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Old Boulder Rd over Sep I 90 008

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

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

Old Boulder Rd over Sep I 90 008 in Sweet Grass 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 1981, making it 44 years old at the 2025 inventory.
It carries about 100 vehicles a day (traffic count year 2025).
Its listed owner is the state highway agency.
It is one of 58 of the 94 inventoried bridges in Sweet Grass County rated fair (61.7%); 6 (6.4%) 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 stringer or multi-beam girder
Length	about 285 ft
Location	1M E Big Timber
NBI structure number	L49103000+07001
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
I 90 over Spring Creek	1980	12,306	Fair
I 90 over Work Creek	1972	10,845	Fair
I 90 over Upper Deer Creek	1980	6,153	Fair
I 90 over Upper Deer Creek	1980	6,153	Fair
I 90 over Lower Deer Creek	1980	6,153	Fair
I 90 over Lower Deer Creek	1980	6,153	Good