Ill 15 & 4 over Kaskaskia River
PoorSt. Clair County, Illinois · 0.2 M E JCT Ill 4 · Structure no. 082007700000000
- Built
- 1946
- 79 years old, rebuilt 2013
- Condition
- Poor
- inspected March 2024
- Type
- Truss - Thru
- Steel
- Length
- 912 ft
- 1 main span
- Daily traffic
- 3,600
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Ill 15 & 4 over Kaskaskia River is a steel truss - thru carrying Ill 15 & 4 over Kaskaskia River in St. Clair County, Illinois. It was built in 1946 and reconstructed in 2013, 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
It carries about 3,600 vehicles a day, roughly 15% of them trucks, projected to reach 3,788 by 2046. The structure is 912 ft (278.1 m) long and 34 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 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Superstructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Ill 15 & 4 over Kaskaskia River built?
It was built in 1946, making it 79 years old in 2025. It was reconstructed in 2013.
What condition is Ill 15 & 4 over Kaskaskia River in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in March 2024.
How much traffic does Ill 15 & 4 over Kaskaskia River carry?
About 3,600 vehicles per day (2023 count), of which roughly 15% are trucks.
How long is Ill 15 & 4 over Kaskaskia River?
The structure is 912 ft (278.1 m) long with a longest span of 200 ft (61.1 m) and a deck 34 ft wide.
Who owns Ill 15 & 4 over Kaskaskia River?
It is owned by the State Highway Agency.