by Justin de Benedictis-Kessner
The Boston Area Research Initiative (BARI) is excited to announce an update to a data set that we’ve made publicly available as part of the Boston Data Portal for several years: the Geographical Infrastructure for the City of Boston. The Geographical Infrastructure is essentially the City’s property records database along with aggregate versions of these data. BARI releases these at the property, parcel, Census block, Census blockgroup, and Census tract levels every year.
I wanted to explore some of the dynamics in the use of individual parcels in the property records. For this I’m going to start with the individual parcel-level dataset (posted on the BARI Dataverse here) rather than one of the geographic aggregated datasets. This database shows a lot of information about each of the many thousands of land parcels in the City, including its land use, its owner, its square footage, and its value.
Specifically, I wanted to explore parking. According to urban transportation planners, both on- and off-street parking is one of the main drivers of induced demand for roads – that is, when more parking is available, more people will drive, but when parking is less available or more expensive, fewer people will drive.
I used the parcel-level data in Boston to look at how off-street parking was distributed across the City. I first wanted to look at the parcel data aggregated using one of the geographic identifiers from the Census Tract-level files that we include with this dataset – the neighborhood as defined by the City’s Inspectional Services Department.
A summary of this information is plotted below. Across the neighborhoods in Boston, we can see that some neighborhoods have very little square footage dedicated to off-street parking while other neighborhoods have orders of magnitude more.
This shows that some of the smallest and densest neighborhoods (e.g. Bay Village and Chinatown) are most heavily dedicated to off-street parking. This is especially interesting considering their proximity to downtown and their proximity to mass transit stations.
Next, let’s look at how has the existence of parking has fluctuated over time. One way to check this is by seeing when a parcel dedicated to off-street parking was developed. I did this for the last few decades, plotted below:
So, overall very little of the overall square footage remodeled in each year is dedicated to parking in most years, with many years having no remodeled parcels dedicated to parking. However, in some years it jumps up notably — for instance, in 2014. As Boston moves towards its goals from its Climate Resilience Plan, it will be interesting to see whether these patterns continue, or if fewer parcels in the City are dedicated to parking in new construction and remodeling.
Using these shapefiles I mapped out where the parcels dedicated to off-street parking are in the city. This map spatially demonstrates what the charts showed: off-street parking (plotted in turquoise on this map) is incredibly concentrated (relative to total area) in the downtown areas of Boston. This corroborates what we saw in the neighborhood summary.
On a policy note, these summaries point out one way in which transportation resources currently exist in the City. As Boston moves towards a more climate-friendly resilience plan, leveraging the area dedicated to cars to instead prioritize non-driving forms of transportation will be important. Currently, dedicating so much of the downtown neighborhoods to parking only serves to increase the number of cars there, which seems counterintuitive for traffic and urban planning more broadly. If the City of Boston wanted to decrease traffic in these central neighborhoods and decrease the number of cars entering such dense neighborhoods, dedicating less of the area in these neighborhoods to cars would be a good first step.
More broadly, these summaries and various visuals together demonstrate the use of BARI’s geographical infrastructure dataset more generally: easily being able to summarize information at various geographic levels across the City.