IRR COUNTY ROAD
Carrying IRR COUNTY ROAD over FLINT ROCK CK
5.5 N & 8.5 W RED EL, Ziebach, South Dakota
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
IRR COUNTY ROAD in Ziebach, South Dakota sits above 15% of rated South Dakota bridges on inventory load rating (18 t), while its 1945 build year is earlier than 87% of Ziebach's recorded-year cohort (30 bridges).
IRR COUNTY ROAD in Ziebach, South Dakota is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1945, 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 SD:000000069030234
PRE-1950 · STEEL · LONG-SPAN-RUN · TIED-CTRL · TRACE-ADT · LIGHT-LOAD · CAT-FAIR
- PRE-1950 Pre-1950
- STEEL Steel
- LONG-SPAN-RUN 5 spans
- TIED-CTRL Tied control
- TRACE-ADT Trace ADT
- LIGHT-LOAD Light 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: IRR COUNTY ROAD
The IRR COUNTY ROAD bridge in Ziebach, South Dakota carries IRR COUNTY ROAD over FLINT ROCK CK. It was built in 1945, making it 81 years old today. The structure is built primarily of steel and spans 5 sections, stretching 41.5 meters (136 feet) end to end. Daily traffic averages 16 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 7/9, superstructure at 6/9, substructure at 6/9. The weakest component sits in fair condition. All reported major components score above the Poor range.
How IRR COUNTY ROAD compares
Age against the county: built in 1945, earlier than 26 of Ziebach's 30 bridges with a recorded construction year (87%), against a county median build year of 1969. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across South Dakota bridges with a recorded inventory load rating (5,886 of 5,887 rated).
IRR COUNTY ROAD vs every rated South Dakota bridge
Inventory load rating (metric tons), FHWA NBI, this state
18 Top 85% higher than 15% of 5,886 bridges
rated South Dakota 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.
Ziebach inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 30 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
- 1945
- Material
- Steel
- Number of Spans
- 5
- Structure Length
- 41.5 m (136 ft)
- Deck Width
- 6.7 m (22 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 16 vehicles/day
- Structure Number
- 000000069030234
Condition Analysis
- • The deck (driving surface) is in good condition (7/9), showing no significant deterioration.
- • The superstructure (beams and supports above the deck) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • At 6/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
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 IRR COUNTY ROAD 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 IRR COUNTY ROAD against other structures in Ziebach 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 IRR COUNTY ROAD?
IRR COUNTY ROAD in Ziebach, South Dakota has a deck rating of 7/9, superstructure rating of 6/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is IRR COUNTY ROAD inspected?
IRR COUNTY ROAD'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 16 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. IRR COUNTY ROAD 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 IRR COUNTY ROAD?
IRR COUNTY ROAD has an NBI inventory load rating of 18.4 metric tons.
Who is responsible for maintaining IRR COUNTY ROAD?
IRR COUNTY ROAD is owned and maintained by County Highway Agency.
How old is IRR COUNTY ROAD and does age affect safety?
IRR COUNTY ROAD was built in 1945, making it 81 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.
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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.