South Tongass HWY over Water ST Viaduct
PoorKetchikan Gateway Borough, Alaska · Mile Point 1.7 · Structure no. 0797
- Built
- 1955
- 70 years old
- Condition
- Poor
- inspected June 2023
- Type
- Tee Beam
- Prestressed Concrete
- Length
- 1,624 ft
- 81 main spans
- Daily traffic
- 14,046
- 2018 count
- Owner
- State
- State Highway Agency
About this bridge
South Tongass HWY over Water ST Viaduct is a prestressed concrete tee beam carrying South Tongass HWY over Water ST Viaduct in Ketchikan Gateway Borough, Alaska. It was built in 1955, so it is 70 years old, older than the Alaska average of 35.9 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 14,046 vehicles a day, roughly 5% of them trucks, projected to reach 15,000 by 2035. The structure is 1,624 ft (495 m) long and 53 ft wide. If it were closed, the detour would be 1.2 mi (2 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 | 7 Good | Some minor problems. |
| Superstructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was South Tongass HWY over Water ST Viaduct built?
It was built in 1955, making it 70 years old in 2025.
What condition is South Tongass HWY over Water ST Viaduct 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 June 2023.
How much traffic does South Tongass HWY over Water ST Viaduct carry?
About 14,046 vehicles per day (2018 count), of which roughly 5% are trucks.
How long is South Tongass HWY over Water ST Viaduct?
The structure is 1,624 ft (495 m) long with a longest span of 19 ft (5.8 m) and a deck 53 ft wide.
Who owns South Tongass HWY over Water ST Viaduct?
It is owned by the State Highway Agency.