Bridges

The New Zealand Transport Agency recently carried out a nation-wide screening of state highway bridges for scour and other bridge waterway risks. This paper outlines lessons learned from the implementation of the screening programme and reviews the findings of the screening including what knowledge has been obtained about the risks that the state highway bridge stock is exposed to. The paper also outlines how the observations from the screening programme are being audited to assist in compiling a national priority list of bridges requiring risk treatment. Finally the paper reviews two recent failures at the Whitestone River and Walker Creek Bridges on State Highway 94 between Te Anau and Milford Sound which were both damaged by scour during an April 2010 storm event. The primary factors influencing the failure in each case are identified and the observations from the inspection of each bridge examined to see if sufficient weight was accorded to those risk factors which influenced their failure.