Development and application of an expert system for evaluation of scour and stream stability

This paper describes a field-deployable decision support system that assists state highway department bridge inspectors in recognizing potential scour hazards and assessing the vulnerability of bridge sites in a cost effective manner. Scour and stream stability is an extremely important problem related to bridge safety as approximately 75% of all bridge failures are related to scour. The purpose of the expert system is to: (1) determine the state of scour risk at a bridge based upon site observations and site history and (2) catalog/store/retrieve information describing bridge site conditions. The system requests from the user a wide range of information about the bridge and bridge site, such as bank countermeasure presence and damage, location erosion, debris accumulation, and bed cross section profile and based upon an extensive rule base determines if abatement actions are necessary. This paper briefly describes what the system does and how the "knowledge" contained in the system is implemented. Major features of the system are described, including Stream Cross Sectional Analysis, Photographic Cataloging/Storage/ Retrieval, System Help, and a Logic Tracing Facility. The range of System Conclusions that the system produces is also briefly presented. Testing and evaluation of the system are also described as well as potential future modifications.