The National Bridge Inspection Standards (NBIS) mandate the frequency and methods used for the safety inspection of highway bridges. The inspection intervals specified in the NBIS require routine inspections to be conducted every 24 months, and that interval may be extended to 4 years for bridges that meet certain criteria and are approved by FHWA. For bridges with fracture-critical elements, hands-on inspections are required every 2 years. The specified intervals are generally not based on performance of bridge materials or designs, but rather on experience from managing almost 600,000 bridges in the National Bridge Inventory.
These inspection intervals are applied to the entire bridge inventory, but they may not be appropriate for all bridges. For example, recently constructed bridges typically experience few problems during their first decade of service and those problems are typically minor. Under the present requirements, these bridges must have the same inspection frequency and intensity as a 50-year-old bridge that is reaching the end of its service life. In the case of bridges with fracture-critical elements, newer bridges with improved fabrication processes and designs that mitigate the effects of fatigue are inspected on the same interval and to the same intensity as older bridges that do not share these characteristics.
A more rational approach to determine appropriate inspection practices for bridges would consider the structure type, age, condition, importance, environment, loading, prior problems, and other characteristics of the bridge. There is a growing consensus that these inspection practices should meet two goals: (1) improving the safety and reliability of bridges and (2) optimizing resources for bridge inspection. These goals can be accomplished through the application of reliability theory.
The objective of this project is to develop a recommended bridge inspection practice for consideration for adoption by AASHTO. The practice shall be based on rational methods to ensure bridge safety, serviceability, and effective use of resources.
Products Availability: There are no products available for distribution. The final report will be available after completing NCHRP Project 12-82(01).