New Street Square Bridges in London: steel-and-glass bridge

New Street Square Bridges in London made by seele

2

bridges (Level 1 & 7)

22t

steelwork per bridge

12

insulating glass units

two steel-and-glass link bridges for deloitte's headquarters in london

A new headquarters for Deloitte UK and north-west Europe has been developed in New Street Square, London. Two link bridges created by seele have connected new work and amenity spaces for Deloitte’s people, creating a seamless journey between buildings.

Both bridges, the “Lower Bridge” on Level 1 and the “Upper Bridge” on Level 7, span about 12m. Ramps and steps within the bridge compensate for the different floor levels at the ends of each bridge, which resulted in an unusual design for the bridge deck itself, the so-called monocoque. The soffit of each bridge is cladded with 12m long triangular stainless steel plates, alternately polished to a mirror finish or blasted with glass beads to produce an interlocking zigzag pattern. Panes of insulating glass measuring 4m x 3m form the sides of each bridge. The roof is made from glass fibre-reinforced plastic (GFRP) and a rooflight consisting of 12 panes of insulating glass extending the full length of each bridge so that plenty of light reaches the interior.

In terms of structural engineering, this project was very challenging because, with an existing building on one side, the depth available for the primary steel structure was limited. That led to the bridges being very prone to vibration. Furthermore, the differential movement of the two buildings on either side and the expansion behaviour of the bridges has to be accommodated by the adjoining unitised façades.

Once again, the use of highly diverse materials such as steel, glass, aluminium and GFRP, the precision in fabrication and an ingenious erection concept plus the short completion time confirm seele’s all-round expertise.

Header Image: © Ben Bisek for WilkinsonEyre

Two link bridges in steel-and-glass design made by seele — © Ben Bisek for WilkinsonEyre

Two link bridges with spans of 12m made by seele — © Ben Bisek for WilkinsonEyre

New Street Square Bridges made of steel and glass for Deloitte headquarter by seele — © Ben Bisek for WilkinsonEyre

Steel-and-glass design for the link bridges on new street square in London made by seele — © seele

Challenges during production and on site

The erection concept for the location in the heart of London had an effect on production. Owing to small time slot available for work on site, the portal frames were attached to the bridge deck (monocoque) at seele’s plant in Pilsen, checked for accuracy and then disassembled again. On site, the portal frames were first mounted on the two buildings and temporarily moved back into the buildings because the space available between end of bridge and building was only 10cm at most. After each pre-assembled bridge had been lifted into position with a mobile crane, the portal frames were moved outwards again so the bridges could be bolted to them.

Monocoque in Gauda design: This engineering solution was devised to achieve the headroom needed to allow London’s double-decker buses to pass beneath the “Lower Bridge”; there is only 5cm clearance between bus and bridge. Threaded fittings therefore connect the soffit panels to the monocoque in order to create more space.

Pre-assembly of 4t portal frame: All bolted connections were checked for accuracy of fit in order to rule out errors during the final positioning of the bridges on site.

Credits

Client	Deloitte LLP
Main contractor	Overbury
Architect	Wilkinson Eyre
Engineer	Eckersley O’Callaghan
Date of completion	2019
Scope of work by seele	Design, engineering, production and erection Lower Bridge (Level 1) & Upper Bridge (Level 7) Dimensions of each bridge: 12m long x 6.5m wide x 4.5m high 22t steelwork per bridge Soffit cladding: 6mm stainless steel, mirror/glass bead-blasted finish Vertical glazing: 4m x 3m insulating glass units Roof glazing: 12 insulating glass units, 2m x 1m, per bridge 12m long GFRP panels Adaptation work on both façades
Awards	2022 Bridge Award (best bridge design over £5m)