Cascade Tunnel
The Cascade Tunnel is a single-track railway tunnel and runs at Stevens Pass through the Cascade Range in North America. The name Cascade Tunnel refers to both the current tunnel between Scenic and Berne in the U.S. state of Washington with a length of 12.5 km and an older 1929 disused summit tunnel between Tye (formerly Wellington ) and the operating station Cascade Station with a length of 4, 2 km.
- 2.1 construction
- 2.2 Operation 2.2.1 Electrical operation 1929-1956
- 2.2.2 Operating since 1956
The old tunnel
The first tunnel replaced the old railway line through the Stevens Pass, which had eight switchbacks and difficult operation in the winter of heavy snowfall.
Construction
Construction began on 20 August 1897, led by John Frank Stevens, after whom the Stevens Pass is named. On 20 December 1900, the tunnel was put into operation.
Operation
The slope of the line was inside the tunnel 17 ‰, on the leading to the tunnel ramps 22 ‰. Especially cross -heavy trains could the tunnel therefore only passed slowly, leading to operational problems: Although the tunnel was created in east-west direction and contributed to the prevailing westerly winds for ventilation of the tunnel, the smoke of the steam locomotives pulled from poorly.
To solve this problem, the 6.4 km long section between Wellington and the operating station Cascade Station was electrified. The electrical operation began on 10 July 1909. The Great Northern Railway procured for their 4 first electric locomotives.
As current system three-phase alternating current was chosen with a voltage of 6,600 volts and a power frequency of 25 Hertz. The power supply was provided by a two-pole catenary and the rails as the third phase conductor. In this case, the neutral point of the three-phase system was insulated, so that it was safe to touch the rails. The electrical energy supplied to the purpose-built Tumwater Dam.
In 1927, the electrical equipment was extended in anticipation of the new tunnel under construction west to Skykomish. On this occasion, the three-phase alternating current system was abandoned, dismantled the two-pole overhead line and newly electrified track with 11 kV, 25 Hz AC voltage. The four three-phase locomotives were replaced by the electric locomotives of the Class Z -1.
Accidents and incidents
The operation of the tunnel was made more difficult in the winter due to extreme snowfall and endangered by avalanches. On March 1, 1910 96 people died in an avalanche disaster, the railway accident of Wellington, died. Two trains were torn valley. Wellington was then renamed to Tye.
Closure
1929, the old tunnel was shut down after the commissioning of the new tunnel. The tunnel still exists today, but is in danger of collapsing and therefore must not be entered.
The tunnel and the system of hairpins were taken in 1993 by the American Society of Civil Engineers in the List of Historic Civil Engineering Landmarks
The new tunnel
The avalanche disaster of Wellington was the impetus for the planning of the new tunnel. This is 153 m (502 ft) deeper than the old one and shortens the rail line to 14 km (8.7 miles).
Construction
Construction began on 28 December 1925 and were carried out by A. Guthrie and Company. The aim was to complete the tunnel before the winter 1928/1929 in order to reduce the time required to keep the avalanche galleries effort can. On January 12, 1929, the 25 million -US-dollar tunnel was put into operation. With a length of 12.5 km ( 7.77 miles ) of the Cascade Tunnel, making it the longest railway tunnel in the Western Hemisphere, while the third longest in the world.
Operation
The slope of the line is within the tunnel 16 ‰, for the remainder of the range up to 22 ‰. There were therefore provided with the same problems as the old tunnel.
Electrical operation 1929-1956
With the opening of the tunnel of the electrical equipment was extended in 1929 to the 117 km ( 73.9 miles ) long distance between Wenatchee and Skykomish in the east to the west. By the use of the classes Umformerlokomotiven Z-1 and Y-1 it was possible to feed back energy into the overhead line during braking. The class W -1 is the largest electric locomotives ever used in North America have been used on this route since 1946.
Operating since 1956
The electrical equipment should have been renewed in 1956. The Great Northern Railway decided to abandon the electrical operation and instead to invest in mechanical ventilation to make the tunnel for diesel locomotives passable. This eliminated the required until then re-clamping.
At the eastern tunnel portal a gate and a machine room for the tunnel ventilation system were built. The tunnel thus lengthened by 10 m. There are two fans installed with a capacity of 597 kW ( 800 hp ).
Once a train from the west enters the tunnel, closes the door and there is fresh air blown into the tunnel. In this way, the diesel engines of the locomotives supplied to cool, oxygen-rich air. As long as the train is in the tunnel, the fans operate at reduced power, because it would give too much of a difference in pressure between the tunnel and the outside air. The gate is opened in front of the train and closed again after the passage immediately. Then the fan run for 20 minutes on full power, to remove fumes from the tunnel. For trains the opposite direction to open the door if they are still about 1 km away.
The train crew leads respirators in the event that the ventilation system fails or the train in the tunnel comes to a halt. For emergencies, also are in the tunnel at a distance of 460-760 m ( 1,500-2,500 ft) oxygen cylinders and other equipment ready.
The speed limit in the tunnel of 40 km / h (25 mph). Given the aforementioned aeration process, the number of the tunnel passing trains is limited to 28 per day.
The Great Northern Railway came in 1970 in the Burlington Northern Railroad on. This in turn merged in 2005 with the Atchison, Topeka and Santa Fe Railway for BNSF Railway, from which the tunnel is operated today.
Through the tunnel service also operated by the Amtrak Empire Builder.
Accidents and incidents
On April 4, 1996, an eastward moving train broke through the gate after this had not opened on time. Injuries or deaths were not complaining. In autumn 2001, a derailed in the tunnel car damaged various technical institutions.