Dissertations and Theses

Date of Award


Document Type




First Advisor

Ahmed Mohamed


Subway, Electric Bus, MTA, NYCT, Quantification, Regenerative Braking, Recuperation, Energy, Charging, Energy Demand


The New York Metropolitan Transportation Authority (MTA) is one of the biggest consumers of electricity in east coast of the United States. According to a report published by Dayton T. Brown in 2013, MTA consumes approximately 2150 GWh electrical energy per year for traction power, where the New York City Transit (NYCT) alone is a consumer of about 80% of the total annual MTA energy consumption. This continuous high demand for electricity from a single organization opens research opportunities to search for alternative ways to reduce the needs. NYCT Subways has an existing total rolling stock of 6,418 train cars where more than half of these existing cars have and all future cars will have the capability of regenerating energy while braking. This huge rolling stock operating in a 24/7 active revenue service environment holds tremendous potential to reduce energy demand by proper capture and use of regenerative energy from braking trains.

In New York city, bus operations play a vital role in public transportation. NYCT & MTA Bus have a joint fleet of 5700+ buses providing transportation services to the city by continuously operating on 238 local, 13 select bus service and 74 express bus routes within the five boroughs. Currently, this huge fleet has a combination of Compressed Natural Gas (CNG) buses, diesel and hybrid diesel buses. In 2014, the MTA released a total of .27 pounds of carbon dioxide (CO2) gases per passenger mile. Even though on a per passenger-mile basis, emissions from single occupancy vehicles are up to five times higher than the per-passenger mile emissions of mass transit, MTA is making efforts to reduce this emission to support environmental sustainability. An announcement made by MTA in January 2018 revealed MTA’s plan to gradually transition its large bus fleet into zero emission electric buses. To start with, MTA has launched a pilot program to operate 10 all-electric buses in some of the busiest streets of NYC. This gradual transition and future addition of new all electric buses will increase energy demands and will need a charging infrastructure. This infrastructure could be established for assuming the total demand or could be shared with other existing installations. The use of existing railway electrical infrastructure to provide electrical energy to charge Electric buses may provide many benefits.

This paper explores the huge potential of using regenerated energy from braking trains to charge electric buses in context of NYCT Subways and Buses. NYCT subways and bus operations were studied, existing train rolling stock profiles and new-all electric bus profiles were examined. A quantification method was developed to generate close estimation of energy availability reproduced through regenerative braking for 24-hour time cycles at targeted subway station locations considering NYCT’s current operational procedures. An approximation of energy demands for current all-electric buses was estimated. Two potential demographic locations within MTA operational boundaries were selected for this analysis. An overall quantification analysis was performed to show the huge potential of electrical energy availability possible through regenerative braking and it was proven that this available energy would be enough to support electric bus charging demands.



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