others, 25 percent. These were used in the mathematical model to ensure that the various 

 methods were compared on an equal basis. Delay values are called "DELAY" in the program 

 and entered as decimals . 



Logs/ cycle was derived by averaging the number of logs observed for each operating 

 cycle. Values averaged from data gathered closely approached the even increment separations 

 as shown below for each of the logs/MBF categories: 





4 



fS 



KJ 



« 



(J 



1 n 



1 2 



14 



1 A 



















25-40 DBHP 



1.2 



1 . 8 



2.4 



3.0 



3.6 



4 2 



4 8 



Crawler tractor, 

















41-60 DBHP 



2 



3 



4 



5 



6 



7 



8 



Crawler tractor. 

















61-80 DBHP 



3.6 



5.4 



7.2 



9.0 



10.8 



12.6 



14.4 



Crawler tractor, 

















110-130 DBHP 



8 



12 



16 



16 



16 



16 



16 



Rubber -tired vehicle, 

















55-80 BHP 



1.6 



2.4 



3.2 



4.0 



4.8 



5.6 



6.4 



Rubber-tired vehicle. 

















81-117 BHP 



2 



3 



4 



5 



6 



7 



8 



High -lead portable tower 



4 



4 



4 



4 



4 



4 



4 



Idaho jammer 



1 



1 



1 



1 



1 



1 



1 



Shovel (w/tongs) 



1 



1 



1 



1 



1 



1 



1 



For example, in the case of the 25-40 DBHP crawler tractor, the separation is exactly 0.6 

 for each category of log sizes from 4 through 16 logs/MBF. Although it is unlikely that exact 

 separations would be the real case, we assumed linearity because (1) the data closely approxi- 

 mated a straight line, hence it did represent the apparent situation; and (2) the total weight for 

 each turn involving a tracked or wheeled skidder remained essentially the same for each class 

 regardless of the number of logs skidded. Of course, shovels, jammers, and portable towers 

 each skidded the same number of logs /cycle regardless of total weight. Logs /cycle appears in 

 the program as "XXGPC" or "XLGPC. " 



Hours/ 3Cre means setup time for each acre of skidding area covered. It is the 

 elapsed time from the moment a piece of equipment is in its new location until it begins a 

 skidding cycle. This input was not considered applicable to tracklaying and wheeled skidder 

 operations because the equipment is always in movement with its load. Setup times/acre are 

 derived as functions of average skidding distances as follows: 



FOR HIGH -LEAD, PORTABLE TOWER OPERATIONS. 

 (See figure 2 next page for typical area configuration.) 



1. Average setup time = 0.84 hour (mean of eight setups, one setup being a single tower 

 positioned with its corresponding tail block locations at A, B, C, D, and E). 



2. Area for setup = 250,000 sq. ft. or 5.74 acres. 



3. Combining steps 1 and 2 get 0.1463 hour /acre or 0.15. 



4. Average skidding distance = 662 feet (distance to centroid of sector assuming uniform 

 density throughout). 



8 



