Union Square D2.1 | 10 Prospect Street | Somerville

Steve H

New member
Nov 18, 2021
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Loving all these photos, especially from David Z!

I have a question related to the "Union Square Mobility Plan" for the D2 parcel, prepared by Stantec waaaay back in 2019 (available here). I realize that thinking about parking and traffic may be a little off-topic for an Architecture forum, so please forgive me (or delete the post!) if this is inappropriate.

The Mobility Plan makes some assumptions that seem extremely optimistic – none more so than in section 2.3, on Mode Share, which states
…existing non-vehicle mode share is approximately 34%. Existing US Census non-vehicle mode share for the Union Square Census tract was grown to 60% based on assumptions regarding proposed TDM measures to be required by the City as part of the development.
Through magic numbers and wishful thinking, this Mobility Management Plan makes it seem like we can easily add more than a thousand new people to an area that previously housed a few people and a bunch of rusty radiators, without causing much additional vehicle traffic.

The Plan's Table 10 estimates that 450 new units of housing and almost 200,000 square feet of office/lab/retail space will generate 768 new "person trips" per day, but only 258 new vehicle trips – and only 23 new vehicle trips in the PM peak hour. They're assuming a gigantic mode shift onto the new Green Line, but it's hard to imagine all these hundreds of new residents getting jobs somewhere convenient to the Green Line, and all these hundreds of new employees likewise living somewhere that the Green Line would help them quickly get to Union Square.

I realize that, permit-wise, this train (ahem) has long since left the station, but, as a Union Square resident, I feel that the developers and the city will have to do a LOT more to mitigate traffic into and through Union Square. It's already impossible for me to traverse Union Square from Prospect St or Webster St in a car during the afternoon rush; even if every single new person avoided using a car, the situation isn't tenable.

I'm interested in how folks have seen this stuff handled in other areas. The Mobility Management Plan reads like so much hand waving and wishful thinking.


Senior Member
May 6, 2007
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That little dinky triangle park on the auto sales lot needs to be decked over the tracks. Ideally, put a park over the whole substation like they're doing in Kendall. They even render the path in that park leading into the void, as if to say "yeah, there should be more park here... we're just half-assing it to meet our open space obligation."

This would be so much better: