320 AVENUE
Carrying 320 AVENUE over CK
16E & 10.2S ONIDA, Sully, South Dakota
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: 320 AVENUE
The 320 AVENUE bridge in Sully, South Dakota carries 320 AVENUE over CK. It was built in 1961, making it 65 years old today. The structure is built primarily of concrete and spans 1 section, stretching 7.6 meters (25 feet) end to end. Daily traffic averages 25 vehicles, placing it in the lower-traffic tier of South Dakota bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 6/9, superstructure at 4/9, substructure at 5/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules. Its NBI inventory load rating is 24.5 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How 320 AVENUE compares
Live comparison across South Dakota.
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 How the historical reference is calculated.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
- 1961
- Material
- Concrete
- Number of Spans
- 1
- Structure Length
- 7.6 m (25 ft)
- Deck Width
- 8.7 m (29 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 25 vehicles/day
- Structure Number
- 000000060470231
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗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) rates poor at 4/9, advanced deterioration that should be prioritized for repair.
- • At 5/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
How to read this record
320 AVENUE 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 320 AVENUE against other structures in Sully and across South Dakota. South Dakota 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 320 AVENUE?
320 AVENUE in Sully, South Dakota has a deck rating of 6/9, superstructure rating of 4/9, and substructure rating of 5/9 on the FHWA's 0–9 scale.
How often is 320 AVENUE inspected?
320 AVENUE'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. 320 AVENUE 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 320 AVENUE?
320 AVENUE has an NBI inventory load rating of 24.5 metric tons.
Who is responsible for maintaining 320 AVENUE?
320 AVENUE is owned and maintained by County Highway Agency.
How old is 320 AVENUE and does age affect safety?
320 AVENUE was built in 1961, making it 65 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.