Philly Reduced Its Public Parking Supply and More Spaces Opened Up

The Center City development boom reduced the number of public parking spaces by 7.2 percent between 2010 and 2015, according to the Planning Commission's 2015 update to the Center City Parking Inventory.

The inventory, which the Commission updates every five years, found that about 3,623 off-street public parking spaces disappeared during this period as several lots and garages were replaced by high-rise buildings. A "public" space in this sense is one than anyone can rent, as opposed to a private space that's exclusive to building tenants or employees.

One might guess that losing more than 3,600 parking spaces in a five year span would drive up occupancy rates in the remaining lots and garages, but on the whole this hasn't been the case. Counterintuitively, parking occupancy actually declined by 1.7 percent during this period, from 75.6 percent down to 73.9 percent. Parking occupancy peaked at 77.7 percent in 2005, so this is part of a 10-year decline.

The idea that building more parking capacity will only increase the number of cars in a neighborhood, or conversely, that removing parking spaces can reduce the number of cars often gets short shrift at neighborhood zoning meetings, but the evidence here suggests this is basically how things work.

When parking lots go away, parking conditions tighten, driving becomes more unpleasant, and some people respond to this by ditching their cars. Rather than enduring permanent traffic jam conditions, neighborhoods simply level down to a new equilibrium with fewer parking spaces, fewer cars, and higher "alternative" mode share as parking gets tighter.