Research Project Information

Research Project Summary Information

Reducing Electric Losses from Rail Transit Insulators(ST9398-1)

Arun Vohra, P.E. Consulting Engineer


Rail transit cars use power supplied by a third rail that sits on insulators, which are typically spaced about 10 feet apart. Typically each car is equipped with an electrical collector shoe that rides on top of the third rail. Carbon dust from carbon brushes on the traction motor commutators, rust particles, dirt, and grime can short-circuit the insulator and cause smoke, explosive breaking of the insulator, set wood ties on fire, and shut down train operation. Dirty insulators are among the most frequent causes of downtime in many rail transit systems around the country, and are a constant source of electrical energy leakage, and losses. The insulators are extremely difficult to clean because the third rail carries very high voltage, and the third rail cover and tunnel walls limit access to the insulators. With funding from the Transportation Research Board IDEA program, the Contractor has fabricated and tested a proof-of-concept prototype device to clean electrified third rail insulators. An advanced, commercially-ready device could be developed with additional TRB funding, but transit operators such as New York City Transit (NYCT) must first determine if the economic magnitude of the energy losses justifies adopting such a device.

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Project Description

Quantify experimentally and analytically the electrical energy losses from dirty third rail insulators and quantify the cost impacts. The proposed project will, in cooperation with NYCT: obtain thermographic images of more than 100 insulators in the NYCT system; analyze the power losses from the measured insulator temperatures; calculate system-wide power losses; and, quantify the economic, energy, and environmental impacts of a third rail cleaning device in the NYCT subway system. Also in conjunction with NYCT, plans will be laid for a prototype development project and commercialization approach.


Insulator cleaning devices have the potential to improve the safety, security, and energy efficiency of the NYC subway system. Energy, environmental, and economic metrics will be developed as part of the project.

Project Results


Arun Vohra, P.E. Consulting Engineer
7710 Bradley Boulevard
Bethesda, MD 20817

Principle Investigator

Arun Vohra

Universities Involved


Project Type:

Research Study

Technologies Types:


NYSERDA Contact Information

Frank Ralbovsky


R&D -Transport & Power Systems

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST9398-1

Last Updated: 10/15/2014