2666 



Chapter 22 



20 



O 10 



5- 



^ OTHER 



BS SOFTWOODS 



^ GUM 



□ MIXED 

 HARDWOODS 



[13 OAK 



1966 



1967 



YEAR 



Figure 22-54. — Number of crossties treated annually in the United States, 1962-1967. 

 Species categories indicated for 1962 through 1966. (Drawing after Smith 1968.) 



Association (1965) specifications governing crossties and switch ties, as adopt- 

 ed by the Railway Engineering Association (functioning also as the Engineering 

 Division of the Association of American Railroads), which have been made an 

 "American Standard" by the American Standards Association. Cross-sectional 

 sizes of ties manufactured under this Standard are shown in table 22-20. The 

 Standard also contains details of straightness (a straight line along a side from the 

 middle of one end to the middle of the other end must everywhere be more than 2 

 inches from the top and bottom surfaces), depth of axe or saw-tooth marks (not 

 more than '/2-inch), taper between top and bottom surfaces (not to exceed V2- 

 inch), decay (blue stain permissable), shake (allowed if its length does not 

 exceed one-third the tie's width), and split (one which is not over 5 inches long 

 allowed, provided anti-splitting devices are applied). 



On switch ties, a large knot whose diameter exceeds one-fourth the width of 

 the surface on which it appears may be allowed if it occurs outside the section 

 between 12 inches from each end of the tie, i.e. , if it occurs on an end of the tie. 

 On crossties, such large knots cannot occur within sections 20 to 40 inches from 

 the middle of standard-gauge ties or 15 to 25 inches from the middle of narrow- 

 gauge ties. 



Readers interested in specifications of crossties should also consult AREA 

 specifications (Association of American Railroads 1980-81) published by the 

 Association of American Railroads. 



Ballast for crossties. — Crossties serve best if they are installed on ballast of 

 crushed hard rock usually measuring y4-inch to 2 inches in diameter, and of 

 sufficient depth ( 1 2 to 18 inches) to firmly support the tie and give it adequate 

 drainage. Stability of the ballast determines the loading mode of crossties (fig. 

 22-56). 



Tie spacing. — Crossties are normally centered 19-1/2 inches apart on mainline 

 tracks — 3,250 per mile; many segments of mainline track, however, have spac- 

 ing of 2I-V4 inches. 



