Mo 21 N over Rock CR
Jefferson County, Missouri · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Mo 21 N over Rock CR in Jefferson County, Missouri, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 1987, making it 38 years old at the 2025 inventory.
- It carries about 11,681 vehicles a day (traffic count year 2024).
- Its listed owner is the state highway agency.
- It is one of 143 of the 410 inventoried bridges in Jefferson County rated good (34.9%); 10 (2.4%) are rated poor.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (38.42672, -90.47243)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous prestressed concrete stringer or multi-beam girder |
| Length | about 276 ft |
| Location | S 1974 T 43 N R 5 E |
| NBI structure number | 2542 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Missouri department of transportation.
Busiest bridges in Jefferson County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Is 55 S over Tom CR | 1965 | 104,603 | Fair |
| Is 55 S over UP RR Desoto Sub | 2024 | 80,923 | Good |
| Is 55 S over Cst Herky-horine Rd | 2025 | 80,923 | Good |
| Is 55 S over Br Sandy CR | 1964 | 80,923 | Fair |
| Is 55 S over Cst Fifth St BNSF RR | 2011 | 70,419 | Good |
| Is 55 S over Cst Central Ave | 2024 | 70,419 | Good |
All bridges nearby: Jefferson County, MO bridge conditions · every bridge in Jefferson County · Missouri bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.