HARMONICA RD
Carrying HARMONICA RD over UP RR
S 34 T 65 N R 24 W, Mercer, Missouri
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: HARMONICA RD
The HARMONICA RD bridge in Mercer, Missouri carries HARMONICA RD over UP RR. It was built in 1901, making it 125 years old today. The structure is built primarily of steel and spans 1 section, stretching 64.3 meters (211 feet) end to end. Daily traffic averages 35 vehicles, placing it in the lower-traffic tier of Missouri bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 4/9, superstructure at 6/9, 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. Its NBI inventory load rating is 9.9 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How HARMONICA RD compares
Live comparison across Missouri.
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 How the historical reference is calculated.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
- 1901
- Material
- Steel
- Number of Spans
- 1
- Structure Length
- 64.3 m (211 ft)
- Deck Width
- 6.4 m (21 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 35 vehicles/day
- Structure Number
- 17756
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • At 4/9, the deck (driving surface) is in poor shape, with advanced wear flagged for priority repair.
- • The superstructure (beams and supports above the deck) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) rates poor at 4/9, advanced deterioration that should be prioritized for repair.
How to read this record
HARMONICA RD 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 HARMONICA RD against other structures in Mercer and across Missouri. Missouri 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 HARMONICA RD?
HARMONICA RD in Mercer, Missouri has a deck rating of 4/9, superstructure rating of 6/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is HARMONICA RD inspected?
HARMONICA 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 35 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. HARMONICA RD 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 HARMONICA RD?
HARMONICA RD has an NBI inventory load rating of 9.9 metric tons.
Who is responsible for maintaining HARMONICA RD?
HARMONICA RD is owned and maintained by County Highway Agency.
How old is HARMONICA RD and does age affect safety?
HARMONICA RD was built in 1901, making it 125 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.