A Guide to Planning for Community Character
By Lane H. Kendig, Bret C. Keast
ISLAND PRESS Copyright © 2011 Lane H. Kendig
All rights reserved.
The rich literature on urban design, from the nineteenth-century Austrian architect Camillo Sitte to today's New Urbanist writers, treats only one of the three urban types, urban, excluding the other two, urban core and auto-urban. A new approach is needed to create vibrant and inviting urban environments. The creation of new development with an urban character is severely threatened by the demands of modern uses and the dependence on automobiles. The automobile must be parked, and if that is at-grade parking, the practice threatens to destroy the enclosure that is the essential element of urban character. The result of at-grade parking design is auto-urban character. In addition to the changes brought about by the automobile, the scale and market area of uses has changed dramatically, stimulating the demand for new building forms. Small neighborhood shops have been replaced by larger stores, which are needed to provide the huge array of goods to which modern consumers have grown accustomed.
Auto-urban grew in response to the changes mentioned above, but because these areas evolved without a design concept, a great many are considered to be unattractive even though they are where a significant portion of the population shops. Urban cores also grew without any design guidance and need to deal with automobiles. The challenges facing planners in the twenty-first century—global warming and the dependence on fossil fuels for energy—suggest that a great deal more development and redevelopment needs to be urban or urban core, rather than auto-urban or sub-urban.
The concept of enclosure is essential to urban and urban cores because it is a measure of the space created for pedestrians. In all urban-type environments, a pedestrian precinct is essential. Historically, the streets and squares that made up the pedestrian precinct were largely pedestrian ways that only occasionally carried vehicular traffic (fig. 1-1) or pack animals. For urban and urban core, the goal should be to return the pedestrian precinct as much as possible to an area where pedestrians do not have to compete with cars to use the space.
Auto-urban uses at-grade parking, which means 65 to 85 percent of the land is used for parking lots and roads. While a whole host of strategies can be used to make auto-urban appear better or to provide small areas of enclosure within the auto-urban environment, these are cosmetic treatments that do not fundamentally change the ratio of building to total land. No matter the design, one must walk from a car through a parking area to one's destination, so there will always be a lack of enclosure. Central to the distinction between urban and auto-urban for nonresidential uses is structured parking and multi-story buildings; without them, all development will be a form of auto-urban that lacks enclosure.
THE AUTO-URBAN CHALLENGE
Auto-urban areas are characterized by roads, drives, and at-grade parking significantly exceeding the area of buildings as a percentage of cover. Most observers, professional and laymen alike, find the auto-urban environments they experience to be generally unpleasant. Strip commercial, industrial parks, and other nonresidential land uses are subject to frequent criticism as a visual blight, and they routinely score poorly in community-preference surveys.
Figure 1-2 illustrates the classic urban street of the nineteenth or early twentieth century, with buildings averaging two to three stories. It provided parking in the street for a limited number of cars, horses, or buggies, and some loading or parking in the rear. This stands in contrast to a modern commercial street, where the need to provide adequate automobile parking alters everything. The street is not big enough to provide all the needed parking for buildings occupying an entire block face, so parking lots are required. Figure 1-3 illustrates what happens when each store must provide its own parking. With the parking mostly to the side, the result is a gapped-tooth condition. This not only destroys the visual sense of enclosure, but also lowers the intensity (amount of floor area) of the block.
A second problem is that many modern commercial uses do not fit in the block. The blocks shown in figures 1-2 and 1-3 have a depth of 150 feet from street to alley. With a typical bay size set by column spacing, the stores themselves range from ten to fifty feet wide and one thousand to eight thousand square feet in area. In 1950, one could find supermarkets that fell within these parameters. With parallel parking, one car per twenty feet can be accommodated on the street. The one neighborhood use that today would be considered an anchor tenant for a neighborhood is a drugstore. The modern drugstore is fifteen thousand to sixteen thousand square feet and thus, is equal in size to five smaller stores of three thousand square feet each. This is a building that is 125 feet in width and would use 31 percent of the block's length. The street in front of the building accommodates only six of the sixty parking spaces the use requires; the alley would provide another thirteen. This leaves a need for forty-one parking spaces in a parking lot alongside the building. The parking lot requires 120 additional feet of street frontage and provides excess parking for other uses. The drugstore and parking use 61 percent of the block area, as illustrated in figure 1-4. There is room for another building, and even if both the drugstore and the second use are pushed to the sidewalk line, only about half the block frontage can be building frontage; the rest becomes parking, which results in gapped-tooth blocks that cannot provide enclosure.
Table 1-1 shows the impact of different parking ratios on floor area in comparison to the floor areas where no parking is required. It also points out that taller buildings or mixed uses do not fundamentally change the situation. A taller building does not improve distance/height (D/H) values, which are used to measure enclosure (see Community Character, chap. 1). An increase in stories produces an increase in the floor area ratio (FAR), which is the ratio of the site's floor area to the total area of the site (seeCommunity Character, chap. 1). Unfortunately, it also dramatically increases the area occupied by parking. For example, the one-story building requiring four parking spaces per thousand square feet (table 1-1) has a FAR of 0.38, leaving 62 percent of the site in parking. A four-story building has an increased FAR of 0.53, resulting in a ground coverage of 0.13 (one quarter of 0.53 for four stories) and 87 percent of the site in parking. Only by using parking structures can new urban areas with adequate enclosure be created.
Parking for most office, service, and retail uses ranges from three to five spaces per thousand square feet of floor area. Only a few uses (e.g., dry cleaners and tanning salons) have low parking ratios and might achieve a FAR of 0.62. Thus, it is impossible with at-grade parking to achieve urban FAR values or enclosure. Design cannot alter low floor area or the fact that, with at-grade parking, most people must walk through parking lots to get to their destination. Large stores—supermarkets, discounters like Wal-Mart, or category killers like Best Buy—are typically one story tall and normally have at-grade parking; only in urban cores is the density high enough for the market-area population to be within walking distance. (See Community Character, chap. 2, for more on the populations needed to support stores.) Most two-story discount stores have parking structures. In urban cores such as New York or Chicago, downtown department stores do not have dedicated parking; rather, they rely on city or private parking for those who come by car. To achieve urban character, parking structures are essential.
Table 1-2 illustrates the impact of structured parking. By going to a two-level parking structure, the area occupied by parking for a given amount of floor area is cut in half; a three-level structure reduces it by two-thirds. This allows for an increase in floor area per acre of developed land for each parking level added. As can be seen, the more floors of parking, the higher the floor area ratio. Since parking typically has lower floor-to-floor heights than commercial or office, dedicated park-ing structures are very effective. An urban environment should have lower parking ratios due to uses with different peak hours of demand, thereby lowering the parking required. Transit can lower parking demand as well, if frequency of service is high.
Structured parking is essential to modern urban environments, whether it is the developer or the local government that funds the structures. If the community cannot find a means to provide structured parking, it will not be able to create the urban FAR and sense of enclosure. With only at-grade parking, the environment will be auto-urban. Structured parking solves two of the problems that face the designer of a new urban area. First it increases the FAR. Using parking structures, which are buildings that enclose space (as opposed to creating space, as do surface parking fields), lowers D/H values and provides a figure-ground plan (see Community Character, chap. 1) similar to historic urban places.
Urban areas are based on having strong enclosure and an enjoyable pedestrian precinct. All will have structured parking with some on-street parking, except for lower-density urban residential. The introduction of structured parking suggests rethinking the urban design paradigm. Cars and pedestrians do not mix well, presenting a constant safety hazard. Even on a two-lane road, the two traffic lanes and parking squeeze pedestrians to a small area of sidewalk and limit their movement across the street. A street with a fifty-foot right-of-way has 80 percent of its width devoted to the automobile.
Four Urban Design Paradigms
The introduction of the automobile to streets has reduced the area for pedestrians and restricted movement along the street. In approaching how to organize such urban areas, there are four principal design paradigms: the traditional street and block, spine, internal pedestrian precinct (mall), and offset pedestrian and street pattern. The four approaches to urban design are based on different relationships of streets, buildings, structured parking, and pedestrian precincts. All have different relationships, and there are pros and cons for each.
Traditional Street and Block
For most existing communities, the pattern of development was set decades ago, and the only challenge is fitting larger, more intense buildings and parking structures into the pattern. This is primarily an urban-renewal planning issue that is totally dependent on existing conditions. The main concern is to look at sidewalk widths and ensure that sidewalks can accommodate the increase in pedestrian volume. For the new development using this pattern, the street cross section should be designed for the dual purpose of moving automobiles and pedestrians. Sidewalks define the pedestrian precinct, and their width is critical to creating a desirable pedestrian experience. This includes a pedestrian traffic area, buffer to street, and potential activity areas for outdoor seating or window-shopping. In general, ten to twenty feet are minimums, and variable setbacks should be encouraged to provide activity areas. The number of travel lanes is determined by traffic flow. Adding traffic lanes or parking increases street width and can squeeze the pedestrian precinct. Note that the concept of increasing on-street parking in urban areas by using perpendicular parking increases the width devoted to the automobile and the difficulty of crossing the street. This is even more important where there is a square or where consideration is given to a center island in the street and adding two more parking lanes. Figure 1-5a shows the historic town square in Trujillo, Spain, which is generally off-limits to automobiles. At siesta, however, parents are allowed to park in the square while picking up their children from school, as shown in figure 1-5b.
Clearly, the automobile converts the character of the space from a pedestrian-friendly area to one that is potentially dangerous and inhibits movement in the space. The parked cars partially block the view of buildings and force pedestrians to be aware of moving vehicles. This contrasts with the historic pedestrian street, prior to the advent of the automobile, where the pedestrian could cross to the other side of the street at will. The traditional street works best in very small communities where automobile traffic is low, allowing for free crossing of the street. The higher the traffic volume, the more the pedestrian experience is degraded. As the number of lanes increases to four or six lanes, the distance and time needed to cross the street is increased (fig. 1-6). The increased traffic also decreases the efficiency of automobile movement because pedestrians conflict with right turns and often force the creation of one-way streets in order to increase the traffic capacity.
This paradigm is based on a parking structure that parallels the block, forming a spine. Parking structures occupy the location where an alley would be, running down the center of the long axis of the block. Thus the block has two faces on either side of the parking structure. This will alter the block dimensions and size, with blocks being wider and longer. Typical alleys are 20 feet wide, while the parking structure would be a minimum of 120 feet in width. Vehicle access to the parking structures would be at either end of the block, on a secondary street. Pedestrian access can be on the secondary street adjacent to the automobile access, at a mid-block pedestrian access on the primary shopping street (fig. 1-7), or directly through the larger stores or office buildings. It is possible to have one mid-block access, or several that create a loop by detaching a building from the garage, so one can walk all around a small group of stores without walking around the block. The block pattern would need to reflect the use of central spine parking from the beginning of development. The second item of consideration is the depth of the commercial frontage. Is this to remain 100 to 150 feet in depth, as it now exists in many urban areas, or should it be deeper? In developing a new area with a central spine, the zoning needs to allow for the needed block width. The long axis streets could have a variety of designs with a range of widths. They can be treated as conventional streets or enhanced with larger sidewalks, landscaped parkways, or plazas, as was done in Mizner Park in Boca Raton, Florida (fig. 1-8). The plaza in Mizner Park, however, adds a very important recreational component, allowing residents of the apartments to walk the plaza and children to play in the fountains. The central shopping street and pedestrian parkway can be very wide to emphasize the complex as an address. It is also possible to have a street that has wide parkways in some areas but also narrows down where two larger anchor uses face each other. This would allow the street to handle the more traditional 100-to-150-foot store depths where the parkway exists, but also enable sections to provide depths of 200 feet or more. Large anchor stores may occupy an entire face adjoining the parking or be on a separate, freestanding, short block.
The spine concept is best suited to larger-scale commercial and office nodes. It is least suited to community shopping centers where supermarkets are the anchor. The supermarket must be at one end of the commercial area, and must be served with an at-grade parking lot. A major challenge to this design is that the street pattern must be laid out long in advance. That means planning must structure the street pattern as part of the plan for a spine-based development. Transit is also adaptable to this scheme, located at grade or elevated and linked to the parking structures, where it does not conflict with pedestrians. If it is at grade, it should be on a cross street or secondary street to minimize conflict with people on the major pedestrian street.
With residential or office located over the ground-floor commercial, the relationship of the buildings to the parking structure needs to be considered. With shallow buildings, the street face can provide all light and air needs and the parking structure can be attached. With deeper buildings, a separation should be provided on upper floors so the parking structure does not block the light from the back side of the building. Many uses will be more marketable if light is available in offices or residential units from both the front and the rear.
Mid-block pedestrian access provides an opportunity to introduce interesting elements to the pedestrian precinct. Simple pedestrian walkways of ten to fifteen feet in width and depth create opportunities to articulate the building facades. Expanding these spaces to twenty to thirty feet will allow room for tables for outdoor restaurant seating, art galleries, or amenities for a pedestrian precinct as well as provide access to parking (fig. 1-7). Such spaces can be either for a single use or provide access to multiple uses. A variety of configurations of these spaces is possible. Figure 1-9 shows an entrance to an interior courtyard under the upper levels of the building. The entrance contains the stairs to the upper-level uses, and then opens up to a small, highly enclosed space. These spaces may also serve to provide a mid-block pedestrian access to the opposite block face. Buildings should average three to five stories to make the structured parking work. While some may object to the taller buildings, height makes enclosure easier. The use of average heights is very valuable in creating interesting streetscapes rather than blocky masses that become monotonous if not varied. (Continues...)
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