Peninsula In Passage

Morrison-Knudsen Company of Boise, Idaho and Interbeton, Inc., the North American subsidiary of one of the oldest building contractors in The Netherlands. The tunnel was constructed in sections that resembled the bore of a double-barreled shotgun. Each of the 15 steel and concrete sections was 80 feet wide, 40 feet tall, 300 feet long and weighed 28,000 tons. The tube ends were sealed with steel bulkheads to trap air inside and allow the sections to float. Tugboats brought the floating sections down the Chesapeake Bay from the Bethlehem Steel shipyard at Sparrow Point, Maryland, near Baltimore. Once each section arrived at the tunnel site it was encased in a concrete jacket to add enough extra weight to sink the tube. The section was kept afloat by a lay barge, a huge catamaran-type vessel, until it was in position. While the tubes were under construction,

contractors dredged an underwater path 120 feet below the center of the shipping channel. A crane with a clamshell bucket laid a rock foundation, scoop by scoop, along the path. A screed barge smoothed the underwater rock foundation, readying it to receive the tubes. Surveyors working with laser beams guided the lay barge in positioning and lowering each tube into place on the foundation. A railroad type coupler joined the two-to-three-foot gap between sections. The bulkheads sealing the tubes were seven and a half feet in from the tube ends so when the sections were joined a 15-foot tank formed between sections and was filled with water. When the water was pumped out, the resulting vacuum forced the gasketed sections together. The inner steel liner was welded into place and the tube joint grouted. Finally the bulkheads were cut out, creating a longer tube. When I-664 and the bridge-tunnel were completed in 1992 the 20-mile project was estimated to cost $800 million spent on 40 contracts to 30 contractors. And a long expected new landscape grew where crops once flourished in North Suffolk.

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