Think about it. Why are the roads one or two floored? Why can't we have multiple floored roads that allow traffic in huge number.
I'm thinking a setup like they do for show-off purposes in bars where they put glasses in pyramids and let the drink fall.
Similarly if we start with roads 32 lanes wide and higher road 16 lanes and such till we have 4 lane on top, we have got 4 floored roads.
One of which can exclusively be used by commercial vehicles, one by pedestrians and cyclists and differently abled etc.
Also put city lungs around them people can jog in peaceful area, drivers can take break and everyone gets fresh air.
And rain ruins roads, why not cover roads with solar panels.