Spiral Tunnels

R.L.Kennedy

Article 1908 page 1 and page 2

Retouched photograph shows location of two spirals. Westbound train is leaving 179-foot tunnel at Mile133.1 on new line. Abandoned line to the right in center of photo. Canadian Pacific Archives

When the Spiral Tunnels of the Canadian Pacific Railway were opened to traffic on August 25, 1909, they were hailed as one of the engineering wonders of the day. Inspiration for this was the Baischina Girge tunnels of the St.Gotthard Railway in Switzerland. John Edward Schwitzer, Senior Engineer Western Lines, Canadian Pacific Railway, was the designer.

In 1884, when Canadian Pacific Railway construction crews first encountered the Kicking Horse Pass they found at the summit a staggering drop with no room in either Kicking Horse Canyon or the Yoho Valley to lengthen the line so as to reduce the gradients. To save time and money the tracks were laid in a steep descent from the top of the pass to Field, dropping 237.5 feet to the mile (4.5%).

Early railroaders named this hazardous stretch the Big Hill. They often worked in blizzards with temperatures dipping to as low as -30°C to -40°C. There was the persistent danger of avalanches and rock slides as well as stalled engines and runaway trains.

By the early 1900s increased traffic over the line made it imperative that something be done about the bottleneck caused by the Big Hill. Engineers were faced with the problems of space due to the steep mountainsides on both sides of the divide. A number of options were considered, other passes were examined in 1902 and 1905 including ones ignored earlier. One such pass was Howse Pass, about 30 miles longer but, offering a lesser grade. This has first been passed over by Major Rogers who considered it unsuitable although he did send off one of his men, Tom Wilson, a young packer to whom he gave a $50 bonus to look it over. Typically under provisioned he was unable to do a thorough job when he wound up starving and nearly dying. Electrification was considered including building a hydroelectric plant on the Kicking Horse River. Likewise discarded was a ten mile tunnel from the crest of Kicking Horse Pass to Field.

The problem was solved by creating two spiral tunnels into the two mountains to gain the track length needed to reduce the grade to an acceptable degree. The result of the project was that the tunnels reduced the gradient of the track from as steep as 4.5% down to a maximum of 2.2%. The spiral configuration increased the length by 8 miles (12.5 km) . With this improvement, two engines of the same class as the four previously required could haul even heavier loads over the pass by means of this Canadian engineering marvel. It also eliminated a dangerous and costly to operate line that was originally intended to be temporary, yet lasted nearly a quarter of a century.

Map of Spiral Tunnels

The rail line, going west from Hector to Field, encounters first the Upper Tunnel, or No. 1, as the railroaders call it, which cuts 3255 feet (992 m) into Cathedral Mountain, turning through an angle of 288° and passing under itself to emerge 48 feet (15 m) lower. The track then snakes northeast, crossing the Kicking Horse River and entering the Lower Tunnel, or No. 2, in Mount Ogden. This tunnel is 2922 feet (891 m) long with a curvature of 226°, to emerge 50 feet (15 m) below the entrance and continues westward. In this intricate system of spiralling track the trains run through the valley by three lines at different elevations and cross and re-cross the river by four bridges.

Lower Spiral Tunnel under construction, 1908. Glenbow Archives NA 4598-7

The monumental task entailed cutting through crystallized limestone of a widely distorted nature. Hardness and brittleness of the rock varied every few feet making drilling operations extremely difficult. These problems were aggravated by water seepage through the rock crevices which hampered progress on the downgrade ends of the tunnels and the high altitude (about 5000 feet or 1500 m) and severe winter weather that compounded the already adverse conditions under which the men worked.

Narrow gauge (36") construction train of contractor MacDonnell and Gzowski Construction Co.

Engine 15 is one of two 2-6-0's acquired from the Alberta Railway and Coal Company for this work.

Telegram sent May 5, 1909 to CPR President advising of "holing through" of both tunnels.
Canadian Pacific Archives

The new line through the Spiral Tunnels, considered an engineering marvel, opened to traffic on August 25, 1909, ending use of the dangerous "temporary" Big Hill line. While adding three miles to the line it reduced the heavy 4.5% grade to 2.2% still a steep grade for a main line.

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