I realized I have not answered the most basic question, “How many cars can you park”, but I have introduced the idea of “peak demand” and vehicle orientation. So to fully answer the question of how many, we need to understand how traditional parking has worked. Any driver that has parked in a traditional ramped parking structure has seen the height restriction notice upon entry.
In this example signage clearly states that the maximum height of vehicles is 8’-2”. However if you look at the underside of a traditional parking structure the ceiling height is closer to 11 feet or more. So if you factor in that that the average height of car is less than 5’-6” there is a significant amount of wasted space in a traditional parking structure volumetrically speaking. So if the average height is of a car is 5’-6” and a Fully Automated System uses only 6’-6” per level then in 33 feet of height in the same square footage a fully automated system parks 5 levels where a traditional approach parks only 3. This is what is meant by volumetrically; taking advantage of the height of a vehicle and building a structure that provides that minimum to park more vehicles.
Ramps, turn radius, drive aisles, passenger elevators, pedestrian stairwells and pedestrian walkways all eat valuable floor space. When these required accessories are added to any parking structure essentially a burden rate is fabricated. So each parking stall is not only the space for a vehicle it is also the space necessary for the previous list of required accessories. At the ICSC 2013 CenterBuild Roundtable Discussion we presented this topic to demonstrate per stall burden rate.
A Fully Automated Parking System is almost half the burden rate as traditional parking because it does not require passenger elevators, passenger walkways, turn radius, drive aisle and ramps. It is replaced with lifts, shuttles, storage areas (cells), and pallets.
So “How Many Cars Can You Park” is simply the combination of
Peak Demand – defined by intended use that drive system resources load bays, lifts, shuttles and cells
Site Specifics – above grade, subterranean, ingress, regress, vehicle queuing, pedestrian traffic, height restrictions, setbacks, soil conditions, adjacent buildings, access to the site, dimensions, traffic patterns etc.
Volumetrically Parking – levels set for the average height of a cars of 5’-6”
Burden Rate – a lower surface burden rate due to automation
Orientation – perpendicular or parallel
A quick rule of thumb – A fully automated parking system can park twice as many cars as a traditional solution. Remember this is only quick estimate and not a universal truth. At the Savannah’s subterranean level for example legally we could parked a single vehicle with a traditional method. Today with a fully automated system it houses 10 vehicles.
However if you are asking, “How many cars can you part on my site?” then we need to dive a bit deeper and discuss cell density.