US Bridges

County Highway 20 over Spoon River

Fair

Knox County, Illinois · W.CTR-35-T10NR3E · Structure no. 048302200000000

Built
1956
69 years old, rebuilt 1971
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
417 ft
6 main spans
Daily traffic
50
2022 count
Owner
County
County Highway Agency

About this bridge

County Highway 20 over Spoon River is a steel continuous stringer/multi-beam or girder carrying County Highway 20 over Spoon River in Knox County, Illinois. It was built in 1956 and reconstructed in 1971, so it is 69 years old, older than the Illinois average of 45.3 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 50 vehicles a day, roughly 24% of them trucks, projected to reach 126 by 2046. The structure is 417 ft (127.1 m) long and 28 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesCounty Highway 20
CrossesSpoon River
LocationW.CTR-35-T10NR3E
RouteCounty Highway 0
CountyKnox County
StateIllinois
Coordinates40.8078, -90.13428
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.
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 inspectionFebruary 2024
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 geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.3 US tons
Inventory rating35.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadHS 15
Structure length417 ft (127.1 m)
Longest span76 ft (23.2 m)
Deck width28 ft (8.5 m)
Roadway width24 ft (7.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2022)
Projected traffic126 by 2046
Trucks24%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was County Highway 20 over Spoon River built?

It was built in 1956, making it 69 years old in 2025. It was reconstructed in 1971.

What condition is County Highway 20 over Spoon 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 County Highway 20 over Spoon River carry?

About 50 vehicles per day (2022 count), of which roughly 24% are trucks.

How long is County Highway 20 over Spoon River?

The structure is 417 ft (127.1 m) long with a longest span of 76 ft (23.2 m) and a deck 28 ft wide.

Who owns County Highway 20 over Spoon River?

It is owned by the County Highway Agency.