Optimum geometric layout of a single cable road

Leo Bont,Hans Rudolf Heinimann

doi:10.1007/s10342-012-0612-y

Abstract

Cable-based technologies have been a backbone for harvesting on steep slopes. The layout of a single cable road is challenging because one must identify intermediate support locations and heights that guarantee structural safety and operational efficiency while minimizing set-up and dismantling costs. Our study objectives were to (1) develop an optimization approach for designing the best possible intermediate support layout for a given ground profile, (2) compare optimization procedures between linearized and nonlinear analyses of a cable structure and (3) investigate the effect of simplifying a multi-span representation. Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions. Those nonlinear assumptions also stipulate lower heights for intermediate supports and a larger span length. Finally, compared with the unloaded case, tensile force in the skyline is increased by as much as 80% under load for a single-span skyline configuration. Our approach provides additional value for cable operations because it ensures greater structural safety at a lower cost for installation. Improvements are still needed in developing a stand-alone application that can be easily distributed. Moreover, our rather simple assumptions regarding set-up and dismantling costs must be refined.

Highlights

Cable-based technologies have been the backbone of steepslope harvesting in mountainous regions of the world, such as the Alps in central Europe, the Pacific Northwest of the United States, and Japan
Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions
Two factors must be considered in the layout of a single cable road—structural safety and the minimum number of intermediate supports

Summary

Introduction

Cable-based technologies have been the backbone of steepslope harvesting in mountainous regions of the world, such as the Alps in central Europe, the Pacific Northwest of the United States, and Japan. From an operational point of view, the spatially explicit layout of a set of cable roads over a given area is a challenging task. Two factors must be considered in the layout of a single cable road—structural safety and the minimum number of intermediate supports. The approach associated with European cable road design has been based on linearized analyses along with strong assumptions, for example, constants that represent the tensile forces in a skyline for both loaded and unloaded configurations. Our research goal was to develop a method that incorporates ‘‘close-to-reality’’ structural analysis and a minimum number of intermediate supports, resulting in greater structural safety as well as lower set-up and dismantling costs. After developing our representation and optimization model, we evaluated the configuration mass of multiple span skylines for real-world cable road in a specific geographical area

Background

Findings

Discussion and conclusions