As an integral part of our Nation’s transportation system, bridges connect us and ensure that
businesses can move their goods seamlessly throughout the country. Bridge inspection
and maintenance activities ensure that our bridges remain safe for all users.
When Agencies inspect and maintain their bridges, unsafe conditions can be addressed and the
possibility of closure minimized.
A bridge failure in 1967 prompted Congress to pass legislation to ensure the safety of
our Nation’s bridges and the traveling public.
The National Bridge Inspection Standards, or NBIS, is the result of this legislation.
The NBIS requires inspection of all publicly owned highway bridges greater than 20 feet
in length.
While State departments of transportation, or State DOTs, are ultimately responsible
for ensuring compliance with the NBIS, many States have delegated functions of this program
to the bridge owner.
Even if your State DOT performs the functions required by the NBIS, all bridge owners are
responsible for understanding and complying with the NBIS requirements and any additional
State requirements.
The NBIS establishes minimum qualifications for inspection personnel, identifies which
bridges to inspect, and defines the information to be collected and reported as part of the
inspection process.
In most cases, routine inspections are required at least every 24 months. Some low-risk
bridges may be inspected at intervals up to 48 months if prior approval is received from
the Federal Highway Administration, or FHWA.
In addition to routine inspections, bridge owners may have to perform other types of
inspections. This may include underwater inspections to verify the condition of bridge elements
below the water surface and above the mudline, fracture critical inspections of steel bridge
elements, whose failure may cause the bridge to collapse, damage inspections after a natural
disaster or accident; and in-depth inspections.
Another important safety aspect of the NBIS is load rating. A load rating determines the
safe load-carrying capacity of each bridge.
After a bridge inspection, the load rating must be verified based upon the observed field
conditions. When it is determined that a bridge cannot safely carry state legal loads, the
bridge must be load restricted or strengthened.
Bridge owners are responsible for properly strengthening, load restricting, or closing
bridges when necessary.
Inspections typically will identify maintenance items, which may need to be addressed to keep
the bridge in good working order.
In some cases, an inspection may identify a critical finding. The NBIS defines a critical
finding as a structural or safety related deficiency that requires immediate follow-up
inspection or action.
The bridge owner must immediately address any identified critical finding because the
finding could have a direct impact on public safety.
Since the NBIS requires that each State have an established procedure to address and report
critical findings, your State DOT can provide guidance on actions to take if a bridge inspection
results in a critical finding.
All bridges over water require a scour assessment. This assessment determines the bridge’s
vulnerability to erosion of material from around bridge supports to a depth that may
cause instability or failure.
Development and implementation of a plan of action, or POA, is required for any bridge
determined to be vulnerable to scour.
The POA details the steps to take if the bridge experiences a flood event.
Maintaining detailed records is an important component of a bridge inspection program.
Bridge owners need to maintain a file for each bridge that includes load ratings, flood
history, relevant maintenance data, and inspection reports documenting findings from each inspection.
The NBIS requires updates of bridge inspection data within 180 days of the inspection, but
States may require this data in a shorter timeframe.
States report bridge inspection annually to the Federal Highway Administration, which
stores the data in the National Bridge Inventory, or NBI.
The NBI contains information on more than 600,000 bridges nationwide.
The FHWA uses the NBI data to track bridge conditions nationwide, monitor NBIS compliance
and prioritize funding decisions.
So you can see that as the bridge owner, understanding your role in meeting the NBIS requirements
and performing the functions delegated to bridge owners by your State DOT is important.
Working together with the State DOT will ensure that all the requirements of
the NBIS are met.
The bridge inspection program can save lives, minimize disruptions of vital services,
and prevent bigger problems before they develop.
Contact your State DOT for a detailed explanation of the bridge inspection
program in your state
and your responsibilities as a bridge owner.