US Bridges

A18 (140th St) over Big Sioux River

Fair

Lyon County, Iowa · 100493503 · Structure no. 000000000231610

Built
1963
62 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
401 ft
5 main spans
Daily traffic
1,607
2022 count
Owner
County
County Highway Agency

About this bridge

A18 (140th St) over Big Sioux River is a steel continuous stringer/multi-beam or girder carrying A18 (140th St) over Big Sioux River in Lyon County, Iowa. It was built in 1963, so it is 62 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.

It carries about 1,607 vehicles a day, roughly 5% of them trucks, projected to reach 1,607 by 2043. The structure is 401 ft (122.2 m) long and 30 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

Location

Open in Google Maps
CarriesA18 (140th St)
CrossesBig Sioux River
Location100493503
RouteCounty Highway 0
CountyLyon County
StateIowa
Coordinates43.448, -96.60148
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating43.4 US tons
Inventory rating30.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadH 20
Structure length401 ft (122.2 m)
Longest span88 ft (26.8 m)
Deck width30 ft (9.1 m)
Roadway width28 ft (8.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,607 (2022)
Projected traffic1,607 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.2 mi (26 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 A18 (140th St) over Big Sioux River built?

It was built in 1963, making it 62 years old in 2025.

What condition is A18 (140th St) over Big Sioux River 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 A18 (140th St) over Big Sioux River carry?

About 1,607 vehicles per day (2022 count), of which roughly 5% are trucks.

How long is A18 (140th St) over Big Sioux River?

The structure is 401 ft (122.2 m) long with a longest span of 88 ft (26.8 m) and a deck 30 ft wide.

Who owns A18 (140th St) over Big Sioux River?

It is owned by the County Highway Agency.