US Bridges

County Road 9 over Boulder Creek

Fair

Boulder County, Colorado · 0.3 MI N of CO RD 42 · Structure no. BC-9-0.9-BO

Built
1960
65 years old
Condition
Fair
inspected February 2025
Type
Tee Beam
Prestressed Concrete
Length
77 ft
2 main spans
Daily traffic
59
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 9 over Boulder Creek is a prestressed concrete tee beam carrying County Road 9 over Boulder Creek in Boulder County, Colorado. It was built in 1960, so it is 65 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 59 vehicles a day, roughly 27% of them trucks, projected to reach 71 by 2043. The structure is 77 ft (23.4 m) long and 28 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesCounty Road 9
CrossesBoulder Creek
Location0.3 MI N of CO RD 42
RouteCounty Highway 0
CountyBoulder County
StateColorado
Coordinates40.05987, -105.09793
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2025
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating40 US tons
Inventory rating36 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length77 ft (23.4 m)
Longest span35 ft (10.6 m)
Deck width28 ft (8.6 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic59 (2023)
Projected traffic71 by 2043
Trucks27%
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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was County Road 9 over Boulder Creek built?

It was built in 1960, making it 65 years old in 2025.

What condition is County Road 9 over Boulder 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 February 2025.

How much traffic does County Road 9 over Boulder Creek carry?

About 59 vehicles per day (2023 count), of which roughly 27% are trucks.

How long is County Road 9 over Boulder Creek?

The structure is 77 ft (23.4 m) long with a longest span of 35 ft (10.6 m) and a deck 28 ft wide.

Who owns County Road 9 over Boulder Creek?

It is owned by the County Highway Agency.