18TH ST SW
Carrying 18TH ST SW over DRAINAGE DITCH
000000000, Linn, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
18TH ST SW in Linn, Iowa sits above 27% of rated Iowa bridges on inventory load rating (23 t), while its 1978 build year is earlier than 71% of Linn's recorded-year cohort (506 bridges).
18TH ST SW in Linn, Iowa is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1978, it carries 1 rated component 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:000000000001450
INTERSTATE-ERA · STEEL · MULTI-SPAN · CULVERT-LED · ARTERIAL-ADT · STANDARD-LOAD · CAT-POOR
- INTERSTATE-ERA 1950–1979
- STEEL Steel
- MULTI-SPAN 2 spans
- CULVERT-LED Culvert-led
- ARTERIAL-ADT Arterial 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: 18TH ST SW
The 18TH ST SW bridge in Linn, Iowa carries 18TH ST SW over DRAINAGE DITCH. It was built in 1978, making it 48 years old today. The structure is built primarily of steel and spans 2 sections, stretching 10.7 meters (35 feet) end to end. Daily traffic averages 1,494 vehicles, placing it in the moderately-trafficked tier of Iowa bridges. It is owned and maintained by City/Municipal Highway Agency.
The latest FHWA inspection records show culvert at 4/9. The weakest component sits in poor condition. Because at least one major component scores 4 or lower, this bridge falls in FHWA's Poor condition category. That category is not a closure order.
How 18TH ST SW compares
Age against the county: built in 1978, earlier than 359 of Linn's 506 bridges with a recorded construction year (71%), 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 Iowa bridges with a recorded inventory load rating (23,718 of 23,719 rated).
18TH ST SW vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
23 Top 73% higher than 27% 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.
Linn inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 506 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
- Steel
- Number of Spans
- 2
- Structure Length
- 10.7 m (35 ft) 0
- Owner
- City/Municipal Highway Agency
- Avg Daily Traffic
- 1,494 vehicles/day
- Structure Number
- 000000000001450
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
18TH ST SW 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 18TH ST SW against other structures in Linn 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 18TH ST SW?
18TH ST SW in Linn, Iowa on the FHWA's 0–9 scale.
How often is 18TH ST SW inspected?
18TH ST SW'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 1,494 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 18TH ST SW 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 18TH ST SW?
18TH ST SW has an NBI inventory load rating of 22.7 metric tons.
Who is responsible for maintaining 18TH ST SW?
18TH ST SW is owned and maintained by City/Municipal Highway Agency.
How old is 18TH ST SW and does age affect safety?
18TH ST SW 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.