In late December 1967, the Silver Bridge in West Virginia collapsed causing 47 fatalities. The cause of the accident was due to a single component that had not been inspected and failed due to severe corrosion. This catastrophe initiated massive reform to the inspection and monitoring of bridge structures throughout the United States and continues to the present where a unique predicament is starting to unfold. The useful lifespan of a bridge has been estimated to be 50 years from time of construction; with this estimate, 30% of the nation's bridges fall beyond this estimate, increasing to 48% in the next 10 years. This maturing has caused an increase in the inspection requirements placed on the labor pool due to the higher cycles of inspection demanded by the aging structures. Therefore, a solution must be developed to maintain the current level of public safety and not require additional resources while reducing the stress placed on the existing inspector pool.; The suggested method to solve this problem is the introduction of a Progressively Phased Bridge Inspection Program. This program will investigate the use of a reduced inspection set based off the present condition of a bridge structure. The result is a process where in the initial stages of a bridge's lifespan a limited inspection group of elements are only required to safely and accurately estimate the condition of the structure. As the bridge matures and the key element estimates for its related elements reach their predictive bounds, more elements are included in the inspection set forming the foundation of a Progressively Phased Bridge Inspection Process.; The implementation of this process will be a significant decrease in the amount of inspection time for defined bands of bridges and likewise a reduction in the cost to inspect those structures; this will allow for a more focused effort on the mature structures that require a higher frequency of inspection. The Progressively Phased Bridge Inspection Program will conserve limited resources while maintaining the public safety at the current levels exhibited by current inspection methods.; The research also introduces the ability to generate a network level bridge condition forecasting by applying the same sub processes used to generate the limited inspection set. The ability to project the future condition at the network level allows for timing of budgeting allocation from an accounting perspective. Knowing the change of the network health over time can identify decision points from which interdiction will be most beneficial. The research can be used to generate those overall network condition ratings from which policy, resources, and funding can be directed.
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