The permeability index measures the ease of making a trip. Figure 6.4a shows that, with 56 intersections per square kilometer, Indira Nagar, Bangalore, not only has a very high connectivity but is highly permeable, due to a large number of four-way intersections and T-junctions. The areas in the south and north-east, highlighted in yellow, become impermeable due to a large number of cul-de-sacs. These areas also do not lie within 54 percent of the walkable catchment within a 500-meter radius of the metro station (Figure 6.4b).
Physical permeability depends on block width. A block of less than 240 feet serves as a traffic-calming device (Sucher, 2010). Pedestrian accessways and courtyards between buildings can provide permeability for pedestrians while retaining larger block sizes for speedier traffic (Figure 6.5).
A low solid:void ratio enhances people-to-place interaction. Buildings with glazing instead of structural components encourage more visual and physical exchanges (Figure 6.6). This can be comforting and convenient even if only perceived subconsciously. Positive interactions between pedestrians boost business and create a pleasant streetscape. Melbourne has a regulation of providing at least 5 meters or 80 percent of the street frontage (whichever is the greater) as entry or display window to a shop or a food premises, which has helped in encouraging a high level of pedestrian interaction (City of Melbourne, 2015, p. 27). Regulations to ensure appropriate design control can promote the aesthetic and functional components of retail streets. Important elements to consider include frontage:access ratio, parking locations, loading/unloading spaces, setbacks, definition of edges, and other design details (Tiwari, 2012).
Figure 6.5 Ill-defined and unsafe pedestrian access through car parks (left); pedestrian accessways and courtyards providing visual and physical permeability
To achieve a sense of enclosure and comfort for users, the generally recommended ratios of height to width are 1:1 for urban scale, 1:2 for medium scale, and 1:3 for suburban scale (Abbate, 2007; Figure 6.7).
In suburban settings, street trees play a more important role in defining a sense of enclosure than buildings do. Walls and fences, either low or over six feet tall, as Kevin Lynch points out, can also provide spatial definition (Lynch, quoted in Ewing & Clemente, 2013, p. 8). Focal points at street ends and irregular grids can help close vistas.
Public art is not simply artworks that are not in a gallery or studio. Public art aims to engage audiences and to create spaces. These spaces with which people can identify can be material, virtual, or imagined. They hold a mirror to the community, reflecting the uses of public spaces or our behavior within them. Public art contributes to the visual attractiveness of the city and to aesthetically rich urban spaces, and creates connection with place. In addition, it allows public authorities to signal their awareness of social and environmental problems (Sharp et al., 2005).
Introduced in 2003 in Victoria, Australia, the Victorian State Government’s Grappling with Graffiti strategy obliges municipalities to develop graffiti management strategies conforming to a particular regulatory template (Crime Prevention Victoria, 2003). The core components are eradication, education, and enforcement. The strategy emphasizes engagement with the communities of graffiti writers and street artists through a partnership model. The stakeholders that are invited to participate are defined broadly, and include residents, traders, community groups, galleries, transport companies, utilities providers, the Victorian Police, construction companies, and hoarding manufacturers as well as the graffiti writers and artists (Tiwari, 2012; Figure 6.8).