29210 421st Avenue
Carrying 29210 421st Avenue over Dawson Creek
3W & 0.1S of Scotland, Bon Homme, South Dakota
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: 29210 421st Avenue
The 29210 421st Avenue bridge in Bon Homme, South Dakota carries 29210 421st Avenue over Dawson Creek. It was built in 1925, making it 101 years old today. It was last reconstructed in 1972, extending its service life. The structure is built primarily of steel and spans 1 section, stretching 9.8 meters (32 feet) end to end. Daily traffic averages 56 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 6/9, substructure at 3/9. 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 15.4 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How 29210 421st 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 How the historical reference is calculated.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
- 1925
- Last Reconstructed
- 1972
- Material
- Steel
- Number of Spans
- 1
- Structure Length
- 9.8 m (32 ft)
- Deck Width
- 8.5 m (28 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 56 vehicles/day
- Structure Number
- 000000005200011
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) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • At 3/9, the substructure (piers and abutments) is in poor shape, with advanced wear flagged for priority repair.
How to read this record
29210 421st 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 29210 421st Avenue against other structures in Bon Homme 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 29210 421st Avenue?
29210 421st Avenue in Bon Homme, South Dakota has a deck rating of 6/9, superstructure rating of 6/9, and substructure rating of 3/9 on the FHWA's 0–9 scale.
How often is 29210 421st Avenue inspected?
29210 421st 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 56 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 29210 421st 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 29210 421st Avenue?
29210 421st Avenue has an NBI inventory load rating of 15.4 metric tons.
Who is responsible for maintaining 29210 421st Avenue?
29210 421st Avenue is owned and maintained by County Highway Agency.
How old is 29210 421st Avenue and does age affect safety?
29210 421st Avenue was built in 1925, making it 101 years old and last reconstructed in 1972.
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.