Design functional and attractive parking lots
Standing on the eighth floor of a downtown building, I looked out the window on a featureless parking lot filled with what seemed like match-box cars parked bumper to bumper. It was an ugly site. However, I also recall a different parking lot full of trees and flowers--an attractive place. The difference was in good planning for the fact that cars are part of everyday life. Increasingly we see underground parking and parking garages address the issue of vehicle storage. These compact multi-floor buildings fit in the urban infrastructure quite well. However, large asphalt and concrete parking lots are often unsightly.
Planning a good parking lot Each parking-lot design must first consider the safety factor. The parking lot is a place where the driver and passengers become pedestrians the moment they leave the car. Thus, pedestrians should have a clear indication of where it is safe to walk. Clear traffic flow is important so drivers follow a planned pattern as they look for a parking spot. In many parking lots, the roadway for cars is also the pedestrian walkway and the two don't mix. Therefore, safe sidewalks that lead the pedestrian from the car to the building or entrance are important.
The infrastructure of a parking lot--how to get from here to there and finding your car--is the most important part of the development of the landscape elements that ultimately make a parking lot visually more attractive and user-friendly. As much as on any other type of project, parking-lot landscapes should be functional. Do not simply drop a few trees in the ground to add some greenery. Trees, shrubs, groundcovers, turf and flowers should have a function. It may be to provide screening or to help define the size of a too-large expanse of concrete. Plants also can help direct traffic, soften glare, provide shade and block wind.
Plant compositions that include a mix of trees, shrubs and groundcovers in a relatively large bed (see figure, page C 13) create a good environment for plant growth, as opposed to a single tree in a small hole surrounded by concrete. Even in parking lots, it is important to understand the needs of plants. I remember consulting on a newly developed parking lot where the trees were dying. The owners had spent much money on plant material, and landscape maintenance had high priority. The trouble was that two companies were maintaining the grounds: one took care of the turf and another company took care of the trees. The underground irrigation system produced lush turf growth, which looked quite attractive in the parking lot. However, trees growing in these turf areas were literally drowning. The soil was clayey and held water, but above all, the trees were the wrong type. This, then, was a plant-selection problem. However, I saw it as going beyond that. Whoever developed the landscape plan and selected the plant palette should have created a composition of plants that needed similar growing conditions and supported each other. Too often we take singular plants and put them in a growing environment where they become stressed.
To dedicate more space for plants and landscaping is a difficult problem in parking lots where parking space is at a premium. Nevertheless, if we want to improve parking lots and make them more aesthetically pleasing, we need to provide more space for plant material and give more attention to plant needs.
Choosing plant material In selecting plant material, adaptability to the region and microclimate of the parking lot is of major importance. Also, be aware of tree forms--round, irregular, oval, vase-shaped, pyramidal, columnar or weeping. The pyramidal and weeping forms are of little use planted between rows of parked cars. However, in a composition where several trees planted together create a buffer or simple eye appeal, these growth forms can be quite useful. The same goes for trees that drop fruit such as nuts or acorns. You can only use these trees in a group as a design statement or as a buffer or screen.
When fruit could be a problem, select male trees. For example, the Kentucky coffee tree (Gymnocladus dioica) and Osage orange (Maclura pomifera), both strong, hardy trees, bear no fruit if you plant the male trees. If you use ginkos, be sure to use male selections--the female tree bears foul-smelling fruit.
I cannot stress enough that you must know the soil type and what has happened to the original soil during site construction. Soil is sure to be compacted, and the building contractor probably removed the topsoil. This is another good reason to leave pockets for trees or plant groups of trees to create plant compositions. The area is larger and therefore can hold more plants. It's easier for construction crews to leave the soil less disturbed and more practical to improve the soil over a larger area.
Larger tree groupings with understory plantings can cause problems with sight lines. Therefore, it is important to plan carefully for the location of tree compositions. Where a sight line is important, plant only groundcover beneath the trees, allowing for a sight line (see figure, page C 12).
Although I favor planting groups of plant material to break up the harshness of a large parking lot, I also encourage planting trees along sidewalks. This provides the necessary shade for pedestrians. The sidewalk should be wide enough for pedestrian traffic, and parked cars should not extend over the walk so that people cannot walk safely. I prefer trees along the south side of an east-west walk (see figure, page C 8). This way, the shadow pattern is advantageous for the pedestrian. Select deciduous trees to provide shade in summer and to allow warming sun rays to filter through in the winter to help melt snow and ice. The open crown of the male Kentucky coffee tree is a good example of this.
When selecting trees for a parking-lot planting, recognize weakly branched species for what they are--widow makers. The cottonwood tree, for example, does not belong on any parking lot unless it's well away from parked cars that would be damaged by falling branches. The same goes for so-called "trash" trees--trees that litter twigs and fruit. As much as I enjoy the oaks, I am reluctant to plant them near sidewalks or parked cars for the obvious reason that they drop acorns. On sidewalks, acorns can cause falls and injury to pedestrians, especially older people. They also pelt cars. It is yet another reason why I like to plant tree and shrub compositions that are plant communities by themselves and create small, green islands in large, open parking lots.
If shrubs are a concern for reasons of public safety (by providing concealment to criminals), then plant groupings of trees with masses of groundcovers underneath rather than automatically installing turf. Not having to mow around and among trees will result in less damage to them. Trash is another potential problem with groundcover plantings, but strategically located trash cans help control litter that otherwise might end up in plantings.
Where it's possible to use them, flowering annuals and perennials are attractive additions to any parking lot. The location and size of the planting bed are important. Keep in mind that the driver is looking for a parking place first, not at the landscaping. Therefore, beds must be large and colorful enough to be noticed without effort. The pleasure of the colorful flower display should be a subconscious experience, just like the parking area should be clean and have a solid surface with no potholes or faded stripes. All aspects of the lot should minimize irritation and frustration.
You can use the emotional effect of different colors for different types of businesses. Along pedestrian walks, use small-scale flower plantings with relaxing cool colors--the blues and grays--as opposed to brighter colors such as flaming red. Pastels--the softer colors--enhance more sophisticated establishments, whereas a fast-food restaurant or toy store could effectively use the brighter colors that speak to children.
Plan for maintenance The maintenance of parking lots with trees, shrubs, flowers and ornamental grasses goes well beyond just sweeping and cleaning the lot. The more sophisticated the planting, the more horticultural knowledge you need to keep the parking lot looking good. Therefore, consider the level of resources and expertise that will be available to the lot on an ongoing basis and match the complexity of the plantings to a realistic level of maintenance.
Because of potential liability and possible damage to trees from ice storms, especially in the North, regular inspection by a certified arborist may be necessary. In the short run, this may seem like a burdensome expense. However, in the long run, well-maintained trees are safer, enhance the experience of parking the vehicle and could even prevent expensive liability.
Where snow is prevalent, snow removal is an important part of parking-lot management. Because parking lots, by their nature, provide space, storage of piled snow is generally no problem. Snowplow operators simply push it into a pile. However, when designing a parking lot, you may wish to lay it out so that crews can easily push snow into holding areas. Where parking is at a premium, it may be necessary to haul snow off the site. If that is the case, make sure the entrances and exits to the parking lot are wide enough to handle the extra traffic of large snow-removal vehicles. If crews will use chemicals to melt snow and ice, keep harmful salts away from plantmaterial or select salt-tolerant plants.To handle melting snow and heavy rain, good drainage in parking lots is important. Cars driving through standing water can splash pedestrians. Another annoying experience is to park your car and then have to step into a puddle before reaching higher ground. Though often ignored, these factors are all common sense, just as providing proper lighting is.
It is the lack of eye appeal and functional landscaping of many parking lots which is my concern. To beautify a parking lot, designers have a tendency to only plant small flowering trees. As I have said earlier, I prefer more larger trees placed together in compositions, creating the natural edge effect: planting from taller trees to the lower understory plants, finishing with the planting of ground covers or similar plants.
Parking lots are a challenge inherent in the modern world. Whenever we aren't driving our cars, they need to be parked somewhere. Wherever we park our cars, we must walk to and from that point. If you can make that walk safe and pleasant, that parking lot will provide extra appeal to attract customers to a shopping mall or the pleasure of simply walking to and from a place of work. Don't think of this as an expense. It is an investment in a quality environment--healthy plants make happy people.
Gus van der Hoeven is professor of landscape architecture at Kansas State University (Manhattan, Kan.).
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