2IO TEE POPULAR SCIENCE MONTHLY 



stances the use of electricity is the only possible way of handling the 

 traffic. The second reason is the invariable one, in this commercial 

 age, for all engineering enterprise — that it pays. 



The development of the engineering methods by which the electrical 

 operation of railways has been made possible is largely due to the first 

 of the reasons mentioned above. Beginning with the electrification of 

 the Mt. Eoyal Tunnel of the B. & 0. Eailroad, in 1896, there have been 

 an increasing number of tunnel and terminal projects which have made 

 use of the possibilities of electric operation in the way of increased 

 traffic and freedom from smoke and gases of combustion. One con- 

 spicuous instance, the Grand Central Terminal in New York city, il- 

 lustrates the typical limitations of tunnels and terminals which have 

 rendered electric operation necessary. In 1903, an act of the New 

 York Legislature was passed providing for the operation before July 

 1, 1908, of all trains into Grand Central Station by some form of 

 motive power not involving the combustion of fuel in the motive units. 

 This action was aimed directly at the elimination of smoke and gases 

 in the tunnels leading to the terminal. The results of the adoption of 

 electricity have in this respect entirely justified expectations. Pas- 

 sengers may now occupy observation platforms in passing through these 

 tunnels which were formerly notorious for their danger and discomfort. 



There was, however, an additional reason why it was necessary to 

 adopt a motive power other than steam in the New York terminals. 

 Traffic into the Grand Central Station is limited by the number of 

 tracks in the tunnels. The minimum three-minute headway between 

 trains operated by steam fixed the maximum traffic at forty trains per 

 hour each way. The capacity of the terminal with this limitation of 

 service was taxed to its utmost and some relief for the increasing traffic 

 was imperative. Owing to the improved conditions of electric opera- 

 tion, trains may be run on a two-minute headway or less, thus increas- 

 ing the station capacity by more than fifty per cent. The conditions 

 in the New York tunnels are typical and other conspicuous instances of 

 similar installations are those of the B. & 0., at Baltimore, the St. Clair 

 tunnel of the Grand Trunk Eailway and a three-mile tunnel on grade 

 on the Great Northern Eailway. The Illinois Central Eailroad is 

 about to electrify 325 miles of track, comprising the approaches to its 

 Chicago terminals. 



The elevated lines of New York city are an additional instance of 

 the necessity of adopting some other system than steam in order to 

 increase the capacity for traffic. The continued growth of the popula- 

 tion of New York city has far surpassed that of the traffic facilities for 

 transportation within the city. As measures for relief the elevated and 

 surface lines were equipped with electricity and in addition the subway 

 system was constructed. Within three years following the adoption 



