Construction World January 2020

O Q 2FWREHU WKH 2OLIDQWV 5LYHU %ULGJH ZRQ WKH DZDUG IRU Technical Excellence at the South African Institute of Civil Engineers (SAICE) Annual Awards. The South African National Roads Agency (SANRAL) appointed global engineering, design and advisory company Aurecon to improve the bridge and associated LQIUDVWUXFWXUH LQ The Bridge was completed in 2018, achieving SANRAL’s goal of improving an important economic link between South Africa and Namibia for tourism and freight. Gustav Rohde, Aurecon Managing Director, Africa, comments: “Aurecon would like to thank SANRAL for entrusting us with this mega project. We are honoured to receive a prestigious SAICE award, which recognises and celebrates the success we have achieved in collaboration with our clients and project partners. The DELOLW\ WR KDUQHVV WKH FUHDWLYLW\ RI D FURVV GLVFLSOLQDU\ WHDP DQG WKH XVH RI VPDUW WHFKQRORJ\ KDV HQDEOHG XV WR FUHDWH D IXWXUH UHDG\ infrastructure solution for South Africa.” About the project The N7 in the Western Cape is a strategic trade route between South Africa and Namibia. The existing bridge over the Olifants River could QRW DFFRPPRGDWH LQFUHDVLQJ WUDͦF ORDGV 7R LPSURYH WKH VHUYLFH level of the road, the design team had to design a new structure next to the existing bridge.

Expansion joints and bearings, which are high maintenance items on bridges, were reduced by providing a continuous deck and integral piers. The integral piers, however, attract forces due to horizontal loads on the deck which are related to their stiffness. The piers of the bridge had to be large enough to resist the vertical reactions from the deck and be slender enough to avoid attracting large forces. This structural compromise could be achieved for the tall piers GXH WR WKHLU QDWXUDO VOHQGHUQHVV EXW LW ZDV D QHDU LPSRVVLEOH WDVN for the shorter piers that are supported on the arch. To overcome this challenge, the design team introduced a concrete hinge at the top of the short piers. The design change led to reduced stiffness of these columns and WKH PRPHQWV ZHUH VLJQLͤFDQWO\ UHGXFHG “From the outset, the design team strived to produce an exceptional structure. Through the innovative use of an ancient structural form, constructed with modern materials and analysis techniques, we believe that we have achieved our goal. The recognition that we have received from our peers through the 6$,&( DZDUG PDNHV XV H[WUHPHO\ SURXG DQG VHUYHV WR DͦUP WKLV belief,” says Hennie Niehaus, Aurecon Technical Director. Local residents were upskilled via training programmes and employed for the construction of the Bridge. In June 2019, the project won a Fulton Award for Infrastructure projects up to 5 PLOOLRQ LQ YDOXH ƒ

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CONSTRUCTION WORLD JANUARY 2020