Il 31 & 120 over Boone Creek
McHenry County, Illinois · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Il 31 & 120 over Boone Creek in McHenry 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 1990 and reconstructed in 2014, making it 35 years old at the 2025 inventory.
- It carries about 30,300 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 92 of the 227 inventoried bridges in McHenry County rated good (40.5%); 48 (21.1%) 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 June 2024, 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 → (42.34572, -88.26888)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 94 ft |
| Location | 1.6M W of Chapel Hil |
| NBI structure number | 056006000000000 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | June 2024 |
| 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 McHenry County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Il 62 over Fox River | 1988 | 43,100 | Fair |
| Il 31 over RR - UP | 1971 | 34,400 | Fair |
| Algonquin Road over Woods Creek | 2004 | 31,600 | Fair |
| Algonquin Road over Crystal Creek | 2004 | 31,600 | Fair |
| Algonquin Road over Gravel Pit Creek | 2004 | 31,600 | Fair |
| Rakow Rd (ch V-29) over Crystal Creek | 1994 | 30,600 | Good |
All bridges nearby: McHenry County, IL bridge conditions · every bridge in McHenry County · Illinois bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.