US Bridges

550th Ave over Keigley Branch

Fair

Story County, Iowa · 085243602 · Structure no. 000000000316480

Built
1913
112 years old
Condition
Fair
inspected November 2022
Type
Culvert
Concrete
Length
47 ft
1 main span
Daily traffic
80
2022 count
Owner
County
County Highway Agency

About this bridge

550th Ave over Keigley Branch is a concrete culvert carrying 550th Ave over Keigley Branch in Story County, Iowa. It was built in 1913, so it is 112 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.

It carries about 80 vehicles a day, projected to reach 80 by 2043. The structure is 47 ft (14.3 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
Carries550th Ave
CrossesKeigley Branch
Location085243602
RouteCounty Highway 0
CountyStory County
StateIowa
Coordinates42.1368, -93.60101
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2022
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating25.1 US tons
Inventory rating15 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadUnknown
Structure length47 ft (14.3 m)
Longest span45 ft (13.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic80 (2022)
Projected traffic80 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 statusListed on the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 550th Ave over Keigley Branch built?

It was built in 1913, making it 112 years old in 2025.

What condition is 550th Ave over Keigley Branch 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 November 2022.

How much traffic does 550th Ave over Keigley Branch carry?

About 80 vehicles per day (2022 count).

How long is 550th Ave over Keigley Branch?

The structure is 47 ft (14.3 m) long with a longest span of 45 ft (13.7 m).

Who owns 550th Ave over Keigley Branch?

It is owned by the County Highway Agency.