Road Location and Design Concepts 



Traditionally, the concepts of road location and design have stressed the economics 

 of transportation from origin to destination. This has encompassed not only the cost 

 of the facility (fixed cost, depreciation, and maintenance) but also the cost to the 

 user (principally concerned with speed of travel) . More sophisticated analyses are 

 evolving as more of the impacts of location and design are considered. However, this 

 evolution has not generally developed on forest roads. Methods of analysis that could 

 be helpful in evaluating effects of all major factors are available, but usually the 

 inputs are not. For example, we do not have accurate values, nor in most cases, any 

 value to assign to the influence that erosion may have on the functioning of the total 

 system (ecosystem). Instinctively, from our ocular estimates, and in some instances 

 from quantitative measurements of damage from erosion, we know that we must improve our 

 present practices. Fortunately (or unfortunately, when viewed from its lack of use in 

 the past), we are close to having sufficient technical knowledge to accomplish this 

 obj ective . 



To help illustrate what can be done and how it is done in areas such as the Idaho 

 Batholith, information from a recent research study of logging roads in the Zena Creek 

 drainage (tributary to the Secesh and South Fork Salmon Rivers) on the Payette National 

 Forest will be used (figs. 3a and 3b). 



Zena Creek Experimental Logging Study 



In 1957, Region 4 (Intermountain) of the USDA Forest Service began a study of log- 

 ging methods that could be used for harvesting timber on some of the steep slopes of 

 the Batholith. The basic objective of the study was to determine if logging could be 

 carried out economically without unacceptable damage to the watersheds. Tractors, jam- 

 mers, and portable towers (skyline systems) were used for skidding timber during the 

 study. In general, it was concluded that logging the steeper slopes with skyline sys- 

 tems caused little damage to the watershed and that the cost of logging, although high, 

 still wouldn't prevent a logging operator from making an acceptable profit. 



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