US Bridges

170th ST over Argo Slough

FairPosted for load

Lyon County, Iowa · 99431601 · Structure no. 000000000229631

Built
2017
8 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
32 ft
2 main spans
Daily traffic
11
2022 count
Owner
County
County Highway Agency

About this bridge

170th ST over Argo Slough is a wood or timber stringer/multi-beam or girder carrying 170th ST over Argo Slough in Lyon County, Iowa. It was built in 2017, so it is 8 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 6 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 other load-capacity restriction.

It carries about 11 vehicles a day, projected to reach 11 by 2043. The structure is 32 ft (9.8 m) long and 20 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
Carries170th ST
CrossesArgo Slough
Location99431601
RouteCounty Highway 0
CountyLyon County
StateIowa
Coordinates43.40344, -95.92801
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusPosted for other load-capacity restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating45.1 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans2
Design loadUnknown
Structure length32 ft (9.8 m)
Longest span15 ft (4.6 m)
Deck width20 ft (6.1 m)
Roadway width20 ft (6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11 (2022)
Projected traffic11 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 statusNot eligible for the National Register of Historic Places
Work proposedOther structural work, including hydraulic replacements
Estimated improvement cost$30,000 (2024 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 170th ST over Argo Slough built?

It was built in 2017, making it 8 years old in 2025.

What condition is 170th ST over Argo Slough 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 July 2023.

How much traffic does 170th ST over Argo Slough carry?

About 11 vehicles per day (2022 count).

How long is 170th ST over Argo Slough?

The structure is 32 ft (9.8 m) long with a longest span of 15 ft (4.6 m) and a deck 20 ft wide.

Who owns 170th ST over Argo Slough?

It is owned by the County Highway Agency.