US Bridges

US 18 over Old Channel Rock River

Good

Sioux County, Iowa · 0.7 Mi. W of JCT SR K24 · Structure no. 000000000048221

Built
1989
36 years old
Condition
Good
inspected June 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
204 ft
3 main spans
Daily traffic
3,160
2023 count
Owner
State
State Highway Agency

About this bridge

US 18 over Old Channel Rock River is a prestressed concrete stringer/multi-beam or girder carrying US 18 over Old Channel Rock River in Sioux County, Iowa. It was built in 1989, so it is 36 years old, younger than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 3,160 vehicles a day, roughly 19% of them trucks, projected to reach 3,160 by 2043. The structure is 204 ft (62.2 m) long and 43 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

CarriesUS 18
CrossesOld Channel Rock River
Location0.7 Mi. W of JCT SR K24
RouteU.S. Route 18
StateIowa
Coordinates43.19971, -96.34743
Functional classRural Principal Arterial - Other

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating76.3 US tons
Inventory rating41.6 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length204 ft (62.2 m)
Longest span82 ft (25 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,160 (2023)
Projected traffic3,160 by 2043
Trucks19%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 18 over Old Channel Rock River built?

It was built in 1989, making it 36 years old in 2025.

What condition is US 18 over Old Channel Rock River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in June 2024.

How much traffic does US 18 over Old Channel Rock River carry?

About 3,160 vehicles per day (2023 count), of which roughly 19% are trucks.

How long is US 18 over Old Channel Rock River?

The structure is 204 ft (62.2 m) long with a longest span of 82 ft (25 m) and a deck 43 ft wide.

Who owns US 18 over Old Channel Rock River?

It is owned by the State Highway Agency.