Admiral Electric corporation has asked us to prepare a proposal to create $50,000,000 worth of urban amenities in Boston. The Chairman of Admiral Electric saw a television program about environmental injustice (the proposition that historically, lower income, and other marginalized groups consistently seem to have more noxious land uses in their neigborhood) and as a result, he wants to spend some of his personal fortune to compensate. Your task is to analyze the situation in Boston with regard to environmental justice. Please prepare a confidential report with an appendix of maps and charts (not to be shared with the client.) that will help us understand the truth to this E.I. theory in the Boston context.

Thanks,
Walrus

To : Walrus Floyd
From : Sonali Soneji

In response to the E.I. theory, I created a data model : "Residential Property values are lower near noxious land uses".
My aim was to analyze this model to see if physical conditions in Allston- Brighton, a part of Boston, prove this hypothesis right.

I chose Allston-Brighton because it is an area of diverse land uses, income groups, population densities and ethnicities.
I defined "Property values" as Total Property Values from the 1996 Tax Assessor database. "Noxious land uses" were obtained from the EPA Toxic Release Inventory.
The area analyzed was Ward 21 and 22 which is Allston-Brighton. Within this area, the land uses and property values near the TRI Facilities in this area were compared to Oak Square, a popular and prestigious neighbourhood in Brighton.

Notes about the Data

The latest version of the Tax Assessor data was not easily available. But since this is a comparison of neighbourhoods (and not a quantitaive analysis) I felt it was adequate. The EPA data is fairly recent. The data from both the databases is comparable with reference to Level of Accuracy. It was collected for property parcels or street addresses. So we can expect locational accuracy to be quite good.

My first task was to understand the data. I manipulated the data by Sorts, Summaries and Joins to find out flaws and inconsistencies.
One of the inconsistencies was that each condo parcel data was split up under two Standard Classification Codes (STCL codes). "995" was Condo Main for which Total Value was listed as 0, and "102" or "108" or "110" for which Total Value was the value for an individual property within the condo. The Parcels data has only one Parcel ID per parcel. So the total value for each Parcel ID had to be calculated by creating a new field which I called Short Parcel ID consisting of the first 7 characters of the Tax Assessor Parcel ID. Then I summarized the records for condos and added the proprty values to get Total Value and then joined these to the corresponding record for Condo Main with Short parcel ID as primary key.

I split up the residential data into 3 categories because the Total Values need to be evaluated differently. The categories are:
Residential - consist of Single family, 2 family, 3 family, multiple buildings / lots, (these have building values + land values = total value) and Residential land, Residential
ancilliary improvement (these have only land value)
Condo - total value calculated by sum of individual property values
Residential exempt - No listed value
I have attached hard copies of Summary Tables indicating the Standard Classification codes and Land use codes for 'Residential Properties in the Tax assessor database', 'Residential Properties in the Parcels data' and 'Commercial properties in Tax assessor database'.

The Commercial data contained records with Apartments and Group Housing Land uses. I ignored those records because I felt that they may not be taxed as residential properties and their Property value would reflect that. So direct comparisons could not be made.

I used the Geoprocessing extension "Merge" to combine Ward 21 and 22 data to get a shape file for the study area.
 

Analysis

Part 1

I noticed that TRI facilities seem to be located in the vicinity of the Mass Turnpike. I used "buffers" and "select by theme" to find the property parcels within 500 m of TRI Facilities. I assumed that these would be the affected parcels. The land uses of these parcels are indicated - undifferentiated residential in Red and various Industrial / Commercial land uses. I find that in Allston- Brighton there is a good mix of residential and industrial/commercial uses but I noticed a trend of TRI facilities being located in Industrial/commercial areas. The ratio of residential : ind/comm land is affected by the fact that residential parcels tend to be smaller in area.
 

 
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Part 2

When I mapped the 3 categories of residential land and undifferentiated ind/comm land, I found that there are pockets of residential neighbourhoods and ind/comm land. Due to this it is inevitable that the TRI facilities are close to some residential parcels. When I looked at the property values of residential land in Allston- Brighton, I found no obvious trends or patterns applicable to the whole area.

So I selected smaller areas within Allston- Brighton for comparison. Comparing an area with a number of TRI facilities (area 1) to residences near Oak Square (area 2), I found that area 1 had a wide range of property values from very low to very high. Area 2 had more uniform property values close to the median value for Allston- Brighton. I concluded that unstable or diverse property values indicated an unstable neighbourhood which could be fighting to stay in existence and stop the ind/comm land uses from swallowing the residences up. This may be a potential area where funding can be used for neighbourhood stabilization. Residenial parcels that are surrounded and stranded within ind/comm uses can be very unpleasant to live in. Area 2 shows a strength in the residential fabric that is missing in area 1.
 
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Part 3

Another way I looked at the areas was by mapping Types of Residential parcels by Land Use Classification e.g. Single Family (R1), 2 family (R2), 3 family (R3), Residential land (RL), Condos (CM) and Residential Exempt (RE). I found that area 1 has a larger proprtion of Residential Land and Condo parcels. Area 2 is mostly made up of single family, two family and three family residences. (The exception is a large parcel near Chestnut Hill which is an aberration and needs investigation.) This may indicate a correlation between zoning and neighbourhood stability. If interspersed zones of ind/comm and residential land uses can affect residential property values and residential land uses adversely, it can indicate a potential for planning strategies towards neighbourhood stabilization. This can be another area for use of the funds.
 
  Click on thumbnails for details
 

Conclusion

"Residential Property values are lower near noxious land uses"

I have found that this hypothesis can hold little or no water. I found a fairly diverse mix of property values near noxious land uses. But this hypothesis lead me to investigate correlations between property values and land uses. I think there is a correlation between the two, but it is a complex one that deserves investigation.