308TH AVE.
Carrying 308TH AVE. over SUGAR CREEK
083E40404, Clinton, Iowa
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
308TH AVE. in Clinton, Iowa sits above 73% of rated Iowa bridges on inventory load rating (36 t), while its 1985 build year is earlier than 56% of Clinton's recorded-year cohort (372 bridges).
308TH AVE. in Clinton, Iowa is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1985, 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:000000000125251
LATE-CENTURY · PRESTRESS · SINGLE-SPAN · SUB-LED · LOCAL-ADT · STANDARD-LOAD · CAT-POOR
- LATE-CENTURY 1980–1999
- PRESTRESS Prestressed concrete
- SINGLE-SPAN Single span
- SUB-LED Substructure-led
- LOCAL-ADT Local 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: 308TH AVE.
The 308TH AVE. bridge in Clinton, Iowa carries 308TH AVE. over SUGAR CREEK. It was built in 1985, making it 41 years old today. The structure is built primarily of prestressed concrete and spans 1 section, stretching 14.9 meters (49 feet) end to end. Daily traffic averages 70 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 7/9, superstructure at 7/9, substructure at 4/9. 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 308TH AVE. compares
Age against the county: built in 1985, earlier than 207 of Clinton's 372 bridges with a recorded construction year (56%), 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).
308TH AVE. vs every rated Iowa bridge
Inventory load rating (metric tons), FHWA NBI, this state
36 Top 27% higher than 73% 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.
Clinton 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
- 1985
- Material
- Prestressed Concrete
- Number of Spans
- 1
- Structure Length
- 14.9 m (49 ft)
- Deck Width
- 6.1 m (20 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 70 vehicles/day
- Structure Number
- 000000000125251
Condition Analysis
- • At 7/9, the deck (driving surface) is in good shape and shows no significant wear.
- • The superstructure (beams and supports above the deck) rates good at 7/9, with no significant deterioration on file.
- • 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
308TH 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 308TH AVE. against other structures in Clinton 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 308TH AVE.?
308TH AVE. in Clinton, Iowa has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is 308TH AVE. inspected?
308TH 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 70 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 308TH 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 308TH AVE.?
308TH AVE. has an NBI inventory load rating of 36.0 metric tons.
Who is responsible for maintaining 308TH AVE.?
308TH AVE. is owned and maintained by County Highway Agency.
How old is 308TH AVE. and does age affect safety?
308TH AVE. was built in 1985, making it 41 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.