Long-Span Systems for Road Yarding: Road Densities, Economics, and Silvicultural Options

1. Long-Span VS.Conventional Skyline Yarding:Road Densities, Economicsand Silvicultural OptionsPeter Schiess & Weikko JarossForest Engineering, University of Washington & Departement of Natural Resources, Washington

2. Overview • Issues and Objectives - why are we interested in long-span systems, what are the objectives • General Skyline Systems Developments European Long-Span Systems North American Slackline Systems • Production and Cost Issues • Discussion and Conclusions

3. Issues • Agreement between DNR and the Federal Government resulted in a Habitat Conservation Plan • Ultimate goal is to reduce impact on sensitive habitats (fish/wildlife/water quality)

4. Several Approaches • minimize road densities by increasing yarding distances (Current External Yarding Distances are < 1200 ft) • reduce sediment deliveries to streams -road locations -construction practices -road system management (traffic/closures)

5. Road Densities in Relation to Yarding Distances (AYD’s) for Several Harvest Plans in Western Washington

6. Objectives • assess current state of cable yarding production and costs for EYD > 2000 ft (1500 to 4000 ft EYD) • Outline the critical issues

7. Skyline Operations - Turn of the Century • Yarding Distances > 4000 ft • up to 40,000 ft of cable • crew of 26 people and more • cheap labor - expensive transportation system (railroads)

8. Skyline System Developments • changes in labor markets increased wages • improved transportation (diesel trucks- dozer) • cheaper to haul/build roads than to yard • Slackline systems EYD< 2000ftHighlead < 1000ft

9. European Long-Span Cable Systems • cheap labor -high priced timber -difficult terrain • long-span cable systems • Standing skylines (or Wyssen Systems) Wyssen, Gantner, Baco • Yarding spans 1500 - 4000 ft

10. System Characteristics for a Wyssen-type Cable System • Low-power, one-drum system with low drum speeds • Relies on gravity for inhaul (down) • Outhaul under power to get carriage out (up) • Simple set-up (except for intermediate supports) • Yarder W-90, 4400 lbs. • Carriage • Skyline, 5000 ft, 1 1/4 in • Mainline 5000 ft, 5/8 in • Spool truck • Rigging Hardware • Radios • Landing Cat • Loader

12. SwissExperienceswithLong-SpanSystems

13. Cycle Elements for a Wyssen-TypeLong-Span System Reported byDifferent Authors

14. Total Cycle Times for Three Cable Systems, a Highlead, Large Tower and Wyssen Systems

15. North American Long-Span Tower System • Only few, documented studies Binkley, 1965 • Skagit BX 185, 3-drum yarder • 4,400 ft of 1-inch mainline • 5700 ft of 3/4-inch haulback • 5000 ft of 7/16 • 5,000 ft of 1 3/4 inch skyline on spool truck • Average cycle time 9 min. for 1300 ft of AYD

16. Model Development & Comparison

17. Owning & Operating Costs for a Large Tower and a Wyssen System

18. Variables and Values Used in Production Equations

19. Production Rates for Three Cable Systems, a Highlead, Large Tower and Wyssen System

20. Production Costs for Three Systems, a Highlead, a Large Tower and a Wyssen System

21. Rigging Times for Three Systems:a Highlead, a Large Tower and a Wyssen System

22. What does it mean? • North American experiences with Wysssen long-span systems are well correlated with European experiences • Production = f( distance, rigging supports, volume/station of corridor removed) • Production not correlated with silviculture (clearcut - selection cut)

23. What does it mean? • Available volume > .7 mbf/station of corridor • Line speeds are important • Large, old towers (rebuilt) appear to offer a feasible solution • Full suspension a key to successful operations over long spans

24. Conclusions • Time studies for Wyssen systems on the West Coast agreed well with models developed in Switzerland • Rigging times are a significant factor • Long-span systems are a promising alternative, when used with appropriate silvicultural systems (selection cuts with appropriate volume removal) • Turn assembly becomes important (like Heli)