Walkability is a measure of how friendly an area is to walking. Walkability has many health, environmental, and economic benefits. Factors influencing walkability include the presence or absence and quality of footpaths, sidewalks or other pedestrian rights-of-way, traffic and road conditions, land use patterns, building accessibility, and safety, among others. Walkability is an important concept in sustainable urban design.
One proposed definition for walkability is: "The extent to which the built environment is friendly to the presence of people living, shopping, visiting, enjoying or spending time in an area". Factors affecting walkability include, but are not limited to: street connectivity; land use mix; residential density (residential units per area of residential use); the presence of trees and vegetation; frequency and variety of buildings, entrances and other sensations along street frontages, "transparency" which includes amount of glass in windows and doors, as well as orientation and proximity of homes and buildings to watch over the street; plenty of places to go to near the majority of homes; placemaking, street designs that work for people, not just cars and retail floor area ratio. Major infrastructural factors include access to mass transit, presence and quality of footpaths, buffers to moving traffic (planter strips, on-street parking or bike lanes) and pedestrian crossings, aesthetics, nearby local destinations, air quality, shade or sun in appropriate seasons, street furniture, traffic volume and speed. and wind conditions.
One of the best ways to quickly determine the walkability of a block, corridor or neighborhood is to count the number of people walking, lingering and engaging in optional activities within a space. While this process is a vast improvement upon pedestrian level of service (LOS) indicators recommended within the Highway Capacity Manual, it may not translate well to non-Western locations where the idea of "optional" activities may be different. in any case, the diversity of people, and especially the presence of children, seniors and people with disabilities, denotes the quality, completeness and health of a walkable space.
Walkability indices have been found to correlate with both Body Mass Index (BMI) and physical activity of local populations. Due to discrepancies between residents' health in inner city neighborhoods and suburban neighborhoods with similar walkability measures, it has been suggested that further research is needed to find additional built environment factors to be included in walkability indices.
Increased walkability has proven to have many other individual and community health benefits, such as opportunities for increased social interaction, an increase in the average number of friends and associates where people live, reduced crime (with more people walking and watching over neighborhoods, open space and main streets), increased sense of pride, and increased volunteerism. One of most important benefits of walkability is the decrease of the automobile footprint in the community. Carbon emissions can be reduced if more people choose to walk rather than drive.
Walkability has also been found to have many economic benefits, including accessibility, cost savings both to individuals and to the public, increased efficiency of land use, increased livability, economic benefits from improved public health, and economic development, among others. The benefits of walkability are best guaranteed if the entire system of public corridors is walkable - not limited to certain specialized routes. The World Cancer Research Fund and American Institute for Cancer Research released a report that new developments should be designed to encourage walking, on the grounds that walking contributes to a reduction of cancer.
Many communities have embraced pedestrian mobility as an alternative to older building practices that favor automobiles. Reasons for this shift include a belief that dependency on automobiles is ecologically unsustainable; automobile-oriented environments engender dangerous conditions to both motorists and pedestrians, and are generally bereft of aesthetics. Auto-focused designs also diminish walking and needed "eyes on the street" provided by the steady presence of people in an area. Reduced walking also reduces social interaction, mixing of populations and pride in streets and other civic space.
There are several ways to make a community more walkable. Sidewalks should be implemented where there are "sidewalk gaps", with priority to areas where walking should be encouraged, such as around schools or transit stations. In Atlanta, safe routes to transit is a growing campaign to provide safer access to transit stops for pedestrians. When implementing new sidewalks, there are several aspects to consider. For example, the width of the sidewalk is important for walkability. The Americans with Disabilities Act (ADA) requires that sidewalks be at least five feet in width.
Obstructions like sign posts and utility poles can decrease the walkable width of the sidewalk, so alternative locations for these obstructions, especially sign posts, should be used. Quality maintenance and proper lighting of sidewalks should be sustained to reduce obstructions, improve safety, and overall encourage walking. Another way to make sidewalks safer is to implement buffers, which are areas of grass between the street and the sidewalk. An additional benefit of buffers is that the vegetation absorbs the carbon dioxide from automobile emissions and assists with water drainage.
Making crosswalks safer is also key to walkability. Curb extensions decrease the radii of the corners of the curb at intersections. Curb extensions calm traffic and decrease the distance pedestrians have to cross. On streets with parking, curb extensions allow pedestrians to see oncoming traffic better where they otherwise would be forced to walk into the street to see past parked cars. Striped crosswalks, or zebra crossings, also provide safer crossings because they provide better visibility for both drivers and pedestrians.
A further justification for walkability as a consideration in urban design and planning, is founded upon evolutionary and philosophical grounds, contending that gait has been vital to the cerebral development in humans. After millennia of human development firmly based upon gait, the twentieth century automotive and automated metropolis has separated walking from thinking, and in this sense it has become an agent of regression rather than human progress. Walkability, therefore, is offered as a critical component in contemporary urban design considerations, with implications far beyond the scope of current concerns.
One way of assessing and measuring walkability is to undertake a walking audit. An established and widely used walking audit tool is PERS (Pedestrian Environment Review System) which has been used extensively in the UK.
Walk Score is an algorithmically derived walkability index based on the distance to amenities such as grocery stores, schools, parks, libraries, restaurants, and coffee shops.  Amenities within 5 minutes' walk (.25 mi) are awarded maximum points, while a decay function assigns additional points for amenities up to 30 minutes away. Scores are normalized from 0 to 100; a 2009 study by CEOs For Cites showed each point to correlate to between $700 and $3000 increase in property value. The efficacy of the Walk Score index has been demonstrated by studies in the British Journal of Sports Medicine and Transportation Research, among other publications.  The creators of Walk Score have also developed Transit Score and Bike Score metrics.
Walkability™ is a customizable set of three walk rating indexes with an algorithm that considers numerous factors not considered in other walk rating solutions, including factors such as street type, intersection complexity, POI accessibility, population density, freeways and bodies of water. Add-on scores include crime, weather, public transit and more.
Walkonomics is a web-app that combines Open Data and Crowdsourcing to rate and review the walkability of each street. So far every street in England (over 600,000 streets) and New York City have been rated.
RateMyStreet is a website that uses Crowdsourcing, Google Maps and a five star rating system to empower local communities to rate the walkability of their local streets. Users can rate a street using eight different categories: Crossing the street, Pavement/Sidewalk width, Trip hazards, Wayfinding, Safety from crime, Road safety, Clean/attractive, and Disabled peoples' access.
Walkability App developed by Clean Air Asia allows users to rate the walkability of a street qualitatively through 9 essential parameters. The individual scores are converted to a total out of 100 and each street gets a rating. Higher the rating better the walking environment. The parameters scored ranges from modal conflict to disability infrastructure, to safety perception to availability of crossing points and motorist behaviour among others. With a GPS on the mobile phone, the scores are mapped which allows people to know the most walkable and unwalkable streets. The most unsafe areas are highlighted which will enable vulnerable groups to avoid those areas.
A newly developing concept is the transit time map (sometimes called a transit shed map, not to be confused with the railroad structure), which are types of isochrone maps. These are maps (often online and interactive) that display the areas of a metropolis which can be reached from a given starting point, in a given amount of travel time (say, 30 minutes). Such maps are useful for evaluating how well-connected a given address is to other possible urban destinations, or conversely, how large a territory can quickly get to a given address (for example, a particular retail store location). The calculation of transit time maps is computationally intensive, and considerable work is being done on more efficient algorithms for quickly producing such maps. To be useful, the production of a transit time map must take into consideration detailed transit schedules, service frequency, time of day, and day of week.
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- levelofservice.com, Walkability tools research and walking level of service calculator.
- Walkshed.org, an online walkability mapping application using personal preferences.
- Pedestrian Environment Review System (PERS)
- RateMyStreet Walkability crowdsourcing project
- Get Your Walk Score - A Walkability Score For Any Address
- Walkonomics - How walkable is your street?
- making metro Atlanta walkable step by step