Walkability is just what it sounds: a "walkable" place is easy to walk around.
Walkability depends upon characteristics of the built environment that influence the likelihood of walking
being used as a mode of travel. Let's explore what this really means, with the help of two places you
might be
familiar with:
Washington, DC
Questions to consider:
- How easy is it to cross these roads?
- Are there necessities such as grocery stores, train/metro/bus stations, etc nearby?
- How might the wide sidewalks and the grass patches impact how pleasant walking feels here?
College Park, MD
More questions to consider:
- How easy it is to cross the road here?
- Would you feel safe walking here at night - are there streetlights?
- How much tree coverage is there?
- How close are the cars to you, a pedestrian? Is there any margin? How would you feel about that?
> How would you rate the overall "walkability" of these two locations?
Walkability of a county can be a very important consideration – whether you are a prospective homeowner,
a
curious resident, or a relocated employee. Some may have a personal preference for a more or less
walkable
home, and understanding walkability can help people make informed decisions about where to live, work,
or
move in the future.
In this project, we have created maps to visualize walkability across the United States at the county level,
highlighting regional
trends
and helping users explore their area and the factors that contribute to and hinder walkability.
Quantifying Walkability: 4 Variables
The main variables that contribute to “walkability” of a census block group (CBG) are intersection
density, proximity to transit stops, diversity of land uses, employment mix, and employment and
household mix.
These four variables are quantified based on the CBG's score for each variable. For simplicity and
interactivity, we
aggregated the CBGs by county. Multiple CBGs belong in each county, so we averaged the corresponding
values.
Intersection density (measured in square miles): Higher intersection density is correlated
with
more walk trips
Proximity to transit stops (measured in meters):The distance in meters from the
population center to the nearest
transit
stop.
Transit stops greater than ¾ miles away were assigned a value of -99999 and not included. Shorter
distances
correlate with more walk trips.
Diversity of Land Use
The employment and household mix variables are part of diversity of land use and are quantified by the 8-tier employment entropy. The eight-tier classification summarizes
employment into the following groups: retail, office, service, industrial, entertainment,
education, healthcare, and public administration
Employment mix: The mix of employment types in a block group (such
as
retail, office, or
industrial). Higher
values correlate with more walk trips
Employment and household mix: The mix of employment types and
occupied
housing. A block group
with a diverse
set of employment types (such as office, retail, and service) plus many occupied housing units will have
a
relatively high value. Higher values correlate with more walk trips.
Click on a county to zoom in. Double click to zoom out. Shift + Drag to pan
around.
The Walkability Formula
The previous ranked scores were then weighted by the following formula:
Where:
w = block group’s ranked score for intersection density
x = block group’s ranked score for proximity to transit stops
y = block group’s ranked score for employment mix
z = block group’s ranked score for employment and household mix
The National Walkability Index is assigned for each CBG between 1 and 20, with least walkable
(1.0-5.75),
below
average
walkable (5.76-10.5), above average walkable
(10.51-15.25) and most walkable (15.26-20.0).
To analyze walkability, we used data from the
Walkability Index dataset.
Further documentation is available on the
dataset summary page.
Let's Dive into DC!
Now that you know what walkability is, let's return to DC and go a little deeper. The Distric of Columbia
provides access
to
hundreds of
datasets found here. We
composed a
visualization
using multiple datasets to show how complex walkability can be. Before we get started, we have to
introduce
some variables first.
Pedestrian Friendliness Index (PFI): DC scores each Census block showing how walkable
they
are, relative to other Census
blocks. An area deemed ‘most walkable’ has a connected street grid with sidewalks, buildings set close
to
the street, and intersections
and blocks that are manageable for pedestrians. It is essentially the same as walkability
Block Density: Calculated by dividing total blocks by the total area of each
neighborhood.
A neighborhood that is more
dense means that there are more buildings and people in the neighborhood.
Average Metrobus Ridership: DC scores every quarter mile in grid format by average
daily
metrobus ridership. Areas
with high average ridership are indicative of the jobs, population and activity generators within and
near
those grid cells.
Attractions Accessible via Walk: This measures how many destinations in a neighborhood
are
accessible by at least 20
minutes of walking.
Four Way Intersection Score: This measures how many four way intersections there are
compared to dead ends and other intersections.
Now, let's take a look at these variables within DC! You can toggle between the different variables and also
view the metro stations in the area as reference points.
Overall, you can see how walkability is a complex topic that is affected by many different factors. We have
visualized the
walkability of the US and DC using multiple datasets. The National Walkability Index is a good starting
point to
understand how walkable an area is, but it is important to consider other factors such as pedestrian
friendliness,
block density, and metro ridership, as we examined in DC. We hope that this project has helped you
understand
the importance of
walkability and how it can be improved in your own neighborhood!
