Rail Defects and Weld Failures

Although the wear resistance of rails is basically controlled by hardness, it is also dependent on the stresses that the rails are subjected to. These stresses control the development of defects in rails that can eventually lead to failure, and include bending stresses, residual stresses, thermal stresses, and contact stresses [16,17]. 

Defects in steel rails may be classified imder the following three categories [16]  

In order to reduce the occurrence of rail-defect-related failures, various methods are used to detect rail defects. These methods include visual inspection by the track maintenance staff, ultrasonic defect detection, eddy-current testing, ground-penetrating radar, impedance spectroscopy, and electromagnetic acoustic transducers [16,17]. 

In railway systems, the construction of continuous welded rails (CWR) is indispensable in reducing noise and vibration, improving the quality of the ride, and reducing the cost of track maintenance. Over the years, many railway accidents have occurred due to rail weld failures. Thus, it is very important to have reliable welds in order to eliminate the occurrence of weld failures in service as well as to extend the CWR service life. 

Past experiences indicate that most rail weld failures are started from weld discontinuities, and fusion welding tends to easily cause such weld discontinuities [18]. Thus, fusion-welding techniques such as enclosed-arc welding (EA) and aluminothermic welding (TW) are less reliable than pressure-welding techniques such as flash welding (FW) and gas-pressure welding (GP) [18, 19]. In order to eliminate the occurrence of rail weld 

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Chapter 5 is devoted to transportation systems failures. Some of the topics covered in the chapter are mechanical failure-related aviation accidents, vehicle failure classifications, rail defects and weld failures, rail and road tanker failure modes and failure consequences, ship failures and their consequences, and failures in marine environments and microanalysis techniques for failure investigation. Chapter 6 presents a total of 11 mathematical models for performing various types of reliability analysis of transportation systems. 

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