Under Mount Macdonald is Connaught Tunnel.
Connaught Tunnel . The 5.022 mi tunnel carries the Canadian Pacific Railway main line under Mount Macdonald and replaced the railway 's previous routing over Rogers Pass , which had been struck by several deadly avalanches since its completion in 1885 . The Mount Macdonald Tunnel , located in the vicinity of Rogers Pass in the Selkirk Mountains of British Columbia , Canada , is a railway tunnel constructed through Mount Macdonald by the Canadian Pacific Railway ( CPR ) .