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This paper reviews the IUFRO lecture series, Forest Roads: regional perspectives from around the world. In reviewing the presentations in this series, we found that regional factors such as geology, historic climate (glaciation), current climate, topography, and ownership strongly affect forest road networks. In addition to these regional factors, it appears that historic land use affects road design and construction. We define three road classifications: pioneer, mature, and plantation. In a pioneer road network, there is an existing forest resource and no established road network. A pioneer road network strongly reflects the current regulatory environment, current harvesting systems, and regional factors. A plantation road network occurs where there is a land use change, often from agriculture to forestry, and often growing non-native species. Plantation road networks evolve from existing rudimentary roads to road networks planned specifically for a well-defined forest resource. The plantation road network does reflect the existing regulations and harvesting systems; however, it does exist in a more constrained system that is defined by the existing roads and the boundaries of the planted forest. Mature forest road networks have evolved over centuries and incorporate historic and current land use, evolving regulations and technology, and are often interconnected with public roads. Responses specific to these road classes include a pioneer road network using brush mats to help support the subgrade, a plantation road network applying an optimized design, and a mature road network using pavement as the road surface. [ABSTRACT FROM AUTHOR]

Abstract: The design of geosynthetic-reinforced unpaved roads is based on a limit equilibrium analysis of bearing capacity at the ultimate limit state. Two semiempirical design methods are shown to be [...]

This paper presents a solution for a three-stump anchor system using a continuous bridle and assuming frictionless blocks. This solution is unique in that the location of the bridle block is not known a priori. A particle swarm optimization was used to estimate the three coordinates of the bridle block and the tension in the bridle. A method employing trilateration was developed to locate the known points in the three-stump anchor system. The advantage to using this method is that only distances between known points need to be measured in the field (angles are not required). For two of the field cases, the ratio of skyline tension to bridle tension was close to the maximum of 6 (bridal tension reduction factor) that could be achieved given the three-stump anchor system, and the other case had a ratio of 4. It was found for shorter bridle lengths, the three-stump anchor system is more sensitive to how in lead the stumps are with the skyline. For three-stump anchor systems, the bridle tension is more strongly controlled by the location of the two outside stumps, and it is relatively insensitive to the location of the middle stump. [ABSTRACT FROM AUTHOR]

Considering a cylindrical section of a tree subjected to loads independent of x3 as a relaxed Saint-Venant''s problem, it was shown that plane sections remain plane. Since plane sections remain plane, the displacement equations for the neutral fiber derived using either the relaxed Saint-Venant''s problem or elementary beam theory are equivalent. The stresses in the plane of the transverse cross-section were found to equal to zero. Therefore, it is appropriate to use elementary beam theory to estimate the three-dimensional stress functions when the wood is considered to be homogeneous. In addition the three-dimensional displacement equations allow the required elastic coefficients in cylindrical coordinates to be measured from full size samples. [Copyright &y& Elsevier]

Consider a tree that is composed of wood, which is orthotropic with respect to the cylindrical coordinate axes, where the z-axis is directed up the center of the tree. When a section of a tree is considered as a Relaxed Saint-Venant''s Problem the stresses in the plane of a transverse cross section will equal zero. By allowing some of, or all of the compliance coefficients to be functions of the radial coordinate r, the structure of the stress functions can be fundamentally altered. If the compliance coefficient in the z-direction (S3333) is allowed to remain constant, the Srz and Sθz shear stresses will be functions of the coordinates, dimensions, applied loads, and compliance coefficients, while the other stresses will only be functions of the coordinates, dimensions and applied loads. If S3333 is also allowed to be a function of r, then all the nonzero stresses will be functions of the coordinates, dimensions, applied loads, and compliance coefficients. [Copyright &y& Elsevier]

Published values for the elastic coefficients of wood indicate that this material may be considered orthotropic with respect to the cylindrical coordinates. This indicates that simplifying the elasticity tensor to allow for the non-unique strains at r=0, is a simplification that may ignore important structural characteristics of a tree. The constitutive equations for a cylindrical section of a tree were posed in cylindrical coordinates as a linear function of the radial coordinate r. The constitutive equations were transformed to a Cartesian basis so that a solution to Saint-Venant''s Problem, proposed by Iesan (Lecture Notes in Mathematics (1987) 161) could be employed for a cylindrical section of a tree. From Iesan''s solution it was possible to determine that the auxiliary generalized plane strain stresses can only be a function of r, and that the total stresses (in cylindrical coordinates) in the plane of the transverse cross-section must be equal to zero. [Copyright &y& Elsevier]