BIG FLOAT Building bridge-tunnel was tough in Chesapeake's unpredictable environment. Photo courtesy of Sverdrup Corp.

The 17.65-mile crossing of the Chesapeake's mouth between the Delmarva Pensinsula and Virginia's Tidewater area was a monumental construction challenge. At that point, the bay is an open sea in an area given to hurricanes in the fall, foul weather all winter and quick, violent storms in the spring and summer. The crossing area was shallow, about 30 ft deep, but included four navigation channels, two in the middle of the bay mouth.

P. C. Michener, project engineer for bridge-tunnel designer, Sverdrup & Parcel, St. Louis, decided to span two of the channels with high bridges and build under—rather than over— the two central shipping channels. The resulting crossing is a combination of high bridges, trestles, four artificial islands and two tunnels.

The islands, each 1,476 x 230 ft, were created by dumping sand, gravel, rocks and boulders onto the bay floor until they reached an elevation of 30 ft. Each pair of islands, about a mile apart, was linked by a sunken-tube tunnel. Most of the crossing, 12.2 miles, is made up of two-lane trestle supported by prestressed-concrete piles (ENR 11/28/63 p. 24).

Pile driving began in late 1960, with 3,000 piles of 7,000-psi concrete in lengths from 60 to 172 ft driven. A near record storm in spring 1962 destroyed the $1.5-million Big D pile driver. After pile caps were placed, the 75-ft deck sections went on. The crossing's entire length, except for two steel bridge sections, was paved with asphaltic concrete.

The 37 tubes that made up the two tunnel sections, each 300 ft long, were fabricated in Texas and towed 2,000 miles to the job site. Guided by divers, a lifting barge lowered the tube into place. Tremied concrete formed a seal with the previous tube. Central mix plants on the artificial islands provided 4,000-psi concrete to line the tubes. The $200-million crossing finally opened for traffic in spring 1964. Its manager, the Chesapeake Bay Bridge and Tunnel Commission, planned to operate it as a toll road. Contractor for the project was TMRK, a joint venture of Tidewater Construction Corp., Norfolk, Va.; Merritt-Chapman & Scott Corp., New York; Raymond International Inc., New York; and Peter Kiewit Sons' Co., Omaha, Neb. In 1999, the first phase of a 12-mile parallel crossing was completed.

Cash from Trash
(ENR March 26, 1964, p. 32)—Westinghouse Electric Corp. plans to design, engineer and erect Salvage and Conversion Systems, disposal plants that reclaim salable material from domestic refuse. Available as a package to communities, the plants would be complete with grinders, digesters, shredders, magnetic separators and aerobic thermophil microorganisms, which digest material. Almost 100% of all domestic refuse would be converted into salable products. Its first full-scale plant was built in San Fernando, Calif.

Column Design of World Trade Center
(ENR April 2, 1964, p. 48)—The design being prepared for the 1,350-ft-tall World Trade Center in New York City gave the exterior columns tremendous reserve strength. Because of the great length of the columns, structural engineer Worthington, Skilling, Helle and Jackson, Seattle, proportioned the columns in each story for the same unit stress under gravity loads regardless of the grade of steel in the columns. All columns would shorten the same amount, eliminating the possibility that differential shortening would cause warped floors. Various high-strength steels were planned for exterior columns, which would be spaced 39 in. c-c. The exterior column design called for 14-in.-square, hollow-box sections for high torsional and bending resistance. Spandrels welded to the columns at each floor would convert the exterior walls into giant Vierendeel trusses. Design for the interior columns around the core called for A36 steel.

The Alaskan Temblor
(ENR April 2, 1964, p. 45)—On March 27, 1964 an earthquake, whose magnitude was between 8.2 and 8.7 on the Richter scale, ripped through the southern coast of Alaska shearing buildings, slicing avenues, bursting pipelines and wiping out at least 17 bridges. Massive curtain wall panels dropped off the five-story J.C. Penney department store in downtown Anchorage. The cities of Anchorage, Kodiak and Valdez were hardest hit. New buildings in Anchorage, which were required to meet the earthquake provisions of the Uniform Building Code, were severely damaged inside, though they appeared sound from the outside. A newly completed apartment building crashed to the ground. Tsunami battered coastal Seward as well as coastal cities of California, 1,000 miles from the epicenter.