BOSTON CENTRAL ARTERY/TUNNEL PROJECT FORT POINT CHANNEL I-90 TUNNEL CROSSING. IN: PREPARING FOR CONSTRUCTION IN THE 21ST CENTURY, PROCEEDINGS OF CONSTRUCTION CONGRESS '91, SPONSORED BY THE AMERICAN SOCIETY OF CIVIL ENGINEERS IN COOPERATION WITH THE AMERICAN INSTITUTE OF MINING ENGINEERS AND THE AMERICAN ARBITRATION ASSOCIATION, CAMBRIDGE, MASSACHUSETTS, APRIL 13-16, 1991

Part of the Central Artery and Third Harbor Tunnel Project involves the construction of a very unusual section of immersed tunnel. While the Third Harbor Tunnel which will cross Boston Harbor will be of very conventional double shell steel binocular construction used widely in this country, the Fort Point Channel Tunnel will be very unconventional. A conceptual design has been completed for the relatively short crossing of Fort Point Channel and is described in this paper. The crossing will be accomplished with two parallel immersed tunnels each using a single concrete box element of varying width and height. This paper is intended to describe the reasons for the selection of this design, the difficult challenges which must be met, and the proposed method of staged construction.