Widening of existing bridges on State Highway 16 in Auckland

Abstract

The State Highway 16 Causeway upgrade project is one of the packages in the Waterview Connection project portfolio, which forms the final section of the 48 km Western Ring Route in Auckland, New Zealand. The project improves, widens and raises an approximately 4·8 km long section of the existing motorway, to provide additional capacity and to safeguard it against coastal erosion and flooding. Two existing bridges on the motorway, Whau River Bridge and Causeway Bridge, are being widened and upgraded to extend their usable lives. Both bridges are a mix of structural forms, presenting many technical and logistical challenges for design and construction, in terms of the integration of further widening work and the assessment of the existing structural elements. This paper discusses the innovative approach taken towards the complex bridge widening, how durability, constructability and traffic management have been taken into consideration and how the results of assessments, including non-linear seismic ‘pushover’ analyses, have been used to confirm the functionality of the bridges in the final scheme.