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SD029 P over I029

Union County, South Dakota · rated Fair in the 2025 National Bridge Inventory

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

SD029 P over I029 in Union County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1961, making it 64 years old at the 2025 inventory.
It carries about 3,276 vehicles a day (traffic count year 2024).
Its listed owner is the state highway agency.
It is one of 77 of the 169 inventoried bridges in Union County rated fair (45.6%); 41 (24.3%) 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	Continuous concrete multiple box beam
Length	about 293 ft
Location	1.9 N of N Sioux City Int
NBI structure number	000000064149367
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
I029 S over Big Sioux Rv	1990	18,090	Good
I029 N over Big Sioux Rv	1963	18,090	Fair
I029 over Ck	1961	11,970	Good
I029 over Ck	1961	11,970	Good
I029 over Ck	1961	11,970	Good
I029 S over River Drive	1981	9,870	Good