Church Lane Road Bridge is located in Frampton Cotterell near Bristol. The 8m single span bridge over a small river was constructed in 1968 and was formed from a reinforced concrete slab.
Over four decades the bridge deteriorated significantly, with low cover and reinforcement corrosion apparent. Subject to a load restriction, it was clear that a new bridge was required.
Client South Gloucestershire Council set a key objective – develop a solution that would minimise closure time to limit impact on local residents.
“We used a glass fibre, polyester resin composite with an Asset bridge deck pultrusion made by Fiberline” James Henderson, Atkins
FRP offered offsite fabrication to reduce the construction period on site and significant lifecycle durability benefits. The new, lighter, bridge could be supported on the existing abutments, further reducing the construction time and enabling it to be built within the six week school summer holiday period.
South Gloucestershire Council used its own street care team for construction. No wet joints were allowed onsite so complete off site fabrication was required. Pultruded sections fitted the bill.
Using pultrusion also created a secondary challenge for the supply chain as different manufacturers and suppliers had very different design solutions. As a result, comparable quotations were requested on a “design and fabricate” basis. This allowed the FRP manufacturers to be as innovative as possible in the deployment of their products.
The winning tender came from CTS Bridges using pultrusions sourced from Fiberline Composites in Denmark.
“We used a glass fibre, polyester resin composite with an Asset bridge deck pultrusion made by Fiberline,” says Atkins technical authority for composites in construction James Henderson. “It came off the shelf but then it was a bespoke application.
“The deck is made up of triangular sections which are about 225mm deep and bonded together.
“Then we put some box beams underneath. They act like stiffening ribs. There are then 2mm thick FRP plates bonded to the bottom of the beams along their length.”
The pultruded profiles were shipped to CTS Bridges in Huddersfield, partially manufactured by CTS and then transported down to the National Composites Centre (NCC) for final fabrication. The hybrid FRP Deck was then transported to site on 24 August 2014 and lifted into place in one operation.
“The bridge was installed in a day,” says Henderson. “Resurfacing of the road took place the next day and then traffic was running over it the next. It’s one of the biggest FRP road bridges in the UK at the moment.”
With the bridge open to traffic and a 7km diversion removed, a masonry parapet was then constructed to meet conservation requirements. Watch the timelapse video here.
As a legacy, Atkins and the University of Bristol arranged for sensors to be installed on the bridge. With time, these will provide valuable data about the behaviour of the FRP deck to inform future designs.
Client: South Gloucestershire Council
Contractor: Street Care
FRP manufacturer/bridge fabricator: Fibreline Composites/CTS Bridges