ILL 15
Carrying ILL 15 over HARDING DITCH
0.3 M W JCT 157, St. Clair, Illinois
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: ILL 15
The ILL 15 bridge in St. Clair, Illinois carries ILL 15 over HARDING DITCH. It was built in 1940, making it 86 years old today. It was last reconstructed in 1984, extending its service life. The structure is built primarily of steel continuous and spans 3 sections, stretching 47.9 meters (157 feet) end to end. Daily traffic averages 30,000 vehicles, placing it in the heavily-trafficked tier of Illinois bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 8/9, superstructure at 7/9, substructure at 6/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range. Its NBI inventory load rating is 32.7 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How ILL 15 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 How the historical reference is calculated.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
- 1940
- Last Reconstructed
- 1984
- Material
- Steel Continuous
- Number of Spans
- 3
- Structure Length
- 47.9 m (157 ft)
- Deck Width
- 21.7 m (71 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 30,000 vehicles/day
- Structure Number
- 082003900000000
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) is in good condition (8/9), showing no significant deterioration.
- • The superstructure (beams and supports above the deck) rates good at 7/9, with no significant deterioration on file.
- • At 6/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
How to read this record
This page shows what the last federal inspection recorded, not whether ILL 15 is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare ILL 15 against other structures in St. Clair 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 ILL 15?
ILL 15 in St. Clair, Illinois has a deck rating of 8/9, superstructure rating of 7/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is ILL 15 inspected?
ILL 15'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 30,000 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. ILL 15 is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for ILL 15?
ILL 15 has an NBI inventory load rating of 32.7 metric tons.
Who is responsible for maintaining ILL 15?
ILL 15 is owned and maintained by State Highway Agency.
How old is ILL 15 and does age affect safety?
ILL 15 was built in 1940, making it 86 years old and last reconstructed in 1984.
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.