1 UW Forest Engineering Schiess & Jaross Long-Span VS. Conventional Skyline Yarding: Road Densities, Economics and Silvicultural Options Peter Schiess & Weikko Jaross Forest Engineering, University of Washington & Departement of Natural Resources, Washington

2 UW Forest Engineering Schiess & Jaross 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 UW Forest Engineering Schiess & Jaross 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 UW Forest Engineering Schiess & Jaross 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 UW Forest Engineering Schiess & Jaross Road Densities in Relation to Yarding Distances (AYD’s) for Several Harvest Plans in Western Washington

6 UW Forest Engineering Schiess & Jaross Objectives assess current state of cable yarding production and costs for EYD > 2000 ft (1500 to 4000 ft EYD) Outline the critical issues

7 UW Forest Engineering Schiess & Jaross Skyline Operations - Turn of the Century YardingYarding Distances > 4000 ft Distances > 4000 ft up to 40,000 ft of cableup to 40,000 ft of cable crew of 26 people and morecrew of 26 people and more cheap labor - expensive transportation system (railroads)cheap labor - expensive transportation system (railroads)

8 UW Forest Engineering Schiess & Jaross Skyline System Developments changes in labor marketschanges in labor markets increased wages improved transportationimproved transportation (diesel trucks- dozer) cheaper to haul/build roads than to yardcheaper to haul/build roads than to yard Slackline systems EYD < 2000 ft Highlead < 1000ftSlackline systems EYD < 2000 ft Highlead < 1000ft

9 UW Forest Engineering Schiess & Jaross European Long-Span Cable Systems cheap laborcheap labor -high priced timber -difficult terrain long-span cable systemslong-span cable systems Standing skylinesStanding skylines (or Wyssen Systems) Wyssen, Gantner, Baco Yarding spans ftYarding spans ft

10 UW Forest Engineering Schiess & Jaross System Characteristics for a Wyssen-type Cable System 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 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)

11 UW Forest Engineering Schiess & Jaross

12 UW Forest Engineering Schiess & Jaross Swiss Experiences with Long-Span Systems

13 UW Forest Engineering Schiess & Jaross Cycle Elements for a Wyssen-Type Long-Span System Reported by Different Authors

14 UW Forest Engineering Schiess & Jaross Total Cycle Times for Three Cable Systems, a Highlead, Large Tower and Wyssen Systems

15 UW Forest Engineering Schiess & Jaross North American Long-Span Tower System Only few, documented studiesOnly few, documented studies Binkley, 1965 Skagit BX 185, 3-drum yarderSkagit BX 185, 3-drum yarder 4,400 ft of 1-inch mainline4,400 ft of 1-inch mainline 5700 ft of 3/4-inch haulback5700 ft of 3/4-inch haulback 5000 ft of 7/ ft of 7/16 5,000 ft of 1 3/4 inch skyline on spool truck5,000 ft of 1 3/4 inch skyline on spool truck Average cycle time 9 min. for 1300 ft of AYDAverage cycle time 9 min. for 1300 ft of AYD

16 UW Forest Engineering Schiess & Jaross Model Development & Comparison

17 UW Forest Engineering Schiess & Jaross Owning & Operating Costs for a Large Tower and a Wyssen System

18 UW Forest Engineering Schiess & Jaross Variables and Values Used in Production Equations

19 UW Forest Engineering Schiess & Jaross Production Rates for Three Cable Systems, a Highlead, Large Tower and Wyssen System

20 UW Forest Engineering Schiess & Jaross Production Costs for Three Systems, a Highlead, a Large Tower and a Wyssen System

21 UW Forest Engineering Schiess & Jaross Rigging Times for Three Systems : a Highlead, a Large Tower and a Wyssen System

22 UW Forest Engineering Schiess & Jaross 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 UW Forest Engineering Schiess & Jaross 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 UW Forest Engineering Schiess & Jaross 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)