Contractors were this week scrambling to resurface Poole’s brand new Twin Sails bridge after cracks appeared in the road and the opening had to be put back.
Contractor Hochtief was forced to resurface the bridge before it has even opened to traffic because cracks began appearing on the road surface of its two triangular lifting sections during full loading tests.
Hochtief now hopes the £21.6M bridge will be able to open to traffic in early April.
The 140m-long, five-span bridge - which crosses Poole harbour on the south coast - was due to open on 12 March.
“Although the surfacing has been on for two months, it wasn’t until just before the weekend [of 10 March] of the opening that the cracking began to appear following final load testing,” Hochtief project manager Richard Bruten told NCE.
Bruten said the cracking occurred on the abutment end of both lifting leaves in an area about 1m2.
The original road surface consisted of a waterproof membrane topped by a sand asphalt and a thin Masterflex asphalt surfacing layer - together 35mm and 50mm thick.
Masterflex is a standard highway surface top layer used across Poole’s road network.
Bruten said traditional lifting bridge road surfacing - such as mastic asphalt bonds or shear studs that produce a stronger bond to the deck - were ruled out by the client because it wanted a standard highway surface as thiswould be easier to maintain.
Following the discovery of the cracks, Hochtief has decided to replace the surfacing with a single 35mm to 50mm thick layer of hot rolled asphalt on a waterproof membrane as originally specified.