Austin's consultants are turning out reports faster than I can digest them.
ROMA's proposal for a permanent density bonus program downtown is worth a read. The ultimate recommendation -- make residential developments pay bonuses for extra floor space -- is a bad one. But the report contains some interesting tidbits, including this description of how parking requirements dictate building size:
It will be difficult to take advantage of a density bonus if the subject site is less than one-quarter block, as incorporating structured parking becomes extremely inefficient (space consumed per parking space yield is very high) and therefore costly. Off-site parking provisions made possible through a parking management or enterprise may change this in the future.
Current market and financing-driven parking practices which lead to high numbers of on-site parking spaces being required and built limit the ability for projects to achieve densities significantly above what the existing zoning prescribes. This is due to a number of things. First, few developments will build more than nine or ten floors of parking, as beyond this, accessing parking becomes cumbersome and inconvenient for the building users. Second, providing suburban or near-suburban parking quantities can cause projects to reach their height maximums sooner, which has the effect of reducing the amount of habitable space possible. Third, at some point the sheer cost of providing onsite structured parking becomes a deterrent to providing more habitable space/density.
In other words, figure out how much parking you can build and then you'll know how much you can build of whatever it is you want to build.
I worked in downtown Houston right out of law school in the third tallest skyscraper in the United States outside of New York City and Chicago. It had a paltry amount of parking, all below grade. We plebes schlepped through the tunnel to a parking garage a couple blocks away.
Houston by any measure has tons of downtown parking, but I don't recall every tall building in downtown Houston being erected in a big bathtub of parking. Downtown Houston developers have somehow managed to figure out how to share parking (or have relied on their tenants to figure it out). In Austin, though, each new development is built as if there were not another parking garage around for miles in any direction. We might have more parking spots downtown than workers.
ROMA says the market or lenders are driving developers to build more than the city requires. That's consistent with my three-project "survey." Some bright entrepreneur ought to figure out how to help these developers share.
