US Bridges

170th Lane over Allen Creek

FairPosted for load

Harrison County, Iowa · 080430507 · Structure no. 000000000178730

Built
1969
56 years old, rebuilt 1988
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
33 ft
1 main span
Daily traffic
11
2022 count
Owner
County
County Highway Agency

About this bridge

170th Lane over Allen Creek is a steel stringer/multi-beam or girder carrying 170th Lane over Allen Creek in Harrison County, Iowa. It was built in 1969 and reconstructed in 1988, so it is 56 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. Its operating status is: posted for load restriction.

It carries about 11 vehicles a day, projected to reach 11 by 2044. The structure is 33 ft (10.1 m) long and 21 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
Carries170th Lane
CrossesAllen Creek
Location080430507
RouteCounty Highway 0
CountyHarrison County
StateIowa
Coordinates41.76223, -95.86842
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
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating31.4 US tons
Inventory rating18.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadHS 20
Structure length33 ft (10.1 m)
Longest span31 ft (9.4 m)
Deck width21 ft (6.5 m)
Roadway width21 ft (6.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11 (2022)
Projected traffic11 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 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 170th Lane over Allen Creek built?

It was built in 1969, making it 56 years old in 2025. It was reconstructed in 1988.

What condition is 170th Lane over Allen 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 2024.

How much traffic does 170th Lane over Allen Creek carry?

About 11 vehicles per day (2022 count).

How long is 170th Lane over Allen Creek?

The structure is 33 ft (10.1 m) long with a longest span of 31 ft (9.4 m) and a deck 21 ft wide.

Who owns 170th Lane over Allen Creek?

It is owned by the County Highway Agency.