CROSS TIES 



279 



By counting the number of trees per acre of each diameter and mul- 

 tiplying this by the average number of ties per tree the yield of ties per 

 acre can be easily derived. 



In western yellow pine, suitable for hewing into ties in the Southwest, 

 the average number of ties per tree is only 2.7, but here the trees do not 

 grow to a very good height. 



Tie hackers do not like trees of too small diameter because an insuf- 

 ficient number of No. i ties can be cut from them for the labor involved 

 in felling, limbing, etc., whereas in trees of 16 in. or over in diameter the 

 hewing is more difficult and the ties are difficult to handle on account of 

 their large size. 



The following table is interesting in that it shows the minimum diam- 

 eter of logs from which the various-sized pole ties may be hewed together, 

 with the cubic feet contained in the pole tie that conforms to the exact 

 specifications of 1917. They are given for some of our larger railroad 

 systems. A length of 8 ft. is used for all. 



Number of Ties per Thousand Board Feet. 



It is customary to use the converting factor of 30 ties per thousand 

 board feet for the average standard gauge pole tie, cut 8 ft. long. This 

 means, therefore, that the average tie contains 33^ board feet. It is very 

 apparent from the above discussion and specifications that this factor 

 is a variable one. 



Sawed ties are usually cut to conform exactly with the specifications 

 and are sold by the board feet as well as by the piece so that the converting 

 factor is usually applied only to hewed pole ties. The number of board 

 feet contained in each tie, therefore, depends upon the specifications and 

 also upon how closely the tie hacker conforms to these given dimensions. 



The following study by Koch in western Montana contains some 

 valuable data on the average number of hewed ties per thousand board 



