Harmonica Rd over UP RR
Mercer County, Missouri · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Harmonica Rd over UP RR in Mercer County, Missouri, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 4 (poor condition) on the 0-9 scale.
- It was built in 1901, making it 124 years old at the 2025 inventory.
- It carries about 35 vehicles a day (traffic count year 2024).
- Its listed owner is the county highway agency.
- It is one of 23 of the 135 inventoried bridges in Mercer County rated poor (17.0%); 23 (17.0%) are rated poor.
- Its traffic status in the 2025 inventory is posted for load (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated February 2024, on a 24-month routine inspection cycle.
- It has fracture-critical members (NBI item 92A): steel tension members without a redundant load path, which get their own scheduled inspections.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (40.38989, -93.58006)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 4 | 4 | Poor condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 4 | 4 | Poor condition |
Bridge details
| Structure | Steel girder and floorbeam |
| Length | about 210 ft |
| Location | S 34 T 65 N R 24 W |
| NBI structure number | 17756 |
| Condition class | Poor |
| Traffic status (item 41) | Posted for load |
| Last inspection (item 90) | February 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
| Fracture critical (item 92A) | Yes |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Missouri department of transportation.
Busiest bridges in Mercer County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 65 S over Wildcat CR | 2001 | 2,192 | Fair |
| US 136 E over Weldon Fk of Grand | 1971 | 1,917 | Fair |
| US 136 E over Grand Rvr Ovrfl | 1971 | 1,917 | Poor |
| US 136 E over W Muddy CR | 1971 | 1,221 | Fair |
| US 136 E over W Muddy CR | 1971 | 1,221 | Fair |
| US 136 E over Sandy CR | 1985 | 1,084 | Good |
All bridges nearby: Mercer County, MO bridge conditions · every bridge in Mercer County · Missouri bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.