I believe this may be a rumoured tunneled widening of the 401 through Central Toronto. The PCs had some telephone polling on it a while ago, apparently in partnership with
Transurban, an Australian company which has built many of the tunneled highways in Australia. Transurban already operates a toll bridge in Montreal, so they do have a presence here.
I imagine it would be tolled to finance it as it would be ridiculously expensive.
I also wouldn't put too much stock into it actually happening as it would be insanely expensive and likely not supported by other parties, which would be basically required to get it to construction, unless the PCs have an illustriously long term in government.
With regards to funding levels for roads - Ford is actually spending about the same as Wynne did on the provincial highway network ($2.8 billion annually). He just likes to advertise it a lot more.