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Great Ormond Street Hospital Children’s Cancer Centre

 

Back to projects

Creating extra works space above a constrained basement excavation

ContractorGetjar and John Sisk & Son (Sisk)

LocationLondon, UK

 

Read transcript here.

Setting the Scene

A new Children’s Cancer Centre at Great Ormond Street Hospital is a major redevelopment that will provide additional clinical, ward and treatment space for patients and staff.

Sisk is the main contractor on this project, with Getjar responsible for the demolition of the previous building, enabling works, pile wall, basement bulk excavation and delivery of the RC frame.

The project is being delivered inside the existing hospital estate in central London, surrounded by operational hospital buildings. With a highly restricted footprint, access, logistics and construction sequencing are critical throughout the programme.

Delivering Complex Works Where Space is a Premium

A single-lane pit lane runs along the southern boundary of the project and must remain available for vehicles moving to and from the site. Positioning excavation plant or mobile cranes within this area at any time, would restrict access and disrupt the wider logistics strategy.

With limited space inside the hoarding line, Getjar and Sisk required a temporary works solution that could create additional operational space without closing the pit lane or compromising access to the basement excavation.

Early Contractor Involvement

Getjar worked with Conquip during the pre-construction phase, almost two years before the temporary works equipment was installed, based on two requirements:

  • To prop the two-storey basement excavation area
  • To provide additional operational logistics areas.

The working relationship allowed Conquip’s Temporary Works Team to collaborate with Getjar, Sisk, the permanent works designers and the hospital estate. Together, the teams coordinated the placement of the temporary propping and the location of the two Temporary Logistics Decks with the excavation sequence, basement construction and wider programme.

Early collaboration was particularly important due to the project’s Building Safety Act requirements and the interfaces between the temporary works, permanent structure and site logistics.

Design development considered plant loading, installation methodology, construction sequencing and the changing use of the temporary structures. The team also used 4D planning to coordinate the propping with construction of the raft slab, including the timing for striking the props.

“Collaboration with Conquip early on has really assisted. We’ve been able to plan for things a lot better, understand where our risks might be, where we may have program issues, and also where we can potentially gain time.”
Jessica Dru | Project Manager, John Sisk & Son

Temporary Logistics Decks

Conquip designed, supplied and installed two Temporary Logistics Decks along the southern elevation, in a pile-supported configuration.

The design of the Temporary Logistics Deck is a modular system that can be easily configured to a site’s requirements, allowing sites to easily install each module rather than create a bespoke scheme for each project.

At the Great Ormond Street Hospital Children’s Cancer Centre, both the Temporary Logistics Decks were configured using the deck modules, with a subframe to suit the site geometry, support arrangement and required plant loads. They were positioned above the excavation to increase the usable logistics footprint and create additional access to the basement.

The two Temporary Logistics Decks were designed to assist different stages of the construction sequence, during the basement phase, before the project’s tower cranes are erected:

  • The first deck provides a platform for a mobile crane, supporting the movement of equipment and materials into and out of the basement.
  • The second deck initially supports an excavator during bulk excavation and muck-away operations.
  • Once excavation is complete, the second deck will be repurposed as a mobile crane platform.

This phased use was incorporated into the temporary works design, allowing the structures to respond to changing operational requirements without occupying additional space at ground level.

“The two temporary logistics decks have increased the logistics footprint for the project, allowing Getjar to sit excavators and cranes off the public highway above the excavation, giving them additional access to the excavation and construction phases of the project.”
Kevin Ryall | Senior Bid Manager, Conquip

By positioning plant above the excavation, Getjar can access the basement while keeping the pit lane dedicated for deliveries and site traffic. The decks support bulk excavation, muck away, lifting and material movements while helping to keep the site’s logistics flowing.

A Coordinated Basement Propping Solution

In addition to the Temporary Logistics Decks, Conquip provided the engineered temporary propping design for the basement excavation.

The design package included:

  • Temporary basement propping
  • The design of the corbels
  • Design check of the capping beam in the temporary condition
  • Coordination with the excavation and basement construction sequence.

Conquip also provided specialist installation and supervision services, supporting the site team throughout delivery of the works.

Collaboration Across the Project Team

The solution was developed through continued collaboration between Sisk, Getjar and Conquip, overseen by the wider project design and hospital estate teams.

By considering the temporary propping, excavation access, logistics and plant loading operations together, the team created a solution that increased the site’s usable footprint and supported several stages of the programme.

“Working on complex projects such as this one, it is imperative that you have a good team around you. That’s what we have here between Sisk, Getjar and Conquip.”
Neil Young | Contracts Manager, Getjar

Learn more about Conquip’s Temporary Logistics Deck, Temporary Propping Solution and Pre-Construction engineering design services.