Cable yarding distances were not only constrained by topography, tailhold height, and payloads, but also by the direction of yarding. Yarding constraints are determined by Logger’s preferences. Sidehill and downhill yarding was confined to a distance of 500 feet without full suspension and allowed to extend beyond 500 feet with full suspension. A yarding corridor width for sidehill yarding had to be incorporated for the protection of leave trees. This yarding corridor should have a minimum width of 12-ft when logs are fully suspended and a maximum width of 65-ft (calculated from a 20-ft choker, 40-ft design log and 5-ft of uphill spacing). Full suspension on sidehill and downhill yarding was rarely acquired, due to various limiting factors, such as terrain and steepness. Therefore, distances that were greater than 500 ft occasionally occur without full suspension. Design for uphill yarding has no distance restrictions since this is the preferred yarding direction for ease and safety. See Logger’s Preference for more details on distance, direction and topography preferences.

To use PLANS analysis for cable yarding systems, the input of machine specifications for each yarder, rigged as either standing, live or running skyline, is required. Swing yarder specifications were also added to provide analysis for single profile yarding. Most of the settings used the designated specifications. However, each specification could be altered for any given profile analysis, even within the same setting.

All radial profiles were analyzed with a 70-foot tower set as a standing skyline, while single profile settings were analyzed with a 50-foot swing yarder set as a running skyline. Standing skylines were used for the PLANS analysis because it gave the most conservative estimate on payloads and distances. Using live or running skylines would have given larger payloads or longer span distances. To be conservative with the swing yarder a higher desired payload of 10,000 lbs. was used instead of the 7000 lbs. used by the standing skyline. Single profile settings were planned for steep sidehill slopes and other areas where a central landing was not practical. In these areas the road is used for a continuous landing.

Table 9.1 shows the standing skyline specifications. A one-inch skyline and a three-quarter inch mainline were used for the tower. Table 9.2 shows the specifications for a running skyline used for single span profiles (continuous landings). The haulback, mainline and slackpulling line on the swing yarder are all ¾ inch. The skyline and mainline diameters used could also have been adjusted, if needed, for longer spans or heavier payloads. Ground clearances are based on a 40-ft design log and 20 ft choker plus a 5-ft factor of safety. For every setting the default tailhold height was set at two feet with increments of twenty and forty feet. Twenty feet tailholds were the mid-range height and forty feet tailholds (max. height) were used for areas where maximum deflection was needed.

PLANS analyzed twelve profiles per central landing location. Twelve was chosen as a middle range for speed and coverage. While eighteen spokes would have given a more accurate representation of each setting the amount of accuracy did not justify the extra time involved. Each profile in the settings was limited to a distance of 2500 feet for the 70-ft tower and 2000 feet for the 50-ft swing yarder. The initial PLANS analysis consisted of 331 central landing locations plus a few single profiles (3815 profiles total) covering an area of about 6000 acres.

The goal was to achieve the desired payload while limiting tailhold heights for each profile within the setting. The ideal setting profile has a tailhold of two feet and a payload of 7000 lbs. Table 9.3 shows the distribution of these profiles for each tailhold height and their designated payload weights.

Along with the number of profiles, the average profile length was also compiled for the initial setting design. The long cable lengths correspond with the ridge to ridge spanning needed to attain the amount of deflection for full suspension over the numerous streams. Ridge to ridge spanning is also needed, in many cases, to yard over the general terrain of the landscape. The span distance will not always be the yarding distance for the profile.

Table 9.4 shows the average profile length for each tailhold height and their designated payload weights. Some of the initial profiles are less than 100 feet in length. The profiles that fall in this category will not be yarded but they exist in the profile count so they will interfere with the actual average span distances.

All of the landing locations were digitized into PLANS then transferred into Arc/Info as a coverage by using the ARCPLANS program. The setting coverage consisted of landing location, payload per span and tailhold height per span. Some of the landing locations would later be verified or rejected in the field.

The preliminary road design objective was to design a road system that accessed landing sites and maintained safe driving grades. The acceptable driving grade limit was understood to be no more than sixteen percent for the initial road system.

The landing locations designed in PLANS were the basis for the initial road layout. The road layout was designed to access as many of these original landings as possible. Road density was not a major concern for the basic plan. In some cases alternative routes for the same access road were made to ensure the best route possible. The routes for the final road design would later be selected during the field exercises and the remaining routes dumped from the design.

The rudimentary road design was pegged in by hand with colored pencils on a map that consisted of twenty-foot contour intervals and landing locations. The roads were pegged in by "walking" a set of dividers along the contour lines at a set percent grade. Any changes in grade were marked on the map as an attribute for the digitizing process.

The road locations were digitized into Arc/Info and combined with the original transportation layer to create the road coverage that was to be used to create the field maps. The road coverage consisted of road classes, grades and names. A total of 4646 stations (88 miles) of roads were initially created.

After verifying the road design in the field, the final road design was started. The objective for the final road design was to access the majority of the setting locations while minimizing road density and cost. The idea was to create a system of roads that not only had been verified on paper but one that was based on field reconnaissance work as well. To minimize road construction costs, abandoned road grades considered to be in good condition were used in the road system as much possible. The road coverage was finalized by keeping the best alternate routes and eliminating the rest.

The final road layout was labeled on the working maps in blue, green and red. The colors aided in the digitizing process and made clear what roads were to be kept and which were to be rejected. Blue represented roads that had been walked and flagged. Green represented roads that had been walked but not flagged. Red represented roads that had not been walked but would be able to be constructed and needed to be a part of the final road system.

To create the final road coverage the preliminary road layer had to be altered to show the final road system. The accepted roads were kept in the road coverage and the additional roads were digitized in. A new naming convention was created and grades were changed if needed. Any roads that were no longer to be used were deleted. A total of 3709 stations (70.25 miles) had been designed for the final road coverage, including existing abandoned roads that are part of the design system.

Table 9.5 shows the distribution of the roads by miles based on road grade and slope conditions. The majority of the road mileage has a grade of 7% to 14% with sideslopes of 50% to 70%.

The objective for the final setting design was to create units that did not exceed 100 acres and that contained no overlap. These unit boundaries were drawn in by hand and then digitized into Arc/Info. The unit polygons were to cover the entire planning area and designate some sort of harvesting activity for their usage in LMS and SNAP. The harvesting activities available to choose from were central landing, continuous landing, ground systems and helicopter yarding. The final setting coverage has a total of 483 units covering 11,144 acres.

After all the settings and landings had been finalized, a sampling of the entire area was performed. Because the area is over 12,000 acres, it proved to be more time efficient to chose approximately ten settings per map to examine. This would allow a sufficient number of settings of various characteristics to be analyzed.

For each map the number of test settings selected was based on the number of total settings on the map. If the area was larger with more settings, more samples were taken. All of the selected settings well represented the various settings in the planning area. Settings were selected based on ridge top and sidehill landings, various shapes and sizes, and tower or swing yarders.

For each setting, the original profiles were adjusted so that they corresponded more accurately to the final boundary settings. This meant adjusting tailhold heights and span lengths, which in turn often changed the payloads for many profiles. A new file in PLANS was created of the adjusted settings then they were transferred into Arc/Info, using the AML "getplans.aml". The PLANS file was then converted into a coverage. Each profile was then analyzed within ArcView according to payload, tailhold height, and span length. These results are in Chapter 12. Setting and Harvest Systems.