Parking lots and parking decks usually have a finite amount of space available for vehicles. It may not be economically feasible to extend the boundaries of a parking lot or construct another parking deck. One viable solution to this parking problem is called stack parking. Traditional stack parking involves trained car valets parking cars bumper-to-bumper in a regular parking structure, but there is also a high-tech form of this parking which uses hydraulic lifts and a significant amount of engineering skill.
If a venue or institution offers stack parking, it is generally an alternative to self-parking in distant locations or metered parking. The driver pulls up to a designated location and hands over his or her car keys to a valet. The valet, often working in tandem with other parking attendants, drives the vehicle to a reserved parking area. Since the parking area is usually restricted to authorized valets, they are free to park the cars as close together as possible. If a car's owner needs to reclaim his or her car, the valets can move several cars at once to release it. Otherwise, the cars remain parked until the event is over and the cars can be driven out in order.
Stack parking is not always an ideal arrangement for drivers who may need to leave an event early or cannot wait for the valet's return after the event. This type of parking works best when the driver knows he or she won't be returning for the car for a significant length of time. Students attending large urban campuses, for example, may allow their cars to be stacked in a university-owned parking deck rather than pay for metered city parking or fail to find a space in student parking lots.
Another type of stack parking involves an elaborate hydraulic system and a considerable amount of investment for the owners of the site. This high-tech version first involves excavating a very deep hole on the property. A complex hydraulic system with individual slots for vehicles is then installed over the reinforced void. A hydraulic stack parking system can be three or four decks in height, and some can be moved vertically or horizontally with powerful hydraulic lifts.
A trained parking attendant may be assigned to park a customer's car in a designated slot, or the driver may be given a set of keys to operate the hydraulic lifts himself or herself. Once an empty slot is maneuvered into place, the valet or driver parks the vehicle and exits the stack parking system. When the driver is ready to leave the venue, the decks are raised or lowered until the desired vehicle is on the ground level. This type of system maximizes the amount of available parking by literally stacking three or four cars in the space traditionally occupied by a single vehicle.
One of the main drawbacks of a hydraulic stack parking system is the slowness of the retrieval system. It could take a significant amount of time for a stacked car to reach ground level, especially if the parking system moves both vertically and horizontally. This type of parking may be a viable solution to a limited parking situation, but drivers may have to learn a new set of coping skills as they wait for their vehicles to reach the ground.