US Bridges

Il 121 (fap 320) over Kaskaskia River

Fair

Moultrie County, Illinois · N of Allenville · Structure no. 070000400000000

Built
1967
58 years old, rebuilt 1999
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
498 ft
6 main spans
Daily traffic
4,250
2023 count
Owner
State
State Highway Agency

About this bridge

Il 121 (fap 320) over Kaskaskia River is a steel continuous stringer/multi-beam or girder carrying Il 121 (fap 320) over Kaskaskia River in Moultrie County, Illinois. It was built in 1967 and reconstructed in 1999, so it is 58 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 6 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 4,250 vehicles a day, roughly 10% of them trucks, projected to reach 4,253 by 2046. The structure is 498 ft (151.9 m) long and 39 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesIl 121 (fap 320)
CrossesKaskaskia River
LocationN of Allenville
RouteState Highway 121
CountyMoultrie County
StateIllinois
Coordinates39.5727, -88.53262
Functional classRural Principal Arterial - Other

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78.6 US tons
Inventory rating47.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadHS 20
Structure length498 ft (151.9 m)
Longest span96 ft (29.4 m)
Deck width39 ft (11.8 m)
Roadway width35 ft (10.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,250 (2023)
Projected traffic4,253 by 2046
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 Il 121 (fap 320) over Kaskaskia River built?

It was built in 1967, making it 58 years old in 2025. It was reconstructed in 1999.

What condition is Il 121 (fap 320) over Kaskaskia 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 November 2024.

How much traffic does Il 121 (fap 320) over Kaskaskia River carry?

About 4,250 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Il 121 (fap 320) over Kaskaskia River?

The structure is 498 ft (151.9 m) long with a longest span of 96 ft (29.4 m) and a deck 39 ft wide.

Who owns Il 121 (fap 320) over Kaskaskia River?

It is owned by the State Highway Agency.