In recent years, architects and urban planners have been developing tools to measure the quality of the walking environment. But the question remains, “what makes strolling down a particular street enjoyable?”
Researchers, governments and communities are using tools and metrics to measure the health benefits of pedestrian oriented city designs and factors that make them pedestrian-friendly such as park planning, building setback, block length, and street and footpath width.
A recently published book in the United States, Measuring Urban Design: Metrics for Livable Places, by renewed urban planning experts Reid Ewing and Otto Clemente aims to provide a guide for sustainable communities specifying urban design elements that can make one street more pedestrian-friendly than another.
“Our challenge in creating a tool to measure urban design qualities was to move from highly subjective definitions to operational definitions that capture the essence of each quality and can be measured reliably across raters, including those without training in urban design,” the authors explained.
The study examines five intangible qualities of urban design: imageability, visual enclosure, human scale, transparency, and complexity.
This concerns what makes a place unique and recognizable. A place has high imageability when certain elements are able to capture people’s attention, evoke feelings, and create a lasting impression.
Landmarks are the most important component of imageability, though landmarks are not necessarily large civic structures or buildings. They can consist of anything from a graffiti-painted on a wall to the Eiffel Tower. The important factor with a landmark is in its singularity and location in connection with its context and surroundings, and its function as a visual termination point, orientation point and meeting point in the urban grid.
In addition to landmarks, striking views, unusual topography, and marquee signage influence the imageabilty of the urban landscape. It is also affected by the other urban design qualities (visual enclosure, human scale, transparency and complexity) and its effects on the public realm.
Visual enclosure describes how streets and other public open spaces are visually defined by vertical elements, such as buildings, walls and street trees. Visual enclosure is reliant on the relation between the height of vertical elements and the width of the space, which has to be proportional.
In outdoor areas at city centres, vertical elements interrupt viewers’ sight lines, creating a sense of enclosure where lines of sight are so decisively blocked as to make outdoor spaces seem room-like. Buildings become the walls of the outdoor "room," streets and sidewalks become the floor, and if the buildings are of similar height, the sky might project as the ceiling.
On the other hand, in low-density suburban areas, built masses become less important in defining space, and street trees are paramount. Rows of trees on both sides of a street can help to create an enclosed space, but only if the trees are closely spaced. When properly scaled, walls and fences, on-street parking, planted medians, and even traffic itself can also provide spatial definition in urban and suburban settings.
Human scale - possibly the most important quality in making a street pedestrian-friendly - refers to the relation between the size, texture, and articulation of physical elements and the proportions of humans and, equally important, correspond to the speed at which citizens walk around the city.
Street trees and furniture, building details and pavement texture are all physical elements contributing to improve human scale. While moderately-sized buildings, narrow streets, and small spaces can create an intimate environment, large buildings, wide streets, and open spaces can negatively impact walking areas.
Large buildings can use architectural detailing to help mitigate their large scale. In addition, the correct proportion between buildings’ width and height, the intricacy of paving patterns, the amount of street furniture, the depth of setbacks on tall buildings, the ornamentation of buildings, and the spacing of windows and doors are important factors for human scale.
In areas where tall buildings and wide streets intimidate pedestrians, a canopy of leaves and branches can make a space feel smaller and less intimidating. Additional rows of trees and other small-scale elements such as clock towers can be used to moderate the scale of buildings and streets.
Transparency represents what people are able to see beyond the edge of a street or other public space and, more specifically, what they can perceive from the human activity beyond the edge of a street or buildings’ facades. Physical elements that affect transparency include walls, windows, doors, fences, landscaping and paths into central block spaces.
Streets with many entryways or lanes contribute to the perception of human activity beyond the street, whereas those with blank walls and garages suggest that the area is uninhabited. Ideally, blank walls would exhibit some transparency if overhung by trees or bushes, providing signs of life.
Transparency is most critical at the street level, where the greatest interaction occurs between the pedestrian and the built environment.
Courtyards, signs, and buildings that convey specific uses such as schools and churches help to gain transparency. In addition, reflective materials, glass, arcades, large building setbacks, and interior lighting have an important role in the perception of transparency.
Complexity refers to the visual richness of a place, including the number and kinds of buildings, architectural diversity and ornamentation, landscape elements, street furniture, street signs, and human activity.
While most streets are now designed primarily for vehicles, there is a large difference between the complexity requirements of pedestrians and those of motorists. Unlike fast-moving motorists, slow-moving pedestrians require a high level of complexity to hold their interest.
Streets that are high in complexity provide interesting things to look at such as building details, signs, other people, surfaces, changing light patterns and movement, and signs of habitation.
The problem in contemporary cities is that these elements are too few or too similar, too predictable for surprise or novelty, and too unordered for comprehension.
Street signs are a major source of complexity in urban and suburban areas. If properly arranged, they can add visual interest, make public spaces more inviting, and help create a sense of place.
Complexity can be improved by varying building shapes, sizes, materials, colours, and ornamentation. Street trees can help to add textural detail to modern architecture by filtering sunlight and creating different shades that can transform stone, asphalt and concrete into textured surfaces.
Street furniture, pedestrian-scaled streetlights, fountains, benches, special paving and even public art can also contribute to the complexity of the urban landscape.
By considering these qualities, architects, urban planners, and researchers can better understand the relationship between the physical features of the street environment and the walking behaviour of its inhabitants. As a result, they can develop more effective urban design planning solutions for creating quality pedestrian oriented city designs.