Street Design: Part 2 - Sustainable Streets |
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David J. Carlson, Ellen Greenberg, and Morgan Kanninen
Public Roads
March/April 2011
Road projects around the country are demonstrating that they can deliver livability and environmental benefits while achieving mobility and safety objectives.
Transportation professionals face an increasingly complex set of competing demands in the delivery of road projects that involve public rights-of-way. Designing a safe facility, constructing the roadway, and installing traffic control measures are only part of a much larger picture. In many cases, today’s road projects also need to meet the objectives of regulatory, policy, and community requirements aimed at integrating the roadway into the existing natural and built environments. Many projects call for features that promote livability and sustainability objectives, such as providing transportation alternatives, protecting public spaces, preserving landscapes and natural elements, meeting climate change goals and regulations, and using natural resources responsibly and efficiently.
Interest in developing a framework for creating more sustainable streets is gaining traction in the United States, as evidenced by efforts such as the Interagency Partnership for Sustainable Communities. Established in June 2009 by the U.S. Department of Transportation, U.S. Environmental Protection Agency (EPA), and U.S. Department of Housing and Urban Development, the partnership has put a national focus on livability. The interagency partnership ties the quality and location of transportation facilities to the need for access to good jobs, affordable housing, quality schools, and safe streets, while aligning Federal resources and encouraging place-based solutions. Creating an effective and sustainable transportation network requires this kind of multidisciplinary approach that draws from diverse perspectives.
“The interest in complete streets is part of a growing demand for retooling the rights-of-way in cities to reflect changing values that citizens have now,” says Clark Wilson, senior urban designer, with EPA’s Office of Policy, Economics, and Innovation. “Federal departments and agencies are responding by, for instance, including criteria related to livability and sustainability. This approach not only addresses community values, but also is more fiscally sound because of multiple objectives being met with limited funding.”
To help transportation professionals respond to the emerging demand for sustainability, the Federal Highway Administration (FHWA), EPA, and other partners are collaborating to identify and define sustainability concepts and develop rating tools for sustainability features. In support of EPA’s Smart Growth program, researchers with the Sustainable Transportation Center at the University of California, Davis, recently cataloged a variety of case study projects that demonstrate a comprehensive approach to creating complete, multimodal, green, and livable streets. In Sustainable Streets: Foundations for an Emerging Practice, the researchers define sustainable streets as “multimodal rights-of-way designed and operated to create benefits relating to movement, ecology, and community that together support a broad sustainability agenda embracing the three Es: environment, equity, and economy.”
From storm water management on high-volume streets to pedestrian-friendly enhancements on a downtown street, cities are applying sustainability principles to real-world situations. Several case studies are described below. They include two high-volume streets, one urban State highway, and one downtown local street. All the projects were completed within the past decade, and all involve economic development and improvements to pedestrian rights-of-way. Two projects increase multimodal access, and three incorporate natural drainage features for managing storm water.
Plus, a number of evaluation and ratings systems -- including one being developed by FHWA -- are available to help assess the overall sustainability of highway infrastructure.
Michigan Avenue Bioretention
Responding to a 2004 mayoral task force on livability and economic development, city officials in Lansing, MI, incorporated rain gardens, known as bioretention cells, into a streetscape redesign in the downtown area. When the city required storm water improvements as part of an ongoing sewer separation project, the Public Service Department spearheaded a project to line six blocks of Michigan Avenue -- a main thoroughfare leading to the State’s capitol building -- with bioretention cells.
Designed in 2006 and constructed in 2007, the Michigan Avenue cells look like wide planting strips built into the sidewalks. They help protect local streams and marshes by treating runoff, filtering out pollutants, and preventing sewer overflows after heavy storms. Decorative ironwork fencing and new benches adjoin the cells and offer attractive seating areas along sidewalks and corner bulbouts. The city also integrated educational signage to explain various features of the project, including ground water protection, use of pervious surfaces, and selection of native plants for landscaping.
Developing a solution responsive to the city’s diverse needs required engaging a variety of stakeholders, including elected officials and city staff from other offices. According to Chad Gamble, Lansing’s director of public service, a comprehensive approach to stakeholder involvement was critical because of the urban context. Engineering solutions arose only after presenting project goals to a diverse panel of experts. “Any successful project in an urban core has to synthesize the pedestrian, economic, environmental, and traffic variables to yield a true complete/smart growth street,” Gamble says.
The Clean Michigan Initiative of the Michigan Department of Environmental Quality (now the Department of Natural Resources and Environment) funded the project, along with the Michigan Department of Transportation in conjunction with FHWA. The $1 million project included a hydraulics analysis, design of a retaining wall and footing, adoption of an engineered soil specification, and selection of plants and trees. Community co-benefits are evident, as city officials report increased pedestrian traffic in the area.
Aurora Avenue Retrofits
In Shoreline, WA, city officials and the Washington State Department of Transportation (WSDOT) used a 32-point checklist of features approved by a citizens advisory task force to help guide the redesign of a 1-mile (1.6-kilometer) portion of Aurora Avenue, which carries State Route 99 through the suburban community. Improving the high-volume arterial, which has an average daily traffic volume of 45,000 vehicles, had been on the city’s to-do list since Shoreline incorporated in 1995. In 1998, the city kicked off a predesign study, including extensive outreach involving public meetings, open houses, and presentations at city council meetings. With the support of a citizens advisory group made up of businesses, residents, and transit users, the city council unanimously approved a preferred design concept in 1999.
Constructed in 2007, the project brought dramatic change to the street, which now stands in stark contrast to the unimproved segments to the north and south. The area features pedestrian access enhancements such as two bridges for pedestrians and bicyclists that are part of a 20-mile (32-kilometer) interurban trail system, of which 3 miles (4.8 kilometers) are in the city of Shoreline, and continuous 7-foot (2.1-meter) sidewalks where no continuous sidewalks had existed previously. In addition, Aurora Avenue features new street lighting, intersection capacity improvements, medians for access management, curb lanes dedicated to business access and bus movement, and underground utilities.
Measures to manage storm water include landscaping; gravel interceptors and underdrains installed along the bicycling and walking trail; and storm water treatment devices for the roadway including gravity separation treatment, vaulted filtering systems, oil-control facilities at high-traffic volume intersections, and a large biofiltration swale on a side street.
The project received the Best Practices Award from the Institute of Transportation Engineers’ Transportation Planning Council, the Washington Quality and National Quality Awards from the American Public Works Association, the 2008 WSDOT/FHWA Award of Excellence for “Best City Project,” and a Globe Award for excellence in environmental protection and mitigation from the American Road & Transportation Builders Association.
Sandy Boulevard Redesign
In Portland, OR, a streetscape improvement project on Sandy Boulevard addressed community, ecological, and mobility objectives. With average daily traffic of almost 30,000 vehicles, Sandy Boulevard is an important arterial route through Portland and is the city’s first project to install green facilities on a high-volume street. The city initiated the redesign after identifying several problems, including pavement damage, distress, and rutting; few and difficult crossings for pedestrians and bicyclists; confusing street circulation; inadequate separation between vehicles and pedestrians; and inadequate space for bus shelters.
Completed in 2007, the Sandy Boulevard project included intersection reconfigurations to improve safety and installation of curb extensions at transit stops, median pedestrian refuges at larger intersections, street trees and benches, parking, wayfinding information, and 70 custom-designed bike racks. A key green feature was incorporation of five landscaped storm water treatment areas in the right-of-way. Infiltration basins and landscaped curb extensions achieve the dual purposes of managing storm water and improving aesthetics at select intersections.
“The angle of Sandy Boulevard against the city grid provided opportunities to reduce the asphalt-paved areas and create sizable vegetated storm water facilities that also increase pedestrian safety by reducing the crossing distances at intersections,” says Chris Armes, project manager with Portland’s Office of Transportation.
According to a followup report released by the city, “The new construction has successfully made pedestrians crossing Sandy [Boulevard] safer and more comfortable. . . [H]ousehold surveys showed a statistically significant increase in respondents’ perception of safety while crossing Sandy [Boulevard].”
This project provides an example of how transportation agencies can put remnant right-of-way segments to use for community purposes and serve ecological functions while maintaining necessary roadway capacity.
Riverfront Parkway and Downtown Street Conversions
In Chattanooga, TN, a major downtown revitalization transformed a riverfront highway from a five-lane, limited-access facility into a two-lane surface street with new intersections at downtown streets, continuous sidewalks, a 13-foot (4-meter)-wide riverfront promenade, and pedestrian access to major visitor attractions. The improvements were part of an ambitious strategy to attract investment to downtown Chattanooga.
Completed in 2005, the redesign of the Riverfront Parkway, which now carries about 19,000 vehicles per day, included narrowing travel lanes, reducing the posted speed limit, and adding onstreet parking and crosswalks. The city also created a park along the waterfront and now uses the area for festivals and special events. Realignment of the roadway created new downtown housing sites, supporting compact development. The changes demonstrate the city’s new emphasis on livability rather than accommodating movement of through traffic.
In addition to the parkway redesign, the city converted two downtown one-way couplets (pairs of one-way streets that run in opposite directions to provide two-way mobility in a specific area) into four separate two-way streets with additional parking and landscaping. The conversions slow traffic, facilitate pedestrian and bicyclist access on the commercial streets, and disperse through traffic onto underutilized streets. The route from Riverfront Parkway to major downtown destinations now is more direct, as are routes to employment at nearby health care and educational centers.
Prior to construction, proponents feared the planned changes might be incompatible with the Tennessee Department of Transportation’s (TDOT) design guidance. To avoid potential conflicts, TDOT delisted the facility from the State’s system and transferred responsibility for maintenance to the city before implementation.
“Before the redesign, the facility felt like a highway, but now it feels like a road through a park,” says Karen Hundt, director of the Chattanooga-Hamilton County Regional Planning Agency’s Planning and Design Studio, which contributed to the project. “Chattanooga’s experience is quite transferable because other cities still have similar highways along their waterfronts.”
Evaluation and Rating Systems
In each of these case studies, the cities employed a variety of strategies and techniques to make their streets and roads more sustainable within their specific contexts. Now that the projects are completed, how can these cities -- and others doing similar types of sustainability projects -- measure success and continue the progress and momentum?
In general, evaluation processes seek to provide tools for monitoring progress toward sustainability goals and incentivizing sustainable practices. Sustainability evaluation and rating systems also provide a framework to examine and balance the interconnections among social, economic, and environmental factors. Several ratings systems have been developed recently that do not specifically focus on transportation infrastructure, but may nevertheless benefit road projects.
For example, for projects where landscape preservation or enhancement is desired, there is the Sustainable Sites Initiative (SITESTM), launched in 2005 by the American Society of Landscape Architects, the Lady Bird Johnson Wildflower Center at the University of Texas at Austin, and the United States Botanic Garden. The SITES system, slated for release in 2013, takes a comprehensive view of the impacts of landscaping in a variety of project types. The system is organized into categories such as site selection, predesign assessment and planning, site design, construction, and operations and maintenance. A 2-year pilot study of more than 150 projects, including 16 transportation corridor and streetscape projects, began in June 2010.
For road projects that are developed as part of a neighborhood, the Leadership in Energy and Environmental Design (LEED) rating system, a product of the U.S. Green Building Council, includes land use and transportation elements. The LEED® for Neighborhood Development (LEED-ND) certification, launched in April 2009, offers credits in two categories that reference transportation. The Smart Location and Linkage category encourages communities to consider location, transportation alternatives, and preservation of sensitive lands, while discouraging sprawl. The Neighborhood Pattern and Design category emphasizes vibrant, equitable communities that are healthy, walkable, and mixed use. In LEED-ND, streets are not rated individually but factor into an evaluation of the broader context, including buildings, parks, and other features.
Sustainability evaluation systems designed specifically for road projects also have been developed, such as New York’s Green Leadership in Transportation Environmental Sustainability (GreenLITES) program, Washington State’s Greenroads™ system, and FHWA’s Sustainable Highways Self-Evaluation Tool. The goal is to provide information and direction to practitioners for making sustainable choices and measuring performance and progress rather than labeling winners or losers. Another goal of the transportation sustainability systems is to stimulate conversations within the transportation community regarding how to build “smart” projects and determine if the right project is being built.
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Sustainable Streets in Small Towns
The principles of sustainable street design can serve small and rural towns, even where municipal infrastructure budgets are small. These two recent projects, from Duncanville, TX, and West Union, IA, address ecological concerns and community economic priorities in small towns. The city of Duncanville, TX, with a population around 38,500, established a vision and formbased codes for its Main Street corridor to ensure future economic vitality as land for new development becomes scarce. The codes emphasize creating a pedestrian-friendly environment where non-auto trips are possible. As explained in the city’s visioning document, "Main Street Vision is a formal plan the city has put into place to transform Main Street from a disconnected chain of disparate businesses into a seamless, integrated socioeconomic epicenter." The first phase, design of streetscape improvements, is underway. Shown here is a rendering of the reconstructed N. Main Street between Wes Jespersen Way and East Davis Street, with street parking, sidewalks, and landscaping improvements. Construction began in 2010 for sustainable streetscape treatments in a six-block downtown district of West Union, IA, which is home to about 2,400 residents. The planned treatments include porous pavement, rainwater harvesting, geothermal heating, midblock sidewalk bump-outs, and street furnishings. The upgrades are part of a larger "green infrastructure" effort that aims to renovate each city block with an eye toward sustainability, supporting the local economy and lowering operating costs. |
State-Level Developments in Rating Systems
New York and Washington State have taken the lead in creating rating systems. New York’s GreenLITES program, established in 2008, is the primary internal management tool for the New York State Department of Transportation (NYSDOT). GreenLITES is a self-certification program that distinguishes transportation projects and operations based on the extent to which they incorporate sustainable choices.
NYSDOT uses GreenLITES to measure performance, recognize effective practices, and identify needs in roadway design and maintenance. Federally funded local projects also use GreenLITES, and NYSDOT is developing a new regional awards program to highlight those road investments that most benefit each region in the State. In April 2009, GreenLITES released a companion Operations Certification Program, which encourages mobility, community, and ecological sustainability principles in all aspects of maintenance and operations. This program was designed in recognition of the fact that much of a State DOT’s day-to-day work consists of operating and maintaining lane miles, bridges, small and large culverts, and hundreds of thousands of acres of right-of-way, rest areas, and facilities. Through this daily work, a DOT has numerous opportunities to make either a positive or negative impact on the environment, the economy, and social equity. GreenLITES Operations, therefore, includes some 100 tasks that a DOT can incorporate into maintenance and operations planning so sustainability tradeoffs can be quantified and performance can be tracked. NYSDOT also is developing GreenLITES for Sustainable Planning, which is a project solicitation tool to assist municipalities in identifying and developing sustainable transportation projects.
In January 2010, the University of Washington released its rating system called Greenroads. The Greenroads rating system specifies up to 37 credits and 11 project requirements, such as having an environmental review process, performing a lifecycle cost analysis, and developing waste management and pollution prevention plans. Point levels then qualify projects for one of four achievement levels (certified, silver, gold, and evergreen). All points are independently verified by a Greenroads review team based on documentation.
Greenroads focuses on the technical design and construction phases, though prerequisites include plans for context sensitive solutions and pedestrian, bicycle, and transit or high-occupancy vehicle access. Currently in a pilot phase, Greenroads is evaluating 30 projects across the country.
FHWA’s Evaluation System
For FHWA, sustainable transportation means providing exceptional mobility and access in a manner that meets development needs without compromising the quality of life of future generations. A sustainable transportation system is safe, healthy, affordable, renewable, operates fairly, and limits emissions. The development and use of a sustainability framework and rating system allows for the establishment of a shared vision of sustainability in planning, design, construction, operations, and maintenance.
In October 2010, FHWA announced the availability of its own sustainable evaluation system for roads and highways. The Sustainable Highways Self-Evaluation Tool, available online at sustainablehighways.org, covers the transportation process from planning through funding, project development, design, construction, operations, and maintenance. For each phase of a project, practitioners can select sustainability goals and objectives that reflect stakeholder values and expectations, and fit within the project’s context. As practitioners select the goals, they begin to populate a sustainability course-of-action spreadsheet. The spreadsheet is project-specific and provides easy identification and evaluation of the selected criteria, evaluates performance based on the weight of the activities, and offers best practices to fulfill criteria and potential benefits.The evaluation system also contains illustrative practices to demonstrate the outcomes of the selected objectives. For example, for the storm water runoff management credit, the FHWA tool discusses a project in Bellingham, WA, that used porous pavements and a new storm water management system that offered measureable benefits to water quality.
The FHWA self-evaluation tool enables stakeholders to apply the metrics to quantify outcomes and make decisions. Although FHWA plans to sponsor an awards program to recognize projects that use the tool successfully, there is neither an independent certification process nor a comparison among projects or States.
“By creating the sustainable roads evaluation system, FHWA is building upon a longstanding commitment to context sensitive solutions, planning and environment linkages, and environmental stewardship,” says April Marchese, director of FHWA’s Office of Natural and Human Environment. “We have taken a leadership role to provide technical assistance to our State and local sponsors that will enable them to create solutions that work on all three levels of sustainability -- environment, equity, and economy.”
Toward a Sustainable Future
The emerging focus on designing sustainable streets and highways reflects the diversity of contemporary demands on public rights-of-way. In response, the practice of design is changing as Federal, State, and local policies and objectives increasingly require integration of livability and sustainability features such as multimodal facilities, space for social interaction, and natural landscaping elements. To support and stimulate sustainable practices, evaluation and ratings systems establish benchmarks and create a blueprint within a framework of context sensitive design.
Looking ahead, the road design, construction, and maintenance fields can expect further innovations in sustainable streets. With the development of intelligent transportation systems, tomorrow’s roads will need to respond to emerging vehicle technologies, such as vehicle-to-infrastructure communications, where drivers are given real-time data, such as road conditions, transit time tables, or parking availability, to make better choices and potentially reduce congestion. Electric vehicles and their charging infrastructure may need to be part of sustainable design. Advancements in rooftop and building photovoltaics could influence roadway network and building orientation for optimal solar gain and maximum energy generation. The emergence of new materials with multiple co-benefits -- such as 100 percent recycled concrete and stone pavers, recycled aluminum LED light standards, and photocatalytic cement (also known as pollution-eating cement) -- could provide new opportunities for designing sustainable streets. Additional innovations could include integration of dynamic information systems that provide real-time information in response to community indicators (such as ambient noise levels or energy use), space dedicated to new models for vehicle ownership and use (such as neighborhood- and district-level fleet vehicles, bike stations, and car-sharing programs), increased use of shared rights-of-way, and analyses that provide a greater understanding of transportation’s role in developing sustainable communities.
Without a doubt, stretched Federal, State, and local budgets underscore the growing need to obtain as much value from investments in transportation as possible. By aiming for sustainability, departments of transportation can find innovative ways to design road projects that meet safety and mobility requirements while delivering maximum benefits to communities, motorists, and the environment.
Benefits of Sustainable Streets
Perspectives on Multifunctional StreetsMany jurisdictions and organizations have coined various phrases to describe multifunctional roads and their benefits, such as smart growth streets, complete streets, green streets, etc. Smart growth streets are roadways designed and operated to support compact communities, promote least polluting transportation performance, and preserve environmental resources within and beyond the right-of-way. According to EPA, the concept of smart growth streets includes the following principles:
Complete streets, according to the National Complete Streets Coalition, are public rights-of-way that are safe and comfortable for all users, such as pedestrians, bicyclists, motorists, transit riders, and people of all ages and abilities, including children, older adults, and people with disabilities. Green streets, according to the Charles River Watershed Association, can be defined as streets designed to meet the following objectives:
Living streets, as defined by the Denver Living Streets initiative, are vibrant places where people of all ages and physical abilities feel safe and comfortable using any mode of travel, including walking, biking, transit, or automobile. Context sensitive solutions, as defined by FHWA, are collaborative, interdisciplinary approaches that involve all stakeholders in providing a transportation facility that fits its setting. Context sensitive solutions lead to preserving and enhancing scenic, aesthetic, historical, community, and environmental resources, while maintaining or improving safety, mobility, and infrastructure conditions. |
Ellen Greenberg, AICP, is associate principal at Arup in San Francisco, CA, where she leads the integrated planning practice. Greenberg is an urban planner who holds master’s degrees in both city planning and civil engineering from the University of California, Berkeley. In 2007–2008, she was a visiting practitioner at the University of California, Davis’s Sustainable Transportation Center.
David J. Carlson is director of sustainable development with Parsons Corporation’s Transportation group. He was formerly a senior environmental specialist on the Sustainable Transport and Climate Change Team in FHWA’s Office of Natural and Human Environment. He holds a bachelor’s degree in natural resource management from the University of Massachusetts.
Morgan Kanninen is a graduate urban planner in the integrated planning group at Arup’s San Francisco office. She holds a bachelor’s degree in community and regional development from the University of California, Davis, where she contributed research to the Sustainable Transportation Center’s sustainable streets project.
For more information, contact Ellen Greenberg at 415–946–0248 or ellen.greenberg@arup.com, David Carlson at 202–775–3355 or david.carlson@parsons.com, or Morgan Kanninen at 415–946–0272 or morgan.kanninen@arup.com.
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Correction: This article was changed in this online version and differs from the printed version in the following manner: David Carlson's e-mail address was changed from dave.carlson@parsons.com to david.carlson@parsons.com.