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S 80 over Boyle-o`hanlon Coulees

Chouteau County, Montana · rated Fair in the 2025 National Bridge Inventory

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

S 80 over Boyle-o`hanlon Coulees in Chouteau County, Montana, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
It was built in 1939, making it 86 years old at the 2025 inventory.
It carries about 479 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 16 of the 43 inventoried bridges in Chouteau County rated fair (37.2%); 2 (4.7%) 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	Timber stringer or multi-beam girder
Length	about 75 ft
Location	6M SE Fort Benton
NBI structure number	P00080008+07611
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US 87 over Abandoned Railroad	1974	1,727	Fair
Irr - US 87 over School Section Coulee	1970	1,694	Good
Irr - US 87 over Big Sandy Creek	1990	1,694	Good
US 87 over Marias River	1988	1,417	Good
S 80-13th St over Missouri River	1962	930	Poor
S 80 over RR	1953	849	Fair