Research Project Information

Research Project Summary Information

Study: NYC Transit Rail Traction & Regenerative Energy (ST9281-1)

New York Power Authority


There are more than 2,500 AC propulsion subway railcars (AC) in the New York City Transit (NYCT) fleet that can generate and accept regenerative (regen) braking energy. These railcars are excellent candidates for energy efficiency improvements. The R142 model subway railcar is the most common of these and the results of studying this model will be applicable to the balance of the regen-capable fleet. Improvements in the AC regeneration capabilities on NYCT's subway railcars are both possible and necessary, and are the subject of two separate but related elements of analysis led by the New York Power Authority, with co-funding by NYSERDA and active participation of NYCT.

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Project Description

The objective of two related studies was to identify the benefits and technical issues involved in implementing energy storage systems and improved regenerative braking in the NYC subway. The two studies were led by the New York Power Authority, and engaged transit engineering contractors for the bulk of the work. NYSERDA co-funded approximately half of each project with NYPA. The first project, for a “NYCT Traction Power System Study and Energy Storage System Analysis” consisted of tasks to: 1. develop energy storage system model for the traction power simulation software 2. Simulate energy storage system on typical rail transit system line configurations, 3. Analyze and determine the potential benefits of a generic energy storage system on a typical rail transit system line Configuration, 4. Analyze the benefits of energy storage systems and prepare cost-benefit analyses, 5. Perform additional simulations for two Locations on the NYCT system, if analysis in Task 4 demonstrates economic benefits. The second project, for “NYCT Regenerative Energy Improvement” consisted of tasks to: 1.develop a regenerative energy improvement project test plan, 2. perform AC effect and DC effect analysis, 3. analysis of regeneration optimization, 4. design and fabricate a prototype third rail ripple signal generator (TRSG), 5. Perform evaluation of third rail ripple signal generator, 6. TRSG specification and deployment plan, 7. Training and reporting.


Improvement in both regenerative energy utilization, use of aluminum third rail, energy storage, and improved system operation can result in significant energy benefits in the reduction of propulsive power requirements of the NYC subway system. Quantified benefits will be an outcome of the study projects.

Project Results

Each separate element of the project was completed successfully and final reports generated. Based on the results, an implementation phase of the regenerative braking improvement initiative was proposed by NYPA and NYCT and was awarded.


New York Power Authority
1 Barney Road Suite 240
Clifton Park, NY 12065

Principle Investigator

John Markowitz

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: ST9281-1

Last Updated: 10/15/2014