| Abstract |
- The systems currently available for forest road design are not capable of making computer-aided design judgments such as: 1) automated generation of alternative grade lines, 2) optimizing vertical alignment, 3) minimizing total cost of construction, maintenance, and transportation costs, and 4) aiming for least environmental impacts. In recent years, advances in the processing speed and realtime rendering and viewing of high-resolution three dimensional (3D) graphics on microcomputers, combined with improved resolution in mapping technologies have made it possible to locate a route interactively between two given points on a 3D display of a ground surface. A 3D forest road alignment model, TRACER, aided by an interactive computer system, was developed to help a designer with rapid evaluation of alternatives. The road design objective is to design a path with the lowest total construction, maintenance, and transportation costs, while conforming to design specifications, environmental requirements, and driver safety. The model relies on a high-resolution digital elevation model (DEM) to provide terrain data for supporting the analysis of road design features such as ground slope, topographic aspect, and other landform characteristics. Light Detection and Ranging (LIDAR) system is one of the systems that provide high-resolution and accurate DEM data. The contributions of the TRACER program are: (1) data input is enhanced through a 3D graphic interface, (2) user efficiency is enhanced through automated horizontal and vertical curve fitting routines, cross section generation, and cost routines for construction, maintenance, and vehicle use, (3) road feasibility is ensured by considering terrain conditions, geometric specifications, and driver safety, (4) design time is reduced in the early stage of the forest road design by allowing the designer to quickly examine alternative routes, (5) economic efficiency is enhanced by combining modern optimization techniques to minimize earthwork allocation cost using linear programming and to optimize vertical alignment using a heuristic technique (Simulated Annealing), and (6) environmental impacts are considered by estimating the average annual volume of sediment delivered to a stream from the road section. It is anticipated that the computer-aided analysis of route selection will improve the efficiency of road designers in identifying road alignment alternatives that are best suited to local conditions considering costs, environmental impacts, and driver safety.
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