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Irr US012 over Missouri Rv (oahe Lk)

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

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

Irr US012 over Missouri Rv (oahe Lk) in Walworth 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 5 (fair condition) on the 0-9 scale.
It was built in 1959 and reconstructed in 1980, making it 66 years old at the 2025 inventory.
It carries about 2,071 vehicles a day (traffic count year 2024).
Its listed owner is the state highway agency.
It is one of 21 of the 33 inventoried bridges in Walworth County rated fair (63.6%); 1 (3.0%) 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 steel through truss
Length	about 5,058 ft
Location	Corson - Walworth Co Ln
NBI structure number	000000065000020
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US012 over Burlington Northern RR	1969	2,111	Good
US012 over Ck	1969	2,111	Good
Irr Ar US012 over Burlington Northern RR	1957	2,071	Fair
US012 over Blue Blanket Ck	1964	1,963	Fair
US012 over Ck	1965	1,544	Fair
US012 Wf over Ck	1965	1,374	Fair