| Summary: Route determination is a complex process in which many variables are to be simultaneously analyzed and is one of the important steps for all Linear Engineering Structures (LES) projects. This process affects all other processes required from the beginning and during the life time of the project such as construction, maintenance, repairs etc. Establishment of LES in an optimal way is dependant on the determination of related route optimally. For this, factors effecting LES route should initially be determined. The degree of effect to route for each factor should be determined as a weighted coefficient and these should be interpreted and analyzed all together. When lengths of LES and factors effecting the route determination process considered, the need for managing a large spatial data set emerges. Analysis of such large data sets and population of quick and accurate outcomes may be possible with Geographical Information System (GIS) technologies, which is an effective decision support system.
In this study, a dynamic raster based route determination model which may be customized for the majority of LES was developed. Application of this model was only carried out for Natural Gas Transmission Pipelines (NGTP). For this purpose, the factors effecting routes of NGTP were determined and weights of these factors were designated with using Analytical Hierarchy Process (AHP), which is one of Multi Criteria Decision Support (MCDS) methods. By applying AHP method also for sub criteria for these factors, surface friction grading was calculated. By considering these weight values, raster based route determination model was developed. In accordance with the requirements of this model, an interface based on ArcGIS9.2 development environment was developed. In this interface, the user can do factor selection dynamically based on current integral data in the interface and can determine alternative routes for different purposes by optionally changing pre-determined factor weights. The model was first applied for the process of the optimization of current Trabzon NGTP, and, in this process, it was tested in view of some criteria such as its performance, speed and accuracy etc. In addition, a raster based cost surface map was produced using this model. Route proposals were done for two samples of NGTP by using this surface map.
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