Bridges

Transport for NSW currently manages about 6000 bridges and bridge-sized culverts in New South Wales (NSW) for road traffic. These bridges were built during the last 130 years for various design loadings, clear heights, structural forms and materials. Some of these bridges were designed to carry even horse carriages and traction engine vehicles but are satisfactorily carrying present day legal vehicles with or without strengthening. Heavy vehicle impact on these bridges, both on overhead bridges and on through truss road bridges is not uncommon. There are even instances where vehicular impact has occurred for overhead bridges which are designed to current Australian Bridge Design Standard clear height requirements. These impacts not only disrupt traffic flow, both along the route and along the overhead bridges, but also compromise structural integrity of the impacted bridges. This paper selects case studies from recent past and discusses how systematic risk assessment methodologies, both short term and long term, were carried out so that carriageways can be opened to traffic with minimal disruptions. These case studies involve, two through truss steel bridges, a Super-T girder bridge and a prestressed concrete plank bridge. This paper discusses how post-accident field inspections, non-destructive material testings, structural health monitoring instrumentation, load testing and innovative Finite Element (FE) analysis can be used in an efficient manner to risk manage these bridges, so that vehicular traffic can be allowed until necessary structural rehabilitation works are designed and implemented.