Bridge Inspection Program


Bridge Inspection Overview

The Wyoming Department of Transportation owns and maintains approximately 1960 structures. Each of these, and approximately 840 bridges owned and maintained by the towns, cities, counties, and other state agencies, are inspected at least once every 24 months by teams of certified bridge inspectors.  Bridges having certain levels of deterioration are inspected more frequently.  Bridges requiring specialized access to specific elements, such as nonredundant steel tension members or submerged members, receive special inspections designed to inspect these members.

 

These inspections are completed in accordance with the requirements set forth in the National Bridge Inspection Standards (NBIS). The inspection procedures are based on the codes, instructions, assessment criteria, and reporting requirements of the FHWA Specifications for the National Bridge Inventory, the AASHTO Manual for Bridge Element Inspection, and the AASHTO Manual for Bridge Evaluation.

 

Bridges require periodic maintenance to remain safe and serviceable, and regular inspections help to identify those elements needing repair or replacement. When a condition is found that may affect the ability of the bridge to carry the anticipated loads, a load rating is completed and when necessary, the bridge may be load posted or other restrictions imposed until the condition can be corrected or the bridge is replaced.

 

The inspection results are submitted to the FHWA annually.

The WYDOT Bridge Program ensures certified bridge inspection teams are working hard to ensure your safety on Wyoming’s bridges.

Definitions

●    AASHTO - American Association of State Highway and Transportation Officials

●    Bridge - A structure erected over a depression or an obstruction, such as a waterway, highway or railway, having a passageway for carrying traffic and an opening, measured along the center of the roadway, of more than 20 feet. This may include multiple pipe culvert installations where the clear distance between openings is less than half of the smaller opening.

 ●   Bridge Performance Rating – An overall performance rating based on the minimum component condition rating for the bridge (Deck, Superstructure, Substructure, or Culvert) that is in accordance with the FHWA Specifications for the National Bridge Inventory.

●   Bridges with a Good performance rating have a minimum component condition rating of 9 (Excellent), 8 (Very Good), or 7 (Good). 

●   Bridges with a Fair performance rating have a minimum component condition rating of 5 (Satisfactory) or 6 (Fair). 

●   Bridges with a Poor performance rating have a minimum component condition rating of 4 (Poor), 3 (Serious), 2 (Critical), 1 (Imminent Failure), or 0 (Failed).

●    Certified Inspector – An individual having completed an FHWA-approved comprehensive bridge inspection training with an end-of-course assessment score of 70 percent or greater; has 5 years of bridge inspection experience, or the appropriate combination of education and experience as described in the NBIS; and completes a cumulative total of 18 hours of FHWA-approved bridge inspection refresher training over each 60 month period.

●    Critical Finding - A structural or safety-related condition that requires immediate action to ensure public safety. Critical findings are tied to a structural condition or deficiency affecting the load carrying capacity of the bridge or affecting safety of the traveling public.

●    FHWA – Federal Highway Administration

●    Load Posted or Restricted Bridge - A bridge having maximum weight limitations, lane restrictions, or both

●    Load Rating - A numerical analysis that is based on the structural configuration and condition of the bridge and estimates the weight of a vehicle that can safely cross the bridge without causing damage.

●   Inventory Rating - The weight of a given vehicle that can safely cross the structure on a routine or daily basis.

●   Operating Rating - The maximum weight of a given vehicle that can safely cross the bridge on an occasional basis.

●    National Bridge Inspection Standards (NBIS) - National minimum standards for the proper safety inspection and evaluation of all highway bridges outlined in the Code of Federal Regulations Title 23, Part 650, Subpart C

●    Nonredundant Steel Tension Member (NSTM) - A primary steel member fully or partially in tension, and without load path redundancy, system redundancy, or internal redundancy, whose failure may cause a portion of or the entire bridge to collapse.

●   Load path redundancy - A redundancy that exists when there are more than two  primary load-carrying members between points of support

●   System redundancy - A redundancy that exists in a bridge system without load path redundancy, such that fracture of the cross section at one location of a primary member will not cause a portion of or the entire bridge to collapse

●   Internal redundancy - A redundancy that exists within a primary member cross-section without load path redundancy, such that fracture of one component will not propagate through the entire member

●    Submerged Member – A submerged element of a bridge substructure that cannot be inspected visually at low water by wading or probing.