INTRODUCTION 



The nine tables presented on pages 15-23 permit a logging operator to compare relative 

 operating costs among five different skidding methods. Tables 1-4 provide data for operations 

 in which crawler tractors ranging from 25 to 130 drawbar horsepower (DBHP) are used; tables 

 5 and 6 for operations in which rubber-tired vehicles with a 55-80 or 81-117 brake horsepower 

 (BHP) rating are used; table 7 for high-lead operations in which portable towers are used; table 

 8 for Idaho jammer operations, which consisted of a portable boom with a continuous haul-back 

 line and chokers in every operation observed; and table 9 for what are called "shovel logging" 

 operations . 



The costs in these tables represent estimates based upon observations made at one 

 shovel logging operation, eight portable tower operations, and from 10 to 20 different 

 operations employing each of the three remaining skidding methods . 



The shovel logging operation was found on the Gallatin National Forest, which is located 

 in the vicinity of Bozeman, Montana. The rig consisted of a portable boom in which the A-frame 

 is either of logs or fabricated steel and single drum pulley with a half-inch line and tongs. An 

 operator worked along a skidding road or trail, casting the tongs either downhill 125 feet or up- 

 hill as far as 50 feet. Some tong setters carried tongs beyond the downhill cast another 25 feet, 

 which allowed a maximum skidding distance of 150 feet. A good operator was capable of re- 

 leasing the tongs from a log without leaving the cab. One log was handled at a time. We found 

 that this method was uneconomical when skidding distances were beyond 150 feet. 



Among the high-lead operations studied, towers ranged from 40 to 70 feet high and power 

 plants ranged from 165 to 225 BHP. Remote-controlled carriage units were not used in any of 

 these operations. High-lead operations were found to be the most economical in situations 

 where skidding distances were over 500 feet and where there were steep slopes, large trees, 

 and high acre densities . . : 



For most operations observed, rubber-tired vehicles were found to be the most economi- 

 cal, assuming equal operator efficiencies. This is reflected by the increasing use of these 

 vehicles throughout the country. In our contacts, however, we found some contractors who 

 felt that downtime and operator unfamiliarity with rubber-tired vehicles do not permit them to 

 realize maximum potential efficiency from such skidders . Furthermore , they preferred 

 crawler tractors because they are needed in other phases of logging operations. 



Not all of the operations studied were cutting logs large enough to fall within the 4, 6, or 

 8 logs/MBF categories. Therefore, costs had to be extrapolated using the mathematical model 

 described in the Appendix. For example, in tables 1,5, and 9, extrapolated values are used 

 for all three of these categories; in tables 2 and 6, for only the 4 and 6 logs/MBF categories; 

 and in table 3, for only the 4 logs/MBF category. Extrapolated costs are so indicated by being 

 enclosed in rectangles on these tables . 



Extrapolated costs can be compared directly with other extrapolated costs. However, 

 when estimated costs are used, the lowest estimated cost is considered more economical than 

 the lowest extrapolated cost unless the latter shows a cost savings of at least 20 percent. Those 

 operators who have had experience using the skidding methods for which extrapolated costs are 

 presented may wish to shave this percentage to 15 percent or less. Example 2 on page 3 deals 

 with a situation involving both extrapolated and estimated costs. 



