Example of Use 



Use of the model developed in this paper will be illustrated by an example that 

 is a typical situation in the northern Rocky Mountains. Also, it should be remembered 

 that this model shares a common characteristic with any other model in that the results 

 vary in direct proportion to the reliability of the inputs. For this example we will 

 use the following values: 



Terrain and Stand Charaateristios:'^ 



Ro, percent rock in excavation (decimal %) =0.20 



S, sidehill slope (decimal %) = 0.40 



V, timber volume density in MBF/acre = 20.0 



Zb , level road in ft. per switchback = 5,000 



Lv, log size in logs/MBF = 10.0 



A, size in acres of total logging site = 500.0 



Mx, maximum road grade (decimal %) =0.06 



Nc , cost in dollars to move-in construction equip. = $500.00 



Ns, cost in dollars to move-in skidding equip. = $400.00 



A large crawler tractor equipped with a ripper tooth will be used for road con- 

 struction. The equipment and layout are as follows: 



Layout: 



Dm, cost of two-man crew in $/hr. = $10.00 



I'm, cocrficicnt of production of layout crew . =0.75 



I'm, productivity of layout crew in ft./hr. = 500.0 



W, road width in feet without landings = 16.0 



W, road width in feet with landings =12.0 



Wl , landing width in feet = 30.0 



Le, length of landings in feet = 100.0 



Construction Equipment: 



Pc, productivity coefficient of equipment = 0.8 



Dc/F, average cost of excavation in cu. yd. = $0.21 



Two methods of skidding will be evaluated--a medium crawler tractor (61-80 DBHP) 

 and a large crawler tractor (110-130 DBHP). 



Skidding Equipment: 



Ds , cost in $/hr. to operate medium tractor = $14.00 



Ds , cost in $/hr. to operate large tractor = $16.00 



Ps, productivity coefficient for both methods = 0.75 



Sp, time in hrs , to set up the equipment = 0.0 



Zs, distance in feet between setups = 0.0 



Vc, volume in MBF/cycle of medium crawler " =0.7 



Vc, volume in MBF/cycle of large crawler = 1.0 



^All symbols are defined in table 1. 

 ''DBHP = Drawbar horsei)owcr. 



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