Big Dig: Boston Harbor Tunnels At Shipyard 1992
Six of the 12 tube segments for the new Boston Harbor tunnel sit at the Bethlehem Steel shipyard in Baltimore on Sept. 1, 1992. The segments are 325 feet long and have a diameter of 37 feet. They will be floated to Boston at the rate of about one a month with each end covered by thick, flat steel "dam plates" to keep water out and finished in Boston.
David L. Ryan