400th Avenue
Carrying 400th Avenue over Mud Creek
4E & 0.9S of Stratford, Brown, South Dakota
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
400th Avenue in Brown, South Dakota sits above 7% of rated South Dakota bridges on inventory load rating (12 t), while its 1956 build year is earlier than 79% of Brown's recorded-year cohort (170 bridges).
400th Avenue in Brown, South Dakota is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1956, 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:000000007240439
INTERSTATE-ERA · CONCRETE · LONG-SPAN-RUN · TIED-CTRL · TRACE-ADT · LIGHT-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- 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: 400th Avenue
The 400th Avenue bridge in Brown, South Dakota carries 400th Avenue over Mud Creek. It was built in 1956, making it 70 years old today. The structure is built primarily of concrete continuous and spans 5 sections, stretching 56.7 meters (186 feet) end to end. Daily traffic averages 46 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 6/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How 400th Avenue compares
Age against the county: built in 1956, earlier than 134 of Brown's 170 bridges with a recorded construction year (79%), against a county median build year of 1989. 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).
400th Avenue vs every rated South Dakota bridge
Inventory load rating (metric tons), FHWA NBI, this state
12 Top 93% higher than 7% 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.
Brown inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 170 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
- 1956
- Material
- Concrete Continuous
- Number of Spans
- 5
- Structure Length
- 56.7 m (186 ft)
- Deck Width
- 8.7 m (29 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 46 vehicles/day
- Structure Number
- 000000007240439
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) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) rates fair at 6/9, minor deterioration that routine maintenance should address.
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 400th Avenue 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 400th Avenue against other structures in Brown 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 400th Avenue?
400th Avenue in Brown, South Dakota has a deck rating of 6/9, superstructure rating of 6/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is 400th Avenue inspected?
400th 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 46 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 400th Avenue 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 400th Avenue?
400th Avenue has an NBI inventory load rating of 11.7 metric tons.
Who is responsible for maintaining 400th Avenue?
400th Avenue is owned and maintained by County Highway Agency.
How old is 400th Avenue and does age affect safety?
400th Avenue was built in 1956, making it 70 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.
Share this inspection record
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.