STH 59
Carrying STH 59 over YAHARA RIVER
3.7M E JCT STH 138, Rock, Wisconsin
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
STH 59 in Rock, Wisconsin sits above 28% of rated Wisconsin bridges on inventory load rating (31 t), while its 1946 build year is earlier than 98% of Rock's recorded-year cohort (304 bridges).
STH 59 in Rock, Wisconsin is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1946, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 5. 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 WI:B53091000000000
PRE-1950 · STEEL · MULTI-SPAN · SUB-LED · ARTERIAL-ADT · STANDARD-LOAD · CAT-FAIR
- PRE-1950 Pre-1950
- STEEL Steel
- MULTI-SPAN 2 spans
- SUB-LED Substructure-led
- ARTERIAL-ADT Arterial ADT
- STANDARD-LOAD Standard 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: STH 59
The STH 59 bridge in Rock, Wisconsin carries STH 59 over YAHARA RIVER. It was built in 1946, making it 80 years old today. It was last reconstructed in 1989, extending its service life. The structure is built primarily of steel and spans 2 sections, stretching 43.5 meters (143 feet) end to end. Daily traffic averages 2,000 vehicles, placing it in the moderately-trafficked tier of Wisconsin bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure at 5/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How STH 59 compares
Age against the county: built in 1946, earlier than 297 of Rock's 304 bridges with a recorded construction year (98%), against a county median build year of 1997. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Wisconsin bridges with a recorded inventory load rating (14,446 rated).
STH 59 vs every rated Wisconsin bridge
Inventory load rating (metric tons), FHWA NBI, this state
31 Top 72% higher than 28% of 14,446 bridges
rated Wisconsin 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.
Rock 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
- 1946
- Last Reconstructed
- 1989
- Material
- Steel
- Number of Spans
- 2
- Structure Length
- 43.5 m (143 ft)
- Deck Width
- 9.1 m (30 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 2,000 vehicles/day
- Structure Number
- B53091000000000
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) rates good at 7/9, with no significant deterioration on file.
- • The substructure (piers and abutments) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
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 STH 59 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 STH 59 against other structures in Rock and across Wisconsin. Wisconsin 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 STH 59?
STH 59 in Rock, Wisconsin has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 5/9 on the FHWA's 0–9 scale.
How often is STH 59 inspected?
STH 59'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 2,000 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. STH 59 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 STH 59?
STH 59 has an NBI inventory load rating of 30.8 metric tons.
Who is responsible for maintaining STH 59?
STH 59 is owned and maintained by State Highway Agency.
How old is STH 59 and does age affect safety?
STH 59 was built in 1946, making it 80 years old and last reconstructed in 1989.
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.