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Big Sioux River Rd over Big Sioux River

Plymouth County, Iowa · rated Fair in the 2025 National Bridge Inventory

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

Big Sioux River Rd over Big Sioux River in Plymouth County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1996, making it 29 years old at the 2025 inventory.
It carries about 1,121 vehicles a day (traffic count year 2022).
It is one of 107 of the 430 inventoried bridges in Plymouth County rated fair (24.9%); 90 (20.9%) 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 489 ft
Location	0.5 Mi. N of Jct. Ia 12
NBI structure number	000000000603911
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US 75 over Stream	1999	18,200	Fair
US 75 over Stream	2019	14,900	Good
US 75 over Stream	2019	14,900	Good
US 75 over Stream	2019	14,900	Good
US 75 over Stream	2019	14,900	Good
US 75 over Stream	1926	14,000	Poor