US Bridges

N-70 over Willow Creek

Fair

Guthrie County, Iowa · 081321006 · Structure no. 000000000170091

Built
2004
21 years old
Condition
Fair
inspected November 2023
Type
Slab
Concrete Continuous
Length
125 ft
3 main spans
Daily traffic
428
2022 count
Owner
County
County Highway Agency

About this bridge

N-70 over Willow Creek is a concrete continuous slab carrying N-70 over Willow Creek in Guthrie County, Iowa. It was built in 2004, so it is 21 years old, younger 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 428 vehicles a day, roughly 19% of them trucks, projected to reach 428 by 2043. The structure is 125 ft (38.1 m) long and 33 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesN-70
CrossesWillow Creek
Location081321006
RouteCounty Highway 0
CountyGuthrie County
StateIowa
Coordinates41.84232, -94.56152
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 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 rating97.6 US tons
Inventory rating58.3 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length125 ft (38.1 m)
Longest span49 ft (14.9 m)
Deck width33 ft (10.1 m)
Roadway width31 ft (9.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic428 (2022)
Projected traffic428 by 2043
Trucks19%
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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was N-70 over Willow Creek built?

It was built in 2004, making it 21 years old in 2025.

What condition is N-70 over Willow 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 November 2023.

How much traffic does N-70 over Willow Creek carry?

About 428 vehicles per day (2022 count), of which roughly 19% are trucks.

How long is N-70 over Willow Creek?

The structure is 125 ft (38.1 m) long with a longest span of 49 ft (14.9 m) and a deck 33 ft wide.

Who owns N-70 over Willow Creek?

It is owned by the County Highway Agency.