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MBTA Communities Multi-Family Zoning Law


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What is Section 3A?

In 2021, the Massachusetts Legislature passed the Multi-Family Zoning Requirement for MBTA Communities Section 3A of MGL c. 40A. The new law applies to 175 municipalities within the MBTA's transit service district. Section 3A requires MBTA communities to have zoning that provides for at least one district where multi-family housing is permitted as of right. The district must have a minimum gross density of 15 dwelling units per acre and be of a reasonable size to accommodate the minimum number of residential units established in the Section 3A Guidelines.

What was RKG's Role?

RKG, in close partnership with colleagues at Innes Associates, worked with staff from Mass Housing Partnership (MHP) and the Department of Housing and Community Development (DHCD) to build a model that could test compliance with the Section 3A Guidelines. The Excel-based model allows users to test district sizes, parcel configurations, and zoning regulations to meet the size and unit capacity requirements in the Guidelines. The model uses dozens of zoning restrictions commonly found in municipal zoning ordinances to conduct a residential build-out for each parcel in the district and provides model users with information to analyze the effectiveness of the district compared to the requirements in the Guidelines. DHCD will also use the model to test compliance as applications are submitted by MBTA communities over time.

RKG and Innes Associates also conducted several beta tests of the model with nine MBTA communities, developed a user guide for the model, and training videos for users.


​RKG will continue to assist DHCD with technical assistance for communities looking to create and test zoning districts for compliance with Section 3A. If you are interested in working with us, send us an email!

For more information on the law and compliance:

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