Engineering Wonders of the World
Volume I

344 ENGINEERING WONDERS OF THE WORLD. Section of Twin Tunnels under Street-Car Tirrmel at Murray Bill, Fourth Avz., 33 to 41 s* St. Fig. 3.—TYPICAL CROSS-SECTIONS OF THE NEW YORK SUBWAY. Reinforced concrete was used—that is, the concrete was strengthened by slender steel rods distributed within its mass in such a way as to render steel frame-beams un- necessary. Very special construction was, of course, needed for the two river crossings. The Subway passes under the East River from the Battery to Joralemon Street (Brooklyn) by two shield-driven cast-iron circular tubes, lying in rock and quicksand. Under the Harlem River (at 145th Street) it crosses by a con- crete-lined cast-iron twin tunnel of peculiar construction. These are remarkable examples of the tunnel-builder’s art. The elevated railway parts of the line, of which Fig. 14 gives a representative view, are quite like the usual types of railway viaduct in city streets. A single contract was let for building the entire Subway. Mr. John B. M‘Donald was the successful bidder. But he knew that the enterprise demanded the association of many Preparing for the Work of Construction. experienced contractors. Him- self acting only as generalis- simo, therefore, he split the contract into a large number of sections, and sublet them to different contractors. These men put their working forces into the field to dig and build. M‘Donald paid them, co-ordi- nated their work, hurried them up, and attended to eliminat- ing friction in cases where, in a single section, one contractor handled the excavation, an- other supplied the steel frame, a third erected it, etc. At the same time the Rapid Transit Commission’s engi- neering forces, under Mr. William Barclay Parsons, the engineer who planned the Subway, directed and supervised all the constructive work. M‘Donald’s engineers had another and much larger task—to provide for “ equipment,” which was not included in the Commission’s plans. This term covered power-house, ma- chinery, track, signals, cars, motors, etc. His men had to plan for all these items, locate and design them, and let contracts for their construction. On this plan active digging was begun early in 1900, and soon every foot of the line was being attacked energetically. Less than five years later (1904) half the line was inaug- urated, and in 1908 the last bit was com- pleted, including th© three mile Brooklyn Extension (extending from City Hall south and, by way of the Battery Tunnels, to Atlantic Avenue in Brooklyn). A great drawback to building a subway close to the surface is that it has to encounter the network of buried pipes—gas and water pipes, electric light and telephone conduits,