It's a proposal that's been thrown out seven times since 1955, writes the Toronto Star today. Once again, however, Toronto city council will talk about burying the Gardiner Expressway at its meeting today.

Construction companies Aecon Group, Dragados Canada and ACS Infrastructure Canada previously submitted a proposal to the city's executive committee for a 6.5 kilometre, two tunnel project that would cost $5 billion to build. It would be ready in approximately six years.

Proponents say it's a great opportunity for the city because it would not only free up land, but would reduce carbon emissions (and traffic) and motorists could continue using the existing Expressway during the construction period.

Others, such as city staff, are against this plan, noting it's multi-billion dollar price tag. And, as the Star reports, tunnelling by Lake Ontario is no simple task and could make the proposed project even more expensive.

What do you think of a Gardiner tunnel? Let us know in the comments.

Photo by Lori Whelan in the blogTO Flickr pool