Floating. New midtown Manhattan ferry terminal features floating dock (above) moored by tubular towers (left). The dock floats because the Lincoln Tunnel below prohibited driving of new piles into the river bottom.

Working around and atop the underwater tubes of the Lincoln Tunnel, crews constructed a new $56-million ferry terminal in midtown Manhattan that opened Oct. 24. In addition to sprucing up the New York City waterfront along the Hudson River, the terminal is seen as a potential evacuation route should a 9/11-like event ever occur again.

Designed by William Nicholas Boudouva + Associates, New York City, the two-story glass-and-steel terminal sits on clusters of timber and concrete piles that had supported an old timber dock. It is wedged between the river and two ventilation towers that pump air out of the Lincoln Tunnel. Local contractor Skanska USA Building Inc. demolished an old bus storage shed, reinforced the 30-in.-dia piles with new caps and built the new 30,000-sq-ft terminal while 5,000 daily passengers coming on and off tourist buses continued to use an adjacent dock.

The terminal’s new steel dock, accommodating six ferry slips, is a floating structure because "we couldn’t drive new piles due to the tunnel," says Pradeep Mehra, Skanska project manager. Two specially designed mooring towers on either end anchor the 300-ft-long, 30-ft-wide dock in place. The tubular towers consist of 36-in.-dia steel piles driven 120 ft into rock, says Ronald Treveloni, owner of TrevCon Construction Co. Inc., Liberty Corner, N.J., the marine subcontractor. "It was difficult driving piles through an existing pier," he says. "There were 60 to 70 years worth of debris."

The terminal’s walls consist of glass squares supported by 2-ft-dia tubular steel frames that transfer loads to the roof girders. Engineered by Thornton Tomasetti Group, New York City, the structural glazing is designed to accommodate 1-in. movements due to lateral wind loads and tides, says Mohammed Elwakil, a Skanska project consultant.

The 230-ft-long, 90-ft-wide terminal features motorized shades that automatically lower to minimize glare when the sun is setting. Sensors recycle air, which is distributed through ducts below the floor, says Mehra. A second-floor walkway includes a "diving board" extension jutting out from the terminal’s northeast end for a sweeping view of the river.

Work began in 2003 but was suspended for a few months last year as the owner, the New York City Dept. of Transportation, added extra bollards and reinforcements to foundations. The security extras added about $3 million to the project.

(Photo top courtesy of Bruce Ross Associates; photos middle and bottom courtesy of Skanska USA)