Bridges

Evidence gathered on some Queensland bridges has raised questions about what heavy vehicles are really doing to bridges. Visual evidence includes the deterioration of concrete bridge decks, headstock cracking, fatigue cracking, settlement of bridge piers, and extrusion of PTFE from bearings. These observations coupled with the results of structural assessments led to long-term bridge monitoring of bridges experiencing distress supplemented by weigh-in-motion (WiM) data. The findings have provided valuable insights into the response of bridges to heavy vehicles and the now frequent passage of indivisible loads that were once infrequent. This data has supported the further assessment of the performance of these bridges at the serviceability, fatigue, and ultimate limit states. This contrasts with the current practice that focuses on ultimate limit state assessments. The paper will present the evidence and discuss the implications for the risk-informed management of bridges and access to bridges. It will discuss the performance of the heavy-vehicle-bridge system and the implications of these interactions, and what information is important to collect and measure in the appreciation of asset service life. It seeks to open a conversation about bridge performance and understanding what risks really need to be managed.