Vancouver Mayor Gregor Robertson is promising that the construction of any new underground subway line along the Broadway corridor will not be "cut-and-cover."

"I don't think it's possible to do cut-and-cover and, certainly, I won't be supportive of that as mayor. As long as I'm mayor with a council majority, we won't let that happen," Robertson told reporters Tuesday.

During the construction of the Canada Line, a "cut and cover" method was used for parts of the subway, which involved digging a deep trench to lay the tunnel. (CBC)

Cut-and-cover construction was used on Cambie Street to build the Canada Line ahead of the 2010 Olympic games. It was originally supposed to be a bored tunnel, but the plan changed.

With cut-and-cover tunnel construction, a trench is dug out, a tunnel built and it is the covered off. When that happened along the Cambie corridor, a number of businesses suffered from the disruption.

There's now a class action lawsuit underway with 200 co-plaintiffs who blame those who built the Canada Line for causing an unreasonable disturbance to them by opting for the cheaper construction method.

For the Broadway Subway line to go ahead, a transit referendum must pass next spring. That would put into motion a multi-billion dollar regional transit plan that would include budgets for more regional buses, rapid rail in Surrey and the new subway.

Robertson said his counterparts already know that Vancouver is aiming for a bored construction for the line.

"The mayors in the region agreed to a tunnelled Broadway subway. That is part of the 10-year plan," he said.

If everything goes according to plan, the first trains could be running in 2020 or 2021.