US Bridges

County Road 80 over North St. Vrain Creek

Fair

Boulder County, Colorado · 20 Feet South of US High · Structure no. BC-80-0.1-NSV1

Built
1988
37 years old
Condition
Fair
inspected January 2025
Type
Box Beam or Girders - Single or Spread
Prestressed Concrete
Length
61 ft
1 main span
Daily traffic
268
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 80 over North St. Vrain Creek is a prestressed concrete box beam or girders - single or spread carrying County Road 80 over North St. Vrain Creek in Boulder County, Colorado. It was built in 1988, so it is 37 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 268 vehicles a day, roughly 18% of them trucks, projected to reach 322 by 2043. The structure is 61 ft (18.6 m) long and 31 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesCounty Road 80
CrossesNorth St. Vrain Creek
Location20 Feet South of US High
RouteCounty Highway 0
CountyBoulder County
StateColorado
Coordinates40.24291, -105.31374
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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating63.3 US tons
Inventory rating38 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length61 ft (18.6 m)
Longest span54 ft (16.5 m)
Deck width31 ft (9.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic268 (2023)
Projected traffic322 by 2043
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 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 80 over North St. Vrain Creek built?

It was built in 1988, making it 37 years old in 2025.

What condition is County Road 80 over North St. Vrain 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 January 2025.

How much traffic does County Road 80 over North St. Vrain Creek carry?

About 268 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is County Road 80 over North St. Vrain Creek?

The structure is 61 ft (18.6 m) long with a longest span of 54 ft (16.5 m) and a deck 31 ft wide.

Who owns County Road 80 over North St. Vrain Creek?

It is owned by the County Highway Agency.