Connaught Tunnel

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Connaught Tunnel, in the Selkirk Mountains under Rogers Pass on the Canadian Pacific Railway main line between Calgary, Alberta, and Revelstoke, British Columbia, at 5.022 miles (8.082 km) long was the longest railway tunnel in North America. Dug under Mount Macdonald (9492 feet or 2893 m) to ease growing traffic experienced between 1910 and 1913, it replaced the dangerous Rogers Pass route. It was named for the Governor General of Canada, Prince Arthur, Duke of Connaught.

Announced in February 1913, the contract was awarded on July 1, 1913, to Foley Bros. Welch and Stewart. A small tunnel was built, from which cross cuts were made to the main tunnel so work could carry on at a number of headings. The sub-contractor guaranteed to drill 900 feet (270 m) of tunnel per month and started on April 2, 1914. Compressed air equipment and narrow gauge locomotives were used inside the tunnel. The company town housed some 300 workers. The tunnel was completed before the original deadline, with operation beginning December 16, 1916. It had a grade of only 0.95 per cent westward, and was tangent; light at one end can be seen at the other, more than five miles away.

It cost $5.5 million, while a further $3 million were spent on track revision, which saw 14.5 miles (23.3 km) abandoned including the Loops and over four miles (6 km) of snow sheds. In all, the route was shortened by 4.3 miles (6.9 km).

Problems were encountered with ventilation, loose rocks and wet rails, which caused trains to stall. The tunnel was later lined with reinforced concrete and equipped with a better ventilation system. Originally double tracked, it was realigned with a single track in 1959 to accommodate higher freight cars.

In the late 1980s, the Mount Macdonald Tunnel was built to supplement the Connaught Tunnel and to lessen the grade on the eastern approach to the pass. Trains predominantly travel east through the Connaught Tunnel and west through the Mount Macdonald.

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The Spiral Tunnels (which in 1909 eliminated the dangerous Big Hill), Field Hill, Rogers Pass and the Mount Macdonald Tunnel and its associated grade reductions are other significant features in the mountain history of the CPR.