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Main Boulder Road over Boulder River

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

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

Main Boulder Road over Boulder River in Park 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 1940, making it 85 years old at the 2025 inventory.
It carries about 157 vehicles a day (traffic count year 2023).
Its listed owner is the county highway agency.
It is one of 86 of the 126 inventoried bridges in Park County rated fair (68.3%); 13 (10.3%) 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 35 ft
Location	40M South of Springdale
NBI structure number	000000202208056
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 Int West Livingston	1962	9,461	Fair
I 90 over Int West Livingston	1962	9,461	Fair
I 90 over Int S Livingston-us Hwy	1962	9,461	Fair
I 90 over Quinn Creek Road	2022	8,272	Good
I 90 over Quinn Creek Road	2022	8,272	Good
I 90 over Int Hopper	1978	8,236	Fair