US 150
Carrying US 150 over SPOON RIVER
4 MI W OF ILL 180, Knox, Illinois
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: US 150
The US 150 bridge in Knox, Illinois carries US 150 over SPOON RIVER. It was built in 1930, making it 96 years old today. It was last reconstructed in 1980, extending its service life. The structure is built primarily of prestressed concrete continuous and spans 11 sections, stretching 181.1 meters (594 feet) end to end. Daily traffic averages 1,100 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 3/9, superstructure at 3/9, substructure at 4/9. The weakest component sits in poor condition. Because at least one major component scores 4 or lower, this bridge falls in FHWA's Poor condition category. That category is not a closure order. Its NBI inventory load rating is 32.4 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How US 150 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 How the historical reference is calculated.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
- 1930
- Last Reconstructed
- 1980
- Material
- Prestressed Concrete Continuous
- Number of Spans
- 11
- Structure Length
- 181.1 m (594 ft)
- Deck Width
- 9.8 m (32 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 1,100 vehicles/day
- Structure Number
- 048003100000000
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • At 3/9, the deck (driving surface) is in poor shape, with advanced wear flagged for priority repair.
- • At 3/9, 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 poor at 4/9, advanced deterioration that should be prioritized for repair.
How to read this record
US 150 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 US 150 against other structures in Knox 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 150?
US 150 in Knox, Illinois has a deck rating of 3/9, superstructure rating of 3/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is US 150 inspected?
US 150'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 1,100 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. US 150 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 US 150?
US 150 has an NBI inventory load rating of 32.4 metric tons.
Who is responsible for maintaining US 150?
US 150 is owned and maintained by State Highway Agency.
How old is US 150 and does age affect safety?
US 150 was built in 1930, making it 96 years old and last reconstructed in 1980.
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.