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M-81 over N Branch Cass River

Tuscola County, Michigan · rated Fair in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

M-81 over N Branch Cass River in Tuscola County, Michigan, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1977, making it 48 years old at the 2025 inventory.
It carries about 2,500 vehicles a day (traffic count year 2010).
Its listed owner is the state highway agency.
It is one of 149 of the 241 inventoried bridges in Tuscola County rated fair (61.8%); 10 (4.1%) are rated poor.
A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

Component ratings


Structure	Prestressed concrete multiple box beam
Length	about 74 ft
Location	1.1 Mi W of Sanilac Col
NBI structure number	000000000010436
Condition class	Fair

Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.

Bridge	Built	Vehicles/day	Condition
M-15 over Cass River	2015	14,550	Good
M-46 over Cheboygan & Branches Drn	1939	6,701	Poor
M-81 over Marsh Drain	2007	6,273	Good
M-25 over Quanicassee River	2013	5,571	Good
M-25 over (no Name) Drain	1932	5,571	Fair
M-25 over Wisner Drain	1985	5,571	Fair