Posted on April 1, 2024
By Judith Powers
Heavy marine construction equipment began arriving at the site of the Francis Scott Key Bridge collapse in the Patapsco River starting on Thursday, March 28th. The allision by the container ship Dali brought the bridge down at 1:28 a.m. Tuesday, March 26th, sending six members of a road work crew to their deaths in the river. Two bodies have been recovered, and the search for the remaining four will resume as a priority after bridge sections are removed from the bottom.
Seaward Corporation of Norfolk, Virginia has mobilized cranes and auxiliary vessels prepared to do diving reconnaissance of the underwater debris, and to facilitate workers from United Demolition by raising them in man baskets into the twisted bridge sections, where they cut manageablepieces from the structure and attached rigging to the sections for removal by heavy lift cranes. The first bridge section, a 200-ton span of metal, was removed on Sunday, March 31 by Seaward’s 650-ton heavy lift crane, a process that took 10 hours.
The initial goal was to clear an auxiliary channel outside the main channel for tugs and barges to access both sides of the debris. That goal was reached on Monday, April 1 when a temporary channel with a controlling depth of 11 feet (over 3 meters), a horizontal clearance of 264 feet (80 meters) and a vertical clearance of 96 feet (29 meters) was created. Certain commercial tug and barge units will be allowed to transit the auxiliary channel. Seaward Corporation, Donjon Marine of Hillside, New Jersey and Weeks Marine, Jersey City, New Jersey had equipment on site by April 1. Seaward’s 650-ton 60 foot ringer platform with 1.1 million pounds of counterweight, and Donjon Marine’s Chesapeake 1000, a 1,000 ton stiff leg heavy lift derrick, the Weeks 533, a 500/600 ton capacity heavy lift derrick and others will lift the heavy bridge sections after they are cut and rigged.The heavy lift cranes, with multiple cables and winches, work extremely slowly, and once attached to the load do a dead lift of the section, raising it straight up, to be placed on a work barge for removal.
Seaward’s Liebherr LR1300 330-ton barge-mounted crawler crane assisted the company’s 650-ton ringer crane in the initial tasks involved with clearing the auxiliary channel. Another LR1300 is acting as a dive platform for Seaward’s divers who are doing underwater reconnaissance of the submerged debris. Engineers use the information the divers gather to calculate the status of how the debris is resting on the bottom, and to calculate the safest places to make the cuts. U.S. Coast Guard Rear Admiral Shannon Gilreath said on April 1 that divers examining the steel girders beneath the surface found them tangled and intertwined, making it difficult to figure out how to cut and lift them out of the water.
Tanks of oxy-acetylene gas and cases of burning rods are transported to the site for the underwater cutting being performed by divers from Seaward and other diving companies.
The cranes are helped by a flotilla of auxiliary vessels. Seaward has mobilized a 10-foot catamaran dive boat, a 65-foot crewboat – the Seaward 15 – which carries 26 passengers, and assist tugs, including the 6,000 hp Ezra Sol, the 3,600 hp Katan and others.
In addition to the Chesapeake, Donjon’s crane barge Ferrell 256, equipped with a Manitowoc 4100 Ringer Series 3 and tug is on site. The Weeks 533, a Clyde Iron Works Model 52-DE crane, arrived on April 1. It can lift 500 short tons, increased to 600 short tons when using the rear hoist. The 533 is celebrated for lifting the US Airways flight 1549 when it crashed into the Hudson River on January 15, 2009.
The Maryland Department of Transportation contracted Skanska for this work, with United Demolition and Seaward Corporation as sub-contractors.
Next steps include mobilizing all the equipment to the site, which is being transformed into a floating jobsite. There has been no estimate of how long it will take to clear the bridge debris, but managers and crew are well trained and familiar with the operation of the equipment.
