Parking and the earth's pull

Noone has missed that Tokyo is tight for space and so many cars and bicycles need to be parked. A considerable amount of people commute with train + bike and it can be really difficult to find a good place to park since it is usually forbidden on the streets anywhere close to a station. A shared trait seen in the many optimistic solutions to the problem seems to be a deep disrespect for gravity, something that applies for many other areas in Tokyo as well such as highways, lifted buildings and homes built on existing rooftops.