IA 12
Carrying IA 12 over DRAINAGE DITCH
2.0 mi. S of S jct SR K18, Plymouth, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
IA 12 in Plymouth, Iowa sits above 14% of rated Iowa bridges on inventory load rating (17 t), while its 1957 build year is earlier than 71% of Plymouth's recorded-year cohort (432 bridges).
IA 12 in Plymouth, Iowa is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1957, it carries 1 rated component 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:000000000039910
INTERSTATE-ERA · CONCRETE · MULTI-SPAN · CULVERT-LED · ARTERIAL-ADT · LIGHT-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- MULTI-SPAN 2 spans
- CULVERT-LED Culvert-led
- ARTERIAL-ADT Arterial 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: IA 12
The IA 12 bridge in Plymouth, Iowa carries IA 12 over DRAINAGE DITCH. It was built in 1957, making it 69 years old today. The structure is built primarily of concrete continuous and spans 2 sections, stretching 8.8 meters (29 feet) end to end. Daily traffic averages 1,840 vehicles, placing it in the moderately-trafficked tier of Iowa bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show culvert 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 IA 12 compares
Age against the county: built in 1957, earlier than 308 of Plymouth's 432 bridges with a recorded construction year (71%), against a county median build year of 1977. 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 12 vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
17 Top 86% higher than 14% 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.
Plymouth inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 432 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
- 1957
- Material
- Concrete Continuous
- Number of Spans
- 2
- Structure Length
- 8.8 m (29 ft) 0
- Owner
- State Highway Agency
- Avg Daily Traffic
- 1,840 vehicles/day
- Structure Number
- 000000000039910
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 IA 12 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 IA 12 against other structures in Plymouth 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 12?
IA 12 in Plymouth, Iowa on the FHWA's 0–9 scale.
How often is IA 12 inspected?
IA 12'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 1,840 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. IA 12 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 IA 12?
IA 12 has an NBI inventory load rating of 17.2 metric tons.
Who is responsible for maintaining IA 12?
IA 12 is owned and maintained by State Highway Agency.
How old is IA 12 and does age affect safety?
IA 12 was built in 1957, making it 69 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.