UBC Theses and Dissertations
Procedures for projecting and evaluating forest road networks in strategic plans Anderson, Axel
Road networks have received limited attention in strategic planning primarily because generating these networks has been a significant barrier. This thesis develops computer algorithms to create and analyze the financial aspects of alternate road networks for strategic planning. The thesis is presented in three chapters. The objective of the first chapter is to develop and test a new computer method of projecting road networks. My method mimics the process professionals use when manually projecting roads using topography and road design standards. The result is a vector-based network defined by road nodes and links. The testing identified two main shortcomings of the road projection algorithm: 1) randomness associated with inputs creates variation in the proposed road networks, and 2) input parameters require considerable manipulation to yield desirable road networks. However, this automated process can create road networks much faster than manual methods and with further research, could be used to develop preliminary road networks for tactical or operational planning. The objective addressed in the second chapter is to create and test a method of determining the optimal mix of road classes within the network. High road classes have high construction costs ($/km) and low hauling costs ($/m³/km) while low road classes have low construction costs and high hauling costs. Therefore, the volume of timber to be hauled is a critical factor in determining which class of road to construct. To determine the optimal road class, I use a strategic harvest schedule to determine the haul volumes over each link within the network. These haul volumes along with construction, maintenance, hauling and deactivation/reactivation costs are used by a dynamic programming algorithm to determine the optimal road class for each unique section of road in the network. The optimal road classes, deactivation strategies and resulting costs can then be used to help evaluate strategic harvest policies and/or road network designs. Sensitivity analysis of the input costs and haul volume determine the robustness of road networks to changes or uncertainties. The optimal road class model provides a useful tool to aid managers in the evaluation of harvesting systems, silviculture systems and transportation networks. Because the harvest schedule is an important determinant of the optimal road class decision, chapter three combines the algorithms developed in the first two chapters with a strategic harvest scheduling algorithm. Six strategic harvest scenarios are used with thirteen road networks to examine road network quality. The harvest scenarios differ in the timing of harvests, the spatial distributions of harvesting, and the block size. Also, the road networks differ in the location/number of landings and when the networks are projected, relative to the harvest schedule. It was found that increased block size reduces the amount of active road under even flow harvest policies. Also, projecting road networks in each period when harvest blocks are selected reduces the length of active road and the amount of early road construction. However, this method created networks with long total lengths and long average haul distances, and poor flow concentration. The total cost of the network was mainly dependent on the total volume harvested, not the harvest policy. The methods developed in the thesis are tested on a small forest of approximately 7,500ha. Computing times to generate and assess these networks (average of 219km) ranged between 6.5 to 10.7min per scenario. Subsequent work with the road projection model has been conducted on large estates (1.5 million ha). This has led to modifications whereby the network is projected in stages (beginning with mainlines, then branch roads and finally spur roads), which generally provides more control over road location and road class, plus it offers some computational efficiency. Further development of the road projection model combined with feedback from professionals could greatly improve its utility in operational and tactical planning, plus other strategic applications including non-timber impacts of forest roads.
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