The Cascade Tunnel
was a 2.6-mile (4.2 km) long single track railroad
tunnel at Stevens Pass
through the Cascade Mountains
approximately to the east of Everett, Washington
. It was built by the Great Northern Railway
in 1900 to avoid problems caused by heavy winter snowfalls on the original line that had eight Zig Zags
The first tunnel (started on August 20, 1897 and completed on December 20, 1900) had a problem with the smoke from the locomotives, because it was built with a 1.7% (1:58.8) gradient
eastbound and too close to the ruling gradient
. The tunnel was electrified
, with the project completed on July 10, 1909, thus eliminating the fume problem.
During the winter of 2007-2008, a section of the original Cascade Tunnel roof caved in and created a debris dam inside the tunnel, making it impassable to pedestrians due to standing water and ceiling debris. A warning was issued to stay clear of the western side of the tunnel for a distance of one-half mile for the indeterminate future.
John Frank Stevens
was the principal engineer on the switchback route and the first Cascade Tunnel. Stevens Pass
, the location of the first Cascade Tunnel, was named after him.
On March 1, 1910, an avalanche at Wellington
(renamed "Tye" after the disaster), the West portal of the original -long Cascade Tunnel, killed 101 people, the deadliest avalanche disaster in U.S. history.
New Cascade Tunnel
The New Cascade Tunnel
is a 7.8-mile (12.5 km) long single-track railroad tunnel at Stevens Pass
through the Cascades approximately to the east of Everett, Washington
It is the longest railroad tunnel in the United States and was constructed by the Great Northern Railway, being put in service on January 12, 1929. The new tunnel reduced the summit by (to an altitude of ) from the original tunnel, which had suffered problems with fumes, and was itself built to avoid problems caused by heavy winter snowfalls on the original line that had eight switchbacks.
It is currently part of the BNSF Railway's Scenic Subdivision between Seattle and Spokane. Amtrak's Empire Builder runs through it. Speed through the tunnel is .
The New Cascade Tunnel was constructed between 1925 and 1929 to replace the shorter, higher-elevation tunnel, which was still plagued by snow slides in the area. The new alignment is a straight-line tunnel running between Berne
. The gradient in this tunnel is 1.565% (1:64), with the rise from west to east. The gradient is 2.2% on the west side from the town of Skykomish. The railroad line was electrified between Skykomish
. 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 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 emergency/safety stations spaced every 1500 and 2500 feet (460 and 760 m) apart, depending on the location within the tunnel, that provide additional air tanks and equipment to be used in the event of a ventilation/other failure.
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.