چكيده به لاتين
Developing the transportation network and facilitating freight and passenger transportation can lead to expanding economic, social and cultural relations and exchanges throughout the country, tourism development, cost reduction and increased productivity and economization of export and import of goods. To achieve this, the most appropriate, cheapest and most efficient method of transportation have to be applied. Among the modes of transportation, rail transportation is one of the most suitable systems in terms of fuel consumption, environmental pollution, safety and security. On the one hand, planning for the development of rail transport infrastructure is one of the important issues for governments. The high cost of developing the rail network and its consuming time have always been one of the major decision-making challenges. Investment and ownership of most of the world's rail networks is related to governments. As governments do this by spending national resources, it is therefore important to select the projects that have the greatest impact on national interests. For example, there are already dozens of railroad development plans in the country, such as increase existing network capacity, build new lines, connecting provincial centers to rail network, connecting international rail borders, covering deprived areas, or create shorter routes between freight and passenger destinations. Each of these projects has a wide range of long-term implications and benefits, whether economic or social, and it is evident that the simultaneous implementation of all projects is not feasible due to the technical, financial and administrative constraints of the country's transportation sector. Therefore, prioritizing and selecting the best package of projects from the long list is essential. On the other hand, most of the time, when the rail line is built or increased capacity project is implemented, it increases the speed and ease of movement of freight and passengers. Since these lines work together in a same network, the impact of that new project on the entire route between origin-to-destination relocation should be examined. Therefore, infrastructure development projects (road and rail) cannot be considered alone. It is necessary to analyze the effects of different projects on each other and on the whole network in order to make the best decision. In the literature of transportation planning, this is called "network design". A review of the literature shows that few studies have been conducted on rail network design. Consequently, this study, aiming at the rail transport sector, has attempted to develop a suitable model for this problem and by developing that model, it is taking a step forward in developing this sector's knowledge and designing tools for decision makers. To do that, the models of "road network design" have been reviewed and the requirements and requirements of rail transport have been taken into account. The basic model has been formulated with the national point view for government to develop the rail transport network. The main inputs of the proposed model include the rail freight demand matrix, direct and indirect costs, network capacity, development projects (new lines and increased capacity of existing lines), and budget. After developing the basic model of rail network design, several developments have been made on it. These developments are designed to increase the model's ability to solve the real problem as well as to respond to different problem states. The most important development is to transform the basic model into a "multi-period rail network design" model that has been the main focus of this thesis. In this model, the network design problem is performed simultaneously for several consecutive time periods by considering different inputs for each period. Another major development of the model is to change the network design approach from national to commercial. In this approach, the developer of rail infrastructure is seen as a company that intends to expand its network with the aim of increasing its revenue. This model has been developed in both single-period and multi-period models. In addition to the two aforementioned developments, the impact of the two modes of arc-based and path-based modeling is also implemented to solve the rail network design problem. Instead of using exemplary networks as used in many research papers and scientific papers, the real network of Iran has been dealt with. The specifications of this network are fully collected and all the blocks of network are modeled. The rail freight demand matrix and its direct and indirect costs have been extracted using previous studies. The list of network development projects, including new lines and capacity increasing of existing lines, together with the amounts allocated budget to the railway lines have been obtained from the relevant approvals. The capacity of the network blocks has been calculated using UIC 405 method and all model inputs have been calculated using the actual figures of the Iran rail transport sector. The proposed models are implemented using Java programming language and powerful optimization software, CPLEX, and implemented for different scenarios of the main parameters of the model such as demand and budget. Since the Iranian rail network is not a complex network, the proposed models are solved in reasonable computing time. Concerning the results, it can be noted that the prioritization of the proposed rail network design model have remarkable differences with other methods. Those prioritization methods evaluate projects individually and assume project independence, which is not the case for transportation projects. Computing time of the proposed path-based models has a much lower time of the arc-based models, which can be very applicable to real-world problems. In addition, the comparison of the results of the single-period (basic) model and the multi-period model shows that the selected projects are the same and the multi-period model specifies the amount of funding allocated to each project and the schedule of each project. The results of the proposed models show the effectiveness and efficiency of the proposed models. Besides, the results of the proposed models are in agreement with the expert opinions.
