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Innovation for Our Energy Future 

Conference Paper Evaluation of Orion/BAE 

NREL/CP-540-37751 Hybrid Buses and Orion CNG May 2005 

Buses at New York City 

Transit 

Preprint 

L. Eudy, R. Barnitt 

National Renewable Energy Laboratory 

K. Chandler 

Battelle 

To be presented at the American Public Transportation 

Association Bus and Paratransit Conference 

Columbus, Ohio 

May 15-18, 2005 

NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 
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Evaluation of Orion/BAE Hybrid Buses and Orion CNG 

Buses at New York City Transit 

Leslie Eudy 

National Renewable 

Kevin Chandler 

Battelle 

Robb Barnitt 

National Renewable 

Energy Laboratory Columbus, Ohio Energy Laboratory 

Golden, Colorado 

ABSTRACT 

The National Renewable Energy Laboratory (NREL) 

is evaluating the Orion VII/BAE SYSTEMS hybrid buses 

at New York City Transit (NYCT). This evaluation is part 

of an ongoing U.S. Department of Energy (DOE) 

evaluation program, the Advanced Vehicle Testing 

Activity (AVTA). The current AVTA evaluation 

activities at NREL are shown at 

www.nrel.gov/vehiclesandfuels/fleettest/avta.html. The 

NREL AVTA project is conducting evaluations of 

medium- and heavy-duty transit buses and trucks, 

including the hybrid and compressed natural gas (CNG) 

buses at NYCT. 

NREL’s evaluation of the NYCT hybrid buses 

follows an evaluation of 10 prototype Orion/BAE hybrid 

buses completed in 2002. The evaluation of the newest 

generation hybrid buses began in 2004 and will cover one 

year of operation in revenue service. Detailed data will be 

collected on two hybrid configurations, the natural gas 

version of the same bus platform, and similar 

conventional buses for comparison. Information being 

collected and analyzed includes operational data such as 

vehicle use, fuel consumption, and maintenance 

performed, as well as descriptions of NYCT’s experience 

implementing this new technology. The objective of the 

evaluation is to provide credible data and results that 

show the progress of hybrid electric technologies toward 

widespread commercialization. This will provide vital 

information to transit agencies considering the use of 

hybrid buses. 

The yearlong evaluation is in progress and will not be 

complete until later in 2005. This paper describes the 

background and start-up experience with the hybrid buses 

at NYCT and details the evaluation plans. Early results of 

the evaluation—including vehicle use, fuel economy, and 

Golden, Colorado 

maintenance costs—should be available for presentation 

at the APTA 2005 Bus and Paratransit Conference. 

INTRODUCTION 

The National Renewable Energy Laboratory (NREL) 

Fleet Test & Evaluation (FT&E) team was formed to 

accomplish the objectives of the U.S. Department of 

Energy (DOE) to reduce our nation’s dependence on 

imported petroleum by developing advanced vehicle 

technologies. The FT&E team looks specifically at realworld experience encountered by fleets as they 

incorporate these new vehicles into their operations. 

Composed of NREL and Battelle personnel, the team 

leads vehicle evaluation projects supported by DOE’s 

Office of FreedomCAR and Vehicle Technologies and 

Office of Hydrogen, Fuel Cells and Infrastructure 

Technologies. 

FT&E projects help inform the purchase decisions of 

fleet owners and operators by providing them with 

comprehensive laboratory and fleet test data on viable 

alternative fuel and advanced technology vehicles. 

Advanced technologies of interest include hybrid electric 

and fuel cell vehicles. The evaluations typically cover one 

year of operational data and include economic, technical, 

emissions, and safety factors. Data are collected on the 

operation, maintenance, performance, and, sometimes, 

emissions characteristics of advanced technology fleets 

and comparable diesel fleets (if available) operating at the 

same site. Operators considering the use of these 

advanced technology vehicles are the primary audience 

for this information. 

The FT&E team has evaluated various technologies 

in use by transit fleets around the country, including the 

early hybrid buses in service at New York City Transit 

(NYCT). The team continues to work with NYCT to 

evaluate the latest hybrid technology developed by BAE 

1
SYSTEMS in the Orion VII bus platform. The following 

sections describe the project team, the technology, and the 

plans for evaluation. 

PROJECT PARTNERS 

NYCT is the largest public transportation system in 

the United States. It currently has more than 4,500 buses 

operating from 18 depots and serving more than 2,100 

miles of routes daily. More than 2 million passengers use 

its 219 bus routes every day. Since 1992, NYCT has 

displayed its commitment to cleaner vehicles by testing 

and evaluating a variety of clean fuel buses in revenue 

service. NYCT’s Clean Fuel Bus Program is a continuing 

effort to lower bus fleet emissions, reduce traffic 

congestion, and improve air quality. The plan includes 

using new clean diesel engines with particulate filters and 

ultra-low sulfur (30 parts per million sulfur content) diesel 

fuel for the entire diesel fleet (starting in 1998), as well as 

purchasing compressed natural gas (CNG) and hybrid 

electric buses. 

NYCT’s hybrid electric buses (Figure 1) are built by 

Orion Bus Industries (DaimlerChrysler Commercial 

Buses North America) and use the BAE SYSTEMS 

HybriDriveTM propulsion system. In this series hybrid 

electric system, a relatively small diesel engine running at 

controlled speed is connected to a generator that produces 

electricity for the electric drive motor and batteries. The 

electric motor drives the vehicle and acts as a generator to 

capture energy during regenerative braking. The batteries 

supply additional power during acceleration and hill 

climbing and store energy recovered during regenerative 

braking and idling. The battery optimization subsystem 

monitors and maintains the charge of each individual 

battery. The propulsion control subsystem manages the 

entire system and optimizes performance for emissions, 

fuel economy, and power. 

Figure 1. NYCT Hybrid Bus 

NYCT’S EARLY EXPERIENCE WITH 

HYBRID BUSES 

NYCT’s experience with hybrid electric buses began 

in 1998 with the purchase of a pilot fleet of 10 Orion VI 

buses with the BAE SYSTEMS HybriDrive propulsion 

system. At the time these buses were ordered, a hybrid 

configuration was not a typical option for transit buses. 

BAE SYSTEMS, Orion, and NYCT collaborated to 

design and build this technology and implement it into 

transit service. Understanding that this was an investment 

in unproven technology, the partnership set specific goals 

for the project to measure success. The goals included 

reducing emissions, significantly increasing fuel 

economy, and demonstrating that hybrid buses could 

operate in regular service with no restrictions and perform 

as well as or better than conventional buses. 

All 10 prototype buses were in service by mid-2000. 

The FT&E team conducted a yearlong evaluation of this 

fleet in operation [1]. The prototype hybrid electric buses 

met or exceeded the project goals. The evaluation also 

helped established a benchmark for hybrid electric 

technology and assessed the progress of 

commercialization to that point. The results of the pilot 

fleet demonstration were very positive, leading NYCT to 

continue its commitment to hybrid technology. 

NYCT’s early experience with the pilot bus fleet 

helped the project team improve and optimize the system 

to increase efficiency and maximize the potential benefits 

to the agency. Compared with the Orion VI hybrid 

electric buses, the next generation Orion VII buses are 

expected to be optimized more fully for fuel economy and 

emissions. Modifications included the following: 

• The bus platform was updated to the Orion VII 

model, a step-up low-floor bus; the Orion VII 

features a removable engine cradle for ease of 

maintenance. 

• The change to a rear step-up design (as opposed 

to a true low floor) allowed more seats and use 

of a standard rear axle configuration, which 

should reduce brake repair costs. 

• The engine-generator connection was modified 

to a “T” configuration to allow easier placement 

in the bus and better access for maintenance. 

2
• The power plant was switched to a Cummins Table 1. NYCT Hybrid Electric Bus Specifications 

ISB engine with an Engelhard DPXTM diesel 

particulate filter. 

• All hybrid components were improved for better 

performance, reliability, availability, and 

serviceability. 

NYCT is purchasing 325 production Orion VII 

hybrid electric buses in two orders, the first for 125 buses 

and the second for 200 buses. These large orders mark the 

continued progress of this hybrid electric technology from 

a demonstration toward commercialization. 

STATUS OF NYCT HYBRID FLEET 

As of early January 2005, 117 of NYCT’s first 125 

Orion VII hybrid electric buses have been delivered and 

are being integrated into fleet operations. Mother Clara 

Hale Depot in Manhattan has 65; staff at this depot have 

experience with hybrid electric buses from operating the 

pilot Orion VI buses. Queens Village Depot in Queens 

has 52 Orion VII hybrid electric buses and is scheduled to 

receive 8 more. Complete delivery of the 125 buses is 

scheduled for early 2005. To date, NYCT’s experience 

with the hybrid electric buses has been positive. Drivers 

like the quick acceleration of the buses, which makes it 

easier to merge into heavy traffic situations typical in 

New York City. 

In addition to the order of 125 Orion VII hybrid 

electric buses, NYCT has agreed to purchase 200 similar, 

but slightly upgraded, hybrid electric buses. According to 

BAE SYSTEMS, four subsystems on this order of buses 

have been improved, including the engine, generator, 

propulsion control, and cooling and packaging. The 

company expects these refinements to result in improved 

emissions, improved power, quieter operation, and 

improved reliability, durability, maintainability and 

performance. Table 1 lists the specifications of the hybrid 

buses at NYCT. 

Delivery of the 200-bus order is scheduled to begin in 

early 2005, and the buses will be split between three 

NYCT depots. Once delivery is complete, NYCT will 

have 325 hybrid electric buses, about 7% of its entire 

fleet. NYCT also expects to be operating 476 CNG buses 

by 2005, bringing its combined clean fuel fleet to 801 

buses, about 18% of its entire fleet. 

Description NYCT Orion/BAE SYSTEMS 

Buses 

Buses 2002, 2004 Orion VII 

Length/Width/Height 40 ft/102 in/132 in 

GVWR/Curb Weight 42,540/31,840 lb 

Seated Passenger Capacity 38-44 passengers 

Engine Cummins ISB, 5.9L (2004 

equipped with EGR) 

Engine Rating 270 hp @ 2,500 rpm 

660 ft-lb @ 1,600 rpm 

Fuel Storage 100 gal (ultra-low sulfur diesel) 

Propulsion BAE SYSTEMS HybriDriveTM 

Motor and Internal Gear Type: AC Induction, highReduction power density 

Horsepower: 250 hp 

continuous (320 hp peak) 

Torque: 2,700 ft-lb @ 0 rpm 

Generator Type: Permanent magnet 

Horsepower: 160 hp 

continuous 

Controls Type: Integrated power 

electronics and controls 

Horsepower: 250 hp 

continuous (320 hp peak), 

J1939 CAN interface 

Energy Storage Type: Sealed lead acid 

Voltage: 520-700 VDC 

Regenerative Braking Yes 

Emissions Equipment Catalyzed diesel particulate 

filter 

EVALUATION PLANS 

The evaluation of NYCT’s Orion VII hybrid electric 

buses will include collecting operation, maintenance, and 

performance data from a selection of hybrid buses from 

the 125-bus order and the 200-bus order. Detailed data 

will be collected from a total of 20 hybrid and 20 

conventional diesel buses. 

NYCT considers the hybrid electric buses to be 

commercial products and plans no special treatment for 

their operation. The depots will not have additional spare 

buses and will be responsible for maintaining bus 

availability at 85% or better, the same as required for 

conventional diesel and CNG buses. Recovery time for 

troubleshooting and repair of the hybrid electric buses is 

extremely important to NYCT. The ability of the 

maintainers to fully integrate the hybrid buses into the 

fleet will be a measure of the success of these bus orders. 

NYCT is also receiving Orion VII CNG buses, which 

will be included as part of this evaluation. The CNG 

buses will be operated out of West Farms Depot in the 

Bronx and Jackie Gleason Depot in Brooklyn. Detailed 

data will be collected on a selection of CNG and 

conventional diesel buses operating from West Farms 

3
Depot. Table 2 outlines the evaluation plan by bus type 

and fleet location. In addition, specific road call data will be collected 

on all hybrids at Fresh Pond and Mother Clara Hale 

Table 2. Buses Included in the NYCT Evaluation Depots and on all the CNG buses at West Farms Depot. 

Depot/ 

Location 

Bus 

Chassis 

Propulsion Technology Number 

of 

Buses 

Mother Clara Orion V Conventional diesel 10 

Hale/ 

Manhattan 

Orion VII BAE SYSTEMS hybrid 

(125-bus order) 

10 

Fresh Pond/ Orion V Conventional diesel 10 

Queens Orion VII BAE SYSTEMS hybrid 

(200-bus order) 

10 

West Farms/ Orion V Conventional diesel 10 

Bronx Orion VII CNG 10 

The detailed data being collected on each of the 60 

study buses include the following: 

• Fuel Consumption - amount of fuel, odometer 

reading, date, price 

• Mileage and route information - miles in service 

per day and month with consideration of duty 

cycle 

• Availability 

• Engine oil additions and oil/filter changes - 

amount of oil, odometer reading, date 

• Preventive maintenance action records - date of 

repair, labor hours, number of days out of 

service, odometer reading, parts replaced, parts 

cost, descriptions of problems and repair 

• Records of unscheduled maintenance - road calls 

and warranty repairs. 

Analysis of these additional data will indicate reliability 

for each order. 

WHAT WILL BE IN THE PRESENTATION 

The presentation at the APTA 2005 Bus and 

Paratransit Conference is intended to provide background 

and hybrid bus introduction experience from NYCT. The 

background information will include a thorough 

description of the buses and the hybrid propulsion system 

as well as a description of the implementation experience 

at NYCT. The introduction experience will include early 

data and evaluation results at the fleet with fuel economy 

and operating costs. 

ACKNOWLEDGEMENTS 

We would like to thank DOE’s Office of Energy 

Efficiency and Renewable Energy, Office of 

FreedomCAR and Vehicle Technologies, and Lee Slezak, 

Manager of the Advanced Vehicle Testing Activity, for 

their support. We would also like to thank the project 

partners, including Gary LaBouff, Doug Zupo, and 

Gordon Coor at NYCT; Thomas Webb at BAE 

SYSTEMS; and Mark Brager at Orion Bus Industries. 

ENDNOTES 

1. Hybrid Electric Transit Buses—New York City Transit 

(NYCT) Diesel Hybrid Electric Buses: Final Results. 

Golden, CO: National Renewable Energy Laboratory. 

Report no. NREL/BR-540-32427, 2002. 

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Evaluation of Orion/BAE Hybrid Buses and Orion CNG Buses at 

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14. ABSTRACT (Maximum 200 Words) 

The National Renewable Energy Laboratory (NREL) is evaluating the Orion VII/BAE SYSTEMS hybrid buses at New 

York City Transit (NYCT). NREL’s evaluation of the NYCT hybrid buses follows an evaluation of 10 prototype 

Orion/BAE hybrid buses completed in 2002. The evaluation of the newest generation hybrid buses began in 2004 

and will cover one year of operation in revenue service. Detailed data will be collected on two hybrid configurations, 

the natural gas version of the same bus platform, and similar conventional buses for comparison. Information being 

analyzed includes operational data such as vehicle use, fuel consumption, and maintenance performed, as well as 

descriptions of NYCT’s experience implementing this new technology. The evaluation is in progress and will not be 

complete until later in 2005. This paper describes the background and start-up experience with the hybrid buses at 

NYCT and details the evaluation plans. 

15. SUBJECT TERMS 

nrel; doe; advanced vehicle testing activity; hybrid electric; bae systems; buses; public transit; new york city transit 

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