Third Rail Insulator Failures: Current State of the Practice

Metro rail systems use an electrified third rail to obtain traction power for the rail cars. The third rail is installed on insulators that get covered with steel dust, rust particles, brake dust, carbon dust, and other conducting particulates generated by operating trains. The particulates accumulate over time, causing the insulators to fail and resulting in leakage currents, electric arcing, smoke, and fire. Insulator failures can cause delays in one portion of the transit system and have cascading effects to an entire metro rail network. This report documents the current practice and lessons learned from the use of the insulator systems by transit agencies. The practical delivery from this synthesis is information that can assist transit organizations in making informed decisions about their third rail insulator systems and mitigation strategies. A literature review and detailed case examples of five different systems are also in the report and provide additional insights on the state of the practice, including lessons learned, challenges, and gaps in information. The results from the survey demonstrated that the transit agencies average 10 insulator failures and less than 10 hours of delays annually. An average of 1,000 passenger hours were lost annually because of insulator failure by each of the eight surveyed transit systems. Porcelain insulators were reported as the most expensive insulators, with an average cost of US$256 per unit, and epoxy insulators were reported as the least expensive, with an average cost of US$108 per unit. Dirt buildup was found to be the most frequent cause of insulator failures, and the penetration of saltwater into the conduit the least frequent cause of failure. The goal of the case example collection and analysis was to perform an in-depth study of third rail characteristics and failures. The results of the analysis revealed that local environmental conditions can cause degradation of third rail insulators over time, the operational cost per insulator failure is higher than the average price of an insulator unit, the lessons learned need to be documented more frequently, and performing regular maintenance and inspections is an effective approach to reducing the number of failures in transit systems.

• Record URL:
  • https://nap.nationalacademies.org/catalog/26010
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9780309673624
• Authors:
  • Kermanshachi, Sharareh
  • Rouhanizadeh, Behzad
• Publication Date: 2020

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; References; Tables;
• Pagination: 79p
• Serial:
  • TCRP Synthesis of Transit Practice
  • Issue Number: 150
  • Publisher: Transportation Research Board
  • ISSN: 1073-4880

Subject/Index Terms

• TRT Terms: Degradation failures; Failure; Failure analysis; Insulators (Electricity); Maintenance of way; Rail transit; Third rail
• Subject Areas: Maintenance and Preservation; Public Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 01759692
• Record Type: Publication
• ISBN: 9780309673624
• Report/Paper Numbers: Project J-7, Topic SD-05
• Files: TRIS, TRB, ATRI
• Created Date: Dec 7 2020 11:32AM