As you travel along the Trans Canada Highway you'll have the opportunity to see one of the greatest engineering feats of the modren world - the Spiral Tunnels.
The Spiral tunnels were built by the CPR (Canadian Pacific Railway) in order to help negotiate the dangerously steep Kicking Horse Pass. When the original line was built through the Kicking Horse Pass, the grade was a steep 4.5% - the steepest railway grade in North America.
Unfortunately this resulted in many accidents as trains tried to climb the pass, or descend it, and the Spiral Tunnels were devised as an alternate method. The tunnels were built to curve around and spiral through the mountain and into the pass below, reducing the grade to a safer 2.2%.
The Spiral Tunnels can be seen from the Trans-Canada Highway (Hwy 1) and there is a very interesting display detailing the history of the tunnels, how they were made, and how the tunnels work. If you arrive at the right time, you may see a train using the tunnels. It's very neat to see as the train looks like a snake in a coil. Unfortunately though there isn't any consistent time when you'll see a train pass through, so it's up to luck.