Rocco Rossi says as mayor he would build a traffic tunnel from the south end of the Allen expressway, at Eglinton Avenue West, right into the downtown core.

Rossi vowed yesterday that, if elected Oct. 25, he’ll have construction on the “Toronto tunnel” started by the end of his four-year term.

Rossi said the megaproject would jump-start Toronto’s economic grow­th, reduce gridlock and encourage businesses to return to the downtown core.

His audacious plan — to be financed, he said, through a public-private partnership — essentially finishes, underground, a project that was cancelled in the 1970s.

Plans to continue the Allen above-ground as the Spadina Expressway all the way to Spadina and Harbord Street sparked a huge battle in the late 1960s, culminating with the cancellation of the project by then-premier Bill Davis in June 1971.

Rossi’s plan assumes that burying the expressway’s new incarnation would largely negate the old complaints that a new thoroughfare would destroy homes and neighbourhoods and cause pollution and noise.

The tunnel would have to be built under the existing subway tunnel, while entry and exit points would require building traffic cloverleafs and therefore the demolition of parts of downtown, said Councillor Adam Vaughan (Ward 20, Trinity-Spa­dina).

“You would have to bomb the downtown core and find another $30 billion or $40 billion to build it,” said Vaughan, whose late father, Colin Vaughan, successfully campaigned against the Spadina Expressway.