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478TH Avenue over Big Sioux River

Moody County, South Dakota · rated Good in the 2025 National Bridge Inventory

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

478TH Avenue over Big Sioux River in Moody County, South Dakota, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
It was built in 1994, making it 31 years old at the 2025 inventory.
It carries about 430 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 28 of the 88 inventoried bridges in Moody County rated good (31.8%); 18 (20.5%) are rated poor.
A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.

Component ratings


Structure	Continuous prestressed concrete stringer or multi-beam girder
Length	about 259 ft
Location	1S of Egan
NBI structure number	000000051120144
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
I029 S over 243 St	1963	10,190	Fair
I029 N over 243 St	1963	10,190	Fair
I029 S over 238 St	1963	10,030	Fair
I029 S over Bachelor Ck	1964	10,030	Fair
I029 N over 238 St	1963	10,030	Fair
I029 N over Bachelor Ck	1964	10,030	Fair