How much did the extension of Boston — Green Line — Green Line Extension cost?
The Green Line Extension added two light-rail branches from a rebuilt Lechmere station through Somerville to Union Square and Medford/Tufts. The roughly 4.7-mile program included six new stations plus relocated Lechmere, rail and bridge work, a maintenance facility, and vehicles. Early construction began in 2013; the redesigned main design-build phase followed in 2018. Union Square service began in March 2022 and the Medford branch opened that December. The published $2.288 billion figure is a 2023 projected total for the program, not an independently audited final construction bill.
Published project estimate
$2.288 billion
Cost basis: 2023
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Cost evidence
Basis of the published figure
Published project estimate2023
Project metrics
Key dimensions
- Total lengthFederal Transit Administration
- 7,600 m
Project record