Great Northern's electrification was used through the Cascade Tunnel in Stevens Pass, Washington. After the first 2.5-mile Cascade Tunnel opened in 1900, the railroad discovered that the heat and exhaust from the steam locomotives could asphixiate the crews. By 1909, overhead was installed and electric locomotives were used in the tunnel. Initially the electrics were only used between Wellington & Cascade Station, a distance of about 3 miles, but over the years the overhead was extended, evenutally stretching 72 miles from Skykomish to Wenatchee. When the new 8-mile Cascade Tunnel opened in 1929, it was also electrified. In the 1950s, Great Northern installed a ventilation system with a door and powerful fans at the east portal to blow exhaust out the west end. This allowed diesels to be used in the tunnel and the electification ended in 1956. The electrics were used on all trains, freight and passenger, through both tunnels. The orientation of the old tunnel gave it some natural ventilation from the wind, and the electrics sometimes simply helped the steam power through so they didn't have to work hard and create a lot of heat and smoke, but some trains were powered solely by electrics. The extreme length of the new tunnel meant steam power was effectively banned from it, and the steam and later diesel power would be cut off and replaced with electrics, and new conventional power put on at the other end. Great Northern had heater cars built to generate steam heat for passenger trains when pulled by the electrics. The electrification was powered by a dam in the Tumwater Canyon, on the east side of the pass. The dam is still there and can be easily viewed from Highway 2. About the time of the new tunnel, another powerhouse was built in Skykomish. For more information and photos, I have a webpage about Stevens Pass at
http://myweb.msoe.edu/~westr/stevens.htm.
