South Tongass Hwy over Water St Viaduct
Ketchikan Gateway Borough, Alaska · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- South Tongass Hwy over Water St Viaduct in Ketchikan Gateway Borough, Alaska, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 4 (poor condition) on the 0-9 scale.
- It was built in 1955, making it 70 years old at the 2025 inventory.
- It carries about 14,046 vehicles a day (traffic count year 2018).
- Its listed owner is the state highway agency.
- It is one of 12 of the 107 inventoried bridges in Ketchikan Gateway Borough rated poor (11.2%); 12 (11.2%) are rated poor.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (55.34389, -131.65111)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 5 | Fair condition |
| Substructure | 4 | Poor condition |
Bridge details
| Structure | Prestressed concrete tee beam |
| Length | about 1,624 ft |
| Location | Mile Point 1.7 |
| NBI structure number | 0797 |
| Condition class | Poor |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Alaska department of transportation.
Busiest bridges in Ketchikan Gateway Borough
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| South Tongass Hwy over Tongass Avenue Viaduct | 1956 | 14,564 | Fair |
| South Tongass Hwy over Hoadley Creek | 1957 | 11,900 | Poor |
| North Tongass Hwy over Carlanna Creek | 1973 | 9,210 | Fair |
| South Tongass Hwy over Front Street Viaduct | 1969 | 8,330 | Fair |
| South Tongass Hwy over Ketchikan Creek | 1944 | 6,850 | Fair |
| South Tongass Hwy over Front and Mill St Viad | 1973 | 6,830 | Good |
All bridges nearby: Ketchikan Gateway Borough, AK bridge conditions · every bridge in Ketchikan Gateway Borough · Alaska bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.