Interstate 280 over Southgate Avenue
PoorSan Mateo County, California · 04-SM-280-R25.04-DLC · Structure no. 35 0178
- Built
- 1967
- 58 years old
- Condition
- Poor
- inspected February 2025
- Type
- Box Beam or Girders - Multiple
- Concrete Continuous
- Length
- 185 ft
- 3 main spans
- Daily traffic
- 178,000
- 2009 count
- Owner
- State
- State Highway Agency
About this bridge
Interstate 280 over Southgate Avenue is a concrete continuous box beam or girders - multiple carrying Interstate 280 over Southgate Avenue in San Mateo County, California. It was built in 1967, so it is 58 years old, older 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 178,000 vehicles a day, roughly 1% of them trucks, projected to reach 267,142 by 2047. The structure is 185 ft (56.4 m) long and 179 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 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 | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Interstate 280 over Southgate Avenue built?
It was built in 1967, making it 58 years old in 2025.
What condition is Interstate 280 over Southgate Avenue 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 Interstate 280 over Southgate Avenue carry?
About 178,000 vehicles per day (2009 count), of which roughly 1% are trucks.
How long is Interstate 280 over Southgate Avenue?
The structure is 185 ft (56.4 m) long with a longest span of 92 ft (27.9 m) and a deck 179 ft wide.
Who owns Interstate 280 over Southgate Avenue?
It is owned by the State Highway Agency.