Claim: Connaught Tunnel is under a mountain range.

For the Connaught tunnel in East London , England , see Eastern Counties and Thames Junction Railway  The Connaught Tunnel is a railway tunnel under the Selkirk Mountains in southeastern British Columbia , Canada , near the city of Revelstoke . 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 . It was named for the Governor General of Canada -- the Prince Arthur , Duke of Connaught -- who in turn was named after the province of Connaught in Ireland .   Announced in February 1913 , the contract was awarded on July 1 , 1913 , to Foley Bros. . Welch and Stewart . The tunnel was designed by John G. Sullivan who joined the Canadian Pacific Railway in 1900 and eventually became Chief Engineer for Canada . 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 ft 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 mi abandoned including the Loops and over 4 mi of snow sheds . In all , the route was shortened by 4.3 mi .   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 now predominantly travel east through the Connaught Tunnel and west through the Mount Macdonald Tunnel .   In 2001 , the Connaught Tunnel was inducted into the North America Railway Hall of Fame . The Hall of Fame recognizes and establishes an enduring tribute to the people and things that have made significant contribution relating to railway industry in North America . The Connaught Tunnel was inducted in the `` Facilities and Structures '' category with `` National '' significance .