I'd like to see the feasibility study recommend an express rail line (something like London's Elizabeth Line) that only stops where it connects to other rail services, and not recommend a vehicular tunnel.
There are millions of origin-destination pairs for which the only currently feasible mobility mode is driving on the 401 (unless you're prepared to pay 407 tolls). For example from the western suburbs to employment centres along the 404/DVP, or from eastern suburbs to the airport employment lands.
Line 5 will help moving folks from Mid-town Toronto to the airport, and from Brampton to the offices at Laird/Don Valley but there will still be large areas north of Eg. that are unserved by fast E-W transit. Give people a practical way to move across the GTA, outside of Mid-town or Downtown Toronto and they'll be happy not to drive.
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