US 20
Carrying US 20 over COON CREEK
2 MI. E. BELVIDERE, Boone, Illinois
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
US 20 in Boone, Illinois sits above 64% of rated Illinois bridges on inventory load rating (34 t), while its 1996 build year is earlier than 37% of Boone's recorded-year cohort (109 bridges).
US 20 in Boone, Illinois is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1996, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 6. The lowest applicable rating sets the federal condition category, so this Fair result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure IL:004001700000000
LATE-CENTURY · PRESTRESS · MULTI-SPAN · TIED-CTRL · ARTERIAL-ADT · STANDARD-LOAD · CAT-FAIR
- LATE-CENTURY 1980–1999
- PRESTRESS Prestressed concrete
- MULTI-SPAN 3 spans
- TIED-CTRL Tied control
- ARTERIAL-ADT Arterial ADT
- STANDARD-LOAD Standard load
- CAT-FAIR Fair
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
Bridge Snapshot: US 20
The US 20 bridge in Boone, Illinois carries US 20 over COON CREEK. It was built in 1996, making it 30 years old today. The structure is built primarily of prestressed concrete continuous and spans 3 sections, stretching 63.7 meters (209 feet) end to end. Daily traffic averages 8,550 vehicles, placing it in the moderately-trafficked tier of Illinois bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 6/9, superstructure at 6/9, substructure at 7/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How US 20 compares
Age against the county: built in 1996, earlier than 40 of Boone's 109 bridges with a recorded construction year (37%), against a county median build year of 1986. This is one of the newer structures in its county.
Live comparison across Illinois bridges with a recorded inventory load rating (26,904 of 26,928 rated).
US 20 vs every rated Illinois bridge
Inventory load rating (metric tons), FHWA NBI, this state
34 Top 36% higher than 64% of 26,904 bridges
rated Illinois bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Reported 0–9 component ratings from the FHWA NBI. The highlighted component is the lowest reported input to this record’s current condition category; it is not a closure or live crossing-safety decision.
Boone inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 109 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
Structural Details
- Year Built
- 1996
- Material
- Prestressed Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 63.7 m (209 ft)
- Deck Width
- 13.2 m (43 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 8,550 vehicles/day
- Structure Number
- 004001700000000
Condition Analysis
- • The deck (driving surface) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The superstructure (beams and supports above the deck) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) rates good at 7/9, with no significant deterioration on file.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
This page shows what the last federal inspection recorded, not whether US 20 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 US 20 against other structures in Boone 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 US 20?
US 20 in Boone, Illinois has a deck rating of 6/9, superstructure rating of 6/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is US 20 inspected?
US 20'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 8,550 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. US 20 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 US 20?
US 20 has an NBI inventory load rating of 33.7 metric tons.
Who is responsible for maintaining US 20?
US 20 is owned and maintained by State Highway Agency.
How old is US 20 and does age affect safety?
US 20 was built in 1996, making it 30 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.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.