熊谷組
On October 5, 1984, the Manning-Kumagai (MK) joint venture (comprising Manning Construction and Kumagai Gumi) began from the west portal. Using the drilling and blasting method, 30 men, rostered in 3 shifts, completed eastward. Meanwhile, the highway was temporarily relocated to construct a long reinforced concrete box in a cut-and-cover trench. This structure carries both the highway and protects the portal from avalanches. In 1985, the words "Mount Macdonald Tunnel 1988" were stamped into the concrete cladding above the portal. The eastern work camp was near the Mt. Shaughnessy Tunnel, and the western one at Flat Creek. A third camp for summer surface workers existed near Rogers.