SR-21 over Tunnel Spring Mtns. Wash
Millard County, Utah · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SR-21 over Tunnel Spring Mtns. Wash in Millard County, Utah, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 7 (good condition) on the 0-9 scale.
- It was built in 1975, making it 50 years old at the 2025 inventory.
- It carries about 231 vehicles a day (traffic count year 2021).
- Its listed owner is the state highway agency.
- It is one of 8 of the 72 inventoried bridges in Millard County rated good (11.1%); 2 (2.8%) 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 2023, 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 → (38.58897, -113.81773)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Culvert | 7 | 7 | Good condition |
Bridge details
| Structure | Steel culvert |
| Length | about 21 ft |
| Location | 28 Miles Se.of Garrison |
| NBI structure number | 0V1360 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | February 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 4: foundations stable, field review says exposed foundations need protection |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Utah department of transportation.
Busiest bridges in Millard County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-15 (SR-15)NB&SB over Chalk Creek | 1972 | 24,744 | Fair |
| I-15 (SR-15)NB&SB over Chalk Creek Overflow Ch. | 1972 | 24,744 | Fair |
| I-15 (SR-15) Nbl over SR-99 Intchg. X-road | 1972 | 24,744 | Fair |
| I-15 (SR-15) Sbl over SR-99 Intchg. X-road | 1972 | 24,744 | Fair |
| I-15 SB over Dog Valley Access Rd | 2022 | 23,000 | Good |
| I-15 (SR-15) Nbl over Co. Rd. Inter X-road | 1966 | 22,567 | Fair |
All bridges nearby: Millard County, UT bridge conditions · every bridge in Millard County · Utah bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.