Before the tunnel's construction, Grand Trunk was forced to use time-consuming rail ferries to transfer cargo.

The tube had a diameter of 19 feet 10 inches (6.05 m) and hosted a single standard gauge track.

The Grand Trunk Railway used the locomotives to transfer both passenger and freight trains through the tunnel.

CN also assumed control of Grand Trunk Western as a subsidiary and the tunnel company and continued operations much as before.

After the World War II, railways in North America started to see the dimensions of freight cars increase.

Canadian National (identified as CN after 1960) was forced to rely upon rail ferries to carry freight cars, such as hicube boxcars, automobile carriers, certain intermodal cars and chemical tankers, which exceeded the limits of the tunnel's dimensions.

[2][3] The construction of the tunnel has also been recognized as National Historic Event by Parks Canada since 1992, with a plaque at the site.

The Canada-U.S. Free Trade Agreement was implemented in 1989 and discussions for a North American Free Trade Agreement between Canada, the United States and Mexico discussions were underway at that time (NAFTA was implemented in 1994).

It has a single standard gauge track that can accommodate all freight cars currently in service in North America; for this reason, the rail ferries were also retired in 1994 when the new tunnel opened.

[12] The Transportation Safety Board of Canada revealed that a modified gondola partial failure caused the car's trucks to become askew and a derailment.