Holding the Hudson at Bay 



When the project is completed New York will have piers large enough to enable 

 the world's largest ocean-liners to dock in a few minutes instead of several hours 



TO make wa\' for the giant steam- 

 ship piers which when finished will 

 enable the world's largest ocean- 

 liners to dock within a few minutes, 

 instead of a few hours, which is now 

 the case, the Citj' of New York, through 

 its Department of Docks and Ferries 

 has constructed a cofferdam which holds 

 sixty-eight feet of the Hudson Ri\L'r 

 at bay while workmen are clearing out 

 rock from the river-bottom and laying 

 the shore-ends of the piers. 



The engineering world was much 

 interested in the raising of the battleship 

 Maine in Havana Harbor, where a head 

 of water thirty-seven feet deep had to 

 be reckoned with, but interest has now 

 shifted to New York. At Havana the 

 cofferdam was elliptical and the rounded 

 ends helped to reinforce the sides. In 

 New York the wall holding back the 

 waters is L-shaped, eight hundred feet 

 long on one side and three hundred feet 

 on the other. 



Interlocking sheet steel-piling was 

 used to form the backbone of the coffer- 

 dam, and this was dri\en so as to make a 

 succession of contiguous pockets ap- 



proximately sixteen feet in width and 

 twenty-four feet in length. These 

 pockets were filled with material dredged 

 from the river-bottom, and as it settled 

 it turned the pockets into steel-clad 

 pillars of earth. The steel piles were 

 driven down to the underlying bed-rock 

 which dipped riverward. But this was 

 not a sufficient guaranty of rigidness. 

 The object of shutting out the ri\-cr was 

 to- enable hundreds^ of workmen, with 

 pneumatic drills, to get at the rock 

 normally below the tide so that it could 

 be blasted away smoothly, and structural 

 work reared upon the resultant clean 

 ledge. This structural work is eventually 

 to support long piers for the accommoda- 

 tion of liners one thousand feet in length. 

 To guard against any possible collapse 

 it was decided to build a slanting rip-rap 

 bank inside the cofferdam, and stone 

 was piled up until the base of the dam 

 had a width of seventy feet. But there 

 was a point where this rip-rap could not 

 be built; it was at the corner where the 

 inshore end of the cofferdam joined the 

 main bod\' of the bulkhead. There the 

 engineers had to have the rock uncovered 



537 



