Main St over Kishwaukee River
Boone County, Illinois · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Main St over Kishwaukee River in Boone County, Illinois, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1972, making it 53 years old at the 2025 inventory.
- It carries about 4,150 vehicles a day (traffic count year 2018).
- Its listed owner is a city or municipal highway agency.
- It is one of 53 of the 109 inventoried bridges in Boone County rated fair (48.6%); 11 (10.1%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated September 2023, on a 24-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (42.26073, -88.84151)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 5 | 5 | Fair condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 6 | 6 | Satisfactory condition |
Bridge details
| Structure | Continuous steel stringer or multi-beam girder |
| Length | about 232 ft |
| Location | S of Lincoln Ave |
| NBI structure number | 004700200000000 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | September 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Boone County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 90 over Stream | 2014 | 51,100 | Fair |
| I-90 over Stream | 1958 | 28,000 | Good |
| I 90 WB over Mosquito Crk | 2013 | 28,000 | Fair |
| I 90 EB over Mosquito Ckr | 2013 | 28,000 | Good |
| I-90 over Stream | 1958 | 25,700 | Fair |
| I-90 over Stream | 1958 | 25,550 | Good |
All bridges nearby: Boone County, IL bridge conditions · every bridge in Boone County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.