188 



STEEL RAILWAY BRIDGES. 



CHAP. IV. 



bridge designed for the Kansas City, Mexico & Orient R. R., by Mr. Ira G. Hedrick, Consulting 

 Engineer, are shown in Fig. 39 and Fig. 40. The end-posts and top chords are made of two 15 

 inch channels with a cover plate, and the lower chords, the posts and the main ties are made of 

 two channels with the flanges turned in. The total weight of the steel in the span was 303,000 Ib. 



For End Rollers 

 ff*3f fo/t f dr/vint/ Fit 

 /"Elastic Lock Nut. 





/z>r Infaatdiaft Rollers 

 &'*&* Turned Pin, 

 driving Fit, with 

 ROLLER NE5T shoulder <?5 shown- 



FIG. 35. DETAILS OF SEGMENTAL ROLLERS FOR GIRDERS. 

 CHICAGO, MILWAUKEE & ST. PAUL RY. 



Details of a double track through riveted truss bridge designed for the Chicago & North- 

 western Ry. are given in Fig. 41. The bridge has a span of 170 ft., the trusses are spaced 29 ft. 

 I in. centers, and the bridge has a vertical clearance of 22 ft. 6 in. This bridge has trusses with 

 triple intersection webs, and has a ballasted track carried on a steel plate trough floor. This 

 bridge was designed for a dead load of 4,570 Ib. per lineal foot for each truss and an E 50 live load. 

 There is a top lateral system of multiple X-bracing made with pairs of angles latticed, and sway 

 bracing of transverse top chord struts and portals. 



Detail shop drawings of the end-post of a pin-connected truss bridge are given in Fig. 42, and 

 the detail shop drawings of the end section of the top chord of the same bridge are given in Fig. 43. 

 The standard methods of detailing compression members are shown. 



Details of a single track pin-connected truss bridge designed by Mr. Ralph Modjeski for the 

 Northern Pacific R. R. are given in Fig. 44, Fig. 45 and Fig. 46. 



SPECIFICATIONS FOR RAILWAY BRIDGES. To determine the present practice in 

 the design of railway bridges the author has made a study of the latest available specifications. 

 As a basis for comparison the sixteen specifications given in Table XI, were selected as being 

 representative of the best practice. Several other prominent railroads have adopted the speci- 

 fications of the American Railway Engineering Association, so that the sixteen specifications cover 

 the major part of the railroad mileage in North America. The standard specifications of the 

 Chicago, Milwaukee and St. Paul Ry., the New York, New Haven and Hartford R. R., and 

 the Canadian Society of Civil Engineers, all adopted in 1912, are based on the standard speci- 



