Figure 1.22 A Diff erent Paradigm for Urban Design

Figure 1.22 A Different Paradigm for Urban Design

the car. These two issues are impossible to separate. Thus, a key strategy for improving overall system performance is to organize land use, densities, connectivity, and access to ensure viable public transit and other infrastructure. Green infrastructure: Integrating natural systems with built systems The integration of natural systems with infrastructure is possible through green infrastructure and ecological engineering. Green infrastructure refers to the city’s naturescape, that is, the mix of trees, shrubs, hedgerows, gardens, green roofs, lawns, parkland, and waterways. These natural elements may be eff ective in providing a variety of services for other sectors (fi gure 1.23). For example, when the mayor of Los Angeles, California, faced brownouts and severe energy shortages in 2004, his response was to invest in the planting of thousands of trees along the streets of the city. Urban forests save energy by reducing temperatures, shading buildings, cooling the air, and refl ecting sunshine. The trees in Los Angeles are part of the city’s energy infrastructure.

The most common examples of green infrastructure are the ribbons of green riparian areas along streams and rivers. These green strips act as fi lters, preventing silt and nutri-

ents from entering streams. Storm water permeates the soil, or is retained on leaves or captured by roots, and the result is less damage to aquatic environments or reduced requirements for investing in treatment systems. Such natural systems may be more or less engineered to suit the city’s needs. For instance, being surrounded by rivers such as the Iguaçu, fl ooding has been a big problem in Curitiba, Brazil. InSource: Author elaboration (Sebastian Moffatt). stead of controlling water fl ow usNote: Big roads, lengthy pipes, big wires, and larger pumps are replaced by a mixed use, compact, pedestrian-friendly design whereby public funds are used for parks and social and local services. ing concrete structures, Curitiba has created natural drainage systems. Riverbanks have been converted to parks that retain fl oodwater in the soil, and lakes have also been constructed to hold fl oodwaters. River water and rainwater that lead to fl ooding may be contained naturally in the lakes and in the parks surrounding the lakes. The ecosystem is preserved in a natural way. As fl oodwater to the park area is released from the ground to the river naturally (rather than being drained at high speeds through straight concrete drains), downstream fl ooding may be avoided. People are less exposed to environmental hazards and the diseases caused by fl ooding. The cost of building parks, including the cost of the relocation of slum dwellers, is estimated to be fi ve times lower than the cost of building concrete canals. Land use plans may also be used to incorporate green infrastructure if they are associated with policies that manage the demand for services. In Freiburg, Germany, for example, land use plans address storm water runoff by taxing land diff erently based on the permeability of the surfaces. As a consequence, developers are careful to minimize hard surfaces on parcels, using crushed stone for pathways, paving stones for parking, and so on. The result is less cost for taxpayers because the city avoids investment in infrastructure for capturing, transporting, and treating storm water.