US Bridges

270th ST over Drainage

FairPosted for load

Story County, Iowa · 083233303 · Structure no. 000000000314810

Built
1950
75 years old, rebuilt 1974
Condition
Fair
inspected January 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
25 ft
1 main span
Daily traffic
34
2022 count
Owner
County
County Highway Agency

About this bridge

270th ST over Drainage is a wood or timber stringer/multi-beam or girder carrying 270th ST over Drainage in Story County, Iowa. It was built in 1950 and reconstructed in 1974, so it is 75 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 5 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 34 vehicles a day, projected to reach 34 by 2042. The structure is 25 ft (7.6 m) long and 25 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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Carries270th ST
CrossesDrainage
Location083233303
RouteCounty Highway 0
CountyStory County
StateIowa
Coordinates41.96498, -93.53637
Functional classRural Local

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJanuary 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating30 US tons
Inventory rating20 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 width25 ft (7.5 m)
Roadway width25 ft (7.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic34 (2022)
Projected traffic34 by 2042
Trucks0%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 270th ST over Drainage built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1974.

What condition is 270th ST over Drainage 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 270th ST over Drainage carry?

About 34 vehicles per day (2022 count).

How long is 270th ST over Drainage?

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

Who owns 270th ST over Drainage?

It is owned by the County Highway Agency.