Guidelines for Risk-Based Management of Bridges with Unknown Foundations

Research is currently being funded by the National Cooperative Highway Research Program (NCHRP) to develop risk-based guidelines to assist bridge owners in evaluating and prioritizing various courses of action for managing bridges with unknown foundations for scour failure. Currently, over 60,000 bridges over water have unknown foundations. Managing these bridges for failure risk is extremely difficult since a critical scour depth to cause failure cannot be determined in the absence of foundation information. The guidelines being developed under this research project focus on the following: (1) Estimating risk of failure as a function of estimated failure probability and associated economic losses, (2) Setting performance standards for various bridge classifications, (3) Recommending data collection activities (including nondestructive testing of foundations), (4) Recommending scour monitoring activities, and (5) Recommending scour countermeasures. The guidelines being developed will present a logical plan of action for bridges with unknown foundations. Given the large population of such bridges and the potential cost of management options, these guidelines will assist bridge owners in selecting and prioritizing management activities. Once the guidelines are developed, they will be applied to dozens of case studies for validation with real-world examples. After the case studies are completed, the guidelines will be finalized and made available to bridge owners nationwide.