Connaught Tunnel is an underground passageway.
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 . At the time it was built , the Connaught Tunnel was the longest railway tunnel in North America . 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 .