Urban Street Stormwater Guide

National Association of City Transportation Officials

• Publisher: Island Press
• Year: 2017
• ISBN:
  9781610918145
• Topic: Tecnologia e ingegneria
• Subtopic: Trasporto e navigazione

Streets make up more than 80 percent of all public space in cities, yet street space is often underutilized or disproportionately allocated to the movement of private motor vehicles. Excess impervious surface contributes to stormwater runoff, posing a threat to the environment and human health, and often overwhelming sewer systems. This excess asphalt also poses a threat to public safety, encouraging faster speeds and dangerous conditions for people walking and biking.The Urban Street Stormwater Guide begins from the principle that street design can support—or degrade—the urban area's overall environmental health. By incorporating Green Stormwater Infrastructure (GSI) into the right-of-way, cities can manage stormwater and reap the public health, environmental, and aesthetic benefits of street trees, planters, and greenery in the public realm. With thoughtful design, GSI can bolster strategies to provide a safe and pleasant walking and biking experience, efficient and reliable transit service, and safer streets for all users.Building on the successful NACTO urban street guides, the Urban Street Stormwater Guide provides the best practices for the design of GSI along transportation corridors. The authors consider context-sensitive design elements related to street design, character and use, zoning, posted speed, traffic volumes, and impacts to non-motorized and vehicular access. The Guide documents and synthesizes current practices being developed by individual agencies and recommends design guidance for implementation, as well as explores innovative new strategies being tested in cities nationwide. The guidance will focus on providing safe, functioning and maintainable infrastructure that meets the unique needs and requirements of the transportation corridors and its various uses and users.The state-of-the-art solutions in this guide will assist urban planners and designers, transportation engineers, city officials, ecologists, public works officials, and others interested in the role of the built urban landscape in protecting the climate, water quality, and natural environment.

Fairmount Avenue & N 3rd Street, PHILADELPHIA, PA

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Streets as Ecosystems

Green Street Principles

Streets are Ecosystems

Why Sustainable Stormwater Management Matters

The Role of Streets

Complete Streets are Green Streets

Green Street Principles

PROTECT AND RESTORE NATURAL RESOURCES

Capturing, filtering, and infiltrating stormwater is critical in urban environments where impervious surface covers 60% or more of all land area. Sustainable stormwater infrastructure filters pollutants from water and restores the natural hydrological cycle, protecting water resources.¹ Green infrastructure also improves air quality, mitigates the urban heat island effect, and increases species habitat, from small oases for birds and insects to the large water bodies that eventually receive stormwater runoff.

PROMOTE HEALTH, EQUITY, & HUMAN HABITAT

Green streets are part of healthy, equitable urban design that views streets as vital public spaces. Incorporating green elements into streets improves mental and physical health through better air quality, valuable shade, beautification, and contact with nature in areas where access to parks is limited. Ensure that the benefits of green stormwater infrastructure are provided equitably, especially in neighborhoods that have historically borne disproportionate air and water pollution or that lack green space.

DESIGN FOR SAFETY & MOBILITY

Street reconstruction projects that incorporate green infrastructure should be aligned with citywide traffic safety and mobility efforts, especially where opportunities arise to move curbs and reallocate street space for people walking and biking. Green infrastructure can be leveraged in conjunction with other street design projects to realize complementary goals, including transit access and safe mobility, providing greater value from city projects.

DESIGN FOR LIFE CYCLE

Green stormwater infrastructure is an asset for cities, providing quantifiable financial benefits. Stormwater management strategies should be planned and implemented with consideration for life-cycle costs and benefits, including the potential impacts of climate change and storm events. Green street elements that are properly designed, operated, and maintained extend the useful life of other infrastructure, especially graywater systems and pavement surfaces.

DESIGN FOR RESILIENCE

As the intensity and frequency of storms increases in many cities, and as drought conditions intensify in other cities, sustainable stormwater management is critical for climate change mitigation and adaptation. Incorporating natural systems into the built environment promotes ecosystem health and urban resilience.

OPTIMIZE FOR PERFORMANCE

Green stormwater infrastructure should be implemented at a network scale, but must be tailored to the specifics of its site. Use an understanding of topography and microclimates, available space, accessibility needs and the many human functions of a street, and desirable infiltration capacity to design appropriate green stormwater systems. Use the street to restore connections to the natural water cycle, and make comprehensive, citywide investments to see watershed-level benefits.

Vine Street, SEATTLE, WA

Streets are Ecosystems

The opportunity is ripe to reimagine how streets function in cities, not just as mobility corridors and public spaces, but as part of the natural ecosystem. With re-urbanization, aging infrastructure, and a changing climate, sustainable stormwater management is a core challenge for resilient cities.

Historically, streets have formed an impermeable paved layer on top of green space, disrupting hydrological cycles and requiring expensive stormwater infrastructure to manage stormwater runoff and protect ground and surface water quality. As cities face storm events of increasing frequency, duration, and intensity, as well as more persistent drought conditions, it is time to ask more of our streets.

Urban streets can reconnect rainfall to the environmental life of the city. Forward-thinking planners, engineers, and designers are treating streets as part of the ecological fabric of cities, integrating green infrastructure into the street alongside transit infrastructure and safe places for people walking and biking. By thinking of streets as ecosystems, we can build cities that are more resilient, sustainable, and enjoyable places to live.

Why Sustainable Stormwater Management Matters

Cities are defined by water. Waterways define city edges and bou...