US Bridges

Rock Canyon Road over Big Thompson River

Fair

Larimer County, Colorado · 10 Ft W of US HWY 34 · Structure no. LRROCKCANYON1

Built
1977
48 years old
Condition
Fair
inspected July 2023
Type
Tee Beam
Prestressed Concrete
Length
49 ft
1 main span
Daily traffic
17
2023 count
Owner
County
County Highway Agency

About this bridge

Rock Canyon Road over Big Thompson River is a prestressed concrete tee beam carrying Rock Canyon Road over Big Thompson River in Larimer County, Colorado. It was built in 1977, so it is 48 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 17 vehicles a day, roughly 6% of them trucks, projected to reach 22 by 2042. The structure is 49 ft (15 m) long and 12 ft wide.

Location

Open in Google Maps
CarriesRock Canyon Road
CrossesBig Thompson River
Location10 Ft W of US HWY 34
RouteCounty Highway 0
CountyLarimer County
StateColorado
Coordinates40.38351, -105.47029
Functional classRural Local

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 inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating40 US tons
Inventory rating36 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadUnknown
Structure length49 ft (15 m)
Longest span49 ft (14.8 m)
Deck width12 ft (3.7 m)
Roadway width11 ft (3.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic17 (2023)
Projected traffic22 by 2042
Trucks6%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byOther Local 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 Rock Canyon Road over Big Thompson River built?

It was built in 1977, making it 48 years old in 2025.

What condition is Rock Canyon Road 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 July 2023.

How much traffic does Rock Canyon Road over Big Thompson River carry?

About 17 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is Rock Canyon Road over Big Thompson River?

The structure is 49 ft (15 m) long with a longest span of 49 ft (14.8 m) and a deck 12 ft wide.

Who owns Rock Canyon Road over Big Thompson River?

It is owned by the County Highway Agency and maintained by the Other Local Agency.