Civil Engineering October 2022 | Vol 30 No 9

8 October 2022 Civil Engineering T he site’s first bridge appeared in 1691 on what was the old wagon road ‘highway’, the earliest formal route into Stellenbosch, and one of the first, if not the first, bridge to have been built in South Africa. The site is considered an integral and authentic piece of Stellenbosch and indeed Cape history, and over the years the bridge was either upgraded or rebuilt. The area’s known historical links can be traced well beyond the 17 th century to the early Stone Age period some two mil- lion years ago. A monument just off the western approach to the bridge marks the point where stone implements, including a Palaeolithic quartzite axe, were discov- ered in 1899. The bridge being replaced was erected in stone and in-situ concrete during the early part of the 20 th century. It was upgraded to a narrow double-lane thoroughfare in the 1950s when its abut- ments and central stone pier were enlarged and strengthened. During the 1960s the structure gradually fell out of use as one of the main routes into Stellenbosch after the construction of the Adam Tas Road Bridge over the Plankenbrug River had provided more direct and faster access. From the first decade of the new millennium onwards, Distillery Road was closed as a route into town and only served Bosman’s Crossing, which it still does today. DESIGNING A NEW BRIDGE The growth of the Bosman’s Crossing precinct during the second decade of the 2000s, an increase in traffic, and the dete- riorating condition of the bridge, prompted the Stellenbosch Municipality to investi- gate widening and strengthening options. AECOM SA was appointed to inspect the bridge in 2020 and found the structure to be neither safe nor practical for existing and anticipated traffic volumes. Based on this finding AECOM was commissioned to evaluate alternatives which compared repair, rehabilitation and upgrading op- tions. And because of the site’s possible historic significance the council also appointed a heritage architect to compile a report to be used as a guideline for the rebuild. Prepared by Rennie Scurr Adendorff Architects and CTS Heritage in consulta- tion with Heritage Western Cape, the report was submitted together with the permit application to upgrade the bridge. Covering the heritage, archaeological, landscape and contextual significance of the site, the report recommended that the new design should respond to the semi-rural character of its immediate sur- roundings rather than the commercial and residential aspects of Bosman’s Crossing. Several design proposals were con- sidered in the report. In each case the improvements required to improve traffic flow and safety were assessed in terms of the bridge’s alignment and positioning; its component features; load bearing capacity of the old elements; river through-flow and flooding; and the need to limit any potential damage to the surrounding landscape and environment. The engineering team tabled six de- sign proposals which were workshopped with the heritage team. Two of these op- tions, which adhered to both heritage and functional requirements, were adopted Mun i ci pal eng i neer i ng and i nfrastruc ture del i very Rebuilding historic Stellenbosch bridge with precast concrete The old bridge over the Plankenbrug River (formerly Dwars River) in Stellenbosch is being rebuilt with precast concrete beams. The first of this two-phase project was completed in August 2022 and the second is scheduled for completion in December 2022. The new bridge will provide improved access to Bosman’s Crossing, a burgeoning residential, commercial and light-industrial precinct situated in the old KWV Industrial Park immediately east of the bridge. The original wooden bridge that gave this section of the Dwars River the name Plankenbrug