Upgrading of three historic arch bridges over the Orange River near Keimoes, South Africa

This project is located on the South African National Roads Agency SOC Ltd’s (SANRAL’s) Route R27 near Keimoes in the Northern Cape Province of South Africa. The overall objective was to improve traffic capacity and safety of the route, with the main focus being the widening of four single traffic lane bridges over the Orange River floodplain. This paper reviews the upgrading of the three main historic arch bridges.

The project included a detailed hydrological and hydraulic assessment which resulted in the raising of two of the structures by approximately 2,5m to prevent overtopping of the structures during larger flood events. The largest of the three bridges, a ten span arch bridge, was at a higher level and the existing deck was therefore retained and widened. The raising and/or widening of the bridges had to comply with heritage requirements as these structures, completed in the early 1930’s, have significant historical importance. This resulted in the original form and appearance to be retained by using a similar arch configuration and detailing. Construction was completed in 2013.