On November 12th, 2011, about 15 members and others visited the Twin Sails Bridge site in Hamworthy to see the progress on the construction of the bridge which is due to open officially in March next year.
Some members of the Unit have already been involved with the bridge as on occasions when the Contractors have been maneuvering bridge components into place it has been necessary to close the backwater channel. Using our launches we have manned an exclusion zone to prevent boats passing through the area whilst the work was in progress.
It was interesting to hear a talk from Frank Miller, the Site Engineer for Poole Council, for about an hour who described the various processes in the construction, problems come across during the building and some of the astronomical costs involved. He described one Mobile (?) crane which was used, had visited the site several times, took three lorries to transport it and a day to erect at enormous cost!
We were all kitted out with hard hats, gloves and glasses before visiting the actual site and walking over the as yet unfinished bridge. Although the bridge is at present sitting in the open position it is not yet completed, all the finishing processes, top surfaces and approach roads have to be finished although the road on the Hamworthy side is now in place. Unfortunately we couldn’t climb down into the caissons as High Pressure Hydraulic hoses were under test but the caissons go down three levels and contain the electrical and switching gear.
When completed the bridge is expected to lift about 5000 times a year and will take 2 minutes to raise and lower. There will be a traffic signal system on both sides to control the flow of vehicles which will automatically divert the cars etc. to whichever bridge is open as a roadway so there will always be an open route between Poole and Hamworthy. It remains to be seen how much delay is involved for boats going from the back water channels to Poole Harbour!
Peter Lockwood
20th November 2011