166 DAVIES— TUNNEL CONSTRUCTION. [February i8, 



the movement has grown, by steady progression, from 164 rides per 

 head of population per annum in 1884, to 300 rides in 1908. The 

 advance in this growth has been marked as each improvement in 

 methods of transportation has been introduced, particularly when 

 electric traction succeeded steam, horses and cable, and again when 

 the subways were opened. 



Prior to the opening of the various bridges and tunnels, the 

 ferries in New York Harbor carried 208,000,000 persons per annum^ 

 of which amount some 120,000,000 crossed the Hudson River. 



No other excuse or explanation than these figures is needed for 

 the construction of the various tunnels under the North and East 

 Rivers. 



In the cities the main arteries are unduly congested, and many 

 of them are inadequate to provide for the various classes of trans- 

 portation imposed upon the surface. In some cases the capacity 

 has been increased by construction of elevated railroads, which, 

 while convenient for the passengers and cheap to construct, are a 

 serious impediment to the full use of the surface, are eyesores to 

 behold, and are a nuisance to the health and nerves of the general 

 public. The use of the sub-surface then, is essential to the develop- 

 ment of the increased facilities for rapid transit, w^here the rail- 

 road can be out of sight and its operation out of hearing; where 

 it is not affected by climatic conditions, and where the maintenance 

 costs of structure and equipment is minimized. 



In our cities the development of subways near the surface, 

 while convenient for public use, introduces very serious questions in 

 relation to sanitation. The first subway built can be carried out by 

 extensive diversion and reconstruction of the sewerage system, 

 but a point must soon be reached where the entire sewerage system 

 must be considered as preempting a definite horizontal section upon 

 which no subways may encroach. After that, subways can be laid 

 out with hardly any limit, at greater depths and to almost any num- 

 mer, tier upon tier, as necessity demands, in the solid rock founda- 

 tion underlying our streets. 



We are rapidly getting to this point in New York, as is illustrated 

 at Sixth Avenue and Thirty-third Street, New York, where, in addi- 

 tion to the elevated and surface lines, provision is made for a 



