US Highway 101 SB over Gannon Slough
FairHumboldt County, California · 01-HUM-101-84.70 · Structure no. 04 0024L
- Built
- 1996
- 29 years old
- Condition
- Fair
- inspected November 2023
- Type
- Slab
- Concrete Continuous
- Length
- 398 ft
- 11 main spans
- Daily traffic
- 17,500
- 2010 count
- Owner
- State
- State Highway Agency
About this bridge
US Highway 101 SB over Gannon Slough is a concrete continuous slab carrying US Highway 101 SB over Gannon Slough in Humboldt County, California. It was built in 1996, so it is 29 years old, younger 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 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 17,500 vehicles a day, roughly 10% of them trucks, projected to reach 20,911 by 2041. The structure is 398 ft (121.2 m) long and 43 ft wide. If it were closed, the detour would be 3.1 mi (5 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 |
|---|---|---|
| Deck | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Superstructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was US Highway 101 SB over Gannon Slough built?
It was built in 1996, making it 29 years old in 2025.
What condition is US Highway 101 SB over Gannon 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 November 2023.
How much traffic does US Highway 101 SB over Gannon Slough carry?
About 17,500 vehicles per day (2010 count), of which roughly 10% are trucks.
How long is US Highway 101 SB over Gannon Slough?
The structure is 398 ft (121.2 m) long with a longest span of 36 ft (11 m) and a deck 43 ft wide.
Who owns US Highway 101 SB over Gannon Slough?
It is owned by the State Highway Agency.