US Bridges

County Road 84S over South St. Vrain Creek

Fair

Boulder County, Colorado · 250 Ft S of HWY 7 · Structure no. BC-84S-1.6-SSV1

Built
2019
6 years old
Condition
Fair
inspected February 2025
Type
Truss - Thru
Steel
Length
182 ft
1 main span
Daily traffic
67
2023 count
Owner
County
County Highway Agency

About this bridge

County Road 84S over South St. Vrain Creek is a steel truss - thru carrying County Road 84S over South St. Vrain Creek in Boulder County, Colorado. It was built in 2019, so it is 6 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 67 vehicles a day, roughly 4% of them trucks, projected to reach 80 by 2043. The structure is 182 ft (55.6 m) long and 33 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesCounty Road 84S
CrossesSouth St. Vrain Creek
Location250 Ft S of HWY 7
RouteCounty Highway 0
CountyBoulder County
StateColorado
Coordinates40.20629, -105.2933
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 rating40 US tons
Inventory rating30.8 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length182 ft (55.6 m)
Longest span176 ft (53.7 m)
Deck width33 ft (10.1 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic67 (2023)
Projected traffic80 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 84S over South St. Vrain Creek built?

It was built in 2019, making it 6 years old in 2025.

What condition is County Road 84S over South 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 February 2025.

How much traffic does County Road 84S over South St. Vrain Creek carry?

About 67 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is County Road 84S over South St. Vrain Creek?

The structure is 182 ft (55.6 m) long with a longest span of 176 ft (53.7 m) and a deck 33 ft wide.

Who owns County Road 84S over South St. Vrain Creek?

It is owned by the County Highway Agency.