US Bridges

County Road 21C over New Mercer Canal

Fair

Larimer County, Colorado · 0.2 MI N of CO RD 50 · Structure no. LR21C-0.2-50-A

Built
1983
42 years old
Condition
Fair
inspected March 2025
Type
Culvert
Aluminum, Wrought Iron, or Cast Iron
Length
23 ft
1 main span
Daily traffic
4,081
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 21C over New Mercer Canal is a aluminum, wrought iron, or cast iron culvert carrying County Road 21C over New Mercer Canal in Larimer County, Colorado. It was built in 1983, so it is 42 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 5 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 4,081 vehicles a day, roughly 20% of them trucks, projected to reach 5,101 by 2042. The structure is 23 ft (7 m) long and 46 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesCounty Road 21C
CrossesNew Mercer Canal
Location0.2 MI N of CO RD 50
RouteCounty Highway 0
CountyLarimer County
StateColorado
Coordinates40.61403, -105.14014
Functional classUrban Minor Arterial

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 protection7 GoodSome minor problems.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMarch 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating110.1 US tons
Inventory rating103.5 US tons

Structure

Structure typeCulvert
MaterialAluminum, Wrought Iron, or Cast Iron
DeckNot applicable
Main spans1
Design loadHS 20 + Mod
Structure length23 ft (7 m)
Longest span23 ft (7 m)
Deck width46 ft (13.9 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,081 (2023)
Projected traffic5,101 by 2042
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 21C over New Mercer Canal built?

It was built in 1983, making it 42 years old in 2025.

What condition is County Road 21C over New Mercer Canal 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 March 2025.

How much traffic does County Road 21C over New Mercer Canal carry?

About 4,081 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is County Road 21C over New Mercer Canal?

The structure is 23 ft (7 m) long with a longest span of 23 ft (7 m) and a deck 46 ft wide.

Who owns County Road 21C over New Mercer Canal?

It is owned by the County Highway Agency.