SR 99 over Lake Union
Fair Condition95 years old61,259 vehicles/day
Location
| State | Washington |
| County | King |
| Location | 7.7 N Jct SR 509 |
| Carries | SR 99 |
| Crosses | Lake Union |
| Coordinates | 47.64317, -122.34719 |
Condition Ratings
| Overall Condition | Fair |
| Deck | 6 (Satisfactory) |
| Superstructure | 5 (Fair) |
| Substructure | 6 (Satisfactory) |
| Channel/Waterway | 8 (Very Good) |
| Scour Critical | 8 — Stable, low risk |
Physical Characteristics
| Material | Steel |
| Design | Truss - Deck |
| Total Length | 2955.1 ft (900.7 m) |
| Max Span | 799.9 ft (243.8 m) |
| Deck Width | 69.6 ft (21.2 m) |
| Deck Area | 19094.8 sq m |
| Main Spans | 8 |
| Year Built | 1931 |
Traffic
| Avg Daily Traffic | 61,259 (2023) |
| Truck Traffic | 4% |
| Lanes On Bridge | 6 |
| Lanes Under Bridge | 24 |
Inspection & Ownership
| Last Inspection | 823 |
| Inspection Frequency | Every 24 months |
| Owner | State Highway Agency |
| Historical Significance | Bridge is on the National Register of Historic Places |
| Structure Number | 0001447A0000000 |