NYC Access to Green Areas
In cities, access to green areas is an important factor than can affect health and habits of people. In some big cities, some people live in total abstraction from the natural environment, having no access to nature in their everyday routine and commute. From the apartment to the office and back to the apartment, they lack the landscape, the freshness, shadow, or clean air that green areas provide. With this in mind, I decided to characterize NYC by its access to green spaces.
By using NYC Open Data, it is possible to get data and geometries of the parks. Here on the right, we can visualize the green areas and NYC divided by zip code.
In order to describe each of the zipcodes and their relationship to green spaces, it is necessary to create a Park Access Index.
The Park Access Index was defined as the sum total of the area of each park divided by the distance between each park area centroid and the zipcode centroid. This is how I created the Park Access Index, which describes each zipcode.
Fig 2. NYC Map showing the Zipcodes identified by their Park Access Index, the parks are identified in green.
Fig 1. NYC Map showing the Zipcodes and the parks in green.
Then, I created the map on the left to visualize which zipcodes of the city have better access to green areas. ellow represents the best access to green areas and violet represents the worst.
This index shows some limitations:
- Zipcodes are big areas in terms of walking distance; it does not make sense to weight the entire area uniformly when the reality of living in different parts of the same zipcode can be completely different.
- The index gets biased by using the centroid of the park to the centroid of the zipcode as the distance. Some parks like Central Park will be weighted depending on the distance of the zipcode's centroid to the distance of the park's centroid, which results in lower rates for the zipcodes at the north and south extremes of the park.
To solve the first problem it is necessary to have more granular units of area, so I decided to use NYC census tracks. On the other hand, to solve the second problem it is necessary to modify the index and consider the weighting distance as the shortest distance between the census block centroid and the park. That way, the shape of the park won’t distort the index.
Below you can observe the granularity of census tracks and the results from the reviewed Park Access Index.
Fig 3. NYC Map showing the Census Tracks and the parks shapes in green.
Fig 4. NYC Map showing the Census Tracks identified by their Park Access Index, the parks are represented in green.
Below, an interactive version of both maps by zipcode and census tracks; you can select which layer you want to observe. For a better performance, click on the link at the bottom of the page.