US Bridges

NW 121st ST over Beaver Creek

Fair

Polk County, Iowa · 080251708 · Structure no. 000000000282161

Built
1972
53 years old
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
247 ft
3 main spans
Daily traffic
1,524
2022 count
Owner
County
County Highway Agency

About this bridge

NW 121st ST over Beaver Creek is a prestressed concrete continuous stringer/multi-beam or girder carrying NW 121st ST over Beaver Creek in Polk County, Iowa. It was built in 1972, so it is 53 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 1,524 vehicles a day, roughly 3% of them trucks, projected to reach 1,524 by 2043. The structure is 247 ft (75.3 m) long and 32 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesNW 121st ST
CrossesBeaver Creek
Location080251708
RouteCounty Highway 0
CountyPolk County
StateIowa
Coordinates41.73909, -93.78512
Functional classUrban 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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no 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 alignment8: Equal to present desirable criteria
Operating rating50.8 US tons
Inventory rating30.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length247 ft (75.3 m)
Longest span82 ft (25 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,524 (2022)
Projected traffic1,524 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was NW 121st ST over Beaver Creek built?

It was built in 1972, making it 53 years old in 2025.

What condition is NW 121st ST over Beaver Creek 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 March 2023.

How much traffic does NW 121st ST over Beaver Creek carry?

About 1,524 vehicles per day (2022 count), of which roughly 3% are trucks.

How long is NW 121st ST over Beaver Creek?

The structure is 247 ft (75.3 m) long with a longest span of 82 ft (25 m) and a deck 32 ft wide.

Who owns NW 121st ST over Beaver Creek?

It is owned by the County Highway Agency.