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STEEL RAILWAY BRIDGES. 



CHAP. IV. 



Floors. Bridges may have open timber floors as in Fig. 23, or ballasted floors as in Fig. 24, 

 or in Fig. 25. For track elevation and for bridges crossing over streets, buildings, and similar 

 locations and for ballasted floors, the bridge floor is waterproofed and the water falling on the 

 floor is carried to the ground through properly arranged drains. 



FIG. 22. TYPES OF COLUMNS AND TOP CHORD SECTIONS. 



Details of the standard timber floors used by the Southern Pacific R. R., the Union Pacific 

 R. R. and other Harriman Lines are given in Fig. 23. For additional details of open timber floors 

 see Fig. I and Fig. 2, Chapter VII. The American Railway Engineering Association in 1912 



