Rapid construction and reduced disruption for road users were important considerations in the decision of the UK Highways Agency to span the M6 motorway in Lancashire with a new lightweight bridge made of GRP composite.

“The innovative bridge, which is 52 metres long and built using Fiberline’s FBD 600 bridge deck profiles, is two-thirds the weight of the one it replaces, but is stronger and offers cost savings through reduced maintenance in the future,” says Phil Davies, Highways Agency project manager.

“This is the first time the Highways Agency has used GRP for road bridge construction on the motorway network, but we have been using it for several years to strengthen existing bridges, and we have also built two footbridges with GRP decks,” says Phil Davies.

The motorway bridge replaces a 40-year-old life-expired bridge and is designed to carry vehicles up to 40 tonnes. The Highways Agency points out that the new bridge has a superior strength/weight ratio to steel or concrete and is non-corrosive to water and salt.

Reduced maintenance costs
“Although GRP is 5% more expensive than a conventional build, significant savings have been achieved through quicker construction, crane costs, installation costs and labour costs. The difference will also be more than offset by future savings in maintenance,” says Phil Davies.

“The project will demonstrate the benefits of GRP to a wide range of clients, consultants and contractors. Feedback has already been received from the contractor Balfour Beatty and the designers AmeyMouchel and Mouchelparkmann, and it is clear that the use of GRP for bridgebuilding is a success”.

“The Highways Agency wishes to promote wider use of GRP and stimulate further development of the technology, thereby paving the way for improved cost effectiveness. Wider experience of the materials is needed by the construction industry. And, as with all construction, workmanship is a key issue”.

“It is a global market and there is potential to export the technology or even develop modular bridge systems, which can be transported to different parts of the world for infrastructure projects or disaster relief,” says Phil Davies.

Electronic monitoring equipment has been installed on and in the bridge, and data from this instrumentation will allow the Highways Agency to review its design standards to achieve still more efficient use of GRP materials in the future.

The Highways Agency will also consider widening the application of GRP to other infrastructure applications. The Agency believes that accelerating the use of GRP will have major benefits in future motorway widening schemes and bridge rehabilitation across the network.

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