New York's Submarine Subway 

 and How It Was Built 



By Howard B. Gates 



The author of this article is a Civil Engineer, who is connected with the Public 

 Service Commission of New York city. His official duties were such that he 

 was closely identified with the daring work that he so interestingly describes. 

 Obviously, he writes from first-hand knowledge. — Editor. 



ATWENTY-story building literally 

 grows out of the ground o^•er 

 night; subways are built beneath 

 our most congested streets and under 

 rivers and we scarceh^ know they are 

 there until they are ready for operation; 

 our water supply is siphoned under 

 rivers at great depths and runs through 

 the very bowels of the earth in arteries 

 hundreds of miles in length for our con- 

 venient use at faucet and hydrant; 

 bridges spring from the opposite banks 

 of our rivers and meet in the center 

 within a fraction of an inch and we talk 

 with our friends across the ocean and 

 continent with perfect ease and under- 

 standing. Not only to the lay mind but 

 to the technically trained as well, do 

 these achievements become a source of 

 wonder, the former accepting the result 

 as sufficiently marvelous in itself, while 

 the latter appreciating the underlying 

 principles of science and laws of nature 

 which contribute to their success, w'on- 

 ders at the ingenuity of their applica- 

 tion. One of the most recent examples 

 of these marvels of engineering is the 

 "submarine" subway or Harlem River 

 tubes built beneath the Harlem River to 

 form the connecting link between the 

 Boroughs of Manhattan and the Bronx 

 subway systems now nearing com- 

 pletion. 



The Harlem River at the point of this 

 crossing is six hundred feet wide and 

 varies in depth from twenty to twenty- 

 six feet. In accordance with the require- 

 ments of the Secretary of War, the top of 

 the structure was fixed at a depth which 

 placed it an average of seven feet below 

 the river bottom and made the lowest 

 point in the structure about fifty-seven 

 feet below water. To start the con- 

 struction at the bulkhead lines was not 

 practicable; hence the tubes were pro- 



jected landwards, so that the total 

 length of this special construction was 

 one thousand and eighty feet. 



The Four Tubes Floated Like Boats 



Brief!}', the method consisted in as- 

 sembling the steel shell or form of the 

 four tubes, in sections about two hundred 

 and twenty feet in length upon timber 

 supports above the water. With the 

 ends sealed or partially closed, a section 

 was launched and floated as a boat. 

 Towing it to and anchoring it above its 

 designed location, its tubes were filled 

 with water under positive and accessible 

 controls and gradually lowered into a 

 previously dredged and prepared trench. 

 As each section was lowered in turn, it 

 was attached to the end of the pre\'iousIy 

 placed section and encased in concrete. 

 When all of the sections had been 

 lowered and properly encased, w^ith their 

 ends closed by watertight walls or 

 bulkheads, the water by which they had 

 been sunk was pumped out, and a 

 reinforced concrete lining was placed 

 inside the steel shell to complete the 

 structure. 



The steel portion of the structure 

 consists of four parallel tubes bolted 

 together, with flat sides on their interior 

 walls. Between the tubes are vertical 

 diaphragm plates which are placed at 

 intervals perpendicularly to the direction 

 of the tracks and which extend to the 

 rectangular limits of the structure. 



Digging Trench for the Tubes in the 

 Bottom of the River 



The safe submerging of this light steel 

 form and the temporary control and final 

 location of it, comprise the most spec- 

 tacular part of this great scheme. The 

 trench into which the subway was to be 

 located was formed by a "clam-shell" 



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