THORNE RD
Carrying THORNE RD over KISHWAUKEE RIV
3.0 MI W OF MARENGO, McHenry, Illinois
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: THORNE RD
The THORNE RD bridge in McHenry, Illinois carries THORNE RD over KISHWAUKEE RIV. It was built in 1992, making it 34 years old today. The structure is built primarily of prestressed concrete and spans 4 sections, stretching 65.9 meters (216 feet) end to end. Daily traffic averages 275 vehicles, placing it in the lower-traffic tier of Illinois bridges. It is owned and maintained by Town/Township Highway Agency.
The latest FHWA inspection records show a deck rating of 4/9, superstructure at 4/9, substructure at 7/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules. Its NBI inventory load rating is 19.8 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How THORNE RD compares
Live comparison across Illinois.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1992
- Material
- Prestressed Concrete
- Number of Spans
- 4
- Structure Length
- 65.9 m (216 ft)
- Deck Width
- 8.5 m (28 ft)
- Owner
- Town/Township Highway Agency
- Avg Daily Traffic
- 275 vehicles/day
- Structure Number
- 056315100000000
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) is in poor condition (4/9), showing advanced deterioration that may require priority repair.
- • At 4/9, the superstructure (beams and supports above the deck) is in poor shape, with advanced wear flagged for priority repair.
- • The substructure (piers and abutments) rates good at 7/9, with no significant deterioration on file.
How to read this record
THORNE RD is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare THORNE RD against other structures in McHenry and across Illinois. Illinois bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for THORNE RD?
THORNE RD in McHenry, Illinois has a deck rating of 4/9, superstructure rating of 4/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is THORNE RD inspected?
THORNE RD's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 275 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. THORNE RD is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for THORNE RD?
THORNE RD has an NBI inventory load rating of 19.8 metric tons.
Who is responsible for maintaining THORNE RD?
THORNE RD is owned and maintained by Town/Township Highway Agency.
How old is THORNE RD and does age affect safety?
THORNE RD was built in 1992, making it 34 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.