Civil Engineering March 2021 | Vol 29 No 2

32 March 2021 Civil Engineering new construction works was integral to the success of the project. Therefore, an intricate demolishing and construc- tion sequence process was developed, involving the following: Q Q Construction of temporary pipe and pedestrian walkway structures attached to the sides of the existing bridge (Figure 1). Q Q Diversion of the existing sewer, water, and cable infrastructure services onto the temporary structures (Figure 1). Q Q Extension of the height of the existing substructure (Figure 2). Q Q Construction of a temporary launching system which comprises two No. steel A-frame structures which slide on a steel rail track (Figure 3). Q Q Launching of the new precast beams in a sequential manner to their respective positions (Figure 3). Q Q Construction of the in-situ gaps between the precast beams. Q Q Laying of the new 400 mm diameter HDPE water and sewerage pipes on the new bridge deck and encasing them in concrete (Figure 4). Q Q Jacking of the 600 mm diameter steel water pipe through the void of the new bridge deck (Figure 4). Q Q Transfer of the water and sewer services from the existing lines to the newly constructed lines. Q Q Stopping the access to the temporary pedestrian structure. Q Q Demolishing the existing bridge steel truss superstructure, temporary structures, and existing services in a sequential manner by utilising the A-frames to transport the various steel elements off the bridge. Q Q Fixing the handrails and the balus- trade screens (Figure 5). INNOVATIVE PROCUREMENT PROCESS Under normal circumstances, the intricate demolition and construction sequences of the bridge would have to be communicated to prospective tenderers at a tender briefing. During the design process, considering the worldwide pandemic, the team brain- stormed various alternatives and proposed an innovative way of eliminating a physical future site tender briefing. This process en- tailed the digitalisation of the construction sequence in a video detailing the intricate demolition and construction sequence by utilising various BIM software programmes. BIM is often marketed for the long- term benefits it can have for a project, but it can also be utilised as a powerful tool at the initial stages of a project. The Canelands Pipe and Pedestrian Bridge project demonstrates that thinking out of the box and embracing technology can provide innovative solutions in an ever‑changing world to ensure that service delivery of infrastructure is prioritised.  Figure 1 Construction of temporary supports and transfer of existing services Figure 2 Extension of height of existing substructure Figure 3 Launching of precast beams utilising A-Frames and steel rails Figure 4 Construction of new water and sewer lines in the bridge deck The new Canelands Bridge modelled using BIM software Existing bridge superstructure New temporary support structures Figure 5 Final deck cross section subsequent to demolition New 400 diameter sewer pipe New 600 diameter steel water pipe New 400 diameter water pipe BridgeCL