Thesis – Chapter 2 Planning Today: 2.2 Street Design
“Suburbia may be paved with good intentions, but mainly it is paved” (Kelbaugh, 2002, p. 51).
“The traditional rectilinear “gridiron” street plan, despised by avant-garde planners of the 1930’s, and used almost exclusively by real estate developers up to that time, has … many things to say for itself. It provides a strong visual order, clarity of orientation, flexibility of circulation (one-way streets) and spatial organization (green squares), and flexible density and land use. But the rectilinear plan does have its defects, particularly in residential areas: it conflicts with a hilly terrain; it has difficulty accepting diagonals; it encourages through traffic; provides excess street capacity at low density while creating too many conflict points at intersections; finally, it becomes monotonous if overly large and undifferentiated” (Tunnard, Puskarev, 1963, p. 89).
One of the most successful historical applications of the grid system can be found in Charleston, South Carolina (Figure 2.2).
The elements that make the streets of Charleston, South Carolina, so pleasurable are anathema to traffic engineers—specifically, narrow streets that end at a T- junction. The marvelous thing about T-junction streets is that they have natural focal points. In the past, the building lots at the junction of the T were reserved for important public structures: a church, a post office, a college. Human beings love focal points. The restless human mind loves to have a goal in view, to savor the approach, to enjoy the reward of reaching the destination, and to then get on with the next thing (Kuntsler, 1993).
As volume on the grid system streets increased, planners developed a functional street system that would differentiate between different kinds of traffic, eliminate points of conflict and unnecessary street area, define comprehensible undisturbed areas for living, and fit the streets to topography (Tunnard, Pushkarev, 1963).
“The functional street plan, in its most consistent and radical form, was first employed by Clarence Stein and Henry Wright in Radburn [New Jersey] in 1928. The venture failed commercially because of the Depression and did not exercise any immediate influence on speculative land development, but with the New Deal the federal government began to participate in promoting sound land planning practices. In 1934 the Federal Housing Administration was organized to provide mortgage insurance to local banks for loans on privately-built housing: to make sure that the housing was marketable and that risks were kept down, insurance was made conditional on detailed construction standards, and pamphlets were issued suggesting desirable street patterns, under such titles as “Planning Profitable Neighborhoods” and “Successful Subdivisions.” The suggestions . . . concentrated on eliminating the most flagrant violations of safety and economy in plan, with heavy emphasis on T-intersections and curvilinear adaptations of the street grid” (Kuntsler, 1993, p. 90).
T-intersections have only three theoretical traffic conflict points as compared to sixteen in a four-legged intersection, and have the added advantage of built in right-of-way assignment (Kuntsler, 1993).
This federal emphasis on the functional street plan, unwittingly abandoned any regard for the pedestrian. The typical condition of the superblock, currently found in suburbia, thwarts efforts to provide a workable pedestrian realm. It has been demonstrated that the post-World War II legacy of cul-de-sac, collector road, and arterial, not only hampers the pedestrian but also creates more, not less traffic congestion (Kelbaugh, 2002).
A quickly-becoming classic illustration of a typical modern subdivision street system is shown in figure 2.3. Traffic from the residents leaving their homes is all funneled to single connections to the collector road, creating traffic jams at peak times of day. The school is only reachable by vehicle. There are no paths to allow students to walk to school, so what could be a two minute walk becomes an extended automobile or bus ride for all students. Unrelenting curves create an environment that is utterly disorienting. It is no wonder that so many people associate visiting suburbia with getting lost (Duany, Plater-Zyberk, Speck, 2000). But curves per se are not the problem. The problem is driving along on a street that heads north and finding oneself heading east, then south, then west (Duany, Plater-Zyberk, Speck, 2000).
That said, curved streets can serve a valuable aesthetic purpose. They provide a constantly changing view as one moves though space, rather than the boring and endless vista that can result from a long straight road. In fact, the use of a controlled curve to terminate a vista is a sophisticated design technique and should not be avoided (Duany, Plater-Zyberk, Speck, 2000).
These design techniques are used to slow down traffic partially in an effort to create safety for the pedestrian. A street that does not terminate in any fixed objective that might be pleasant to look at or offer a visual sense of destination offers little to deter speeding. With no trees arching over the excessively wide streets, and no focal points to direct the eye, and cars whizzing at potentially lethal speeds, the modern suburban street is a bleak, inhospitable, and hazardous environment for the pedestrian (Kuntsler, 1993).
“The ruling principle is that as long as the road is designed with low-speed geometries, traffic generally treats the neighborhood the way that the neighborhood treats it. Friendly house fronts tell drivers to slow down, while blank walls [like walls of garage doors] and house backs tell them to speed up” (Duany, Plater-Zyberk, Speck, 2000, p. 195). The only time that people don’t speed in modern suburbia is when they are lost, which is, fortunately, quite often (Duany, Plater-Zyberk, Speck, 2000).
Streets that once served vehicles and people equitably are now designed for the sole purpose of moving vehicles through them as quickly as possible. They have become in effect traffic sewers. No surprise then that they fail to sustain pedestrian life (Duany, Plater-Zyberk, Speck, 2000).