Future Engineers on Site - The Civil Engineering Contractor , October 2008
The South African Association of Consulting Engineers, now known as Consulting Engineers South Africa, recently encouraged all engineering firms to get involved in Job Shadow Day, which aims to expose learners not only to the engineering environment but to consulting-engineering experience in particular.
Jeffares & Green answered this call by taking a group of excited Grade 11 pupils – all participants in the Protec programme – to the site of the Mgeni Viaduct at KwaMashu near Durban.
Jeffares & Green is a major sponsor of Protec: a three-year supplementary programme for learners who show above-average skills in maths and science. Pupils participate in “Saturday school”’ vacation-school activities, work experience, site visits and life-skills training. The objective is to help these learners obtain the best matric results possible, assist them to discern their career paths and equip them for tertiary education; hoping some of them will become civil engineers.
The Mgeni Viaduct is part of a new road link between New Germany and Duffs Road, which is being funded by the KwaZulu-Natal Department of Transport. The purpose of the road is to alleviate traffic on the N2 by providing an alternative route between greater Pinetown and the areas north of Durban. It will also provide a shorter access route to the new King Shaka Airport at La Mercy.
The scale of the bridge is impressive. On completion it will measure 420 m long with its tallest piers rising 50 m above the valley floor. The bridge will be incrementally launched, which means the structure will be constructed in sections on the river embankment and, as each section is completed, a complicated set of hydraulics will push it across from pier to pier until it reaches the other side. In this way, section by section will be pushed across the divide until the bridge is complete.
The biggest construction challenge has been the slope of the embankment, resulting in a nine-degree launch angle. This has necessitated two sets of hydraulic systems: one to push the bridge out over the valley and one to hold back the deck once it starts to move. Three hydraulic cylinders of 50 t each are in place to push the bridge deck across the river and three more hydraulic cylinders, each with a capacity of 350 t per cylinder, are in place to hold back the bridge deck. A 25 m-long steel girder will guide the bridge deck as the bridge approaches each pier.
George Kustner, site engineer for Rumdel Cape, contractor on the project, told the learners just how challenges like this need maths and innovative thinking to be solved.
Kobus Burger, bridge engineer for Jeffares & Green, assisting Rumdel Cape in the temporary works, talked about the many and varied career opportunities on a construction site, and most of the Protec learners expressed enthusiasm for civil engineering as a career choice.
The bridge was designed by BCP Consulting Engineers, which has now merged with SSI.
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