S 21 over RR
Pondera County, Montana · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- S 21 over RR in Pondera County, Montana, 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 1972, making it 53 years old at the 2025 inventory.
- It carries about 1,725 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 49 of the 96 inventoried bridges in Pondera County rated good (51.0%); 4 (4.2%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated February 2025, on a 24-month routine inspection cycle.
- 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 → (48.18061, -111.93788)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 8 | 8 | Very good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 222 ft |
| Location | Conrad |
| NBI structure number | P00021005+00501 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | February 2025 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Montana department of transportation.
Busiest bridges in Pondera County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 15 over S Pondera Coulee | 1964 | 3,248 | Fair |
| I 15 over RR | 1972 | 1,727 | Good |
| I 15 over RR | 1972 | 1,727 | Good |
| I 15 over Dry Fork Marias River | 1972 | 1,727 | Good |
| I 15 over Dry Fork Marias River | 1972 | 1,727 | Good |
| I 15 over Pondera Canal | 1972 | 1,510 | Fair |
All bridges nearby: Pondera County, MT bridge conditions · every bridge in Pondera County · Montana bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.