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399TH Ave. over Sand Ck

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

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

399TH Ave. over Sand Ck in Sanborn 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 substructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1982, making it 43 years old at the 2025 inventory.
It carries about 56 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 29 of the 54 inventoried bridges in Sanborn County rated fair (53.7%); 7 (13.0%) 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	Prestressed concrete tee beam
Length	about 49 ft
Location	2E & 7.2N Woonsocket
NBI structure number	000000056050028
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
SD034 over Drainage Ditch	1936	1,738	Fair
SD034 W over James Rv	2003	1,484	Fair
SD034 E over James Rv	2004	1,484	Fair
SD037 S over Sand Ck	1977	1,354	Good
SD037 N over Sand Ck	1976	1,354	Good
SD037 S over James Rv	2002	1,271	Good