RailwayTechnologyAvalanche

The Railway Technical Research Institute (RTRI) willcelebrate its 20th anniversary in December 2006. RTRI wasestablished as an incorporated foundation on December 10,1986, as part of the breakup and privatization of JapaneseNational Railways (JNR). It began its research anddevelopment in earnest on April 1, 1987, when the JRgroup of companies was launched.Every five years, RTRI draws up a new master plan andimplements it to fulfill management policies and theoriginal RTRI vision. The current master plan, for the fiscalyears 2005 to 2009, is called Research 2005, and promotesthe following five basic courses of action:• Create new railway technologies for the 21st century• Demonstrate the comprehensive potential of a railway

engineering group• Respond rapidly to the needs of society and the JR Group of

companies• Transfer railway technologies and acquire basic technologies• Spread knowledge of railway technologies and transmit

railway-related informationDuring the last 20 years, we have depended considerably onthe intellectual and physical assets accumulated by JNRover its many years of managing Japan’s national railwayservices. Although some of our equipment andinfrastructure was installed since our establishment, muchof our testing facilities, and the land and buildings we usefor research, were inherited from the former JNR, as weremany of our staff members who developed their technicalexpertise during their years with JNR.During the last two decades, some companies within the JRGroup have established their own technical research centersto actively pursue development programs withmanufacturers, universities, and public research institutesthat were transformed into independent corporate entities.

B e c a u s e o f t h e s e v a r i o u sc i r c u m s t a n c e s ,RTRI must give itsresearch activities anew perspective forthe next 20 years,while at the sametime fully usingas se t s a cqu i r edfrom JNR. Oneexample of theseassets, and the mostimportant, is ourhuman resources.Sixty percent ofRTRI’s technicalstaff joined us sincew e b e c a m e a nindependent incorporated foundation two decades ago.Some fundamental challenges now facing our Institute areto ensure that this technical experience is passed on toyounger generations, to train more high-caliber technicalstaff, and to secure even more highly qualified humanresources. Another important goal is to replace testingfacilities and equipment that are becoming obsolete, and tointroduce new, more advanced ones.The vision that inspired the establishment of RTRIreinforces our intention to continue working well into thefuture for the betterment of society, taking advantage of themost advanced railway technology that we can possess.

1

85

■ Foreword Kazuhiko TEZUKA ............................................................ 85■ RTRI Research and Development Projects Promoting

Advances in Rail Transport Fuminao OKUMURA, Ph.D..................... 86

■ A Study of the Dynamic Behavior of Railway Vehicles DuringSeismic Activity Takefumi MIYAMOTO ............................................. 87

■ Observation, Experimentation and Analysis of Pressure Waves GeneratedWhen a Train Passes a Nearby Structure Hajime TAKAMI ................. 88

■ A New Method to Evaluate Ride Comfort Under Braking ConditionsKoji OMINO ...................................................................................... 89

■ Ground Coil Electromagnetic Vibration Tests Using the MagneticField of a Superconducting Magnet Minoru TANAKA .................... 90

GENERAL INFORMATION

ARTICLES

Octorber 31, 2006 No. 15

Railway Technical Research Institute2-8-38 Hikari-cho, Kokubunji-shiTokyo 185-8540, JAPAN

URL: http://www.rtri.or.jp

Copyright © 2006 Railway Technical Research Institute. All rights reserved.Reproduction in whole or part without permission isprohibited. Printed in Japan.

Newsletter on theLatest TechnologiesDeveloped by RTRI

Foreword

Kazuhiko TEZUKADirector, Planning Division

2

86 Railway Technology Avalanche No. 15, October 31, 2006

When conducting research and development for futureadvances in rail transport, Railway Technical ResearchInstitute (RTRI) promotes small-scale projects that targettechnical breakthroughs, aiming for the practical applicationof R&D results within approximately five to ten years.RTRI s master plan for the fiscal years 2005 - 2009, calledResearch 2005, envisages 12 R&D projects.These projects were given the following themes:• They should respond to the needs of companies in

the JR Group, and to social trends• They should aim for the development of advanced

technologies and for improvements in rail transport• They should take advantage of the strengths and

R&D expertise that RTRI has in specific areas• They should lead to the development of practical

technologies, and the resolution of critical problemssurrounding that development

Outlines of four major R&D projects and the titles of theother eight projects launched by RTRI in fiscal 2005 arelisted below. All projects aim to promote future advances inrail transport.(1) Configuration and application of a signaling system

evaluated with the RAMS indexThis project will study and propose methods forevaluating the RAMS (Reliability, Availability,Maintainability and Safety) characteristics of asignaling system, and methods to improve suchevaluation indices, in order to effectively establish,at low cost, a signaling system having excellentRAMS characteristics.

(2) Development of a method to evaluate thecharacteristics of vehicle dynamics, using a hybridsimulatorThis project will develop a system that effectivelyevaluates vehicle characteristics using mainlyHardware-In-the-Loop (HILS) Simulation (HILS)techniques, symbiotically linking computersimulations, component testing equipment, andvehicle testing stands. HILS are hybrid in nature,using testing equipment that coordinates the use ofcomputerized dynamic models with the simultaneoususe of actual equipment, while transmitting theirresponses to a computer system.

(3) Improvement in the evaluation of existing railwayfacilities ability to withstand earthquakes, anddevelopment of better measures for making facilitiesmore earthquake-resistantRailway systems are composed of a wide variety ofcomponent parts, mainly structures, track, an electricpower system, signaling equipment and rollingstock. Antiseismic measures have traditionally beenapplied to each of these individual component parts.In reality, though, each of these parts influences theothers. RTRI’s antiseismic research emphasizes thisfact while developing (i) methodologies to evaluate,using common criteria, the behavior of railway

facilities during seismic activity, and (ii)methodologies to determine what type ofearthquake-resistance measures should beimplemented, taking into consideration quantitativefactors such as investment cost effectiveness.

(4) Development of human simulation technologies toimprove safety and riding comfortSimulation techniques have advanced rapidly and arenow used to examine human factors such aspassenger traffic patterns, behavior, and decision-making patterns. RTRI is building on these advanceswhile developing new simulation techniques that canbe used to better evaluate and predict the safety andcomfort levels of passengers and railway personnel.Titles of the other eight projects are as follows:

(5) Application of IT and sensing technologies toequipment management

(6) Development of a tool to predict rolling noise andstructure-borne noise, and development of noisereduction measures

(7) Development of high-speed mass storageinformation and telecommunication technologies forrailways

(8) More efficient transport planning based on dynamicdemand estimation

(9) Creation of rail damage/ballast track deteriorationmodels, and evaluation of maintenance work savingtechnologies

(10) Development of a new low-maintenance, low-noisetrack

(11) Development of fuel cell vehicles(12) Application of linear motor technologies to the

conventional railway system

RTRI Research and Development Projects Promoting Advances in Rail TransportFuminao OKUMURA, Ph.D.Deputy Director, Planning Division

3

Railway Technology Avalanche No. 15, October 31, 2006 87

A railway vehicle derails as a result of seismic activityeither because of deformation of a railway structure or thetrack, or because of track vibration caused by theearthquake itself. Since the Hyogo Prefecture NambuEarthquake of 1995, railway structures in Japan are beingmade more earthquake resistant through the gradualimprovement of design standards that adopted the latesttechniques.With regard to the derailment of railway vehicles as a resultof seismic vibrations themselves, the Railway TechnicalResearch Institute (RTRI) has performed numericalsimulations, and conducted advanced experimental researchusing a vibration test rig to examine the behavior of anactual Shinkansen bogie. The results have been reflected innew design standards for railway structures, and are beingused to improve the seismic safety of railway systems.(1) Running safety limits in the presence of sinusoidal

wavesWe developed our own simulation program toanalyze the behavior of railway vehicles during anearthquake. The program uses a conventional vehiclerunning simulation model with added features topermit the accurate analysis of such factors asoscillatory input under the rails, wheel jump on rails,and the large roll displacement of vehicles.Using this simulation model, we determined arunning safety limits during the presence ofsinusoidal waves (see Fig. 1). Figure 1 indicatessinusoidal wave vibration frequency (lateral axis)and maximum amplitude (longitudinal axis) limitsrequired to avoid a derailment when vibrations areinput from directly under a running vehicle. Fromthis it can be determined that if the relativewheel/rail lateral displacement is more than 70 mm,a derailment is almost sure to occur.

(2) Experiments using a Shinkansen bogie on a vibrationtest rigTo determine the validity of our simulation analyses,we performed experiments using a vibration test rig.The test objects used in the experiment are shown inFig. 2. We installed a straight 5-m length of track on

the large vibrationrig, placed ana c t u a lShinkansen bogieon the track, thenmounted a loadequivalent to halfthe weight of aShinkansen car onthe bogie. The total weighto f t h e s e t e s tobjects was 35 tons. Vibrations were input in mainlya lateral direction. During the experiment, vibrationfrequency amplitude was gradually increased untilthe wheels jumped 3 mm or more above the rails.Fig. 3 compares results obtained from thisexperiment with the simulation results. The figure’slateral axis indicates vibration frequencies, while thelongitudinal axis indicates input amplitudes when awheel jumped 3 mm or more. These results validatedresults obtained through simulations.

A Study of the Dynamic Behavior of RailwayVehicles During Seismic ActivityTakefumi MIYAMOTOSenior Researcher, Vehicle Machanics, Railway Dynamics Division

Fig. 1 Running safety limits by relative displacement betweenwheel and rail 70mm- Five lateral sinusoidal waves, simulated run of Shinkansenvehicle at 350 km/h on straight track.

700

600

500

400

300

200

100

00 0.5 1 1.5 2 2.5 3

Frequency (Hz)

Am

plitu

de o

f saf

ety

limit

(mm

)

Fig. 3 Comparison between experiment and simulation resultsfor safety limits when a wheel jumped 3 mm or more- Five lateral sinusoidal waves, load equivalent to half the weightof a Shinkansen carbody, stopped on straight track.

300

250

200

150

100

50

00 0.5 1 1.5 2 2.5

Frequency (Hz)

Am

plitu

de o

f saf

ety

limit

(mm

)

ExperimentSimulation

Fig. 2 Photograph of testing plant

4

88 Railway Technology Avalanche No. 15, October 31, 2006

Fig. 1. Overpass

Fig. 2. Pressure waves observed during experiments anddetermined through analysis[Train velocity 350 km/h; overpass width 24 m]

Fig. 3. Spatial distribution of instantaneous acoustic pressure,obtained by analysis[Train velocity 350 km/h; overpass width 24 m]

Low-frequency sounds are slight pressure fluctuations withfrequencies in the range of approximately 1 to 100 Hz. Theyare hardly perceptible to the human ear, yet have given riseto concern in Japan over the last decade because they cancause the rattling of house windows and shutters, and canalso cause physiological and psychological discomfort, suchas ringing in the ears and an unpleasant sensation ofpressure.Micro-pressure waves generated at tunnel portals when ahigh-speed train enters a tunnel have long been observedalong railway lines as low-frequency sounds. But evenalong some open sections of line, pressure waves may beradiated from a nearby structure when a high-speed trainpasses. These pressure waves, in the form of weak low-frequency sounds, do not cause a problem at present, butthey could negatively affect the adjacent environment whentrains operate at even faster speeds in the future.Our research team therefore conducted on-sitemeasurements along open track sections to examinephenomena when a high-speed train travels under anoverpass (Fig. 1). We measured pressure waves thatdiffered according to train speed, overpass size, and thelocation of the observation point.We then performed experiments using a model scaleapparatus and conducted acoustic analyses, to determine thespeed dependencies, distance attenuation and directionalcharacteristics of pressure waves. We were able to showthat mechanisms generating pressure waves involve bothmicro-pressure waves and a combination of wavesgenerated when the train enters and leaves the portals (withthe overpass acting as a short tunnel). We used thisknowledge to analytically predict the characteristics ofpressure waves radiated from an overpass that is longenough to possibly cause a problem during high-speedoperations. Predicted values agreed well with the results ofour experiments (see Figs. 2 and 3).

This research has furtherimproved the methodologyfor analyzing pressurewaves, thereby aiding inthe prior determination oftrackside low-frequencysound and pressure waveconditions that would existunder higher speedoperations for Shinkansenand other high-speedtrains.

Observation, Experimentation and Analysis of Pressure WavesGenerated When a Train Passes a Nearby StructureHajime TAKAMIAssistant Senior Researcher, Aerodynamics, Environmental Engineering Division

30

20

10

0

-10

-20

-30

Pre

ssur

e [P

a]

Over-bridge Train

Analytical resultsExperiment results

Nose exit

Time (sec)

Nose entry

Pre

ssur

e (P

a)

20

10

0

-10

-20

0 0.2 0.4 0.6 0.8 1

5

Railway Technology Avalanche No. 15, October 31, 2006 89

A New Method to Evaluate Ride Comfort Under Braking Conditions

Koji OminoSenior Researcher Ergonomics, Human Science Division

Faster deceleration when stopping a train at a station wouldimprove transport efficiency. This is an important technicalgoal, due to the need for prompt mass transit services andshort train intervals. We performed tests with humansubjects to examine braking patterns that would not reduceride comfort even under higher deceleration rates, and toclarify the relationship between deceleration, derivative ofdeceleration (jerk), and ride comfort. We have alsoproposed a ride comfort evaluation method based on thetest results. Ride Comfort Levels during BrakingWe assumed the braking patterns used at stations to stop atrain, and performed tests on the Maglev test line of theRailway Technical Research Institute, with human subjectsstanding on board the train (Fig. 1). Our tests revealed thepreviously unknown relationship between deceleration, jerkand ride comfort in a high deceleration range. Fig. 2 showsratios of passengers who could not adequately adjust to thevarious braking pattern used to stop the train, and theseserve as one scale for measuring ride discomfort levels. Thefigure clearly indicates the rate at which ride comfortdeteriorates as deceleration increases. A negative impact onride comfort was observed even at approximately 0.1m/s3

jerk difference, and there is a tendency for ride comfortdeterioration rates to shift toward higher values as jerkincreases.

Proposals for aRide ComfortEvaluation Indexand OptimumBraking PatternsWe used the testdata to propose anindex to evaluateride comfort levelsduring decelerationand jerk that takethe fo rm o f atrapezoidal brakingpattern (Fig. 3). Thecurves in Fig. 2 arebased on this index,and show that ridecomfort deterioratesas the index valueincreases. We alsoanalytically obtained the deceleration and jerk values thatminimize the indices for various combinations of initialspeeds at braking and stopping distances, and haveproposed train-stopping braking patterns that offer optimumride comfort. Future RTRI Research in this FieldIn the future we plan to study the practical application ofbrake controls, in order to introduce our proposed brakingpatterns to commercial operations. During those studies wewill also examine ways to widen application of the index sothat various other factors influencing ride comfort duringbraking, including the congestion often seen on commutertrains, can be taken into account. In addition, in order toexamine ride comfort more effectively, we intend todevelop a system that simulates the swaying of standingpassengers when brakes are applied, using the ride comfortdata obtained during the above-mentioned study.

Jerk (m/s3)

0.0 0.5 1.0 1.5 2.0 2.5

100

90

80

70

60

50

40

30

20

10

0

0.26 0.39 0.52 0.64

Rat

io (

%)

Deceleration (m/s2)

0.64m/s3

0.52m/s3

0.39m/s3

0.26m/s3

Fig. 2 Ratio of passengers unable to adequately adjust tobraking patterns

Fig. 1 Ride Comfort evaluation test during braking

Fig. 3 Index for ride comfort during brakingThe greater the value, the poorer the ride comfort

6

90 Railway Technology Avalanche No. 15, October 31, 2006

Ground coils installed along the guideway of asuperconducting magnetically levitated transportationsystem are vibrated by electromagnetic forces when avehicle passes. To ensure the reliability of the entire system,it is important to verify the dynamic durability of groundcoils. We therefore developed an electromagnetic vibrationtest apparatus for bench tests that can apply anelectromagnetic force on a coil conductor as a distributedload, simulating the load conditions of an actual trainoperation, and that can evaluate the vibration characteristicsand dynamic durability of the coil molding material underarbitrary running conditions. Figs. 1 and 2 show the configuration and appearance of thetest system, respectively. By installing the target groundcoils so that they face the superconducting magnet(maximum magnetomotive force: 800 kA), and by applyingthe current from the inverter power supply under arbitraryconditions (maximum current: 2000 A), it was possible tosimulate actual vibration conditions that occur when a trainpasses the coil. In addition, because a superconductingmagnet generates a larger electromagnetic force than duringactual operations, when it is placed in an alternatingmagnetic field, the ground coil was covered with a shieldplate to insulate it from the alternating magnetic field andthus restrict magnetic vibrations. A ground coil coolingsystem and a soundproof chamber were also installed, andan automatic measuring and monitoring system that we haddeveloped ourselves was used to enable unmanned long-time durability testing. To confirm the equivalence between bench tests and actualoperations, the coil was installed in the test system via load

converters so thatthe load acting onthe coil could bemeasured from 3directions.M e a s u r e m e n t sconfirmed that theelectromagneticforces acted on thecoil as designed. Ina d d i t i o n , w i t hacce le romete rsmounted on thecoil surface, weperformed sweeptests of vibrationfrequency to confirm that the system can vibrate the coil atvibration acceleration rates equivalent to those experiencedduring actual operations.Dynamic durability tests were performed using an actualcoil for propulsion. 1.38 107-cycle vibration tests wereperformed under an electromagnetic force that generatedapprox. 1.2 times the ordinary stress on the coil’s moldingmaterial. The vibration tests were performed only in thedaytime, in consideration of temperature rise characteristicsof coils on a commercial line. The test period wasapproximately 10 days. This test period corresponds toapproximately 35 years of vibration on a commercial line, afact determined by acceleration tests based on S-N curvecharacteristics obtained from separately performed fatiguetests of the molding material. During the tests, accelerometers were mounted on variousportions of the coil to observe how vibration accelerationrates change with time. As is shown in Fig. 3, accelerationincreases slightly at measuring point just after vibrationis started, but this increase is small in value and saturates.This confirmed that there is no problem concerning coildynamic durability. During visual examinations andinsulating characteristic tests performed before and after thevibration tests, no change of properties was seen and adynamic durability equivalent to 35 years of operation on acommercial line was confirmed. Results show that ourground coil electromagnetic vibration test apparatus can beused as an effective means to evaluate dynamic durability.

5

Ground Coil Electromagnetic Vibration Tests Using the Magnetic Field of a Superconducting MagnetMinoru TanakaAssistant Senior Researcher, Electromagnetic Applications, Maglev Systems Technology Division

Cooling system Soundproof chamber

Shield plate(Ground coil set inside the shiele plate)

Superconductigmagnet

Fig. 1 Configuration of ground coil electromagnetic vibrationtest apparatus

Shield plate

Shield plate

Ground coil

Ground coil

Superconducting magnet

Inverter Superconducting magnet

Base +

Fig. 2 Appearance of electromagnetic vibration test apparatus

Number of repeated load cycles ( 106)

0 5 10 15

Acc

cele

ratio

n (m

/s2 )

40

35

30

25

20

15

10

5

0

1

234

5

1

3

5

2

4

1 5~ are the positions of accelerometers.

Shield plate

Propulsion coil

Fig. 3 Dynamic durability test results for a propulsion coil