Rajan as you know parking is one of the problem that we face in our daily lives. First i'd like to question you how many times you have paid parking fee or tried to escape unpaid.
I think you got my point, even if there is a parking complex nobody is going to use that because we never follow rules. also such type of complex is not for the country like nepal. that is not the best use of land. Just compare the income of the parking complex and a commercial complex. The no. of vechicles in kathmandu is not large enough to run parking complex. This is good that you realized the problem but this problem is not so much severe than the problem that really exist in our society.
Best of Luck
I don't have too much comment on importance of parking complexes, other than to say that decisions are always complex and thus context and a proper needs assessment is required on a project by project basis.
That being said I can suggest how they can be built in a better way. I think parking complexes are the absolute best projects on which to institute green roof policies. From a load and an infrastructure perspective, most aspects are already in place given the nature of the structures - so it should really be a no brainer.
One particularly interesting example is the parking complex for the Aga Khan Museum and Ismaili Centre site in Toronto. The plans call for these two buildings important buildings to sit within the context of a an urban park that itself will contain several distinct gardens. Where is the parking complex you ask? That is what the park will be built on top of! You see, the two projects will require a serious amount of parking - so putting a green roof on top was the perfect solution to the problem!