Bridges

Four bridges in the Fiji Islands were recently replaced using a Design and Construction procurement method for the Fiji Road Authority. The bridges provided vehicle, pedestrian and Fiji Sugar Corporation cane trains over waterways subjected to significant flood events. Design of the replacement bridges was specified to Fiji and New Zealand standards for a 100 year design life. This high specification required additional concrete cover and high strength concrete mixes with supplementary cementitious materials and corrosion inhibitors to ensure durability. Ground conditions at the sites were generally poor and one site had no rock proven in investigations to 65m below ground level. Design requirements to NZ standards required stringent seismic performance criteria to be met. To meet these, the design used ground improvements at the abutments to control abutment stability and movements and the bridge structures were detailed for a ductile seismic response. Standardisation of the replacement bridges was developed into the designs to achieve efficiencies through repetition. Construction of the bridges required innovation to build these in remote locations and within the limitations of supply and construction equipment on island.