Society's dependence on motor vehicles continues to take a toll on natural resources, finances, land consumption and social interaction. To reduce these impacts, planners and engineers are working with communities to design transportation options that include more sustainable approaches to transportation. Ideally, these methods address the three pillars of sustainability — economic, environmental and social.
Professor Michelle Beiler, civil & environmental engineering, has participated in numerous research studies and field projects related to sustainable transportation infrastructure and design. She explains what cities and other government entities are doing to increase modal alternatives for transportation.
Question: How are municipalities reducing the impact of new and existing transportation system designs on the environment, economy, and society?
Answer: They are supporting balanced transportation networks, which offer accessible and reliable options for multiple modes including pedestrian, cycling and mass transit, as well as providing multiple routes. Given that roads have been a priority and automobile travel is still the dominant method of choice for many commuters, planners are looking for ways to integrate sustainable design into their existing systems. One of the options is a complete street, which provides several transportation options.
A complete street is a redesigned road that includes features such as sidewalks, bike lanes, transit stops, pedestrian signals, landscaped medians and curb extensions, but still supports vehicular travel. Depending on the context of the community, the design features on complete streets can support social interaction as well as economic growth through increasing pedestrian and cycling mobility. This is especially the case for areas where businesses, residences and places of work are interconnected.
To increase safety for all travelers, some cities have adopted traffic-calming measures as a way to continue automobile travel while supporting the needs of pedestrians and cyclists. Examples of these efforts include converting an automobile lane to a bike lane, raising pedestrian crosswalks and reducing roadway lane widths. These changes encourage drivers to slow down and be more aware of pedestrians and cyclists.
Ideally, non-motorists can travel from the street to the nearest bike route or trail. Transportation engineers can enhance multimodal commuting by providing these connections, which can reduce congestion and travel time, improve public health and physical fitness, and reduce emissions. This addresses all three pillars of sustainability.
Q: How do we measure the impact of these solutions?
A: There are a variety of metrics that can be used either individually or collectively to evaluate existing systems and identify improvements toward a more sustainable network.
Transportation metrics include annual average daily traffic, travel delay, crash rates per 100 million vehicle miles and average travel speed. These relate to infrastructure network metrics such as connectivity, continuity, pedestrian route redundancy and transit stop availability within a designated area. Environmental metrics such as rate of land consumption, air quality, and quantity and quality of stormwater runoff measure the impact of transportation development on the natural environment. In addition, socioeconomic metrics such as transit affordability and household vehicle ownership can provide insight into the equity of transportation systems.
Q: Are there any design solutions or programs that support all three pillars of sustainability?
A: Municipalities and transportation agencies are implementing smart-growth developments in response to the migration of populations away from cities and towns, which is known as urban sprawl. These plans, which generally include the public and other stakeholders in the decision-making process, combine walkable networks, compact building design, mixed land uses, affordable housing options and preservation of natural areas. Smart growth has been supported through federal, state and regional funding in order to encourage communities throughout the nation to adopt sustainable planning and design goals.
Transit-oriented development supports smart growth by blending housing, office, retail space and other amenities into a single, walkable neighborhood located near public transportation. Such a development naturally reduces the need for automobile use, which lowers congestion and emissions — supporting the environmental and economic pillars — and can lead to physical benefits from increased walking and cycling, which is the social benefit.
Safe Routes to School is an example of a federal and state-supported program that provides funding to encourage children to walk and bike to school. The implementation of the program is based on the five "E's" — engineering, encouragement, enforcement, evaluation and education. In terms of engineering, infrastructure improvements such as enhancing sidewalks, signage, lighting and roadway markings can improve accessibility and safety of children walking or biking to school. In addition, more walking routes and improved enforcement techniques, such as additional crossing guards, can encourage students to walk to school.