Urban Design

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 Small neighborhood shops have been replaced by larger stores, which are needed to provide the huge array of goods to which modern consumers have grown accustomed.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...