How Air Rights Work

A 2019 view of construction above Lansdowne Station along the Massachusetts Turnpike, part of the early air-rights work associated with Fenway Center. The deck spanning I-90 is now nearing completion, even as the project's planned life-science towers remain on hold.

Image courtesy of Pi.1415926535 / Wikimedia Commons (CC BY-SA 4.0)

Air-rights development allows builders to construct new buildings above active transportation corridors by leasing the space above state-owned land while maintaining uninterrupted highway or rail operations below. In Massachusetts, these projects typically begin with a long-term ground and air-rights lease administered by MassDOT, which controls the Turnpike corridor and sets milestones for construction, vertical development and public-realm improvements tied to the overall plan.

Because the structures carrying the buildings must be installed without shutting down I-90 or the Framingham/Worcester commuter-rail line, foundation and platform work precede all other phases and are among the most technically complex elements. Contractors install drilled micropiles or driven H-piles between traffic lanes or track beds, often working overnight or in narrow staging windows, before erecting steel substructures capable of supporting full building loads. Only once the deck is complete can utilities, streets or tower cores be extended over the right-of-way.

That sequencing compresses significant costs into early phases and shifts financial risk forward in ways uncommon in ground-up construction. Developers absorb minimal revenue until the towers rise, while contractors complete most of their work before the market fully validates the project. Public agencies retain an oversight role throughout the life of the lease, including monitoring structural maintenance and ensuring that required public benefits—such as open space, pedestrian connections or streetscape improvements—are delivered as planned.

Air-rights projects have historically moved through economic cycles differently than conventional site developments because their infrastructure components cannot be paused or phased easily once work begins. When market conditions soften after the deck is built, as occurred with Fenway Center, platforms can remain complete and unoccupied for extended periods while developers reassess timing, leasing prospects and financing viability. For public agencies and contractors, that interim period introduces unique governance and cost-management challenges that do not arise on typical real-estate sites.

Bryan Gottlieb