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Abstract
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Electric railway vehicles receive their power from the pantograph-catenary system (in overhead contact lines) and the collector shoe (in third rail systems). The collector shoe used in third rail systems has many advantages over the pantograph-catenary system, such as lower cost, less required maintenance, a longer service life, and less impact on the landscape [4]. Third rails are also more compact, making them more practical for tunnels with small diameters, and they use one contact variant among the top contact, side contact, and bottom contact. The top contact is less safe than the other two and is susceptible to interruptions due to ice and snow.
The third rail is originally American, and its use dates back to the dawn of the first subway system in the 1860s. Some railway power supply systems are limited to using overhead contact lines because their voltage levels are above 1 kV; however, third rails provide electric power to a railway vehicle by a rigid conductor that is placed between or along the rails [3]. The train runs from the power drawn from the third rail, which is usually found near the tracks [3] and carries a high voltage that is extremely dangerous if touched.
Failures of third rail insulators, which often impose problems that affect the serviceability of transit systems, rarely have been investigated. This study examines various aspects of third rail systems, identifies causes of insulator failures, and develops and categorizes preventive strategies. To accomplish the goals, the existing literature was reviewed and analyzed to identify various characteristics of third rails and insulators. Then, five transit case studies were analyzed to determine the characteristics of third rails, identify the causes of insulator failures, and evaluate the preventive strategies adopted by transit agencies. The results revealed that local environmental conditions cause degradation of insulators, with dirt build-up being the biggest contributor to failure. Performing maintenance and inspections of insulators at predetermined intervals was also shown to be very effective for preventing failure. The preventive strategies were classified into three categories: regular inspections; preventive maintenance programs; and regulation and safety, with regular inspections being the most frequently adopted.
FINDINGS of this study will serve as an appropriate source of information for practitioners who work with third rail systems and will help them adopt effective strategies.
Language: en |