Emergency rehabilitation of Selby interchange on M2, in Johannesburg, South Africa

Abstract

In this paper, the retrofitting and rehabilitation of the M2 Selby interchange, on the M2 in Johannesburg, Gauteng, South Africa, is presented. After noting large shear cracks on the pier columns, the highway had to be closed down, for 10 months. The client for the project was the Johannesburg Roads Agency (JRA), the contractor was Stefanutti Stocks Civils, and the consultant was WSP. The project commenced with the design of jacking towers which were used to jack up and support the drop-in slabs. The support system was designed to be used as a kit that can be reused in future. The demolition of the piers posed some difficulties due to the small working area within the constraints of the jacked slabs, which remained in the jacked position. The piers were designed in accordance with TMH7. A key design focus was the creep calculation, due to the unique geometry of the mushroom heads. Granite aggregates were chosen to reduce the creep and the cantilever ends were precambered. The jacked slabs were lowered and aligned only at the end of the project timeline just in time for the Thorma joints and asphalt to be added before opening the bridge to the public.