First 100% Domestic LowFloor Tram
MITSUAKI HOSHI* 1

MASAHIRO YAMAGUCHI*1

YOSHIKI OOKUBO*1TOKUHIRO ARAI*1

HIROKI NONAKA* 1

HIROYUKI KONO*2

The first 100% low-floor LRV developed with Japanesetechnology has the vehicle length 30 m and is composed of5-car (3-bogies) configuration. As for the bogies, MHI wasinvolved in the project from development, design, manufacture to verification processes of the bogies based on theachievements of "Technical Research Institute for Low Floor
LRV Bogie" established by Land, Infrastructure, and Transportation Ministry, realizing a wide range of travelingperformances such as barrier-free character, low noise, lowvibration, low speed, and high speed.

1. Introduction
The first 100% domestic independent wheel type lowfloor tram started its service operation on the streets ofHiroshima City on March 30, 2005. The tram, named"Green Mover max," turned into reality, overcoming diverse
problems over a time period of 5 years since its concept
took root. This paper throws light on the details of development and outline of the tram (vehicle).

2. Concept of development

4. Development of technology for independent wheel bogie

The Green Mover max was developed under a joint
project involving Mitsubishi Heavy Industries, Ltd. (MHI),
Kinki Sharyo Co., Ltd., and Toyo Denki Seizo K.K. in addition to Hiroshima Electric Railway Co., Ltd., as an advisor
in the field of operation service. The 4 companies musteredup their efforts in the development and manufacture ofLRV (Light Rail Vehicles) matching with Japanese landscape and Japanese society using Japanese technologies.
Three points were listed as the concept of development:(1) Ultimate, (2) User friendly and (3) Urban. The initialletters of these points were used to name the project: "U3Project." In the U3 project, MHI took over bogies, brakes,
and inner/outer riggings; Kinki Sharyo focused on design,
car body, articulations, and driver's cabin; while Toyo Denki
Seizo took responsibility for electric parts and control anddrive units.

The key to the development of 100% low-floor LRV wasthe bogie with an independent wheel system. Normally,
the left and right wheels are connected with a shaft, which
determines the floor height. Therefore, an independent
wheel system was adopted for our bogie. The electric-powFig. 1)
1 had a motor and drive unit installed toered bogie (Fig.
the outer side of the wheel. The adoption of the new bogie
system led to realization of floor height 330 mm (passagesection 360 mm), enabling step less boarding into the car.
Further, the bogie section intruding into the passenger
cabin was covered with seats to make the cabin comfortable. In addition, the bogie structure was made compact toallow the aisle width of 880 mm, 50 mm wider than the LRV
manufactured by foreign manufacturers. Moreover, the moFig. 2
tor-less bogie (Fig.
2) where no motor is installed was
subjected to special design, resulting in drastically increased
width of aisle up to 1120 mm and thus contributing to smooth
movement of boarding and alighting passengers while ensuring wider and unobstructed view from the passenger
room. Further, the number of seats on the bogie could bemade 20% larger than that of an imported LRV. Elastic
wheels were adopted for the bogie to reduce noise and vibration. As for brakes, three types were used - electric,
hydraulic, and rail - to allow mode change with less shockto bring the car to a safe stop under any conditions.

3. Background of development
The new-generation urban traffic system LRT (LightRail Transit) is drawing attention as a city symbol transport system that is comfortable and friendly not only toenvironment but also to people. Especially, the high-performance, stylish and barrier-free low-floor tram, wellbeyond the concept of an existing tram (street car), hasalready been introduced in Europe and North America, with
its effectiveness highly evaluated. However, the European
manufactures are ahead of Japanese makers in terms ofthe technologies for independent wheel bogies, so that the100% low-floor tram introduced to Japan was limited tothe vehicles manufactured by foreign manufacturers or
partially manufactured by domestic makers by adopting
foreign technologies. This gave rise to problems of operability and maintenance, and the development of domestic
vehicle befitting with the use in Japan was an immediateneed and long-expected item.

Fig. 1 Bird's eye view ofmotorized bogie

Fig. 2 Bird's eye view ofmotorless bogie

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 1 (Jan. 2006)*1 Plant and Transportation Systems Engineering & Construction Center*2 Hiroshima Research & Development Center, Technical Headquarters

1Table 1 General specifications for vehicle

5. General specifications for vehicle

Configuration
Number of passengers
WeightSize

Table 1 shows the general specifications for Green
Mover max. The vehicle main body is equipped with Train
Information System (TIS), with the monitor mounted on
the driver's stand (control platform). Thus the driver's
stand console was made compact, the switches were centralized, the settings were made possible by using monitor
and the support measures for driving and maintenancewere taken such as maintenance and trouble indications,etc., with a view to reducing the work load of the driver
who has to do both: taking care of the service and drive.
The vehicle control system adopts individual motor control system using a VVVF inverter unit with high energy
performance and the difference in rotational speed of theleft and right wheels due to the 100 kW motor installedoutside the driving bogie (4 units/1 train) and the unbalanced torque due to the wheel radius are absorbed toensure outstanding running performance.
The car body is made of steel in view of the tram running on the road with other vehicles and paying attention
to the safety, stiffness, maintenance and so on. Thanks to
the thorough measures taken for reducing the weight, thecar with strong and light body has been realized. In the 5car, 3-bogie configuration, the train-set has the central cars
as floating cars, with the articulations for connecting eachcar body ensuring high reliability while being light inweight, compact in size and needing little maintenance.

(people)(t)(mm)

Floor level and low-floor rate (mm)Electric mode(V)

Track gauge(mm)
Maximum running speed (km/h)
Acceleration(km/h/s)Normal deceleration(km/h/s)
Emergency deceleration (km/h/s)
Main control unit

5-car 3-bogie, low-floor vehicle
149 (56 seats provided)
33.9
L 30 000 x W 2 450 x H 3 450
360 (exit/entrance 330),
low-floor rate 100%
DC 600
1 435
60
3.5
4.8
6.0
2-level IGBT-VVVF inverter,
regenerative and generation
blending brake system

Brake unit

Mechanical (hydraulic) brake system,
regenerative and generative brake,safety brake (track brake),deadman's device

Main motor

3-phase squirrel cage induction motor
100kW x 4 units
Shaftless independent wheel bogie

Bogie

8. Conclusion
As described above, the 100% low-floor LRV Green
Mover max largely differed from existing vehicles in manyways and needed a wide range of verification tests. We
are determined to make further improvements in technology and skill, so that it may be introduced as the citytransportation system in different parts of Japan andoverseas. Finally, we would like to extend our gratitude
to Hiroshima Electric Railway Co., Ltd., Technical Research Institute for Low Floor LRV Bogie, Kinki Sharyo
Co., Ltd., and Toyo Denki Seizo K.K for their valuable
cooperation and guidance in the development of the first
100% domestic low-floor LRV.

6. Vehicle design
The vehicle was designed to have a soft, roundish frontend shape to provide a fresh feeling, and friendly flavor
to the passenger as the new domestic low-floor vehicle.
The interior design, based on the concept of comfortable
space, put maple, the symbol of Hiroshima, as the motif
for the inside and outside of the car body to give a tone of
local characteristics required of a street car.

7. Thorough verification of technology
To verify the vehicle riding efficiency, MHI built a special 900-m long test trail rail track at the "Plant andTransportation Systems Engineering & Construction Center" in the company's Wada-oki Plant. A thoroughverification of technologies was carried out in this test
track to realize development of a vehicle with outstanding performances. In the tests, we verified acceleration/deceleration performance and safe running performanceby measuring the car body behavior and the strength ofbogie and car body parts. We also measured the riding
quality, noise inside and outside the car, air-condition
capacity and so on to verify the riding comfort and efficiency. Through these verifications, the first 100%
domestic low-floor LRV was proved to have enough comp e t i t i v e n e s s a g a i n s t t h e L RV m a d e b y f o r e i g nmanufacturers.

Mitsuaki Hoshi

Masahiro Yamaguchi

Yoshiki Ookubo

Tokuhiro Arai

Hiroki Nonaka

Hiroyuki Kono

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 1 (Jan. 2006)

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