For those interested in the REM in Montreal as a template; the Wikipedia entry on the project may be instructive:

https://en.wikipedia.org/wiki/R%C3%A...%A9tropolitain

To date the project has a running total cost of about 8B CAD or about or about 5.9B USD

The cost per km to build is around 120M CAD, thus far, while the final bill will likely be a bit higher, its also still likely to be well below the cost of a typical subway build.

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The builder merits a bit more of a mention. The builder is CDPQ Infra.

Which is the infrastructure arm of the Quebec Pension Plan [[the local answer to your Social Security).

Like the Canada Pension Plan, in Canada, gov't pensions which are fully funded, have been manage by active investment strategies. They've been builders of toll highways, investors in shopping malls and are stock holders in countless businesses.

That said, Quebec's pension plan [[and I don't say this in a bad way) has always had something of a political homerism to it. In that it sees its role as finding ways to boost Quebec business [[while making a return)

The important bit here though is that its a pension fund, which means it has a long time horizon on its investments. Its not a day trader, its looking at how its investments will produce returns for decades to come.