US Bridges

300 South over Hyrum Dam Spillway

Fair

Cache County, Utah · 490 W 390 S Hyrum · Structure no. 005052D

Built
1935
90 years old
Condition
Fair
inspected May 2024
Type
Frame
Concrete Continuous
Length
58 ft
3 main spans
Daily traffic
1,000
2014 count
Owner
Federal
Bureau of Reclamation

About this bridge

300 South over Hyrum Dam Spillway is a concrete continuous frame carrying 300 South over Hyrum Dam Spillway in Cache County, Utah. It was built in 1935, so it is 90 years old, older than the Utah average of 40.1 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 1,000 vehicles a day, roughly 5% of them trucks, projected to reach 1,250 by 2034. The structure is 58 ft (17.7 m) long and 33 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
Carries300 South
CrossesHyrum Dam Spillway
Location490 W 390 S Hyrum
RouteCounty Highway 1170
CountyCache County
StateUtah
Coordinates41.62694, -111.87167
Functional classUrban Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating35.7 US tons
Inventory rating20 US tons

Structure

Structure typeFrame
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length58 ft (17.7 m)
Longest span17 ft (5.2 m)
Deck width33 ft (10.2 m)
Roadway width22 ft (6.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,000 (2014)
Projected traffic1,250 by 2034
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerBureau of Reclamation
Maintained byBureau of Reclamation
Historic statusEligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 300 South over Hyrum Dam Spillway built?

It was built in 1935, making it 90 years old in 2025.

What condition is 300 South over Hyrum Dam Spillway in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in May 2024.

How much traffic does 300 South over Hyrum Dam Spillway carry?

About 1,000 vehicles per day (2014 count), of which roughly 5% are trucks.

How long is 300 South over Hyrum Dam Spillway?

The structure is 58 ft (17.7 m) long with a longest span of 17 ft (5.2 m) and a deck 33 ft wide.

Who owns 300 South over Hyrum Dam Spillway?

It is owned by the Bureau of Reclamation.