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Published byMireya Pipp Modified over 10 years ago
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Railway noise Gijsjan van Blokland M+P Ard Kuijpers M+P sources:
Müller-BBM (D), D. Thompson (GB), M.Dittrich (TNO)
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topics Relevance Sources Model of generation process of rolling noise
Propulsion noise Aero dynamic noise Model of generation process of rolling noise Force generation in wheel/rail contact Vibrational response of wheel and of rail Effect of parameter changes in wheel system and rail system Mitigation measures Special constructions Curve squeal Generation process
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Dose-effect relation for three transport noise sources
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Sources of railway noise (I)
Areo-dynamic Propulsion system Rolling wheel/rail system
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Speed relation for the three noise sources
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Sources of noise at high speed (>300 km/h)
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Sound emission of train types
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Bronnen en snelheid (II)
aerodynamisch rolgeluid geluidniveau rolgeluid bij afscherming >350 km/h snelheid
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Rolling noise
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Effect of braking system on wheel roughness and sound production
Wavelength translated to frequency: f=v/λ Cast iron blocks lead to significant roughness of the wheel rolling surface due to local high temperatures during braking Disc brakes causes no roughness build-up Disc + blocks is the worst combination Replacing cast iron blocks with composite blocks improves noise characteristics
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level of rail roughness
Rail surface is not completely flat, rail roughness increases by use Cause not fully understood Worst situation is periodic irregularity with a 4 cm wavelength f=v/λ: 4 cm at 40 m/s equals 1 kHz
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Rail corrugation, wavelength of 4 cm clearly visible
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Combined wheel/rail roughness (dB re 1 m)
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Modeling rolling noise (1): force generation
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Modeling rolling noise (2): force sound radiation
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Contribution to rolling noise
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Wheel/rail force reception: mobility (velocity/force) wheel: modal system rail: no boundery, regular support by sleepers
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Wheel: modes of vibration
Calculated using FEM Showing exaggerated cross-section deformation of each mode
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Radiation efficiency σ: log of ratio of sound/vibration
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Vibration of track system
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Rail pad defines coupling between rail and sleeper
high stiffness pad strong coupling good energy transfer from (low damped) rail to (high damped) sleepers
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Track vibration: effect of pad stiffnes
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Effect of pad stiffnes on vibration and noise level
Increased stiffnes baseplate pad Rail noise level difference (dB)
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Dependence of rolling noise on pad stiffness
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Radiation efficiency of rail
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Rail cross-section deformations - only relevant at higher frequencies - not relevant for total dB(A) level
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Contribution to rolling noise (again)
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Speed related wheel and rail contribution
total rail Noise level wheel speed
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Model of rolling noise (Twins)
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Reducing rolling noise
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Effect of braking system on roughness and noise
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Rail grinding Reduces rail rougnes
Regular grinding: longer wavelengths Acoustic grinding: 1mm – 63cm Acoustic effect: 2-4 dB(A) Effect depending on wheel rougness
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Effect of rail grinding after some years
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Effect of wheel shape
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Effect of types of wheel damping
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Effect of wheel geometry
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Effect of pad stiffness
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types of rail dampers
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ISVR/CORUS damper
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Effect of damper
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Skirts (vehicle mounted barriers)
Only effective in combination with track mounted barriers
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Mini barriers mecahnism: effect: 5 dB(A) for rail contribution
Mainly sheilding of rail radiation Added absorption is essential (to prevent multiple reflections) effect: 5 dB(A) for rail contribution
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Results Metarail Project
Influence on Noise
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Cost-benefit study of mitigation measures
Calculate costs & benefits for different noise control strategies. Strategies consist of combinations of noise control measures. Two major freight freeways chosen for study. Rotterdam Köln Basel Milano Bettembourg Lyon 1177 km 490 km Total line length: 1667 km
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Instruments for strategic noise abatement Cost-Benefit Analysis
max. 4 m barriers track system improvement max. 2 m barriers Scenarios of Noise reduction due to rolling stock improvement - 10 dB - 5 dB none rolling stock improvement only
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Non-standard rail construction (slab track)
Preferred construction for high speed lines in Germany and Netherlands Stable system , even at soft soil Low maintenance High initial costs
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Types of track construction
Elasticity in track system is essential to prevent cracks in rail Conventional ballast track Flexible mounted sleepers in concrete slab Rigid mounted sleeper in concrete slab Rail directly mounted in slab
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Case: HSL-Zuid
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Slab tracks are more noisy then conventional ballast tracks. Why?
Less tight rail to sleeper connection less damping No acoustic absorption from ballast Total effect +2 tot +5 dB(A
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Effects of slab track
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Noise increase due to higher rail contribution
TWINS: verschil ballast – 240 km/h: Hz ballast track Slab track (Rheda) total wheel rail/ baseplate Sleeper/ slab
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Noise difference ballast – slab track as a function of frequency
125 250 500 1000 2000 4000 8000 -10 -5 5 10 15 20 frequentie [Hz] L p,UIC 54 beton kaal - L p,UIC 54 ballast [dB(A)] Goederen (Best) ICR (Best) Goederen (Deurne) ICR (Deurne) Effect centered around 800 Hz, rail contribution
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optimal dynamic properties
Noise improved design Higher rail damping Tighter connection with sleeper Damped fixation of sleeper in slab Cork-rubber with optimal dynamic properties
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Noise improved design, adding of absorption
German slab track construction
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Curve squeal
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Curving behavior
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Creep force
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Reducing squeal noise
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Some general points
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