The Massachusetts Bay Transportation Authority announced on Aug. 2 that it plans to delay construction of the $1-billion Green Line extension to Somerville and Medford until fall 2018 or as late as summer 2020.It plans to purchase the required land and obtain permits before putting out a bid for design and construction to avoid loss of time and money—which happened to a commuter-rail project completed south of Boston in 2007. A day after the announcement, the city of Somerville circulated a petition stating that a four-year delay was unacceptable and demanded an accurate timeline for the project. It noted, “The
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.