US Bridges

County Road 31 over Cottonwood Creek

Fair

Larimer County, Colorado · 0.1 MI S of CO RD 18E · Structure no. LR31-4.8-8E

Built
1991
34 years old
Condition
Fair
inspected May 2023
Type
Culvert
Concrete
Length
29 ft
2 main spans
Daily traffic
766
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 31 over Cottonwood Creek is a concrete culvert carrying County Road 31 over Cottonwood Creek in Larimer County, Colorado. It was built in 1991, so it is 34 years old, younger 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 766 vehicles a day, roughly 14% of them trucks, projected to reach 958 by 2042. The structure is 29 ft (8.8 m) long and 65 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesCounty Road 31
CrossesCottonwood Creek
Location0.1 MI S of CO RD 18E
RouteCounty Highway 0
CountyLarimer County
StateColorado
Coordinates40.37508, -105.22752
Functional classRural Major 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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating52.2 US tons
Inventory rating31.3 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans2
Design loadHS 20
Structure length29 ft (8.8 m)
Longest span14 ft (4.2 m)
Deck width65 ft (19.9 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic766 (2023)
Projected traffic958 by 2042
Trucks14%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 County Road 31 over Cottonwood Creek built?

It was built in 1991, making it 34 years old in 2025.

What condition is County Road 31 over Cottonwood Creek 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 2023.

How much traffic does County Road 31 over Cottonwood Creek carry?

About 766 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is County Road 31 over Cottonwood Creek?

The structure is 29 ft (8.8 m) long with a longest span of 14 ft (4.2 m) and a deck 65 ft wide.

Who owns County Road 31 over Cottonwood Creek?

It is owned by the County Highway Agency.