US Bridges

EB US 20 over Boone River

Fair

Hamilton County, Iowa · 1.2 MI E of E JCT Ia 17 · Structure no. 000000000603340

Built
1974
51 years old
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
325 ft
3 main spans
Daily traffic
5,050
2022 count
Owner
State
State Highway Agency

About this bridge

EB US 20 over Boone River is a steel continuous stringer/multi-beam or girder carrying EB US 20 over Boone River in Hamilton County, Iowa. It was built in 1974, so it is 51 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 5,050 vehicles a day, roughly 26% of them trucks, projected to reach 5,050 by 2044. The structure is 325 ft (99.1 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesEB US 20
CrossesBoone River
Location1.2 MI E of E JCT Ia 17
RouteU.S. Route 20
CountyHamilton County
StateIowa
Coordinates42.449, -93.79236
Functional classUrban Other Principal Arterial

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.
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 protection7 GoodSome minor problems.
Last inspectionFebruary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.2 US tons
Inventory rating30.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length325 ft (99.1 m)
Longest span125 ft (38.1 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,050 (2022)
Projected traffic5,050 by 2044
Trucks26%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 EB US 20 over Boone River built?

It was built in 1974, making it 51 years old in 2025.

What condition is EB US 20 over Boone 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 February 2024.

How much traffic does EB US 20 over Boone River carry?

About 5,050 vehicles per day (2022 count), of which roughly 26% are trucks.

How long is EB US 20 over Boone River?

The structure is 325 ft (99.1 m) long with a longest span of 125 ft (38.1 m) and a deck 43 ft wide.

Who owns EB US 20 over Boone River?

It is owned by the State Highway Agency.