That would be my number one suggestion too - largely removing cars from the Melbourne CBD. It has often been done in European cities, it could work here as well.
"An underground network for moving goods and waste on conveyor belts, transforming empty shops into free spaces for artists and a car-free Hoddle Grid are among the 50 big ideas to emerge from a major summit discussing what Melbourne might look like in 2050."
#Melbourne https://www.theage.com.au/national/victoria/the-cbd-s-future-is-car-free-and-open-all-hours-say-these-big-thinkers-20250509-p5lxvh.html