Some tunnels in Australia and Canada...

 https://en.wikipedia.org/wiki/List_of_tunnels_in_Australia

Despite having a smaller population than Canada, Australia seems to have more urban highway tunnels than Canada has.

https://www.cbc.ca/news/canada/toronto/highway-401-tunnel-study-1.7523029#

HOV lanes & express bus tunnels would help to relieve the surface route. 

https://www.cbc.ca/news/canada/toronto/401-tunnel-cost-1.7464404

A truck lane system could also speed up shipping & efficiency.

https://nationalpost.com/news/canada/ford-carney-highway-401-tunnel

https://www.thetrillium.ca/news/municipalities-transit-and-infrastructure/we-wont-be-using-it-premier-ford-suggests-hell-die-before-401-tunnel-is-built-10652845

https://canada.constructconnect.com/dcn/news/government/2024/09/highway-401-tunnel-expressway-could-become-a-reality

https://toronto.citynews.ca/2024/09/25/ontario-highway-401-doug-ford-tunnel-proposal/