S. 18TH AVE
Carrying S. 18TH AVE over OVER UP RR
084173100, Marshall, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
S. 18TH AVE in Marshall, Iowa sits above 71% of rated Iowa bridges on inventory load rating (35 t), while its 1980 build year is earlier than 45% of Marshall's recorded-year cohort (304 bridges).
S. 18TH AVE in Marshall, Iowa is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1980, 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:000000000503240
LATE-CENTURY · PRESTRESS · MULTI-SPAN · SUPER-LED · ARTERIAL-ADT · STANDARD-LOAD · CAT-POOR
- LATE-CENTURY 1980–1999
- PRESTRESS Prestressed concrete
- MULTI-SPAN 3 spans
- SUPER-LED Superstructure-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: S. 18TH AVE
The S. 18TH AVE bridge in Marshall, Iowa carries S. 18TH AVE over OVER UP RR. It was built in 1980, making it 46 years old today. The structure is built primarily of prestressed concrete and spans 3 sections, stretching 85.0 meters (279 feet) end to end. Daily traffic averages 6,813 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 a deck rating of 6/9, superstructure at 4/9, substructure at 6/9. The weakest component sits in poor condition. A component scored 4 or below, placing this bridge in the federal Poor condition category rather than declaring it unsafe or closed.
How S. 18TH AVE compares
Age against the county: built in 1980, earlier than 136 of Marshall's 304 bridges with a recorded construction year (45%), against a county median build year of 1977. This is one of the newer structures in its county.
Live comparison across Iowa bridges with a recorded inventory load rating (23,718 of 23,719 rated).
S. 18TH AVE vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
35 Top 29% higher than 71% 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.
Marshall inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 304 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
- 1980
- Material
- Prestressed Concrete
- Number of Spans
- 3
- Structure Length
- 85.0 m (279 ft)
- Deck Width
- 21.0 m (69 ft)
- Owner
- City/Municipal Highway Agency
- Avg Daily Traffic
- 6,813 vehicles/day
- Structure Number
- 000000000503240
Condition Analysis
- • The deck (driving surface) rates fair at 6/9, minor deterioration that routine maintenance should address.
- • The superstructure (beams and supports above the deck) rates poor at 4/9, with advanced deterioration recorded on the latest inspection.
- • At 6/9, the substructure (piers and abutments) shows fair condition, with minor wear flagged for upkeep.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
S. 18TH AVE 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 S. 18TH AVE against other structures in Marshall 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 S. 18TH AVE?
S. 18TH AVE in Marshall, Iowa has a deck rating of 6/9, superstructure rating of 4/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is S. 18TH AVE inspected?
S. 18TH AVE'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 6,813 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. S. 18TH AVE 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 S. 18TH AVE?
S. 18TH AVE has an NBI inventory load rating of 34.7 metric tons.
Who is responsible for maintaining S. 18TH AVE?
S. 18TH AVE is owned and maintained by City/Municipal Highway Agency.
How old is S. 18TH AVE and does age affect safety?
S. 18TH AVE was built in 1980, making it 46 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.