Boardman Place seems to have the wrong type of highway tag - it is functionally a footway not a pedestrianized street, where vehicles could be expected. 

The presence of a green street sign does not imply the presence of a street - only a public way that is in the city's register. In this case, Boardman Pl does not have an easement as seen in the city assessor's map. https://gis.cambridgema.gov/blockmaps/Block_76.pdf

It does seem like there is a street center line (i.e. registered public way) that surrounds 11-15 Boardman St on three sides - perhaps a footway is better for that case?