Officially opened in 1914, the 48-mi. long Panama Canal connecting the Atlantic and Pacific Oceans via the Caribbean Sea by cutting through the Isthmus of Panama has greatly reduced travel time for ships. Considered one of the largest and most difficult engineering projects ever undertaken, the 100-year-old shortcut also provides safer passage by allowing ships to avoid the hazardous Cape Horn route around the southernmost tip of South America.
Each year, approximately 14,000 cargo and cruise ships pass through the Panama Canal, but recently, one unusual shipment passed through the historic locks.
The “Left Coast Lifter,” the world's largest floating crane, passed through the Central American canal in January, on its way from its home near San Francisco to the Hudson River in New York, where it will be used to dismantle the deteriorating Tappan Zee Bridge and construct a replacement.
Tappan Zee Bridge
Twenty-five miles north of Midtown Manhattan, the Governor Malcolm Wilson Tappan Zee Bridge, sometimes called The Tap, is a cantilever bridge across the widest point of the Hudson River in New York. Built in 1955, the 3.1-mi. (4.9 km) bridge accommodates 140,000 to 170,000 vehicles daily, resulting in congestion during peak hours. Despite a movable center barrier to enhance traffic flow, delays are common on the seven-lane bridge, which is part of Interstates 87 and 287.
In addition, due in part to the fact that it carries more traffic than it was designed to, the bridge is deteriorating and has nearly outlived its 50-year design.
Concerns about the bridge's structural integrity led to plans to replace the bridge. After numerous options were considered, federal and state authorities determined it best to demolish the old structure and build a new double-span bridge to replace it.
Public input gathered for years indicated a desire for public transportation to be included. Several replacement alternatives were studied by the New York State Department of Transportation as part of the required environmental review, each of which included a plan for the inclusion of public transportation. However, in October 2011, Gov. Andrew Cuomo and the Federal Highway Administration came up with a less expensive plan that did not include any form of public transportation.
Estimated cost of the project is $3.9 billion. The first span is expected to open in 2016, with final completion scheduled for 2018.
In 2013, Tappan Zee Constructors LLC (a consortium that includes Fluor, American Bridge, Granite and Traylor Brothers, plus design firms HDR, Buckland & Taylor, URS and GZA), contracted by the New York State Thruway Authority, began taking down the longest span in New York in order to build what will become one of the widest spans in the world. The bridge and approaches will stretch 16,013 ft. (4,880 m), Its cantilever span will be 1,212 ft. (369 m), with 138 ft. (42 m) of clearance over the water.
Up to the Task
Officially registered with the U.S. Coast Guard as the Left Coast Lifter in 2009 when it was used to aid in the erection of the new eastern span of the San Francisco-Oakland Bay Bridge, the 6,750-ton (6,123 t), 400-ft.-long (122 m) crane assembled in Shanghai has been dubbed by New York's governor the “I Lift NY super crane” for the Tappan Zee project.
Outfitted in Asia, the specially made crane that was commissioned by American Bridge and Fluor is one of the world's largest. Permanently mounted on a barge made by U.S. Barge LLC in Portland, Ore., the Lifter is an actual vessel. As such, it was never intended to travel on land.
Owned by Tappan Zee Constructors (TZC), it will allow them to complete the job more quickly at less cost. According to Carla Julian, community outreach/diversity manager?of Tappan Zee Constructors LLC, use of the crane contributed the consortium's ability to bid $800 million less than their competitors.
Gov. Andrew M. Cuomo elaborated about using the crane on what he calls “the state's most ambitious infrastructure project of the 21st century,” telling the New York Times, “The I Lift NY super crane can lift the equivalent of up to 12 Statues of Liberty at once, shortening construction time by months and reducing project costs by millions of dollars.”
Built on a 384-ft. (117 m) barge, the crane's 1,900-ton (1,723 t) lift capacity comes from three diesel-powered 601 kW main generators and one 91 kW auxiliary generator. Its 328-ft. (100 m) shear leg boom, a welded tubular truss structure with a capacity of 3.75 million lbs. (1.7 million kg), will be used to help construct modular sections weighing 900 to 1,100 tons (816 to 998 t) at a nearby assembly yard on the Hudson River. The sections will then be brought to the worksite by barge, where they will be installed by the crane as bridge deck and supports.
“It can pick up large pieces,” Julian said. The crane is capable of hoisting 1,900 tons in a single heave. That allows the crews to perform modular construction activity in a staging yard before the Lifter transports the large blocks to the project site and sets them in place. “It allows us to control the quality better and provide a safer working environment.”
It also allows them to cut costs. The large pieces that will become bridge deck and other portions of the new bridge are so heavy that they would typically require two cranes to lift them into place. Using the Left Coast Lifter reduces the amount of equipment and labor needed to perform the task.
Once the first of two side-by-side spans is open to traffic (scheduled in December 2016), the crane will allow TZC to disassemble the bridge more safely, more quickly and more efficiently because it can remove larger pieces.
Before it could begin work on the Tappan Zee Bridge, the massive crane had to make its way from California to New York. Escorted by two tugboats and a crew of 6 to 8, it departed from Oakland, Calif., on Dec. 22 for its 6,000-mi. (9,656 km) journey.
The crane is designed to fold up for 32.8-ft. (10 m) vertical clearance while navigating U.S. waterways, due to features such as the boom skidding system that allows booming down to a near-flat position of 4 degrees, along with stowage of the collapsible A-frame and boom for transit purposes. The boom heel slides back on rollers from the stern toward mid-ship, allowing the boom tip to rest on a barge-mounted stand. As Structure magazine put it, “In order to lower the A-frame, the backstays were designed to fold like links in a chain.”
Further facilitating transport, “the boom design allows a 66-foot boom tip section to be removed to reduce the length to 262 feet,” according to Structure magazine. The A-frame truss with sea transport braces resists the barge's listing and rolling forces. This substantially reduces the loads on the boom during the voyage.
Structure also reports that a specially designed boom support was fabricated and attached to the crane, extending 86 ft. (26 m) beyond the stern of the barge to allow the boom to be lowered to its transit position. “Components were wrapped with a heavy poly material to protect them from salt spray during the voyage. A temporary electrical generation system was installed so that power to key pieces of equipment could be maintained during the journey, and to power dehumidifiers added to keep rooms and compartments dry.”
Replaceable ductile links were designed to yield to and limit the force on the side of the barge in the case of an accident. This design helps avoid incurring holes or other damage to the barge
Guided by a crew of mariners, the floating crane traveled down the coast of California, Mexico and Central America, about 50 mi. (80 km) from the shore.
On Jan. 15, the crane reached the Panama Canal, where it was lifted 54 ft. (16.4 m) above Pacific sea level in two stages in the Miraflores Locks. According to the New York Times, the Lifter was pulled by the tugboat Lauren Foss and the Canal's locomotive “mules.” Because the barge is only 10 ft. (3 m) narrower than the 110-ft. (33.5 m) locks, it took a half-hour for a Panama Canal Authority pilot to navigate each lock — three times the typical amount of time. (The Canal's third, wider lane of locks is currently under construction and won't be open until 2015.) To protect the crane during transit, “rub rails” were installed along the side to prevent contact with the lock walls.
“After sailing through the main channel of the 48-mi. (77 km) canal and being dropped about 85 ft. (26 m) at the Gatun Locks on the Atlantic side, the engineless barge crane, chaperoned by two tugboats, headed north across the Gulf of Mexico and started up the East Coast,” reported the New York Times.
Julian noted that a crew change took place at the Canal.
While some reports indicate that the toll for traversing the Canal was $70,000, Julian declined to confirm any specific amounts. Tappan Zee Constructors paid a transport company to handle all costs associated with the move.
Settling Into Temporary Quarters
After passing through the Panama Canal, the floating sheerleg crane crossed the Gulf of Mexico and made its way up the East Coast, through the New York Harbor to the Hudson River within the six- to eight-week schedule. It will remain docked in the Port of New York & New Jersey until it's taken to the site of the New NY Bridge project in the spring.
“We don't need it until spring,” Julian said, “but we wanted to have it on site in order to be ready when it's needed.” She said weather, safety and protection of the crane were factors in the timing of its trip to New York.
After undergoing a “birthing process” at a private facility in the spring, the Left Coast Lifter will remain on site for the full duration of the Tappan Zee Bridge project.
“It will be used to set large units — decking for the two new spans — and removing the old bridge,” Julian said, noting that the Tappan Zee Bridge that will be demolished was originally built by American Bridge, which is one of the partners participating in the new bridge project.
Once it gets to work, the barge will be stabilized during large lifts by three removable barge stability floats that are attached to each side of the barge. According to Structure magazine, the float design criteria required that the floats be easy to install and remove on the water; therefore, a guidance system was designed to help align the floats with the barge. Once the floats are guided into the lower connection, the float is attached to the barge deck at the upper connection, using two 2.95-in. (7.5 cm) diameter pins.
After the project is completed in 2018, Julian said American Bridge and Fluor will decide what to do with the special crane next.