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564TH Ave over Walnut Creek

Story County, Iowa · rated Good in the 2025 National Bridge Inventory

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

564TH Ave over Walnut Creek in Story County, Iowa, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the culvert, rated 7 (good condition) on the 0-9 scale.
It was built in 1995, making it 30 years old at the 2025 inventory.
It carries about 71 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 102 of the 302 inventoried bridges in Story County rated good (33.8%); 40 (13.2%) are rated poor.
Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
Its condition class and component ratings are unchanged from the 2024 inventory.
Its most recent inspection on record is dated January 2023, on a 24-month routine inspection cycle.
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

Component	Rating (2024)	Rating (2025)	FHWA scale meaning
Culvert	7	7	Good condition


Structure	Continuous concrete culvert
Length	about 25 ft
Location	082230606
NBI structure number	000000000314021
Condition class	Good
Traffic status (item 41)	Open, no restriction
Last inspection (item 90)	January 2023
Inspection interval (item 91)	24 months
Scour (item 113)	8: foundations stable, scour above the top of the footing

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

Bridge	Built	Vehicles/day	Condition
I-35 over Ballard Creek	1964	48,300	Fair
I-35 over Walnut Creek	1964	48,300	Fair
I 35 over South Skunk Rvr Overflow	2017	48,300	Good
I-35 over Drainage Ditch	1967	28,300	Good
US 69 over Ioway Creek	1924	24,600	Good
NB I-35 over Bike Path	1964	24,150	Fair