US Bridges

120th Avenue over San Arroyo Creek

Fair

Adams County, Colorado · .3 MI W of Shamrock Road · Structure no. ADA120-65.7N178

Built
2000
25 years old
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
30 ft
1 main span
Daily traffic
20
2021 count
Owner
County
County Highway Agency

About this bridge

120th Avenue over San Arroyo Creek is a steel stringer/multi-beam or girder carrying 120th Avenue over San Arroyo Creek in Adams County, Colorado. It was built in 2000, so it is 25 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 20 vehicles a day, projected to reach 26 by 2041. The structure is 30 ft (9.2 m) long and 28 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
Carries120th Avenue
CrossesSan Arroyo Creek
Location.3 MI W of Shamrock Road
RouteCounty Highway 0
CountyAdams County
StateColorado
Coordinates39.91336, -103.82167
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
Deck8 Very GoodNo problems noted.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating47.2 US tons
Inventory rating28.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHS 20
Structure length30 ft (9.2 m)
Longest span28 ft (8.6 m)
Deck width28 ft (8.5 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2021)
Projected traffic26 by 2041
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 120th Avenue over San Arroyo Creek built?

It was built in 2000, making it 25 years old in 2025.

What condition is 120th Avenue over San Arroyo 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 November 2023.

How much traffic does 120th Avenue over San Arroyo Creek carry?

About 20 vehicles per day (2021 count).

How long is 120th Avenue over San Arroyo Creek?

The structure is 30 ft (9.2 m) long with a longest span of 28 ft (8.6 m) and a deck 28 ft wide.

Who owns 120th Avenue over San Arroyo Creek?

It is owned by the County Highway Agency.