US Bridges

SR-21 over Tunnel Spring Mtns. Wash

Good

Millard County, Utah · 28 Miles Se.Of Garrison · Structure no. 0V1360

Built
1975
50 years old
Condition
Good
inspected February 2023
Type
Culvert
Steel
Length
22 ft
1 main span
Daily traffic
231
2021 count
Owner
State
State Highway Agency

About this bridge

SR-21 over Tunnel Spring Mtns. Wash is a steel culvert carrying SR-21 over Tunnel Spring Mtns. Wash in Millard County, Utah. It was built in 1975, so it is 50 years old, older than the Utah average of 40.1 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 231 vehicles a day, roughly 31% of them trucks, projected to reach 277 by 2041. The structure is 22 ft (6.7 m) long. If it were closed, the detour would be 123.7 mi (199 km).

Location

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CarriesSR-21
CrossesTunnel Spring Mtns. Wash
Location28 Miles Se.Of Garrison
RouteState Highway 21
CountyMillard County
StateUtah
Coordinates38.58897, -113.81773
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert7 GoodSome minor problems.
Last inspectionFebruary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation7: Better than present minimum criteria
Waterway adequacy4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating107.1 US tons
Inventory rating106.5 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans1
Design loadHS 20
Structure length22 ft (6.7 m)
Longest span22 ft (6.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic231 (2021)
Projected traffic277 by 2041
Trucks31%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR-21 over Tunnel Spring Mtns. Wash built?

It was built in 1975, making it 50 years old in 2025.

What condition is SR-21 over Tunnel Spring Mtns. Wash in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in February 2023.

How much traffic does SR-21 over Tunnel Spring Mtns. Wash carry?

About 231 vehicles per day (2021 count), of which roughly 31% are trucks.

How long is SR-21 over Tunnel Spring Mtns. Wash?

The structure is 22 ft (6.7 m) long with a longest span of 22 ft (6.7 m).

Who owns SR-21 over Tunnel Spring Mtns. Wash?

It is owned by the State Highway Agency.