Ill 166 over Stream
Williamson County, Illinois · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Ill 166 over Stream in Williamson County, Illinois, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1934, making it 91 years old at the 2025 inventory.
- It carries about 3,000 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 60 of the 200 inventoried bridges in Williamson County rated fair (30.0%); 7 (3.5%) are rated poor.
- 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 → (37.68944, -88.85561)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Culvert | 6 | Satisfactory condition |
Bridge details
| Structure | Continuous concrete culvert |
| Length | about 32 ft |
| Location | 2.7 Mi So of Ill 13 |
| NBI structure number | 100200800000000 |
| Condition class | Fair |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Williamson County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| WB Il 13 over BNSF RR | 2015 | 26,300 | Good |
| EB Il 13 over BNSF RR | 2014 | 26,300 | Fair |
| WB Il 13 over Marathon Dr | 2015 | 26,300 | Good |
| EB Il 13 over Marathon Dr | 2014 | 26,300 | Good |
| Ill 13 over Stream | 1959 | 26,300 | Good |
| Ill 13 EB over Craborchard Lake | 1964 | 25,600 | Poor |
All bridges nearby: Williamson County, IL bridge conditions · every bridge in Williamson County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.