Four O'Clock Factoid is a daily feature on Track Twenty-Nine helping to get you through the workday with a bit of useless knowledge.
The Spiral Tunnels are a feat of engineering in the Canadian Rockies. Constructed from 1906-1909, they became an integral part of the Canadian transcontinental railroad. The tunnels allowed the CP Railway's grade to be reduced from an untenable and unsafe 4.5% to 2.2%. Trains still run through the tunnels, including the Kicking Horse route of the Rocky Mountaineer, so it's possible for passengers to ride through the tunnels (as I have done).