilly

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Setting the Scene

33 Piccadilly is a multi-million-pound urban mixed-use redevelopment in the heart of London’s West End. The scheme, for The Crown Estate, will create approximately 50,000 sq ft of office, leisure and retail space, helping to further bolster this thriving area of the city, attract global investment and contribute to the wider success of the capital.

The compact footprint will be transformed into a space with two basement levels and ground floor retail space, with office accommodation from level 1 up to level 8. The original post-war building on the site was demolished to enable delivery of a new, more space-efficient scheme.

The project is located within a constrained urban and historic environment. As the main contractor, Kier (Construction London and Thames Valley division), along with Realtime Civil Engineering (responsible for all basement box and superstructure works), had to manage the project in a heavily trafficked arterial route, surrounded by sensitive neighbours, including an operational hotel, embassy buildings and active commercial premises.

Engineering Challenges in a Highly Constrained City-Centre Site

The project presented significant challenges due to its small urban footprint and proximity to surrounding structures. Limited available working space, restricted access, neighbouring buildings and complex interfaces with existing structures required a carefully coordinated temporary works solution.

The basement construction involved multiple retaining systems working together, including:

• Existing basement walls
• New underpinned walls
• Sheet pile retaining walls
• Multi-phase underpinning works at approximately 2.7m depth

The combination of relatively weak existing concrete, constrained access, and varied retaining conditions created a complex engineering environment where load transfer and structural stability had to be carefully controlled throughout each stage.

Early Engagement and Collaborative Design Development

Conquip was invited onto the project during the early PSCA stage, working with Realtime Civil Engineering and Kier. This early-stage collaboration was critical in developing a viable temporary propping strategy that could support both design and construction requirements.

The design brief was highly complex, with significant coordination required between temporary works, permanent works and overall sequencing.

The teams at each contractor identified precise, required locations for the temporary propping within the constrained site footprint, ensuring clashes were avoided and construction sequencing in the site could be maintained without disruption.

And, due to its complexity, the temporary works design was subject to Category 3 independent checking, reflecting the high level of engineering risk and coordination required.

The early coordination allowed temporary works design and construction methodology to then progress in parallel, improving buildability and reducing downstream risk.

A Bespoke Propping Solution

The scheme involved a five-level propping system designed to support a combination of existing basement walls, new underpinning structures and sheet pile retaining systems. It was developed to evolve in line with the excavation sequencing:

• Early levels installed to stabilise existing and retained structures
• Additional levels were introduced progressively as excavation deepened
• Final level enabling excavation to the formation level and completion of works

Different zones of the site required different propping approaches. Sheet pile areas were supported at specific levels, while other areas required additional intermediate support due to varying structural conditions.

A key engineering challenge was the presence of low-quality existing concrete, which limited the ability to directly transfer loads into the existing basement walls. This required a bespoke shear transfer connection solution to be developed.

The propping scheme also had to accommodate differing structural behaviours between sheet piles, existing walls, and new underpinning elements, effectively working as a coordinated structural system across all elements.

Conquip’s design team provided ongoing technical support throughout the project, with rapid responses to design queries and changes often delivered within hours. This responsiveness was key in supporting the changing requirements of the project.

Conquip’s temporary works team have been really instrumental in third-party approvals for this project. Their design information and iterative design process has been really clear in demonstrating the temporary propping scheme for retaining the existing highways around the boundary of the site.

Jessica Haskett | Design Manager, Kier

Sustainability and Reuse of Equipment

Sustainability was a fundamental consideration for Realtime and Kier throughout the project. The use of reusable temporary propping equipment helped reduce material waste and supported the project’s wider carbon reduction requirements.

The modular nature of the system meant that components could be efficiently reused and adapted across different phases of the works, improving both sustainability and overall project efficiency.

Without the temporary propping solution, the underpinning works beneath the existing basement structure would not have been achievable within the project’s carbon and programme constraints.

Without Conquip and without the basement’s propping scheme that we had, we would have never achieved our targets. We had quite stringent carbon targets on our project, and the only way we can achieve this is with underpinning under the existing basement wall. That was never going to happen without Conquip’s basement propping solution.

Stoyan Kolev | Project Manager, Kier

Collaboration and Delivery Performance

The success of the 33 Piccadilly temporary works scheme was due to the working relationship between Conquip, Realtime Civil Engineering, and Kier.

The Conquip design team has been absolutely fantastic, they’re always there and available when you need them. There’s been a couple of items where we’ve had to call them and say, “Can we change this?” And they’ve always been incredibly helpful and solution-driven, which has been really handy.
Ed Martin | Project Manager, Realtime Civil Engineering

Learn more about our Temporary Propping Solutions and Pre-Construction Design Services here.