I see no radical worthwhile solutions there.
The best I could come up with was:
Priortising people over traffic flow.
Sending major roads underground and giving the space back to people.
Taking all road lanes in Zone 1 down to 1 lane and giving the other lanes to pedestrians/bikes.
Having lorries restricted from using all roads at certain times, and restricted from certain roads at all times.
Making zone 1 for non-motor vehicles only, and maybe installing a tram like system for those less fit.
Making Oxford Street pedestrian/mobility scooter/bike etc only, no motor vehicles, and instead have e-bike rickshaws or something like that.
.
.
I shall have to put my thinking hat on
, I maybe some time
.