The photo shows two low-profile cranes from the Port of Oakland go through the Panama Canal Aug. 27 on their way to their home at the Port of Boston. The cranes are a critical part of the Massachusetts Port Authority’s plan to meet future demand and accommodate post-Panamax vessels. Massport must use low-profile cranes, because the Conley Container Terminal is under the flight path of a runway at Boston Logan International Airport. The cranes left Oakland on Aug. 2 and are expected to arrive in Boston by mid-September.