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zorostang / chicago_bike_equity

Visualization and analysis of Chicago bike lanes. An effort to determine how the bike lane installations are divided among the entire city.
MIT License
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How to interpret the findings of how many people live within 1/2 mile of a bike lane #57

Open stevevance opened 9 years ago

stevevance commented 9 years ago

Steven will insert his initial results here.

easherma commented 9 years ago

Some example screenshots for context in this discussion: This map shows the density of blacks (darker blue is denser) and protected bike lanes in yellow and buffered bike lanes in pink. Notice the gaps among the buffered and protected bike lanes. These gaps in coverage could be defined as connectivity deficiencies.

bikequity

This map shows the 1/2 mile buffer around protected bike lanes and the density of blacks. Notice how they are disconnected bubbles. It shows the parts of the city accessible to this population via the protected bike lane "network". It also paints a pretty powerful picture, portraying parts of the city as literally disconnected from each other. This is a compelling narrative. It's not talking quite about cycle equity, but it does bring to mind the phrase 'separate but equal'. bubbles

This map shows the 1/2 mile buffer around protected bike lanes and the density of whites. buffer

Steven and I spent some time checking and validating numbers pulled from census analysis, and are confident in our results. I'll quote his summary below for context:

"Breaking it down by bike lane type, the following racial and ethnic groups have this level of access:

Protected bike lanes

Protected bike lanes have only been installed since 2011.

Of the 870,611 whites (white alone), according to the American FactFinder 2013 ACS, 11.99% of whites live within 1/2 mile of a bike lane Of the 862,567 blacks (black alone), 15.94% of blacks live within 1/2 mile of a bike lane Of the 775,748 Hispanics, 5.80% of Hispanics live within 1/2 mile of a bike lane Buffered bike lanes

It appears that bike lane access for non-whites has improved since the introduction of protected and buffered bike lanes, but historically, considering bike path installation for all time, non-whites have had better access to the only two types of bike lanes that CDOT was building prior to 2011 (conventional lanes and trails)."

Together, the above elements can be stitched into a rough narrative: Yes, CDOT is doing a better job at creating equity in cycling infrastructure among various groups. However, these gains have occurred only recently, leaving much work to be done. Furthermore, there remains significant connectivity deficiencies; many protected and buffered lanes do not connect to each other, and each 'path' tends to belong overwhelmingly to a single ethnic group over another. We should discuss this narrative further and decide whether we can support and, if so, whether it furthers the goals of this project to mention it.

Finally, we should be aware that there are two main ways that we can describe equity. We can describe in terms of geographic distribution and in terms of equity among the population. For example, we can look at community areas in Chicago and create output showing that some community areas have more cycling infrastructure than others. Analyzing this geographic distribution doesn't really take into account population or population density, which are factors that are definitely considered by public agencies such as CDOT, who are often seeking to maximize the service provided (typically measured by providing services to the greatest number of citizens at the lowest possible cost).

This isn't specifically a weakness of a geographic approach but is simply something to keep in mind. In fact, we could argue that the methods used to operationalize and justify spending on cycling infrastructure are not optimal for the city overall, and can argue that a greater emphasis on geographic distribution will spread the clear economic and health benefits of cycling over greater areas of the city and will encourage ridership in areas of the city where it may be lower. The app we are working on can serve as a tool to a)Describe these deficiencies and educate the general public, b)Provide a tool for stakeholders to use in order to inform the planning process and c)Provide a resource for activists and advocates to be able to create reports and use data to back up their demands for greater equity in cycling infrastructure.