BIG SIOUX RIVER RD
Carrying BIG SIOUX RIVER RD over BIG SIOUX RIVER
0.5 MI. N OF JCT. IA 12, Plymouth, Iowa
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: BIG SIOUX RIVER RD
The BIG SIOUX RIVER RD bridge in Plymouth, Iowa carries BIG SIOUX RIVER RD over BIG SIOUX RIVER. It was built in 1996, making it 30 years old today. The structure is built primarily of prestressed concrete and spans 4 sections, stretching 149.3 meters (490 feet) end to end. Daily traffic averages 1,121 vehicles, placing it in the moderately-trafficked tier of Iowa bridges. It is owned and maintained by Other State Agencies.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure 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. Its NBI inventory load rating is 50.9 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How BIG SIOUX RIVER RD compares
Live comparison across Iowa.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1996
- Material
- Prestressed Concrete
- Number of Spans
- 4
- Structure Length
- 149.3 m (490 ft)
- Deck Width
- 11.9 m (39 ft)
- Owner
- Other State Agencies
- Avg Daily Traffic
- 1,121 vehicles/day
- Structure Number
- 000000000603911
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) rates good at 7/9, with no significant deterioration on file.
- • The superstructure (beams and supports above the deck) is in good condition (7/9), showing no significant deterioration.
- • The substructure (piers and abutments) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
How to read this record
This page shows what the last federal inspection recorded, not whether BIG SIOUX RIVER RD 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 BIG SIOUX RIVER RD 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 BIG SIOUX RIVER RD?
BIG SIOUX RIVER RD in Plymouth, Iowa has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is BIG SIOUX RIVER RD inspected?
BIG SIOUX RIVER RD'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 1,121 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. BIG SIOUX RIVER RD 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 BIG SIOUX RIVER RD?
BIG SIOUX RIVER RD has an NBI inventory load rating of 50.9 metric tons.
Who is responsible for maintaining BIG SIOUX RIVER RD?
BIG SIOUX RIVER RD is owned and maintained by Other State Agencies.
How old is BIG SIOUX RIVER RD and does age affect safety?
BIG SIOUX RIVER RD was built in 1996, making it 30 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.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.