I-39 & US 51 SB over Kishwaukee River
FairWinnebago County, Illinois · 0.75 MI S Blkhawk RD · Structure no. 101013300000000
- Built
- 1980
- 45 years old, rebuilt 2008
- Condition
- Fair
- inspected May 2024
- Type
- Segmental Box Girder
- Prestressed Concrete
- Length
- 1,170 ft
- 5 main spans
- Daily traffic
- 14,500
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
I-39 & US 51 SB over Kishwaukee River is a prestressed concrete segmental box girder carrying I-39 & US 51 SB over Kishwaukee River in Winnebago County, Illinois. It was built in 1980 and reconstructed in 2008, so it is 45 years old, younger 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 14,500 vehicles a day, roughly 37% of them trucks, projected to reach 15,958 by 2046. The structure is 1,170 ft (356.6 m) long and 42 ft wide. If it were closed, the detour would be 1.2 mi (2 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 | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was I-39 & US 51 SB over Kishwaukee River built?
It was built in 1980, making it 45 years old in 2025. It was reconstructed in 2008.
What condition is I-39 & US 51 SB over Kishwaukee 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 May 2024.
How much traffic does I-39 & US 51 SB over Kishwaukee River carry?
About 14,500 vehicles per day (2023 count), of which roughly 37% are trucks.
How long is I-39 & US 51 SB over Kishwaukee River?
The structure is 1,170 ft (356.6 m) long with a longest span of 250 ft (76.2 m) and a deck 42 ft wide.
Who owns I-39 & US 51 SB over Kishwaukee River?
It is owned by the State Highway Agency.