Robertson Tunnel

Robertson Tunnel
East portal of the tunnel in 2007
Overview
Line
LocationTualatin Mountains, Portland, Oregon, United States 45°30′38″N 122°43′01″W / 45.510661°N 122.716869°W / 45.510661; -122.716869
StatusOperational
SystemMAX Light Rail
StartGoose Hollow 45°31′09″N 122°41′59″W / 45.519087°N 122.699749°W / 45.519087; -122.699749
EndSunset Hills Mortuary 45°30′23″N 122°45′14″W / 45.506324°N 122.753833°W / 45.506324; -122.753833
No. of stations1
Operation
OpenedSeptember 12, 1998
OwnerTriMet
Technical
Line length2.93 miles (4.71 km) (15,450 feet)[1]
No. of tracks2 (double track)
Track gauge1,435 mm (4 ft 8+1⁄2 in)[2]
Electrified750 Vdc, overhead[3]
Operating speed55 mph (90 km/h)
Highest elevation605 feet (184 m) approx. 6,000 feet (1,800 m) inside west portal[4]
Lowest elevation220 feet (67 m) at east portal[4]

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[1] 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.[5] 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.[6] It was placed into service September 12, 1998.[7]

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.[8] 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.[9] 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.[10]

  1. ^ a b Light Rail and Modern Tramway, November 1993, p. 302. UK: Ian Allan Publishing/Light Rail Transit Association.
  2. ^ Mark Kavanagh. "Portland Transit–MAX Light Rail". Kavanagh Transit Systems. Archived from the original on March 29, 2007. Retrieved July 30, 2007.
  3. ^ Kinh D. Pham; Ralph S. Thomas; Xavier Ramirez. "Traction Power Supply for the Portland Interstate MAX Light Rail Extension" (PDF). Transportation Research Board. Retrieved July 29, 2007.
  4. ^ a b Trimet Capital Projects and Facilities Division (August 2011). "TriMet Portland to Milwaukie LRT Type 5 LRV, Contract No. RH120160BW Reference Drawings, Request for Proposal" (PDF). pp. 7–8.
  5. ^ "The world's deepest subway stations". The Moscow News. December 1, 2012. Archived from the original on March 1, 2014. Retrieved March 20, 2013.
  6. ^ "Awards & Recognition". TriMet. Retrieved July 30, 2007.
  7. ^ "Westside MAX Blue Line Project History". TriMet. Archived from the original on September 27, 2007. Retrieved July 30, 2007.
  8. ^ "Westside light rail—the MAX Blue Line extension" (PDF). Retrieved July 26, 2007.
  9. ^ "Portland MAX: East-West MAX (Blue)". world.nycsubway.org. Archived from the original on February 12, 2007. Retrieved August 3, 2007.
  10. ^ Sam's. "Tunneling and Civil Engineering". Archived from the original on September 27, 2007. Retrieved July 26, 2007.