چكيده به لاتين
Over the past two decades, premature failure of sleepers has increased line maintenance costs. One of the main reasons for this is the lack of proper understanding of the mechanisms of failure and deterioration of sleepers as well as replacement of . Efficient maintenance planning requires relevant and up-to-date local decision support tools. These tools address three vital aspects:
• Physical factors that affect railroad wear and therefore the cost of repair and renovation,
• The extent and capability of demolition of existing railways and maintenance planning models, and
• Parameters to be included in considering process and engineering-related factors in process optimization.
In the Australian Department of Transportation, 25% to 35% of train operating costs are related to the maintenance of railways, so a simulation model has been developed to provide a cost-benefit analysis of alternative sleeper strategies, in which the survival of a sleeper from Weibull distribution is obtained and five different alternative replacement strategies for a period of 20 years are simulated on a section of a railway with 50,000 expired sleepers.
In Iran, in general, there are two strategies for replacing defective sleepers, the first strategy is the total replacement of sleepers (reconstruction) and the second strategy is the occasional replacement of defective sleepers (improvement), each of which has its own strategies in both mechanized and manual methods. It can be done. In the mechanized method, according to the machines purchased from Plasser Company, the operation of replacing the sleeper or general line replacement depends on the type and characteristics of the desired machine. In the second method, using the labor force and line repairmen, the sleeper replacement operation is performed traditionally and manually.
One of the important aspects of defective sleeper replacement operations is its economic and temporal analysis and analysis, which one of the objectives of this research is to find the boundary between line reconstruction and improvement to perform optimal sleeper replacement operations.
In the mechanized sleeper replacement method, if the defective line sleeper is more than 71%, it is economically viable to use line reconstruction methods instead of line improvement methods.
But in the manual method of replacing the sleeper, this value reaches 77%, which means that if the defective line traverse is more than 77%, it is economically viable to use line reconstruction methods.
In this regard, a case study has been conducted on the Iranian railway (Karaj-Kordan route), and by navigating the line, the defective sleepers of this line, which were mostly wooden sleepers, with two colors of red (first priority) and Yellow (second priority) is marked according to the degree of damage
Similarly, defective sleepers of the entire Tehran-Hashtgerd railway line have been identified. After identification and marking, cost analysis was performed on the methods of replacing the defective sleepers of this line and considering that 6000 defective sleepers of Tehran-Hashtgerd line includes about 4.8% of the total sleepers of this line, Therefore, according to the strategies explained in Iran, it is economical and time consuming to use mechanized methods of line improvement to replace these sleeper.
