On the other hand, it would be feasible to convert roads into normally-pedestrianised areas, which you need a permit or a one-day pass to drive through.
There are numerous city centres in the UK which use this method. The central portion of Canterbury, Kent, is a great example.
Yeah, that sounds great. The amount and size of roads (and parking space) definitely can be reduced dramatically. Although I imagine this would be a massive endeavor for cities whose urban planning has been based entirely around driving/people owning cars.
Another alternative is allowing driving only at certain times, for example in Spain (and I guess in other places too) it's common to have pedestrianized areas with a few hours (say, from 8 to 10) where vans are permitted to enter for loading and unloading.
There are numerous city centres in the UK which use this method. The central portion of Canterbury, Kent, is a great example.