330 



Popular Science Monthly 



The new local tracks beneath Lexington Avenue near 

 74th Street. It will be noticed how free the street is 

 from serious obstruction. This system, extended in 

 a single track, would reach from New York's city hall 

 into the borders of Eastern Tennessee, some six 

 hundred and twenty-one miles 



These are some of the more striking- 

 features of the work ; but even the mat- 

 ter-of-course features loom big- when 

 one comes to inspect them closely. To 

 make room for the subways, the space 

 just below the street level has to be va- 

 cated of all its various pipes. The ex- 

 pense of moving them is enormous. Take, 

 for example, one item, the cost of relo- 

 cating sewers. Sixty miles or more of 

 new pipes are being laid. The bill for 

 these changes comes to more than six 



million dollars. One of the 

 largest of the diverted sew- 

 ers is in the neighborhood of 

 the Pennsylvania Station, at 

 Seventh Avenue and Thirti- 

 eth Street. Now that a new 

 subway is coming up Sev- 

 enth Avenue, this sewer is 

 being rebuilt to give outlet 

 into North River — at a cost 

 of fi^"e hundred thousand 

 dollars. 



Or consider the fact that 

 while construction is in 

 progress under the street, 

 many gas-mains must be 

 carried over the roadways 

 on trestles. The average 

 cost of doing this is twenty- 

 fi\e hundred dollars ; and 

 v.here larger distribution 

 mains must be handled, the 

 cost runs as high as ten 

 or eleven thousand dollars. 



Street-Cars and IVagons 

 Carried on Dry-Land 

 Bridges 

 Or, again, in accounting 

 for where so many millions 

 must be spent in building 

 subways, consider that the 

 engineers never vacate more 

 than half of the roadway at 

 a time, and that the street- 

 railways overhead and all 

 the stream of vehicles and 

 pedestrians are literally car- 

 ried, while the digging is in 

 process, upon miles and 

 miles of dry-land bridges. 

 They are the longest bridges 

 in the world, and bear as 

 much traffic as the busiest in 

 the world. 

 Then, too, hundreds of buildings must 

 be shored up, for many of them are not 

 built upon the solid rock ; and rotten 

 strata of treacherous stone must be 

 braced to prevent slides. In a number 

 of instances buildings had to be torn 

 down. The famous old Astor House 

 was one of these. It stood on sand at a 

 corner under which a tube had to pass. 

 But one of the most ticklish operations 

 of all is a section of new subway in WiU 

 liam Street, where the underlying mate- 



