Ill 4 & 15 over Kaskaskia Overflow
FairSt. Clair County, Illinois · 0.4 M E JCT Ill 4 · Structure no. 082007800000000
- Built
- 1946
- 79 years old, rebuilt 1991
- Condition
- Fair
- inspected March 2024
- Type
- Stringer/Multi-beam or Girder
- Steel Continuous
- Length
- 500 ft
- 8 main spans
- Daily traffic
- 3,600
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Ill 4 & 15 over Kaskaskia Overflow is a steel continuous stringer/multi-beam or girder carrying Ill 4 & 15 over Kaskaskia Overflow in St. Clair County, Illinois. It was built in 1946 and reconstructed in 1991, so it is 79 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 3,600 vehicles a day, roughly 15% of them trucks, projected to reach 3,788 by 2046. The structure is 500 ft (152.4 m) long and 35 ft wide. If it were closed, the detour would be 39.1 mi (63 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Ill 4 & 15 over Kaskaskia Overflow built?
It was built in 1946, making it 79 years old in 2025. It was reconstructed in 1991.
What condition is Ill 4 & 15 over Kaskaskia Overflow 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 March 2024.
How much traffic does Ill 4 & 15 over Kaskaskia Overflow carry?
About 3,600 vehicles per day (2023 count), of which roughly 15% are trucks.
How long is Ill 4 & 15 over Kaskaskia Overflow?
The structure is 500 ft (152.4 m) long with a longest span of 69 ft (21 m) and a deck 35 ft wide.
Who owns Ill 4 & 15 over Kaskaskia Overflow?
It is owned by the State Highway Agency.