US Bridges

County Road 47 over St. Vrain Supply Canal

Fair

Boulder County, Colorado · 2.7 Miles North of State · Structure no. BC-47-0.1-ID1

Built
1997
28 years old
Condition
Fair
inspected January 2025
Type
Box Beam or Girders - Single or Spread
Prestressed Concrete
Length
54 ft
1 main span
Daily traffic
316
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 47 over St. Vrain Supply Canal is a prestressed concrete box beam or girders - single or spread carrying County Road 47 over St. Vrain Supply Canal in Boulder County, Colorado. It was built in 1997, so it is 28 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 316 vehicles a day, roughly 16% of them trucks, projected to reach 379 by 2043. The structure is 54 ft (16.5 m) long and 37 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesCounty Road 47
CrossesSt. Vrain Supply Canal
Location2.7 Miles North of State
RouteCounty Highway 0
CountyBoulder County
StateColorado
Coordinates40.24579, -105.22505
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating32.7 US tons
Inventory rating20.6 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length54 ft (16.5 m)
Longest span49 ft (15 m)
Deck width37 ft (11.4 m)
Roadway width33 ft (10.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic316 (2023)
Projected traffic379 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was County Road 47 over St. Vrain Supply Canal built?

It was built in 1997, making it 28 years old in 2025.

What condition is County Road 47 over St. Vrain Supply 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 January 2025.

How much traffic does County Road 47 over St. Vrain Supply Canal carry?

About 316 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is County Road 47 over St. Vrain Supply Canal?

The structure is 54 ft (16.5 m) long with a longest span of 49 ft (15 m) and a deck 37 ft wide.

Who owns County Road 47 over St. Vrain Supply Canal?

It is owned by the County Highway Agency.