Walkability is a measure of how accessible an area is to walkers. A walkable area may have easy access to public transportation, pedestrian only areas, or a conveniently navigable grid plan. Walkability of an area is influenced by many factors including city infrastructure design and the general appeal of the environment. Walkability influences home prices and residents quality of life. It provides environmental benefits, health benefits, and creates a more sustainable community.
The General Theory of Walkability
In his The General Theory of Walkability, urban designer and city planner Jeff Speck claims that walkable cities can create a more resilient economy, a healthier community, and a cleaner environment.  He defines a walkable city as one where “the car is an optional instrument of freedom rather than a prosthetic device.” Speck states that people will choose to walk over drive if they are given a walk that is as good as or better than a drive. A better walk is achieved through four components, the Four Pillars of Walkability.
4 Pillars of Walkability
- Reason to Walk: Required services (grocery stores, gyms, commercial, etc.) should be within a walkable vicinity of people’s home. Public transportation should be provided if these services are too far to walk.
- Safe Walk: People should feel safe while walking. Along with lower crimes rates, city infrastructure contributes to increased safety; narrower roads, crosswalks, and bike lanes increase the safety of one’s walk.
- Comfortable Walk: People will choose to walk if it is comfortable. Sidewalk width, heights of buildings, and crowdedness all affect how comfortable people feel walking.
- Interesting Walk: Humans are social beings. Interaction with other humans, animals, and plants increase the enjoyment of the walk.
City Design and Development
Development of the Suburb
Pre-Industrial Revolution cities were compact. These cities contained all the services that residents needed, including residential and commercial, within a walkable distance. The migration of people to cities during the industrial revolution led to crowded and unhealthy cities. Euclidean zoning laws were created to separate the residential from industrial sections to improve health and life spans. The development of the car and a rising middle class further encouraged this separation. Urban Sprawl increased rapidly post World War 2, partly due to Eisenhower’s Interstate Highway Program. 
Mixed Use vs Single Use
Cities are designed based on two models: Euclidean Zoning model, or the single use city, and the compact model, or the multiuse city. Although both models provide the same services, the organization is different. The multiuse city intersperses the different services throughout the city in smaller chunks. The single use city has separated sectioned parts for each service. Each model has its own benefits. The single use city usually provides for quieter, cleaner, and spacious housing. School systems are better and communities are safer.  A city based on the multiuse model has all services in close proximity, is environmentally more sustainable, and can be more economically viable. 
The walkability of the multiuse city is inherently superior to the single use city. The single use city requires road infrastructure to connect the sectioned parts. The need for cars results in the need for larger parking lots, wider roads, and car-related infrastructure. Single use cities develop with the use of cars, discouraging walkability in the city. 
The growth of technology has allowed walkability to be measured in many different ways. Walkonomics is a web and mobile application that uses crowdsourcing and open data to rate streets on their walkability on 5 star scale. Walkonomics has data on many streets in the world. RateMyStreet is another web application that uses crowdsourcing to rate walkability. The application is founded on Google Maps and allows users to rate streets based on 8 specific categories.
There are limits to measuring walkability because of its subjectivity. Firstly, personal preference in crowdedness, distance, greenery, and other factors affect the walkability of any area. Secondly, walkability measurements are made considering the average user. Service requirements (groceries, gym, etc.) vary from person to person – a walk score may be suffer because a gym is not nearby, but a gym is not relevant to someone who prefers to run outdoors. 
Walkscore is a web and mobile application that uses specific rubrics to rate cities on based upon walkability. Its goal is to inform users about walkable communities, improve users’ commutes, and recommend nearby locations to the user. Walkscore uses patented algorithms to provide ratings for four categories: walking, public transit, crime, and biking. Using these four ratings, it generates a final walk score on a scale of 0 – 100. New York leads all United States cities with a walk score of 88. 
Time Transit Maps
Time Transit Maps are methods to measure walkability, specifically the availability of public transportation. These maps display destinations that can be reached from a certain point in a given amount of time using only public transportation. Mapnificent is a web application that uses Google Maps to display time transit maps in many cities throughout the world.
Visual Preference Surveys
A Visual Preference Survey is a means of measuring the aesthetic beauty of an area by asking participants to rate how pleasing it is to the eye when viewing an image on a scale of negative ten to positive ten, with zero being neutral. Visual appeal is important to both the comfort and interest level of pedestrians. Distinguishing characteristics such as unique architecture and environmental characteristics such as the type of greenery present and accessibility of sidewalks greatly change a viewer’s perception of an area. Although this method uses arbitrary ratings based on viewer perception, it is a good indicator of the overall quality of an area.
Better health from increased physical activity is one of the main benefits of walkability. A ten year study by the University of Melbourne found that an increase in access to destinations like parks, public transportation, and shops lead to more people choosing to walk instead of drive. Another study conducted in Salt Lake County, Utah, found that an individual’s risk for diabetes can be reduced by almost 10% by approximately doubling the proportion of people who walk to work, suggesting that improved infrastructure geared towards getting people to walk could have a significant effect on health issues. Advocates of walkability also consistently mention improved social interactions as an important factor. By decreasing the prevalence of cars in favor of walkers, more quality connections can be made and a larger sense of community felt. A study found that social capital, as well as physical and mental health, are all affected by the design of communities, with increased walkability cited as an important aspect of the design. The environmental benefits of less personal car use and more walking and use of public transportation is also an often cited strength of walkability, with the American Public Transportation Association (APTA) estimating that U.S. puiblic transportation saves 37 million metric tons of carbon dioxide annually.
One of the drawbacks to walkability is that it is generally accompanied by highly compact urban neighborhoods. While suburbs and less dense areas can be walkable, it usually is not to the same effect. While many proponents for walkability argue that high-density, walkable cities are peoples’ preference, data from the U.S. Census Bureau shows from 2010-2013 a rate of growth almost 2.5 times greater in suburban areas compared to core municipalities. This trend suggests that the current state of walkability in urban centers is not favorable enough compared to suburbs. Increased congestion on roads is also a downside as walkability inherently hurts the driver. Data collected from over 300 American cities shows about 90% of commuters drive, and thus a more walkable area will addto congestion by slowing down most commuters. The cost to the public needed to update and build new infrastructure is also seen as a detriment to creating more walkable areas.
Pedestrians gain the most from walkability as it represents a power shift from the driver to the walker. More Walkable communities means more crosswalks and pedestrian enhancing features.
Urban Planning and Design Movements
Groups in support of movements like smart growth and new urbanism, such as Smart Growth America and the Congress for the New Urbanism, are also in favor of increased walkability. Advocates for smart growth and new urbanism, as well as other similar planning theories, aim to achieve compact and connected city and town centers that are easy to get around, affordable, and safe, which greatly coincides with walkability. Walkable and Livable Communities Institute (WALC) is another one of many groups that, like Smart Growth America and the Congress for the New Urbanism, aims to provide improved walkability in communities.
Health organizations such as American Diabetes Association (ADA) and the American Heart Association (AHA) have come out in support of walkability due to the health benefits associated with areas that promote walking and physical activity over the more sedentary lifestyle brought about by driving. Gillian Booth, M.D. offers for an article on the American Diabetes Association’s website: “This is one piece of a puzzle that we can potentially do something about. As a society, we have engineered physical activity out of our lives. Every opportunity to walk, to get outside, to go to the corner store or walk our children to school can have a big impact on our risk for diabetes and becoming overweight.” 
Groups like the National Resources Defense Council (NRDC) and the [Environmental Protection Agency (EPA)] would favor a transition away from the high amounts of pollution due to car use towards walking and shared public transportation. The EPA even offers a checklist as a way of “keeping score” of how walkable communities are.
Architectural and Civil Engineering Firms
Firms charged with building infrastructure and organizations such as American Institute of Architects (AIA) and American Planning Association (APA) also back a shift towards walkability because in many cases new developments and substantial improvements to infrastructure must be made.
Drivers, like pedestrians, are the most impacted group; however, increased walkability yields the opposite effect. Favorable walking conditions would impact congestion and increase the time it would take to get around by car.
While not directly at odds with walkability, families tend to clash with one of the main features of walkable communities: compactness. Walkable areas tend to be very compact to improve accessibility, leading to more urban layouts with multi-family residential housing in place of single-family homes.
Car Manufacturers and Dealerships
Higher incentives for walking and taking public transportation will be to the detriment of car manufactures, such as Ford and Chevy, and dealerships that rely on selling cars. Although the car would likely not be eliminated as a form of transportation, especially outside of cities, these groups would lose business.
One Stop Shopping Stores
Superstores such as Walmart and Costco are valuable because they offer many different amenities in one location. This is good for drivers because it is convenient and reduces travel time. In a walkable area, it becomes unnecessary and runs counter to many of walkability’s benefits as people would have increased access to many different shops.
The city of Vancouver, located in the Canadian province of British Columbia, exemplifies sustainability and walkability in urban areas. Vancouver is striving to become the world’s greenest city by 2020, as highlighted by their Greenest City 2020 Action Plan. Their goals include residents making the majority of trips by foot, bicycle, or public transportation and ensuring every resident lives within a five-minute walk of a park, greenway, or other green space. A lower carbon footprint is critical to achieving a greater level of sustainability. To do so, Vancouver is focused on high density, vertical building to preserve green space and reduce sprawl. Large buildings can reduce pedestrian comfort levels and block scenic views. To combat this, Vancouver planners have allowed for smaller buildings to line the street with taller buildings setback behind them. This improves the visual appeal and comfort level of walking by providing more air space and greater line of sight while also increasing social interaction by connecting entrances of tall buildings to smaller businesses, cafes, and restaurants.
Davis, a suburban area in northern California and home to UC Davis, is a sustainable community that emphasizes the ability to walk and bike without being dependent on a personal vehicle. Davis features bike paths that are separate from the stream of vehicle traffic in order to improve safety and prevent unnecessary conflicts. Cooperative housing is common in Davis in order to increase affordability and provide healthy, walkable communities. Houses in these communities often face a collective green area to promote walking and immersion with nature as well as community involvement.
The High Line, Manhattan
The Manhattan High Line in New York City was first opened as a train track as part of the West Side Improvement Project in 1934. The last train ran on the High Line in 1980 and the track remained unused while lobbyists argued whether it should be preserved or demolished. In June of 2009, the High Line reopened to the public as a pedestrian path. The re-purposed area provides an interesting walkway that maintains parts of the old track, incorporates green spaces, and showcases public art which is common on the sides of buildings along the High Line. The area is also safe: the path is elevated over the city like the old rail road used to be which isolates pedestrians from other modes of transportation.
The development practices of Vancouver exemplify sustainable, vertical building in mixed-use areas that prove dense urban centers do not have to feel crowded. The design of bike paths and cooperative housing in Davis, CA show that suburbs do not have to be car dependent or separate from social interaction. The revitalization of the High Line in Manhattan has provided the area with a safe place to walk and interesting social interaction separate from the busy streets below. These areas incorporate the Four Pillars of Walkability in that they are safe, comfortable, interesting, and provide a reason for walking. Walkability is crucial in developing sustainable and healthy urban and suburban areas. It is necessary in creating denser urban centers to reduce personal vehicle dependence and conserve green space outside of cities while promoting stronger communities and increased social interaction. Single-use zoning has propagated suburban and urban sprawl causing increased car usage as opposed to public transportation, biking, and walking. Mixed-use areas that encourage interaction between different people and activities can increase quality of life and make vertical development possible. While walkability is largely beneficial, there are still valid concerns that must be alleviated by improved planning and further research.
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