4TH ST
Carrying 4TH ST over POPE CREEK
IN KEITHSBURG, Mercer, Illinois
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: 4TH ST
The 4TH ST bridge in Mercer, Illinois carries 4TH ST over POPE CREEK. It was built in 1989, making it 37 years old today. The structure is built primarily of steel continuous and spans 3 sections, stretching 44.5 meters (146 feet) end to end. Daily traffic averages 800 vehicles, placing it in the lower-traffic tier of Illinois bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 6/9, substructure at 7/9. The weakest component sits in fair condition. No reported major component scores in the Poor range under the current federal condition thresholds. Its NBI inventory load rating is 36.9 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How 4TH ST 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 How the historical reference is calculated.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
- 1989
- Material
- Steel Continuous
- Number of Spans
- 3
- Structure Length
- 44.5 m (146 ft)
- Deck Width
- 10.5 m (34 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 800 vehicles/day
- Structure Number
- 066001400000000
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) rates fair at 5/9, minor deterioration that routine maintenance should address.
- • The superstructure (beams and supports above the deck) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • The substructure (piers and abutments) rates good at 7/9, with no significant deterioration on file.
How to read this record
This page shows what the last federal inspection recorded, not whether 4TH ST 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 4TH ST against other structures in Mercer 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 4TH ST?
4TH ST in Mercer, Illinois has a deck rating of 5/9, superstructure rating of 6/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is 4TH ST inspected?
4TH ST'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 800 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 4TH ST 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 4TH ST?
4TH ST has an NBI inventory load rating of 36.9 metric tons.
Who is responsible for maintaining 4TH ST?
4TH ST is owned and maintained by State Highway Agency.
How old is 4TH ST and does age affect safety?
4TH ST was built in 1989, making it 37 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.