The Connaught Tunnel is in southeastern British Columbia, on the Revelstoke–Donald segment. The tunnel carries the Canadian Pacific Railway (CP) main line under Mount Macdonald in the Selkirk Mountains, replacing the previous routing over Rogers Pass. History Summit route deficiencies Traffic restrictions imposed by a single track comprising of 2.2 percent gradients, emerging competition, and snow-related costs, were negative factors. The 1910 Rogers Pass avalanche, and other avalanches on the pass, influenced, but did not unduly pressure CP to consider alternatives. However, snow clearing and maintaining snow sheds was an ongoing burden. Rarely assigning more than one pusher locomotive per train, trains over 1,016 tons had to be cut. Higher capacity locomotives had helped, but the next leap forward would not occur until the Selkirk locomotives emerged in 1929. In 1912, the average eight trains (peaking at 11) per day in each direction, were forecast to double over the next four years. The program to double track much of the route through the mountains could create a bottleneck at Rogers Pass. Following the 1906–1908 recession, by 1912, passenger and freight volumes surpassed records. Whereas passenger train length could increase, freight could not, because of weight capacity limits. Furthermore, the former had priority, causing siding waits for the latter. The opening of the Grand Trunk Pacific (GTP) would pose a threat to CP's grain and Asian trade. Using a single locomotive, GTP could haul 2,041 tons from Edmonton to Prince Rupert, via Yellowhead Pass, four times the weight CP could haul across the mountains on its main line. The opening of the Canadian Northern Railway (CNoR) via the Yellowhead to Vancouver, the premier destination, prompted greater alarm. The opening of the Panama Canal, which would bypass all North American rail routes, offered some compensation in that grain traffic destined for Europe could travel westward by rail. Prior significant improvements in the mountains In 1902, the Ottertail Diversion, west from Field, eliminated the need for pushers. In 1887, after a tunnel collapsed near Palliser, the temporary realignment around a bluff of the Kicking Horse River existed until the Palliser Tunnel (1906). In 1909, the Spiral Tunnels replaced the Big Hill. Alternatives Routes The three basic options within the Selkirks were via the Big Bend, double track the summit, or a tunnel. The Big Bend route was not a viable contender. Estimates indicated a tunnel would be cheaper than snow shed and operational