ERECTION OF THE GOKTEIK BRIDGE. 



613 



and weighing- 80 tons. Its niaxiniinn lifting- capacity is 30 tons. 

 It consists of 3 trusses, two of which are connected l>y transverse 

 bracing, built on the cantilever plan, each being 219 feet in length, 

 40 feet in height, and separated by a width of 24^ feet. The lower 

 chords of the travelei' supported four trolleys, each provided with 

 a chain hoist having a lifting capacity of 16 tons. Powerful clamps 

 were especiallj^ designed for holding- the rear end of the traveler 

 to the girders of the viaduct, and it was supported on a sei-ies of 

 wheels enabling it to be easily moved as the work progressed. 

 Most of the material was lowered from above by the traveler. In 



Gorge mill niiiin towers willi bridge iiiider eonstnietioii. 



erecting the towers crossing the deepest portion of the gorge a tem- 

 porar}' track was built on a wooden trestle at an elevation of at)Out 

 100 feet above the base, and material for the lower parts of the towers 

 hauled to the spot and transferred to their positions by special derricks. 

 An idea of the quantity of material placed in position can be gained 

 when it is stated that it comprised most of the cargoes of three steam- 

 ships, and when loaded on the cars at Steelton, Pennsylvania, repre- 

 sented a solid train li miles long. The erection plant alone weighed 

 250 tons, and, in addition to the traveler, included three hoisting 

 engines, a series of air compressors, a telephone system for communi- 

 cation between the gangs working at each end of the viaduct, and the 



