The User Experience

From a superficial perspective, most automated parking systems seem to function in a similar manner. The parker drives into an available parking bay and is guided by sensors and digital signage to park in the center of the parking bay floor. He or she exits the vehicle and walks out of the parking bay to a kiosk on the wall, where they may be asked to estimate their time of departure. Regular users can either swipe a parking pass or enter a personal code, while transient users will be issued a paper ticket for identification purposes.

At this point the parker leaves, the exterior parking bay door closes, and sensors check to make sure nobody is inside the parking bay. Once cleared for storage, the automated machinery removes the car from the parking bay, often depositing it on a lift, which carries it to the storage level, where the machinery stores the car. Vehicles will often be turned 180 degrees at some point in the process so they are ready to be driven straight out of the parking bay when exiting.

Upon returning, the customer scans his or her card, enters a code or inserts the paper ticket, which signals the system to retrieve the car. In a matter of minutes, the customer's ding-free car is delivered to a nearby parking bay, facing outwards, making it easy to drive away.

Retrieval times typically range between 1 and 5 minutes, with an average of about 2.5 minutes, which is similar to the amount of time required to retrieve a car from a conventional ramp-access garage. The actual retrieval time depends on a number of factors at the time of each retrieval request, including but not limited to: the number of paths of lateral movement, location of the target vehicle, the current occupancy level, and number of overlapping retrieval requests.

Car owners like to use automated parking systems because, instead of requiring parkers to drive around and around hunting for a space, they now have immediate access to a conveniently located VIP parking space. Other advantages include being safer for both the driver and the car; no traversing across silent, darkened, exhaust-polluted garages; no backing and turning to squeeze in and out of a tight space; no scratches, dings or dents; no theft; and, since drivers keep their keys, no worries about joyriding or privacy violations by garage attendants.

Different Approaches to Automated Parking

Given the high frequency of vehicle damage and personal assaults in ramp garages, along with the inconvenience of driving around and around hunting for a space, one would think that automated parking systems, which are far more safe and convenient, would be far more prevalent today.

The aforementioned functional description is nearly identical for all automated parking systems; however, the various systems that have evolved over time, differ dramatically in how they perform these tasks. Each approach to automated parking results in fundamental differences in cost, reliability, and performance, which must be understood before implementing this technology in a development project.

“Mono-Path” Automated Parking Systems

The first- and second-generation automated parking systems, each of which will be described in more detail, have been broadly adopted in Asia and to a lesser extent in Europe. The movement of the vehicle transportation machinery varies in each successive generation of technology and has a material impact on the capabilities and performance of the system; however, as their name suggests, “mono-path” automated parking systems are all distinguished by their having a single pair of rails through the center of the system along which machinery would ride to store and retrieve the cars (i.e. its “path”).

Advantages of all mono-path systems include:

• Vertical and visual transparency, which can create interesting designs by exposing the vehicle rack and mechanical movements.
• In a few municipalities, mono-path systems are treated as a single floor for FAR requirements much like a warehouse. (FAR or floor area ratio is the ratio of the building's total floor area to the size of the parcel of land it stands on.)

Unfortunately, mono-path systems have been slow to catch on in the U.S. because conservative developers and traffic engineers have been concerned that the mono-path design of first- and second-generation systems will cause bottlenecks to form when processing simultaneous transactions. This, in turn, limits these systems' hourly throughput, and in the event of certain mechanical failures, may take them offline altogether.

Those who were willing to ignore the fact that systemic design limitations could cause limited or no functionality, often encountered difficulties securing approvals. The open atrium typically found in the middle of many mono-path systems allows fire to spread rapidly and could represent a significant life safety hazard to firefighters who must extinguish a car fire in the upper levels of the system.

First-generation “mono-path” rolling hoist systems process transactions serially (one car at a time). Image courtesy of Boomerang Systems, Inc.

First-Generation Mono-Path Systems

The first generation of mono-path systems use a rolling hoist that follows rails mounted in the floor and ceiling of the garage. These devices move laterally and vertically at the same time and then move longitudinally to store and retrieve the target vehicle. They are actually very fast for one transaction, but they have a number of significant limitations.

Disadvantages of first-generation mono-path systems:

• They can only process one transaction at a time, so queues form instantly.
• If the system is down for maintenance or there is a mechanical failure, the entire facility is shut down.
• The floor-to-ceiling central atrium allows fire to spread easily and poses a life safety threat to fire fighters, thus making approvals of these systems very difficult.
• Erecting the rack is complicated and requires specialty construction methods.
• If the structure shifts or the steel rail expands causing misalignment of the rails, the system may be crippled or unusable.
• This is a single-purpose structure that will be difficult to repurpose if the technology is ever obsolesced.