US Bridges

450th over Small Stream

Fair

Mitchell County, Iowa · 099161201 · Structure no. 000000000248461

Built
1974
51 years old
Condition
Fair
inspected December 2023
Type
Channel Beam
Concrete
Length
31 ft
1 main span
Daily traffic
33
2022 count
Owner
County
County Highway Agency

About this bridge

450th over Small Stream is a concrete channel beam carrying 450th over Small Stream in Mitchell County, Iowa. It was built in 1974, so it is 51 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.

It carries about 33 vehicles a day, projected to reach 33 by 2043. The structure is 31 ft (9.4 m) long and 26 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
Carries450th
CrossesSmall Stream
Location099161201
RouteCounty Highway 0
CountyMitchell County
StateIowa
Coordinates43.41491, -92.69036
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 protection7 GoodSome minor problems.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48 US tons
Inventory rating29 US tons

Structure

Structure typeChannel Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length31 ft (9.4 m)
Longest span30 ft (9.1 m)
Deck width26 ft (7.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic33 (2022)
Projected traffic33 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-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 450th over Small Stream built?

It was built in 1974, making it 51 years old in 2025.

What condition is 450th 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 December 2023.

How much traffic does 450th over Small Stream carry?

About 33 vehicles per day (2022 count).

How long is 450th over Small Stream?

The structure is 31 ft (9.4 m) long with a longest span of 30 ft (9.1 m) and a deck 26 ft wide.

Who owns 450th over Small Stream?

It is owned by the County Highway Agency.