Bridge Inspection Frequency in the United States: Ensuring Structural Safety

Bridges are essential components of America's infrastructure, critical for the safe and efficient movement of people and goods across the nation. Ensuring the structural integrity and safety of these vital structures is of utmost importance. This article explores the inspection frequency of bridges in the United States, drawing insights from the National Bridge Inspection System (NBIS) and the Highway Performance Monitoring System (HPMS).

Introduction to Bridge Inspection in the USA

With over 600,000 bridges across the United States, it's imperative to have a systematic approach to bridge inspection and maintenance. This system was established following the Ohio River's Silver Bridge collapse in 1967, which tragically claimed 46 lives. In response, Congress directed the Department of Transportation to create a National Bridge Inspection System (NBIS).

The National Bridge Inspection System (NBIS)

The NBIS is a comprehensive program designed to ensure the safety of highway bridges. It provides a standardized approach to bridge inspections, which are required at least once every 24 months for bridges over 20 feet in total length on public roads. This system includes detailed inspection procedures and guidelines, ensuring thorough evaluations of each structure.

However, the system is flexible. Some bridges may undergo inspections less frequently, with specific approval from the Federal Highway Administration (FHWA). For example, newly constructed or reconstructed bridges might qualify for inspections every three to four years. This flexibility helps to balance the needs of maintaining structurally sound bridges with the practical realities of limited inspection resources.

Inspection Frequency and Reporting

The inspection frequency of bridges in the United States is regulated by the following criteria:

Approximately 83 percent of bridges are inspected once every 24 months. About 12 percent of bridges are inspected annually. About 5 percent of bridges are inspected on a 48-month cycle.

These inspections are further supported by the Highway Performance Monitoring System (HPMS), which provides detailed reports on the state of highways and bridges. Every two years, the Secretary of Transportation must present a comprehensive report to Congress, detailing the condition of the nation's infrastructure.

Regulatory Overview

The NBIS manual outlines specific training and inspection protocols for bridge inspectors. States and counties are encouraged to impose stricter conditions if necessary. This ensures a high standard of bridge safety across the country. The system has proven effective, and bridge failures, although rare, are typically attributed to unforeseen accidents or bad luck rather than systemic failures in the inspection process.

For those interested in delving deeper into the inspection procedures, the updated HPMS Division Review Guidelines 2017 provide detailed information on the methodologies and criteria used in bridge inspections.

Conclusion

The systematic approach to bridge inspections in the United States, spearheaded by the NBIS and supported by the HPMS, ensures that the nation's bridges are regularly evaluated and maintained for structural soundness. While challenges remain in balancing inspection frequency with resource constraints, the current system effectively safeguards the public's safety on America's highways and bridges.