US Bridges

550th ST over Small Stream

Fair

Buena Vista County, Iowa · 091371201 · Structure no. 000000000604060

Built
1937
88 years old
Condition
Fair
inspected August 2024
Type
Culvert
Concrete Continuous
Length
21 ft
2 main spans
Daily traffic
878
2022 count
Owner
County
County Highway Agency

About this bridge

550th ST over Small Stream is a concrete continuous culvert carrying 550th ST over Small Stream in Buena Vista County, Iowa. It was built in 1937, so it is 88 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 878 vehicles a day, roughly 6% of them trucks, projected to reach 878 by 2044. The structure is 21 ft (6.4 m) long. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
Carries550th ST
CrossesSmall Stream
Location091371201
RouteCounty Highway 0
CountyBuena Vista County
StateIowa
Coordinates42.71983, -95.15965
Functional classRural Major 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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2024
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
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating85.8 US tons
Inventory rating51.4 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadH 20
Structure length21 ft (6.4 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic878 (2022)
Projected traffic878 by 2044
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 550th ST over Small Stream built?

It was built in 1937, making it 88 years old in 2025.

What condition is 550th ST 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 August 2024.

How much traffic does 550th ST over Small Stream carry?

About 878 vehicles per day (2022 count), of which roughly 6% are trucks.

How long is 550th ST over Small Stream?

The structure is 21 ft (6.4 m) long with a longest span of 10 ft (3 m).

Who owns 550th ST over Small Stream?

It is owned by the County Highway Agency.