Federal law, outlined in the National Bridge Inspection Standards (NBIS), defines a bridge as a structure carrying traffic with a span greater than 20 feet and requires that all bridges be inspected every two years to monitor and report condition ratings. The Ambassador exceeds this standard and conducts an inspection every year. The engineering firm that inspects the Ambassador Bridge has also inspected publicly-owned bridges including the Mackinac Bridge and the Blue Water Bridge.
Condition ratings are based on a 0-9 scale and assigned for each culvert, or the deck, superstructure and substructure of each bridge.
These ratings are recorded 1n the National Bridge Inventory (NBI) database. Condition ratings are an important tool for transportation asset management, as they are used to identify preventative maintenance needs, and to determine rehabilitation an d replacement projects.
Below is a summary of the current Ambassador Bridge condition as reported to the Michigan Department of Transportation (MOOT) in 2020: