1. Using the table below discuss how the risks were addressed or how they could have been addressed. Include any additional risks you can think of.

2. State whether the risks listed in the table above are internal or external.

3. Describe how you would determine the expected values of the risks listed in the table.

4. Compile a complete list of information that you would require in order to make an assessment of the risk of a pump failure.

Case 10.3 The Mandela Bridge 33 Nelson railway lines, which exposed workers to the risks of being near continuous rail operations. The pumping method posed the risk of the stone aggregate and cement in the concrete mixture segregating in the pylon tubes before the concrete solidified, which would compromise the strength of the concrete. Another risk was that the pump might fail and result in the concrete solidifying in an uncompleted pylon, rendering further pumping of concrete from the bottom bottom impossible. Two contingencies were considered: an additional pump on standby, and completing the process by pouring concrete from the top of the pylon. Newtown, South Africa is a suburb of Johannesburg that boasts a rich cultural heritage. As part of an attempt to help rejuvenate Newtown, the Nelson Mandela Bridge was constructed to link it to important roads and centers of commerce in Johannesburg. Spanning 42 electrified railway lines, the bridge (Figure 10.10) has been acclaimed for its functionality and beauty. Lack of space for the support pylons (towers) between the railway lines dictated that the bridge design would have a long span. This resulted in a structure with the bridge deck supported by stay cables from pylons of unequal height. The pylons on the northern side are 48 meters high and those in the southern side are 35 meters high. The pylons are composite columns consisting of steel tubes that had to be filled with concrete after being hoisted into the vertical position. The decision was made to pump the concrete into the tubes through a port at the bottom of each tube. This had to be done in a single operation. Although the technology for casting concrete this way was not new, the columns were the highest in South Africa and filling them would set a world record for bottom-up pumping of self-curing concrete. The pump for the concrete was placed at ground level between the electrified Figure 10.10 Nelson Mandela Bridge, Johannesburg. Source: iStock The concrete had to be transported by trucks to the site, which risked interrupting the concrete supply owing to traffic congestion in the city. Despite working over a busy yard with trains running back and forth, no serious accident occurred at any time in the