‘The extension helped transform North York from mainly rural to urban,’ writes Susan Goldenberg

March 30 marks two very significant milestones for when the subway finally came to North York.

On March 30, 1973 the North Yonge subway extension to York Mills opened, and on March 30, 1974 the Sheppard and Finch stations followed — on the 20th anniversary of the opening of the original line from Union Station to Eglinton.

The extension helped transform North York from mainly rural to urban, by attracting enormous residential and commercial development. Discussion about it began in the 1950s, but it took two decades to complete — because of political battles, quarrels over the route, delays due to tremendous construction challenges, and strikes over hours of work and wages. The total cost was $140 million, equivalent to $1 billion today.

The first part of the extension was constructed by “cut and cover,” the way subways had been built from their beginning in London, England in 1890: a large, deep trench was “cut” for the track and stations, and then “covered” with a temporary or permanent road surface. Today, subway tunnels usually are dug by faster, huge “deep bore” machines that dig up to 80 feet per day, compared to as little as four feet by cut and cover. The northwest extension of Toronto’s subway system into Vaughan, opened in 2017, was done by deep bore.

At York Mills station, engineers redirected the Don River; because of the wet soil, the walls of the $8-million underground station were made thicker than normal and the floor of reinforced concrete, so the station wouldn’t float or crack.

North York pushed for a station midway between Sheppard and Finch — but although a level section was designed into the line at this point, the TTC refused to build it until the mid-1980s, when construction began on the North York Civic Centre at the location.

Written by Susan Goldenberg.

Originally published on March 28, 2019, on toronto.com.