Cascade Tunnel
From Wikipedia, the free encyclopedia
The Cascade Tunnel is a 7.8 mile (12.5 km) long single track railroad tunnel at Stevens Pass through the Cascade Mountains approximately 65 miles to the east of Everett, Washington. It is the longest railroad tunnel in the United States. It was built by the Great Northern Railway in 1929 at a lower elevation than the original, 2.6 mile (4.2 km) tunnel which had suffered problems with fumes, itself built to avoid problems caused by heavy winter snowfalls on the original line which had 8 Zig Zags (switchbacks). It is currently part of the BNSF Railway system on their mainline between Seattle and Spokane. Amtrak's Empire Builder runs through it.
Contents |
[edit] History
The first tunnel had a fume problem because it was built too steep and too close to the ruling grade. The tunnel was electrified by 1909, which eliminated the fume problem.
The second Cascade Tunnel was constructed between 1925 and 1929 to replace the shorter, higher-elevation tunnel which was still plagued by snowslides in the area. The new alignment is a straight-line tunnel running between Berne and Scenic. The gradient in this tunnel is 1.7% (1 in 58) with the rise from west to east. The railroad line was electrified between Skykomish and Wenatchee. New electric locomotives were used in this portion which were again powered by overhead catenary.
In 1956 the electrification was removed. However the great length of the tunnel plus its steep gradient meant that the fume problem resurfaced. So a ventilation system was provided. As a train enters the east portal of the tunnel, doors close behind it and huge fans blow in cool air through a second portal to help the diesel engines. As long as the train is within the tunnel, the fans work with reduced power to avoid pressure problems. After the train has left the tunnel they operate for 20-30 minutes with maximum power to clear the tunnel of exhaust before the next train passes through. In the opposite direction the door opens when the train is about 1000 m away from it. Present-day train crews carry portable respirators for use in the event of a fan failure or a train stalling inside the tunnel. In addition there are stations spaced every 1500 and 2500 (based on location in tunnel) that provide additional air tanks and equipment to be used in the event of a failure.
[edit] Engineer
The principal engineer on the switchback route and the first Cascade tunnel was John Frank Stevens, after whom Stevens Pass was named.
[edit] Accidents
On March 1, 1910, an avalanche at Wellington, the West portal of the original 2.6 mile-long Cascade Tunnel, killed 101 people, the deadliest avalanche disaster in U.S. history.
On April 4, 1996, an eastbound freight train broke through the doors at the east portal after they did not open properly. There were no injuries but the broken doors slowed operations for a couple days while replacement doors were brought up from the Seattle area.
In Fall 2001, a single car derailed in the tunnel and was dragged the rest of the way out. It ripped out wiring that was attached to the sides of the tunnel.
[edit] References
- Legg, John F.. UCRS-Reference (GN Stevens Pass). Retrieved on February 25, 2005.
[edit] See also
[edit] External links
- University of Washington Libraries Digital Collections – Lee Pickett Photographs Over 1400 photographs documenting scenes from Snohomish, King and Chelan Counties in Washington State from the early 1900s to the 1940s. Includes images of the Cascade Tunnel construction.
- Cascade Tunnel # 15 - Pictures and details of the Fanhouse at the east portal of the tunnel
