US Highway 101 NB over Gannon Slough
GoodHumboldt County, California · 01-HUM-101-84.70-ARC · Structure no. 04 0024R
- Built
- 1955
- 70 years old
- Condition
- Good
- inspected November 2023
- Type
- Slab
- Concrete Continuous
- Length
- 76 ft
- 4 main spans
- Daily traffic
- 17,500
- 2010 count
- Owner
- State
- State Highway Agency
About this bridge
US Highway 101 NB over Gannon Slough is a concrete continuous slab carrying US Highway 101 NB over Gannon Slough in Humboldt County, California. It was built in 1955, so it is 70 years old, older than the California average of 54.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
It carries about 17,500 vehicles a day, roughly 10% of them trucks, projected to reach 51,366 by 2041. The structure is 76 ft (23.3 m) long and 41 ft wide. If it were closed, the detour would be 3.7 mi (6 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 7 Good | Some minor problems. |
| 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 NB over Gannon Slough built?
It was built in 1955, making it 70 years old in 2025.
What condition is US Highway 101 NB over Gannon Slough in?
The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in November 2023.
How much traffic does US Highway 101 NB over Gannon Slough carry?
About 17,500 vehicles per day (2010 count), of which roughly 10% are trucks.
How long is US Highway 101 NB over Gannon Slough?
The structure is 76 ft (23.3 m) long with a longest span of 21 ft (6.4 m) and a deck 41 ft wide.
Who owns US Highway 101 NB over Gannon Slough?
It is owned by the State Highway Agency.