Four Different ‘Ps’ – Prope BY BILL ARONS


would serve as NorthwestAirlines’Detroit hub, and a parking garage.


I The garage was built


with 11,500 spaces, some of which were taken out of service after Sept. 11, 2001. Currently, the garage has 10,900 spaces, includ- ing short-term, long-term, valet and employee parking areas. Of those, 10,070 are available to the public, along with 7,000 short- term, long-term and econ- omy spaces in a garage and a surface lot at the North Terminal. Walker Parking Con-


sultants prepared the initial studies for the McNamara Terminal garage, and went back in 2007 to review sub- sequent growth and changes.


N1998,THEWAYNECOUNTYAIRPORT Authority embarked on a $1.2 billion termi- nal expansion project at DetroitMetropoli- tanAirport. The project included a new ter- minal (the McNamara Terminal), which


three hours) but “turn” spaces frequently, parking nearest the pedestrian bridge to the terminals was earmarked for this user group. Daily parking was located farther from the pedestrian bridges, and economy parking was given the most remote sec- tions of each level. Employee parking, too, was given a more remote location. The garage was built with 10 parking levels at roughly 1,620’ x 240’ each, for a total floor area of 3.748 million square feet. All floors are flat. The garage contains one pedestrian connection to the terminal, and moving walkways on one level.


Following Up At the time of the


McNamara Terminal Parking Facility - DetroitMetropolitan Airport


Establishing the Parking Facility Capacity Two different analyses were done to determine the best size


for the parking facility, and it turned out that the two approaches yielded similar results. One method was to review the airport’s parking revenue statistics and compare them with enplanement projections. Parking demand was related to “Detroit area” origi- nating enplanements to arrive at a parking generation ratio that could be used to project out to the future. This approach identi- fied a need for 11,000 to 12,000 stalls. Coming at the problem from the other side, we determined


the maximum number of parking spaces that could be provided within the available ground area and structure volume, as limit- ed by FAA height regulations. The airport authority wanted to make themost ofwhatever spacewas going to be used for park- ing, so planning to the physical capacity of the site made sense. We determined that the capacity would be approximately 11,500 stalls. Part of the challenge of planning the facility was determin-


ing the location of parking for different user groups. The design concept was tominimize the internal drive time plus the walking time for themajority of the parkers. Our study of user patterns in the parking system revealed that hourly parkers (“meeters and greeters”) and valet parkers generated 65 percent of the vehicles and 75 percent of the pedestrians. Because of the great percentage of total volume of traffic, and because these cars didn’t stay long (average stay is less than


18 APRIL 2009 • PARKING TODAY • www.parkingtoday.com


study in 1998, enplane- ments at the airport were 15.5 million. Northwest Airlines (NWA) accounted for 76% of this total (11.8 million). The NWA “local area” originations were 40% of its enplanements (4.72 million). NWA origi- nating enplanements were projected to grow to 7.6 million by 2020, an


increase of 61%. This information was utilized to project the future parking needs at theMcNamara Terminal parking facility. (Actual growth far outpaced the projection, as shown in the near- by Sidebar.) Further examination of data collected since our original


study revealed the following patterns: Long-term (LT) Parkers – Comprised 60% of all parkers,


with an average “length of stay” over three days. LT “turnover” was amaximumof 0.80 (on a daily basis). LT parking areas filled to capacity two to three days of a normal week. [The increase in LT parkers as a percentage of the total is a result of building LT parking so close to the terminal. Parkers who might otherwise use off-airport parking are likely to use such convenient long- termparking .] Short-term (ST) Parkers – Comprised 37% of all parkers,


with an average “length of stay” at three to four hours. ST parker “turnover” was a maximum of 3.65 (on a daily basis).When our study began in 1998, ST parkers accounted for 65 percent of the cars. In part, the drop is a result of restricted access for “meeters and greeters.” Valet Parkers – Comprised 3% of all parkers, with an aver-


age “length of stay” at two to three days.Valet parker “turnover” was amaximumof 0.70 (on a daily basis). Parkers Per Originating Enplanement – The ratio of on-air-


port parker per enplanement, at this terminal, was approximately 0.20 (one parked vehicle for every five enplaning passengers). This was true in 1997 also.


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