120th Street over Rock Creek
FairBoulder County, Colorado · 0.5 MI S of S. Boulder RD · Structure no. LAF-120TH-001B
- Built
- 1986
- 39 years old, rebuilt 2000
- Condition
- Fair
- inspected January 2025
- Type
- Culvert
- Concrete
- Length
- 41 ft
- 2 main spans
- Daily traffic
- 3,390
- 2023 count
- Owner
- City
- City or Municipal Highway Agency
About this bridge
120th Street over Rock Creek is a concrete culvert carrying 120th Street over Rock Creek in Boulder County, Colorado. It was built in 1986 and reconstructed in 2000, so it is 39 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 3,390 vehicles a day, roughly 30% of them trucks, projected to reach 4,068 by 2043. The structure is 41 ft (12.6 m) long and 70 ft wide. If it were closed, the detour would be 1.9 mi (3 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Channel and channel protection | 8 Very Good | No problems noted. |
| Culvert | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was 120th Street over Rock Creek built?
It was built in 1986, making it 39 years old in 2025. It was reconstructed in 2000.
What condition is 120th Street over Rock 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 120th Street over Rock Creek carry?
About 3,390 vehicles per day (2023 count), of which roughly 30% are trucks.
How long is 120th Street over Rock Creek?
The structure is 41 ft (12.6 m) long with a longest span of 20 ft (6.1 m) and a deck 70 ft wide.
Who owns 120th Street over Rock Creek?
It is owned by the City or Municipal Highway Agency.