The seven-year old Twin Sails bascule bridge in Poole has been closed for two weeks to allow engineers to investigate a fault with the lifting mechanism.
Over the two week shutdown, a 0.5t pin from the rod end assembly - which allows the bridge deck to rotate and forms part of the lifting mechanism on the Hamworthy side of the bridge – will be removed.
Once removed, engineers will then be able to identify the fault and develop a programme to carry out the appropriate repairs.
Routine maintenance to replace missing and failed LED road studs and lamps, and the servicing of the hydraulic, software and control systems are being brought forward to be carried out during the shutdown.
Further closures are expected to carry out the repairs needed and install any new parts.
Engineers had been called out to the bridge in early December after a grating noise was noticed coming from a hydraulic cylinder when the bridge was being raised.
In late December, works to extract the pin failed after a hydraulic jack and specially manufactured jig was deemed insufficient to carry out the work.
The leaf of the bridge had been operating in a single cylinder operating mode with the bridge being lifted using one ram and operating at half the usual speed.
Borough of Poole interim engineering manager Lynne Wait said: “Engineers have thoroughly assessed all the options for extracting the pin. Significant temporary works are required to enable the pin to be removed and once this has happened the bridge will need to remain closed whilst the ram end assembly is thoroughly inspected and the bridge is recommissioned.
“We will endeavour to carry out these works as quickly as possible and return the bridge to normal operation. We apologise for any inconvenience these works may cause.”
The bridge is a bascule bridge with a lifting mechanism on either side of the bridge to raise the deck. However instead of there being a joint transversely in the middle of the bridge, the joint runs diagonally along the length of the deck creating two “sails” when opened.
It is not the first time the bridge has had to have serious repairs carried out on it. The opening of the bridge was delayed by a month as contractor Hochief was forced to resurface the bridge because cracks began appearing on the road surface of its two triangular lifting sections during full loading tests.
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