US Bridges

US 34 Ml over Big Thompson River

Fair

Larimer County, Colorado · 6 MI W of Loveland · Structure no. C-16-DI

Built
1980
45 years old
Condition
Fair
inspected September 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
149 ft
2 main spans
Daily traffic
4,900
2020 count
Owner
State
State Highway Agency

About this bridge

US 34 Ml over Big Thompson River is a concrete continuous box beam or girders - multiple carrying US 34 Ml over Big Thompson River in Larimer County, Colorado. It was built in 1980, so it is 45 years old, older than the Colorado average of 42.2 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 4,900 vehicles a day, roughly 4% of them trucks, projected to reach 5,684 by 2040. The structure is 149 ft (45.3 m) long and 38 ft wide. If it were closed, the detour would be 62.1 mi (100 km).

CarriesUS 34 Ml
CrossesBig Thompson River
Location6 MI W of Loveland
RouteU.S. Route 34A
Coordinates40.42182, -105.24051
Functional classRural Principal Arterial - Other

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating73 US tons
Inventory rating44.3 US tons

Structure

MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length149 ft (45.3 m)
Longest span73 ft (22.3 m)
Deck width38 ft (11.7 m)
Roadway width36 ft (11 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,900 (2020)
Projected traffic5,684 by 2040
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed62.1 mi (100 km)
TollOn a free road
National Highway SystemYes

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—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 34 Ml over Big Thompson River built?

It was built in 1980, making it 45 years old in 2025.

What condition is US 34 Ml over Big Thompson River 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 September 2023.

How much traffic does US 34 Ml over Big Thompson River carry?

About 4,900 vehicles per day (2020 count), of which roughly 4% are trucks.

How long is US 34 Ml over Big Thompson River?

The structure is 149 ft (45.3 m) long with a longest span of 73 ft (22.3 m) and a deck 38 ft wide.

Who owns US 34 Ml over Big Thompson River?

It is owned by the State Highway Agency.