Spiral Tunnels

Two railway tunnels in Yoho National Park (BC) that solved the deadly “Big Hill” problem on the Canadian Pacific Railway main line through Kicking Horse Pass. Designed by CPR engineer J.E. Schwitzer, modeled on Swiss Alpine tunnels. Opened 1 September 1909.

The Big Hill (1884–1909). Major A.B. Rogers approved the route to save time and prevent bankruptcy. The CPR built a temporary track straight down the mountain; the steepest main-line grade in North America at 4.5% (standard heavy-rail is rarely over 1–2%). Runaway trains were frequent; the first construction train crashed into the river, killing three workers. Uphill trains required four steam locomotives to push them to the top.

The solution. By looping the track inside the mountains to double its length, the grade was cut from 4.5% to 2.2%. Construction: ~1,000 workers, 1.5 million lbs of dynamite, two years through granite.

How they work. The Upper Spiral Tunnel (~992 m) bores through Cathedral Mountain, dropping ~15 m over ~288°; the Lower Spiral Tunnel (~890 m) through Mount Ogden, dropping ~15 m over ~226°. A train enters, corkscrews inside the rock, and exits at a lower elevation. A long freight train (up to ~4,300 m) can wrap around itself; the locomotive emerging from the lower portal while the tail enters the upper portal above. Viewers can watch a train appear in three places at once.

Visiting. Lower Spiral Tunnel Viewpoint on the Trans-Canada Highway (Hwy 1); Upper Spiral Tunnel Viewpoint 2.3 km up Yoho Valley Road (toward Takakkaw Falls). Roughly 10 minutes west of Lake Louise. Mount Stephen and its Burgess Shale fossil beds dominate the view from Field.