IA 1 NB
Carrying IA 1 NB over IOWA RIVER
079061000, Johnson, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
IA 1 NB in Johnson, Iowa sits above 79% of rated Iowa bridges on inventory load rating (39 t), while its 1915 build year is earlier than 94% of Johnson's recorded-year cohort (372 bridges).
IA 1 NB in Johnson, Iowa is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1915, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 4. The lowest applicable rating sets the federal condition category, so this Poor 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:000000000031720
PRE-1950 · CONCRETE · MULTI-SPAN · TIED-CTRL · HEAVY-ADT · STANDARD-LOAD · CAT-POOR
- PRE-1950 Pre-1950
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- TIED-CTRL Tied control
- HEAVY-ADT Heavy ADT
- STANDARD-LOAD Standard load
- CAT-POOR Poor
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: IA 1 NB
The IA 1 NB bridge in Johnson, Iowa carries IA 1 NB over IOWA RIVER. It was built in 1915, making it 111 years old today. It was last reconstructed in 1986, extending its service life. The structure is built primarily of concrete continuous and spans 3 sections, stretching 104.2 meters (342 feet) end to end. Daily traffic averages 10,950 vehicles, placing it in the heavily-trafficked tier of Iowa bridges. It is owned and maintained by City/Municipal Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 4/9, substructure at 4/9. 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.
How IA 1 NB compares
Age against the county: built in 1915, earlier than 349 of Johnson's 372 bridges with a recorded construction year (94%), 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).
IA 1 NB vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
39 Top 21% higher than 79% 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.
Johnson inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 372 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
- 1915
- Last Reconstructed
- 1986
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 104.2 m (342 ft)
- Deck Width
- 15.1 m (50 ft)
- Owner
- City/Municipal Highway Agency
- Avg Daily Traffic
- 10,950 vehicles/day
- Structure Number
- 000000000031720
Condition Analysis
- • At 5/9, the deck (driving surface) shows fair condition, with minor wear flagged for upkeep.
- • At 4/9, the superstructure (beams and supports above the deck) is in poor shape, with advanced wear on file for this vintage.
- • The substructure (piers and abutments) rates poor at 4/9, with advanced deterioration recorded on the latest inspection.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
IA 1 NB 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 IA 1 NB 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 IA 1 NB?
IA 1 NB in Johnson, Iowa has a deck rating of 5/9, superstructure rating of 4/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is IA 1 NB inspected?
IA 1 NB'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 10,950 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. IA 1 NB 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 IA 1 NB?
IA 1 NB has an NBI inventory load rating of 38.5 metric tons.
Who is responsible for maintaining IA 1 NB?
IA 1 NB is owned and maintained by City/Municipal Highway Agency.
How old is IA 1 NB and does age affect safety?
IA 1 NB was built in 1915, making it 111 years old and last reconstructed in 1986.
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.