Copyright by THEODOKE C<*>i 



Consulting Engineer, 45 Broadway, Ne 



General Specifications for Steel Railroad 

 Bridges and Viaducts, 



SEVENTH EDITION. 



GENERAL DESCRIPTION. 



1. All the structures shall be of wrought steel, as 

 specified. ( 133-148) Cast-iron or cast steel may be used 

 in the machinery of movable bridges and in special cases, 

 for bed-plates. 



2. The following kinds of girders shall preferably be K.mdofGinie. 

 employed: 



Spans, up to 20 feet Rolled beams, or longitudinal 



trough floors. 



20 to 75 " . . . . Riveted plate girdc 

 75 to 120 " ... .Riveted plate or lattice girder. 

 1 20 to 150 ' ... Lattice or pin-connected trusses. 

 150 " . . . .Pin-connected trus 



Generally "double track through" bridges will have 

 but two trusses, to avoid spreading the tracks at bridges. 



In calculating strains the length of span shall be under 

 stood to be the distance between centres of end pins lor 

 cs, and between centres of bearings for all beams and 

 gircl< 



3. The girders shall be spaced, with reference to the axis spacing of 

 of the bridge, as required by local circumstances, and ' 

 directed by the Engineer of the Railroad Company. ( 5.) 



