400TH
Carrying 400TH over CREEK
098150201, Mitchell, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
400TH in Mitchell, Iowa sits above 70% of rated Iowa bridges on inventory load rating (35 t), while its 1978 build year is earlier than 53% of Mitchell's recorded-year cohort (167 bridges).
400TH in Mitchell, Iowa is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1978, 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 IA:000000000247661
INTERSTATE-ERA · PRESTRESS · SINGLE-SPAN · TIED-CTRL · TRACE-ADT · STANDARD-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- PRESTRESS Prestressed concrete
- SINGLE-SPAN Single span
- TIED-CTRL Tied control
- TRACE-ADT Trace ADT
- STANDARD-LOAD Standard 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
The 400TH bridge in Mitchell, Iowa carries 400TH over CREEK. It was built in 1978, making it 48 years old today. The structure is built primarily of prestressed concrete and spans 1 section, stretching 13.1 meters (43 feet) end to end. Daily traffic averages 29 vehicles, placing it in the lower-traffic tier of Iowa 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. No reported major component scores in the Poor range under the current federal condition thresholds.
How 400TH compares
Age against the county: built in 1978, earlier than 89 of Mitchell's 167 bridges with a recorded construction year (53%), against a county median build year of 1979. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Iowa bridges with a recorded inventory load rating (23,718 of 23,719 rated).
400TH vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
35 Top 30% higher than 70% of 23,718 bridges
rated Iowa 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.
Mitchell inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 167 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
- 1978
- Material
- Prestressed Concrete
- Number of Spans
- 1
- Structure Length
- 13.1 m (43 ft)
- Deck Width
- 7.4 m (24 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 29 vehicles/day
- Structure Number
- 000000000247661
Condition Analysis
- • At 7/9, the deck (driving surface) is in good shape and shows no significant wear.
- • The superstructure (beams and supports above the deck) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • The substructure (piers and abutments) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
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 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 against other structures in Mitchell and across Iowa. Iowa 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?
400TH in Mitchell, Iowa 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 400TH inspected?
400TH'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 29 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 400TH 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?
400TH has an NBI inventory load rating of 34.5 metric tons.
Who is responsible for maintaining 400TH?
400TH is owned and maintained by County Highway Agency.
How old is 400TH and does age affect safety?
400TH was built in 1978, making it 48 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.