Flat Iron Road over Mokeler Creek
McHenry County, Illinois · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Flat Iron Road over Mokeler Creek in McHenry County, Illinois, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- It was built in 1950, making it 75 years old at the 2025 inventory.
- It carries about 1,550 vehicles a day (traffic count year 2021).
- Its listed owner is the county highway agency.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (42.40855, -88.64234)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 4 | Poor condition |
| Superstructure | 4 | Poor condition |
| Substructure | 5 | Fair condition |
Bridge details
| Structure | Concrete slab |
| Length | about 33 ft |
| Location | 0.4 Mi. S. Ill 173 |
| NBI structure number | 056301900000000 |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Illinois department of transportation.
All bridges nearby: McHenry County, IL bridge conditions · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.