Il 171 SB First Av over I- 55 Stevenson
Cook County, Illinois · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Il 171 SB First Av over I- 55 Stevenson in Cook County, Illinois, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 2015, making it 10 years old at the 2025 inventory.
- It carries about 39,600 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 472 of the 1,722 inventoried bridges in Cook County rated good (27.4%); 246 (14.3%) 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 November 2023, on a 24-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (41.79337, -87.82081)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Continuous steel stringer or multi-beam girder |
| Length | about 258 ft |
| Location | 1.4M SW of Il43 |
| NBI structure number | 016151000000000 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | November 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
Busiest bridges in Cook County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I- 90 94 Dan Ryan over Sanitary Sewer | 1961 | 312,400 | Fair |
| I- 80 94 Kingery over Bikeway Ave (RR Ave) | 2004 | 254,100 | Fair |
| I- 90 94 Ryan Elev over 15TH to 16TH Sts | 1962 | 247,500 | Fair |
| I- 90 94 Ryan Elev over 16TH to 18TH Sts | 1962 | 247,500 | Fair |
| I- 90 94 Ryan Elev over Canal to Stewart Sts | 1962 | 245,500 | Poor |
| I- 90 94 Elev Exp over Stewart Ave to 28 Pl | 1962 | 245,500 | Fair |
All bridges nearby: Cook County, IL bridge conditions · every bridge in Cook County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.