What is
Walkability?
1. Walkability, By Definition
Walkability is a relatively new area of study in America since we've spent the last century expanding car infrastructure. As such, the precise definition of walkability (along with the method by which it's measured) is not concrete from study to study. The most obvious and broad definition of walkability, given by a study at the Hamad Bin Khalifa University in Qatar, is the "quality of which the built environment enables the mobility of pedestrians" (1).
Yet, others define walkability by more concrete, often quantitative measures; Foot Traffic Ahead: 2019, which ranked America's largest metros by walkability, defined walkable urban development as places with higher population densities, "relaxed or overlay zoning" laws, the allowance of mixed-use property types, and access to a multitude of transportation types such as bicycle and rail. They even go a step further to define a walkable area as a place in which the majority of a person's common destinations (such as work and grocery stores) are within walking distance, which they define as a half mile (2). This seems like a good definition for a walkable environment, but comparing it to definitions used by other studies reveals the exact problem I was talking about before — the definition isn't standardized. For example, the Hamad Bin Khalifa University study mentioned before also considers factors such as the "presence of greenness and parks, commercial retail," and "accessibility[...] to include those who use wheelchairs or other assistive devices"(1). Such huge variations in definition will have impacts on the comparability of "walkability" data from study to study, which must be kept in mind.
Certifications
Qualifications
Walk Score is a private company which developed a standardized method for measuring walkability. From Walk Score's website, "Walk Score analyzes hundreds of walking routes to nearby amenities. Points are awarded based on the distance to amenities in each category. Amenities within a 5 minute walk (.25 miles) are given maximum points. Walk Score also measures pedestrian friendliness by analyzing population density and road metrics such as block length and intersection density."
2. Walkability, By Measure
The closest thing we have to a standardized measurement of walkability is Walk Score, "a large scale, public access walkability index that assigns a numerical walkability score to any address in the United States, Canada, and Australia" (3). Walk Scores range from zero to one-hundred and consider a variety of factors from "presence of amenities such as restaurants, grocery stores, [and] schools," as well as "the intersection density" and "average block length" (1).
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Despite the fact that almost every academic study on walkability uses Walk Score, the majority also criticize its methods for neglecting other key factors in the walkability equation. Foot Traffic Ahead: 2019 states that Walk Score is "overly dependent on retail amenity locations as opposed to other built environment features and quality" (2). This is a valid complaint, as simply being near many businesses wouldn't influence
me to walk more if there were no sidewalks, for example. My own house in California had an entire mall located within walking distance (about half a mile), yet the lack of sidewalks meant I had to drive. But, looking at the Walk Score alone may lead one to believe I lived in a walkable area. Outside of the academic world, Walk Score is primarily used to "show how a walkable urban public realm directly translates into an increase in home values" (3). Some researchers claim that since Walk Score is a "private company" which "aims to use the index as a tool to influence housing prices," they left out "other critical factors in inspiring the decision to walk," such as "greenness," "air quality," "pavement quality," and "thermal comfort" (1). Another walkability researcher, William Riggs, added that Walk Score should consider "safety (from traffic or crime)" and "sidewalk width" (4).
Nonetheless, the researchers admit that "Walk Score remains the only walkability metric with U.S. national coverage" which is "consistent, easy to communicate, and has been validated in multiple studies[...] with actual walking activity" (2). And Walk Score is improving with time — just recently they changed their formulas to factor in gravity vs. distance, allowing extremely steep areas to receive lower accessibility / walk scores (4). Ultimately, we have not yet discovered a perfect way to quantify and measure the intricate concept of walkability, but Walk Score gets the job done for most research uses.
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Again, since Walk Score still isn't completely standardized, this isn't the only approach to quantifying walkability. Some alternative methods have been developed, such as Yiye Zhang's study which based its measurements off of the number of transit stations, bike paths, green spaces, traffic exposure, and land usage within a 500-meter radius of a subject's home address (8).
(Hover your mouse to see changes)
3. Walkability, By Design
Diving even further into the concept of walkability, we can look at its meaning from the level of infrastructure design itself. To begin, let's take a close look at a street which was recently redone by King County's Sound Transit as part of something they call "TOD" — Transit Oriented Development. On the right (5), you can see what a common Seattle intersection looked like in 2008. It has no crosswalk, no bike lanes, no public transit access, narrow sidewalks for pedestrians, and a wide two-way road to accommodate high speed car travel.
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Now, hover your mouse over the image to see what this street looks like today (6), after the redesign. A proper painted crosswalk has been added to caution drivers to slow for pedestrians. The street is now entirely for bikes and buses only, with no car access whatsoever; pedestrians only need to look one way when crossing, as bus travel is only in one direction. A new light rail station has been built in place of the old Chase Bank building, allowing bus and bike commuters to easily transfer to the light rail. The sidewalks have been significantly widened to nearly three times larger than before. Seating areas have been added to allow shoppers to eat outside after purchasing food from one of the many nearby businesses, which previously wasn't possible.
Brooklyn Ave NE & NE 43rd St, Seattle WA
The first photo (5), taken from Google Street View in 2008, shows a wide road with narrow sidewalks, favoring cars over people.
The second photo (6) was taken by me in 2022. Cars are no longer allowed through, only bikes and buses. The sidewalks are much wider, favoring alternative modes of transportation.
Note that the 2nd photo was taken during the winter whereas the first was not, so it appears less appealingly green.
Here's another angle of the same street (6). Some more changes become immediately apparent; the sidewalks have been significantly widened to nearly three times larger than before. Seating areas have been added to allow shoppers to eat outside after purchasing food from one of the many nearby businesses, which previously wasn't possible. Certainly, this updated TOD version of the street is much more inviting to walk through than the previous car-dependent road. Hence, urban design directly influences walkability — which is something that Walk Score cannot measure.
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This street is located within Seattle's U District. During the construction of the new light rail station, Sound Transit administered a survey to those who live or work within the U District asking them a series of questions about how an available plot of land should be used for additional TOD. With 1,375 responses, the survey found that the most desirable use of the excess land is to create a more pedestrian friendly environment with access to more affordable housing (7), continuing the pedestrian friendly development trend seen above. They also found that people want to be within walking distance of small businesses and fresh produce stores, and that more public open space was requested frequently among the respondents (7), which sounds shockingly similar to the qualifications for a walkable environment found in the previous sections. Lastly, the survey results found that "Creating a great pedestrian environment around the building is important, with elements such as street trees, safety buffers from traffic and wide sidewalks" (7). Again, these sound exactly like the "greenness," (1) and "sidewalk width" (4) that were factored into walkability above.
It is generally illegal to build walkable urbanism in the suburbs; the zoning and massive neighbor opposition do not allow it without heroic legal and political battles.
You may have noticed that almost every model for defining walkability I've mentioned so far has included the presence of businesses in some way. This goes back to the idea mixed land use zoning, the allowance of different property types within the same area. "Cities Alive: Towards a Walking World" claims that "Promoting walkability goes beyond enhancing the pedestrian system[...] including general land use zoning" (3). The U District is a great example of mixed-use zoning; in the pictures above (6), you can see that apartments are located directly above restaurants, promoting nearness and walkability. As a U District resident, I've found it extremely convenient to walk out my front door and less than 200ft to get lunch at my favorite Gyro restaurant or walk a little over a block when I need to pick up milk from the grocery store. The issue then, as Foot Traffic Ahead: 2019 points out, is that building these types of "affordable pedestrian and transit-accessible multi-family apartments in the suburbs" is quite literally "illegal" (2). Under modern zoning laws, suburbs are to be single family residential homes only, with businesses only being allowed in specific areas such as shopping malls. You can see a visual representation of these zoning policies in the map of Minneapolis above; to see more like this, go to the image credits page. This is perhaps the biggest roadblock for creating walkable environments, especially considering that a case study proved "whether or not different land-uses are within walking distance of each other is the most decisive attribute that gets people walking or choosing alternative modes of transport" (3). After all, how can one walk to accomplish anything if the nearest zoned commercial building is four miles away? From firsthand experience, you can't; especially when sidewalks are allowed to simply end.
