The tunnel and the associated grade revision on the eastern approach to the pass lead to a significantly gentler slope for westbound trains. The new track separates from the old grade at Rogers (approximately 25 km east of the pass) and climbs at a lower grade. Numerous new bridges and the 1.9 km Mount Shaughnessy Tunnel were required to reach the pass. The Mount Macdonald Tunnel is 91 m lower than the Connaught Tunnel. On the west side of the pass, the Mount Macdonald Tunnel track rejoins the older line 5.5 km west of the Connaught Tunnel.