Llano RD over Colgan Creek
PoorSonoma County, California · 1.1 MI N of SH 116 · Structure no. 20C0234
- Built
- 1979
- 46 years old
- Condition
- Poor
- inspected February 2025
- Type
- Slab
- Concrete Continuous
- Length
- 67 ft
- 2 main spans
- Daily traffic
- 1,750
- 2018 count
- Owner
- County
- County Highway Agency
About this bridge
Llano RD over Colgan Creek is a concrete continuous slab carrying Llano RD over Colgan Creek in Sonoma County, California. It was built in 1979, so it is 46 years old, younger than the California average of 54.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
It carries about 1,750 vehicles a day, roughly 5% of them trucks, projected to reach 2,601 by 2047. The structure is 67 ft (20.3 m) long and 32 ft wide. If it were closed, the detour would be 6.2 mi (10 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Superstructure | 4 Poor | Advanced section loss, deterioration, 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 Llano RD over Colgan Creek built?
It was built in 1979, making it 46 years old in 2025.
What condition is Llano RD over Colgan Creek in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in February 2025.
How much traffic does Llano RD over Colgan Creek carry?
About 1,750 vehicles per day (2018 count), of which roughly 5% are trucks.
How long is Llano RD over Colgan Creek?
The structure is 67 ft (20.3 m) long with a longest span of 32 ft (9.8 m) and a deck 32 ft wide.
Who owns Llano RD over Colgan Creek?
It is owned by the County Highway Agency.