The Temple area of Bristol has seen regeneration accelerate over recent years, with high and iconic buildings being developed for residential and commercial use. Many of these are focussed around the popular Temple Quay area on the Bristol waterway known as the Floating Harbour.

Castlemore Securities have been behind much of this development, and in order to allow better pedestrian access over the Floating Harbour for the increasing number of residents and office workers, they have provided the first new bridge over the waterway in 8 years.

The stainless steel structure was required to be ‘...imposing yet simple’, and had to span some 55m over the Floating Harbour. With the gross weight of the designed bridge at just over 75 tonnes, the bridge supports needed to be carefully thought out.

Dean & Dyball, the Main Contractor for the bridge, consulted Foundation Piling on the best type of pile to be used to anchor the bridge abutments for the local ground conditions, and the best pile arrangement to resist the high vertical and lateral loads from the bridge. The piles also needed to be practical to install from a small piling platform at the general site level directly above the Floating Harbour.

From Dean & Dyball’s temporary works design, two rows of sheet piles would be installed at the harbour edge and rear of the abutment positions from the general site level. The ground was then in-filled between the sheet piles for Foundation Piling to access the area and place the abutment piles. Dean & Dyball could then reduce the ground between these sheet piles, form the reinforced concrete pit to house the bridge’s hinge supports, with the pit base acting as the abutment pile cap.

The site was ‘made ground’ to 3-4 metres, followed by a weak clay/alluvium, down to gravel and Mercia mudstone or Redcliffe sandstone at around 15-16m. Foundation Piling considered a number of pile types to support the high loads, from rotary drilled ODEX piles to driven ductile iron piles, and settled on using the very versatile ductile iron piles. These are fast and easy to install and robust enough for the anticipated driving conditions and possibility of obstructions. Also, amending the pile layout would be easy if major obstructions were encountered from previous demolition, from the old dock wall which had been partially left in place, or from the rear row of sheet piles installed to –12m.

Foundation piling piled the south abutment first without problems, the standard 30t piling machine easily gaining access to install the vertical and raking piles to the designed arrangement, and without clashing with the temporary sheet piled walls.

On the north abutment, however, the ductile piles found the old dock wall at depth, and the pile arrangement had to be re-assessed, the new piling layout being completed without further problems.

The scheme illustrates the flexibility of Foundation Piling’s ductile iron piling system- the piles are robust and easy to handle, drive and extend, and the simplicity allows for changes to the plan should difficulties arise- particularly in brown field sites where the ground can never be fully described by any site investigation.

Dean & Dyball continued construction of the abutments, and the bridge was located onto the new abutments on 23rd July 2008 with much public attention. The bridge is open to public use from 20^th August, with an official opening planned for the 3^rd October. It is set to become one of Bristol’s landmark structures.