U.S. Highway 101 over West Slough
FairSonoma County, California · 04-SON-101-34.65-HLBG · Structure no. 20 0213
- Built
- 1960
- 65 years old
- Condition
- Fair
- inspected April 2023
- Type
- Culvert
- Concrete Continuous
- Length
- 20 ft
- 2 main spans
- Daily traffic
- 45,500
- 2015 count
- Owner
- State
- State Highway Agency
About this bridge
U.S. Highway 101 over West Slough is a concrete continuous culvert carrying U.S. Highway 101 over West Slough in Sonoma County, California. It was built in 1960, so it is 65 years old, older than the California average of 54.8 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 45,500 vehicles a day, roughly 13% of them trucks, projected to reach 88,047 by 2045. The structure is 20 ft (6.1 m) long. If it were closed, the detour would be 19.9 mi (32 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 | 6 Satisfactory | Structural elements show some minor deterioration. |
| Culvert | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was U.S. Highway 101 over West Slough built?
It was built in 1960, making it 65 years old in 2025.
What condition is U.S. Highway 101 over West Slough 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 April 2023.
How much traffic does U.S. Highway 101 over West Slough carry?
About 45,500 vehicles per day (2015 count), of which roughly 13% are trucks.
How long is U.S. Highway 101 over West Slough?
The structure is 20 ft (6.1 m) long with a longest span of 10 ft (3 m).
Who owns U.S. Highway 101 over West Slough?
It is owned by the State Highway Agency.