SW 400TH ST
Carrying SW 400TH ST over OLD MANS CREEK
079082301, Johnson, Iowa
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: SW 400TH ST
The SW 400TH ST bridge in Johnson, Iowa carries SW 400TH ST over OLD MANS CREEK. It was built in 1975, making it 51 years old today. The structure is built primarily of concrete continuous and spans 3 sections, stretching 39.0 meters (128 feet) end to end. Daily traffic averages 51 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 6/9, superstructure at 6/9, substructure at 7/9. The weakest component sits in fair condition. All reported major components score above the Poor range. Its NBI inventory load rating is 32.2 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How SW 400TH ST compares
Live comparison across Iowa.
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 How the historical reference is calculated.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
- 1975
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 39.0 m (128 ft)
- Deck Width
- 8.1 m (27 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 51 vehicles/day
- Structure Number
- 000000000204441
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 fair at 6/9, minor deterioration that routine maintenance should address.
- • At 7/9, the substructure (piers and abutments) is in good shape and shows no significant wear.
How to read this record
This page shows what the last federal inspection recorded, not whether SW 400TH ST 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 SW 400TH ST against other structures in Johnson 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 SW 400TH ST?
SW 400TH ST in Johnson, Iowa has a deck rating of 6/9, superstructure rating of 6/9, and substructure rating of 7/9 on the FHWA's 0–9 scale.
How often is SW 400TH ST inspected?
SW 400TH ST'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 51 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. SW 400TH ST 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 SW 400TH ST?
SW 400TH ST has an NBI inventory load rating of 32.2 metric tons.
Who is responsible for maintaining SW 400TH ST?
SW 400TH ST is owned and maintained by County Highway Agency.
How old is SW 400TH ST and does age affect safety?
SW 400TH ST was built in 1975, making it 51 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.