Students build bridge to link up old Groynes with new

Press, 14 December 1977, Page 12

Students build bridge to link up old Groynes with new

Twelve senior pupils at Burnside High School have joined Waimairi County Council in a bridge-building venture. The boys have completed their part of the job — the prefabrication of the decking for the 55m-long suspension bridge. And next year another group will rig the bridge when the council has built the reinforced concrete towers and abutments. The joint project originated through the school’s metalwork teacher, Mr T. Feringa, who wanted to start a pilot scheme for a sixthform certificate course in metalwork. He sought something that the pupils could work at together, that was practical, that was needed, and that would be a community project. His talks with the council’s engineers revealed that a suspension bridge was needed to link the existing picnic area at the Groynes, Belfast, with

an 80 ha piece of land that was being developed for future recreation use. Although the design had not been decided at that stage, Mr Feringa and his 12 U.E. students decided to tackle the job. It was essentially a “volunteers only” project — additional to the boy’s school course. In the event, a good deal of the work spilled over into lunch hours and after school, but it was not solely because of the amount to be done. The boys enjoyed being involved in the scheme. Because the work was extra to the school curriculum it was not done in the metalwork room, the welding and cutting gear were carted each time to an empty garage in the school grounds. And according to Mr Feringa, that was a job in itself. The designer of the bridge is Mr Mike Somers, an assistant engineer with the council, who works from the Parklands office. It was his first such

project — and, as he readily admits, it has been quite a challenge. There is not much call for suspension bridges in Christchurch and he found it difficult to have his calculations checked. Finally, a local consulting engineer agreed to help. For a few years the Imwide footbridge will be the only access to the new area. Mr Somers forcasts up to 2000 people using it every Sunday during the summer. Ultimately, there will be access for cars further along Johns Road. The Bm-high towers should be completed by February, and the job of rigging the bridge with its cables and prefabricated decking sections will then begin. Although the towers will be stayed by two 32 mm cables, they have been designed to take the load of the bridge plus 10 per cent without them. “I don’t think cables that size could be cut with an axe,” says Mr

Somers. “But we are involved with vandalism all the time on our reserves. Vandals can make a mess of anything.” The possibility of thrillseekers piling on to the bridge and bouncing around to cause it to undulate also sent Mr Somers back to the drawing board after he had completed his original design. In addition to the cable supports, the bridge will now have a stiffening beam that will make it “less lively.” “The only real unknown is what effect the wind will have on the bridge,” he says. “But we have done everything right according to the information available on suspension bridges.” Mr Feringa is hopeful that the council will also entrust to his pupils some of the metalwork that has to be done in the new Groynes area. A weir and its controls will be built to regulate the level of the lake that has been formed in the

middle of the picnic area. “It is easier to teach engineering principles — such things as friction — on the job. Theory gets pretty mundane in the classroom, but on these jobs the practical and the theory can be taught together,” say s Mr Feringa. But in the near future he hopes the boys will get the opportunity to start something at the design stage, some project on which they will all agree at the outset and take through to finality as a team. Mr Feringa sees a real need for schools to offer this type of course. “There are now more and more sixth-formers at school who are not really U.E. candidates," he says. “We have learned a great deal. There were plenty of headaches, but we enjoyed it. However, our next project may have to be a bit smaller. This one,” he added with a wry smile, “may have been too ambitious.”