MassDOT commits $700 million toward Cape bridges rebuild

Massachusetts will commit $700 million in state funding toward the construction of two new bridges to replace the aging spans connecting Cape Cod to the mainland, officials announced Thursday.

The U.S. Army Corps of Engineers, which owns and operates both the Bourne and Sagamore bridges, and the state Department of Transportation announced a new memorandum of understanding that calls on Massachusetts to foot $700 million of the bill and the Corps to provide another $600 million, subject to congressional appropriation.

Officials have previously estimated replacing both bridges could cost more than $4.5 billion, and the announcement of a new agreement did not address the full funding needs of the two projects.

Massachusetts recently received $372 million in federal grants and another $350 million in a federal appropriations bill to help cover Sagamore Bridge replacement costs.

The project timeline calls for replacing the Sagamore Bridge before moving on to the Bourne Bridge. Crews plan to build the successor span "fully offset from the existing bridge," according to a press release, so vehicles can continue to use the Sagamore while construction is underway.

Gov. Maura Healey called the new agreement "an important step forward in our efforts to replace the Bourne and Sagamore Bridges."