Robertson Tunnel
Robertson Tunnel is named mid-platform in the Washington Park station
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| Overview | |
|---|---|
| Line | westside MAX Blue Line and MAX Red Line |
| Location | Tualatin Mountains, Portland, Oregon, United States 45°30′38″N 122°43′01″W / 45.510661°N 122.716869°W |
| Status | in service |
| System | MAX Light Rail |
| Start | Goose Hollow 45°31′09″N 122°41′59″W / 45.519087°N 122.699749°W |
| End | Sunset Hills Mortuary 45°30′23″N 122°45′14″W / 45.506324°N 122.753833°W |
| No. of stations | 1 |
| Operation | |
| Opened | September 12, 1998 |
| Owner | TriMet |
| Character | mass transit |
| Technical | |
| Line length | 2.93 miles (4.71 km) (15,450 feet) |
| No. of tracks | 2 (double track) |
| Track gauge | 1,435 mm (4 ft 8 1⁄2 in) |
| Electrified | 750 Vdc, overhead |
| Operating speed | 55 mph (90 km/h) |
| Highest elevation | 605 feet (184 m) approx. 6,000 feet (1,800 m) inside west portal |
| Lowest elevation | 220 feet (67 m) at east portal |
The Robertson Tunnel is a twin-bore light rail tunnel through the Tualatin Mountains west of Portland, Oregon, United States, used by the MAX Blue and Red Lines. The tunnel is 2.9 miles (4.7 kilometers) long and consists of twin 21-foot-diameter (6.4 m) tunnels. There is one station within the tunnel at Washington Park, which at 259 feet (79 m) deep is the deepest subway station in the United States and the fifth-deepest in the world. Trains are in the tunnel for about 5 minutes, which includes a stop at the Washington Park station. The tunnel has won several worldwide engineering and environmental awards. It was placed into service September 12, 1998.
The tunnels pass through basalt layers up to 16 million years old. Due to variations in the rock composition, the tunnel curves mildly side to side and up and down to follow the best rock construction conditions. The tunnels vary from 80 to 300 feet (24–91 m) below the surface. A core sample taken during construction is on display with a timeline of local geologic history. The east tunnel entrance is near Vista Bridge at the edge of the Goose Hollow neighborhood at the foot of Washington Park. The west entrance is along U.S. Highway 26 just west of the Finley-Sunset Hills cemetery, about a mile east of the junction with Oregon Highway 217.
The tunnel is named for William D. Robertson, who served on the TriMet board of directors and was its president at the time of his death.
Originally, it was expected that the westside MAX line would be adjacent to the Sunset Highway, despite the six percent average grade. Reliability, weather conditions, public opinion, and environmental concerns led to choosing to tunnel through the Tualatin Mountains instead.
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