I would think that contractors need to dig a deep hole to ensure the foundations of the building are secure - get into the bedrock, especially in earthquake zones.
Whether the car parks are below or above ground is moot.
That said - The High Cost of Free Parking (1) and The Walkable City (2) are both excellent reads on the matter of parking and car parks. The second is the more readable.
I would think that contractors need to dig a deep hole to ensure the foundations of the building are secure - get into the bedrock, especially in earthquake zones
Not necessarily, spread footings or piles can work if designed properly and the soil can support it.
That said - The High Cost of Free Parking (1) and The Walkable City (2) are both excellent reads on the matter of parking and car parks. The second is the more readable.
(1) http://www.amazon.com/High-Cost-Parking-Updated-Edition/dp/1... (2) http://www.amazon.com/Walkable-City-Downtown-Save-America/dp...