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

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 Mitigation measures

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Dose-effect relation for three transport noise sources

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Sources of railway noise (I)

Areo-dynamic

Rolling wheel/rail system

Propulsion 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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50

55

60

65

70

snelheid [km/h]

emis

sieg

etal

[d

B(A

)]

40 60 80 100 140 160 200

2

7

1

3

6

9

8

4

5

Sound emission of train types

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Bronnen en snelheid (II)

snelheid

gelu

idn

ivea

u

aerodynamischrolgeluid

>350 km/h

rolgeluid bijafscherming

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Rolling noise

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Effect of braking system on wheel roughness and sound production

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

Wavelength translated to

frequency: f=v/λ

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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 systemrail: 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

-8

-6

-4

-2

0

2

4

6

8

10

12

63 125 250 500 1000 2000 4000 8000

octave band frequency [Hz]

LA

eq

[dB

]

25 MN

30 MN

40 MN

70 MN

Increased stiffnes baseplate pad

Rail

nois

e level d

iffere

nce

(d

B)

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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

speed

Nois

e level

wheel

rail

total

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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: 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

0123456789

Dif

f. N

ois

e d

B(A

)

Type of Influence

Stiffness of ballast

Type of rail

Distance of sleepers

Track width

Corrugation of rail

Pad stiffness

Corrugation of wheel

Influence on Noise

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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 km490 km

Total line length: 1667 km

Bordeaux

M arseille

Lyon

Paris

Basel

London

A ntw erpen M ainz

Rotterd amH am burg

M ilan o

Cost-benefit study of mitigation measures

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Costs and benefitsnot including costs for insulated windows

0

50

100

150

200

250

300

0 20000 40000 60000 80000 100000 120000

Costs (EURO/km/year)

Ben

efits

(red

uctio

n pe

rson

s >

60 d

B/k

m)

rolling stock improvement only

max. 4 m barriersmax. 2 m barrierstrack system improvement

Scenarios of Noise reductiondue to rolling stockimprovement

none- 5 dB- 10 dB

Instruments for strategic noise abatementCost-Benefit Analysis

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

Flexible mounted sleepers in concrete slab

Rigid mounted sleeper in concrete slab

Rail directly mounted in slab

Conventional ballast track

Elasticity in track system is essential to prevent cracks in rail

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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 – Rheda @ 240 km/h: 250 -1000 Hz

rail/baseplate

wheel

total

Sleeper/slab

ballast track Slab track (Rheda)

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Noise difference ballast – slab track as a function of frequency

125 250 500 1000 2000 4000 8000-10

-5

0

5

10

15

20

frequentie [Hz]

L p,U

IC 5

4 b

eto

n k

aal

- L

p,U

IC 5

4 b

alla

st [

dB(A

)]

Goederen (Best)

ICR (Best)

Goederen (Deurne)

ICR (Deurne)

Goederen (Best)

ICR (Best)

Goederen (Deurne)

ICR (Deurne)

Goederen (Best)

ICR (Best)

Goederen (Deurne)

ICR (Deurne)

Effect centered around 800 Hz, rail contribution

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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

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