Can Complete Streets be Green Streets Too?
Sidewalks and Bike Lanes Add Impervious Surface
Sep 7, 2008
Environmentalists and leaders who are concerned about climate change and green living are right to question the Complete Streets movement for adding more paved area to our landscapes.
But planners are looking at building complete streets that also return ecological function to the places where we live. They believe we can accommodate cars, bicyclists, pedestrians, and habitats within our cities. Drainage can do more than move water. It can mimic natural processes when native plants fill swales to provide food, nectar, cover for birds and pollinators while filtering water. In fact, some credit the Americans with Disabilities Act as a positive force for moving them to better incorporate wellbeing in the process and helping them to plan infrastructure that incorporates all people in the community.
Make Transportation Corridors Work Like a Forest
During the National Center for Bicycling and Walking Pro Walk/Pro Bike Conference in September 2008, bike/ped professionals were able to learn more about Seattle’s development of green and sustainable infrastructure. Planners presented numerous workshops where they illustrated how they have supercharged the landscape to deliver sustainability.
As the city became more dense, there was a push to also make the environment more liveable by developing a strategy that increases the quality and extent of landscaping. Business districts aren’t as gray anymore as planners strive to cover 30% of site in vegetation. As new and re-development comes about, the city becomes prettier and more liveable. In residential areas, planners cover 60% to 70% of the site in vegetation.
In addition, one-third of the city is owned by the municipality. There has been a change in thinking about that area as an asset to be managed by looking at services, costs, and maintenance. Streets are examples of infrascture that can do more than simply move traffic. Landscaping can support the drainage functionality and buffer the city against climate change. The city is integrating its approach by building to mimic nature and provide more than one service while impacting the wellbeing of the city’s population.
Complete Streets
Gone are the days when the street edge didn’t matter to anybody. General planning now recognizes diverse needs by requiring new development to implement multiuse trails, meet ADA regulations, and incorporate planting to separate directional lanes and sidewalks.
Green interventions insure that complete streets – streets with lanes for cars, bikes, and pedestrians – are truly complete. Green strategies ensure that refuge medians include trees and planter strips. Paving materials of sidewalks and bike lanes can be porous to allow water infiltration. Swales that separate streets can be filled with native plants that require less maintenance and use water more efficiently (rain gardens). Planners and leaders are working to take back the streets from cars alone by dropping lanes as they consider their functions for community, mobility, habitat, water, and underground utilities all at once. Green strategies improve both transportation, business, and livability.
Bringing Green Complete Streets to the East Coast
In Seattle, planners built complete streets over glacial granite underpinnings and don’t share the same concerns as those on the east coast for impervious materials that allow infiltration and recharge underground aquifers. In places like the Chesapeake Bay watershed, however, the complete street equation includes porous surface materials. Studies by Maryland and North Carolina universities are collecting data that should be available in a few years to show how and when it pays to pave with pervious materials. Right now, planners have a gut feeling that pervious materials make a difference and rising demand should lower their cost.
Still Skeptical
How green can infrastructure be if we are adding to the overall paved surface? Can we eliminate paving? While low traffic areas can be ideal for the use of new porous paving, planners are still trying to find ways to minimize pavement. Paving bike lane zones with pervious pavement should be essentially like no paving at all.
Sharrows or shared lanes may become more common in the future if driving motorized vehicles becomes less common due to fuel costs. Suburban areas can use more mulched offroad trails that are more runner friendly. Curbs can incorporate more drains or cuts to allow water to exit and not sheet off of paved surface. Whatever the solution, green streets must prevent stormwater runoff and the permeability rate of has to be slow to adequately filter the water.
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