US Bridges

US 34 Ml over Big Thompson River

Good

Larimer County, Colorado · 2.8 MI from JCT CO RD 43 · Structure no. C-15-AP

Built
2018
7 years old
Condition
Good
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
380 ft
3 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 steel continuous stringer/multi-beam or girder carrying US 34 Ml over Big Thompson River in Larimer County, Colorado. It was built in 2018, so it is 7 years old, younger than the Colorado average of 42.2 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 4,900 vehicles a day, roughly 4% of them trucks, projected to reach 5,684 by 2040. The structure is 380 ft (115.8 m) long and 39 ft wide.

CarriesUS 34 Ml
CrossesBig Thompson River
Location2.8 MI from JCT CO RD 43
RouteU.S. Route 34A
Coordinates40.42653, -105.29382
Functional classRural Principal Arterial - Other

Condition and inspection

Good

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46.4 US tons
Inventory rating35.7 US tons

Structure

MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHL 93
Structure length380 ft (115.8 m)
Longest span130 ft (39.6 m)
Deck width39 ft (11.9 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 closed—
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 2018, making it 7 years old in 2025.

What condition is US 34 Ml over Big Thompson River 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 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 380 ft (115.8 m) long with a longest span of 130 ft (39.6 m) and a deck 39 ft wide.

Who owns US 34 Ml over Big Thompson River?

It is owned by the State Highway Agency.