Life-saving bridge is tops - The Witness
A life-saving, eco-friendly bridge constructed in the Umkomaas Valley near Richmond has won its designer, local engineer Corrie Meintjes, three engineering awards.
The KwaZulu-Natal Transport Department commissioned the bridge in response to urgent requests from the community.
For his efforts, Meintjes, a bridge engineer and senior partner in Jeffares & Green Consulting Engineers, was awarded the KZN Concrete Society’s Achiever of the Year award, the Fulton Award for Engineering Design Aspects, and the SA Engineering Society Award for best project with a value of less than R5 million.
The Umkomaas Bridge is the first pre-stressed ribbon bridge in Africa, and its clear span of 150 metres equals the world record for this type of bridge.
Prior to the construction of the Umkomaas River pedestrian bridge, the river posed a grave danger to a community in the valley, with some children losing their lives while attempting to cross the river to and from school during the rainy season.
The community lives on both sides of the Umkomaas River and there is a trading store on one side and a school and a clinic on the other side.
One of the challenges the designers faced was the sheer difficulty of the terrain itself. Precast elements had to be used in order to reduce the amount of on-site construction required.
The bridge is also eco-friendly as it does not interfere with the flow of the river and does not have stabilisers, towers or large abutments that would have imposed on the rural landscape.
It is an innovative all-concrete design, aesthetically pleasing and environmentally responsible and functional, Meintjes said.
The construction of the bridge began in November 2005 and was completed in April this year.
The estimated cost of the project upon completion was about R3,5 million.
Meintjes said the design and construction of this bridge are unique.
An innovative design was required to prevent the swaying motion associated with several types of popular bridge such as cable stay, suspension and hybrid bridges, capable of providing a single span for the required 150 metres, he added.
To avoid fears expressed by the community of crossing a bridge that was moving, Meintjes researched design options and decided on a pre-stressed concrete ribbon structure.
The curved bridge is made of a ribbon of pre-cast concrete elements that are suspended from cables tensioned between supports at each end of the bridge.
The elements are joined and compressed along the bridge by tensioning a second set of cables placed in ducts through the elements.
The compression provides continuity in the deck and compensates for the tensile stress resulting form live loads.
Jeffares & Green is celebrating its 85th anniversary this year, establishing it as one of the oldest structural and civil engineering consultancy firms in South Africa.
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