Subsidized rental units are concentrated in only certain areas of Somerville, and typically not in commercial districts like this section of Washington Street. There are good reasons for this since noise, pollution and traffic may pose problems for the tenants, and property on commercial streets is usually more expensive. Compared to the smaller but more upscale Davis Square, Union Square has far more subsidized rental units, 534 here versus 58 in Davis. The decision to locate a major project here apparently is part of SCC's speculative strategy to focus projects in Union Square before the Green Line comes (if it ever does).
Although the addresses of a few subsidized housing units are not published, the table below shows the locations of units in Somerville's 2011 Subsidized Housing Inventory. It is apparent that Union Square has far more subsidized units than any other commercial square.
SCC has stated that they intend to focus their development of affordable housing in Union Square to prevent gentrification due to the Green Line Extension, but many other neighborhoods in Somerville will also receive their first access to rapid transit when the extension is built. Gilman Square, Inner Belt, Magoun Square and Ball Square combined have less subsidized units than Union Square, but SCC is silent as to why they do not give them the same priority.