Finding A Parking Space Can Be A Science, Operations Research Study Shows

The first and more conservative strategy, called Pick a Row, Closest Space, turns out to be slightly faster. Upon entering a parking lot from any of its entrances, the driver selects a row flowing in the correct direction. The driver then proceeds to that row, enters it, and selects the closest available space. A second strategy, described with a more aggressive driver in mind, is referred to as Cycling: The driver enters the closest row to the entrance. If any of the 20 closest parking spaces are available, the driver selects the closest one.

Otherwise, the driver cycles to the next adjacent row. If any of the 40 closest parking spaces are available there, the driver selects the closest. Otherwise, the driver returns to the first row and parks in the closest available spot. A comparison showed that the average time spent by a driver using the first, speedier approach is 61 seconds. In contrast, the average time using the second approach is 71 seconds. Drivers who have trouble on their feet, though, should note that the first approach requires less driving but more walking.

In developing and comparing strategies for finding a space, the researchers considered three performance measures of what constitutes a good parking spot: (1) the total walking distance between the space and the mall's front door, including the distance walked to the door, back to the car after the shopping trip, and to return a shopping cart; (2) driving time in search of a space, and (3) a combination of 1 and 2: the amount of time to reach the front door after entering the parking lot.

For the purposes of this study, the authors considered a typical parking lot with four entrances, seven rows with 72 spaces each, handicapped parking, employee spaces, shopping cart return locations, and directional restrictions. A key assumption of both strategies is that drivers can identify empty parking spaces within a row as soon as they enter it.

The authors write that further study on parking strategy performance could be incorporated into sophisticated driver information systems that provide cars with real-time optimal parking strategies. Additional study could also help architects design parking lots that better satisfy users and better utilize available space.

The authors applied probability modeling, an operations research technique, to their analysis.

The study, "A Probabilistic Approach to Evaluate Strategies for Selecting a Parking Space," was written by two operations researchers, Dr. C. Richard Cassady of the Department of Industrial Engineering at Mississippi State University, and Dr. John E. Kobza of the Department of Industrial and Systems Engineering at Virginia Polytechnic Institute and State University in Blacksburg, VA. It appears in the current issue of the journal Transportation Science, a publication of INFORMS.

The Institute for Operations Research and the Management Sciences (INFORMS) is an international scientific society with 12,000 members, including Nobel Prize laureates, dedicated to applying scientific methods to help improve decision-making, management, and operations. Members of INFORMS work primarily in business, government, and academia. They are represented in fields as diverse as airlines, health care, law enforcement, the military, the stock market, and telecommunications. ***