Bridge health monitoring is a method of evaluating the ability of a bridge to perform its required task (also called fitness for purpose) by monitoring the response of the bridge to the traffic loads it has to withstand.
This research project, carried out in 1998–1999, is part of the short-term health monitoring and 'fitness for purpose' assessment of 10 bridges on New Zealand roads, to develop and evaluate the methodology. The Big Wainihinihi River road bridge, on State Highway 73, between Kumara and Otira, West Coast region, South Island, built in 1935, was selected as one of these 10 because it is an aging single-lane steel-girder bridge with a timber deck. The conventional rating for it is relatively low, and it is also representative of a large number of road bridges maintained by local government agencies throughout New Zealand. However, the fitness for purpose evaluation for this bridge indicates that the bridge is safely carrying the heavy vehicle traffic currently using the route.