US Bridges

670th Ave over Small Stream

FairPosted for load

Story County, Iowa · 082223602 · Structure no. 000000000313950

Built
1953
72 years old, rebuilt 1975
Condition
Fair
inspected January 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
25 ft
1 main span
Daily traffic
150
2022 count
Owner
County
County Highway Agency

About this bridge

670th Ave over Small Stream is a wood or timber stringer/multi-beam or girder carrying 670th Ave over Small Stream in Story County, Iowa. It was built in 1953 and reconstructed in 1975, so it is 72 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 150 vehicles a day, projected to reach 150 by 2043. The structure is 25 ft (7.6 m) long and 27 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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Carries670th Ave
CrossesSmall Stream
Location082223602
RouteCounty Highway 0
CountyStory County
StateIowa
Coordinates41.87352, -93.36728
Functional classRural Minor Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJanuary 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating39.5 US tons
Inventory rating27.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadUnknown
Structure length25 ft (7.6 m)
Longest span24 ft (7.3 m)
Deck width27 ft (8.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic150 (2022)
Projected traffic150 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 670th Ave over Small Stream built?

It was built in 1953, making it 72 years old in 2025. It was reconstructed in 1975.

What condition is 670th Ave over Small Stream in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in January 2023.

How much traffic does 670th Ave over Small Stream carry?

About 150 vehicles per day (2022 count).

How long is 670th Ave over Small Stream?

The structure is 25 ft (7.6 m) long with a longest span of 24 ft (7.3 m) and a deck 27 ft wide.

Who owns 670th Ave over Small Stream?

It is owned by the County Highway Agency.