TR 320
Carrying TR 320 over MARTINTON DITCH #3
2.5MI E MARTINTON, Iroquois, Illinois
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: TR 320
The TR 320 bridge in Iroquois, Illinois carries TR 320 over MARTINTON DITCH #3. It was built in 1955, making it 71 years old today. The structure is built primarily of steel and spans 1 section, stretching 17.4 meters (57 feet) end to end. Daily traffic averages 25 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 6/9, superstructure at 4/9, substructure at 2/9. The weakest component sits in critical condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How TR 320 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 How the historical reference is calculated.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
- 1955
- Material
- Steel
- Number of Spans
- 1
- Structure Length
- 17.4 m (57 ft)
- Deck Width
- 6.1 m (20 ft)
- Owner
- Town/Township Highway Agency
- Avg Daily Traffic
- 25 vehicles/day
- Structure Number
- 038454500000000
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • At 6/9, the deck (driving surface) shows fair condition, with minor wear flagged for upkeep.
- • The superstructure (beams and supports above the deck) is in poor condition (4/9), showing advanced deterioration that may require priority repair.
- • The substructure (piers and abutments) rates critical at 2/9, severe deterioration that needs urgent attention.
How to read this record
TR 320 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 TR 320 against other structures in Iroquois 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 TR 320?
TR 320 in Iroquois, Illinois has a deck rating of 6/9, superstructure rating of 4/9, and substructure rating of 2/9 on the FHWA's 0–9 scale.
How often is TR 320 inspected?
TR 320'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 25 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. TR 320 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 TR 320?
An inventory load rating is not recorded for TR 320.
Who is responsible for maintaining TR 320?
TR 320 is owned and maintained by Town/Township Highway Agency.
How old is TR 320 and does age affect safety?
TR 320 was built in 1955, making it 71 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.