Inspection Planning Based on Risk Analysis

Abstract

This paper provides an overview of an innovative new approach for the safety inspection of highway bridges. The National Bridge Inspection Standards (NBIS) mandate a uniform 24-month inspection interval for most highway bridges. The uniform intervals were based on engineering judgment at the time the NBIS was implemented in the 1970's and do not consider the typical performance characteristics of bridges with different designs, materials, exposure environments, or existing condition. A more rational approach to determining inspection frequency and scope would consider the structure type, age, condition, environment, and other characteristics of bridges. This paper will discuss reliability-based inspection practices that utilize a risk assessment framework to determine appropriate inspection frequency and scope. This approach utilizes engineering analysis of typical damage modes and deterioration mechanisms for different types of bridges, combined with the exposure environments and loading, to assess the inspection needs for a bridge. Under such an approach, inspection efforts are focused where deterioration and damage are most likely and where consequences of that damage are greatest. The approach is intended to improve the safety of bridges by optimizing the use of resources, focusing inspection efforts where inspection needs are greatest.