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170TH Lane over Allen Creek

Harrison County, Iowa · rated Fair in the 2025 National Bridge Inventory

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

170TH Lane over Allen Creek in Harrison County, Iowa, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
It was built in 1969 and reconstructed in 1988, making it 56 years old at the 2025 inventory.
It carries about 11 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 120 of the 222 inventoried bridges in Harrison County rated fair (54.1%); 41 (18.5%) 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	Steel stringer or multi-beam girder
Length	about 33 ft
Location	080430507
NBI structure number	000000000178730
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US 30 over Willow Creek	1972	10,300	Fair
US 30 over UPRR	1998	10,300	Good
NB I-29 over Boyer River	1958	10,050	Fair
SB I-29 over Boyer River	1958	10,050	Fair
SB I-29 over over UP RR	1967	7,750	Fair
NB I-29 over Allen Creek	1967	7,750	Fair