CROSS TIES 



267 



NUMBER OF CROSS TIES REPORTED PURCHASED, 1907 TO 1911 AND 1915, BY 



KINDS OF WOOD 



of former years not obtainable. 



REQUIREMENTS OF A GOOD TIE 



The selection of tie material to satisfy the various requirements of the 

 railroads is of large importance. Altogether the following are the prin- 

 cipal points which determine the desirability of any wood for use as 

 cross ties: 



1. Durability. This is of prime importance. It is estimated by 

 various railway officials that the average tie of all species used by the 

 railroads in this country does not last, untreated, more than five years. 

 White oak ordinarily lasts from eight to ten years, untreated. The life 

 of untreated ties will be discussed later. 



2. Ability to resist impact. The crushing of ties by heavy rails and 

 rolling stock, resulting in serious checking and splitting, precludes the 

 use of soft woods such as cedar, redwood, cypress, etc., where the rolling 

 stock is heavy and trains are frequent. The American Railway Engineer- 

 ing Association announced in 1907 that a maximum of 75 per cent of 

 cedar ties used by one railroad failed because of mechanical destruction. 

 Other railroads report failures of from 10 per cent to 75 per cent due to 

 that cause rather than to decay. 



