NOISE & VIBRATION MITIGATION IN RAILWAY TRACK

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Benedict McGee
6 years ago
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1 NOISE & VIBRATION MITIGATION IN RAILWAY TRACK Coenraad Esveld Esveld Consulting Services Emeritus Professor of Railway Engineering TU Delft 1

2 Noise: Rolling; Engines; Curves; Braking; Aerodynamics. Vibration: Rayleigh waves (at surface); Compression waves (tunnels); Shear waves (tunnels). 2

3 CLASSIFICATION NOISE ANNOYANCE 3

4 SQUEALING NOISE Mitigating measures: Lubrication; Asymmetric rail grinding, shift of contact point wheel rail. 4

5 CONTRIBUTION OF NOISE SOURCES Total Sleeper Wagon Rail Wheel Sleeper 5

6 METHODS OF NOISE REDUCTION Track Design Component selection (pads/sleepers) Embedded rail/special slabtracks Damping Barriers Up to 10dB but affected by layout of tracks/buildings Expensive & visual impact Low barriers & shrouds: not interoperable Acoustic grinding Effective for corrugation Not so effective for tracks in good condition Absorptive Layers Low results on the rail Higher results on slab track - absorbs wheel noise Vehicle Design Wheel diameter Wheel damping 6

7 ENERGY DISTRIBUTED IN STRESS WAVES: Rayleigh 67 % Shear 26 % Compression 7 % R -2 R -2 R -0.5 Geometrical Damping Law Vibrating source + ν = 0.25 Rayleigh Wave Vert. Comp. Horiz. Comp. R -1 Geometrical Damping Law Shear Wave + Relative Amplitude R -1 Shear Window Compression wave 7

8 VIBRATION PROPAGATION AT GRADE 8

9 VIBRATION PROPAGATION BY UNDERGROUND 9

10 SUSCEPTIBILITY OF HUMAN BODY The human body is susceptible to the following frequencies: Hz : resonance of the organ of balance, resulting in phenomena characteristic of seasickness; 4-8 Hz: resonance of the contents of abdomen and thorax; Hz: resonance of eyes in the eye sockets, resulting in loss of focus; The audibility limit lies at a frequency of approximately 20 Hz. 10

CURVES OF EQUAL VIBRATION PERCEPTION Vibration velocity (rms-value) [mm/s] 5 3 2 10 1 8 5 3 2 10 0 8 5 3 2 10-1 8 Vibration velocity (peak value) [mm/s] 10 2 8 5 3 2 10 1 8 5 3 2 10 0 8 5 3 2 10-1 EP

11 CURVES OF EQUAL VIBRATION PERCEPTION Vibration velocity (rms-value) [mm/s] Vibration velocity (peak value) [mm/s] EP = equal perception EP = 25.6 EP = 12.8 Very strong EP = 6.4 EP = 3.2 Strong EP = 1.6 EP = 0.8 Good EP = 0.56 EP = 0.4 Weak EP = 0.28 EP = 0.2 Very weak EP = 0.14 EP = 0.1 Not noticeable Frequency f [Hz] 0.18 f EP = v 2 rms ( f ) f v peak = 2v rms 2 a = 2πfv = (2πf ) d 11

12 CLASSIFICATION OF VIBRATION LEVELS Reference v 0 not standardized GERMANY ISO L EP [db] = 20 log 10 (v/v 0 ), with for instance v 0 = 10-8 m/s 12

13 MEASURED VIBRATION NEAR UNDERGROUND 13

14 EFFECT OF HIGH-SPEED MEASURED AT DB 14

15 transmission ratio K(f)/F(f) VIBRATION TRANSFER ζ 0.01 ζ = f/f n f = excitation (impressed) frequency [Hz] ζ = 1.0 ζ = 0.5 ζ = 0.2 ζ = 0.1 k m F excitation c w K response Mitigating measures: mw + cw + kw = F ( t ) 1 k f 2π m ( ) ( ) ( ) K = kw f = F f H f Transmission Ratio Reduce force, cq excitation: grinding, weld straightening; Change natural frequency relative to dominant excitation frequency: softer rail pads, resilient layers,. 15

16 VIBRATION TRANSFER II 1 Natural frequency structure f excit > 2f natural Dominant excitation frequency Excitation spectrum X = Transfer function Response spectrum f f f 16

17 PRACTICAL LIMITS Low-frequency excitations are difficult to reduce f 1 k 2π m Low stiffness and large mass necessary to achieve low frequency! Not with sleeper and rail pad, but with elastically supported slab. 17

18 BLOCK TRACK Concrete block Cork rubber Casting 18

19 STEDEF 19

20 PANDROL VANGUARD 20

21 WHISPER RAIL THYSSENKRUPP Vertical up to 10 mm Lateral < 2 mm 21

22 KÖLNER EI 22

23 ELASTIC RAIL SUPPORT 23

24 SA 42 RAIL LOW NOISE -5 db(a) compared to ballasted track -7 db(a) compared to conventional slab track 60 % less consumption of corkelast compared to UIC 54 24

25 EMBEDDED RAIL ON STEEL BRIDGE 25

26 SILENT BRIDGE WITH EMBEDDED RAIL 26

27 SILENT BRIDGE VERSUS CONVENTIONAL 27

28 CAST-IN SLEEPER Elastic supported sleeper Ballast Polyurethane Filler concrete Reinforced concrete 28

29 TRACK ON ELASTICALLY SUPPORTED SLAB 29

30 GERB Floating Slab Track Systems 30

31 UNDER SLEEPER PAD (USP) USP Under Sleeper Pads Wege für Menschen 31

32 UNDER SLEEPER PADS (USP) Increase of contact area between concrete and ballast (Riessberger): 5-10 % without USP ~ 35 % with USP Adding resilience and thus reducing dynamic forces Very effective in areas with high impact forces: frog area of turnouts; transitions near engineering structures; Effective solution at spots with maintenance problems due to poor subgrade; 33

33 CONCLUSIONS Apply mitigating measures preferably at the source: smooth wheel-rail interface; sufficient track resilience; Reduction of natural frequency: low spring stiffness; large mass; f 1 k 2π m 37

Railway induced ground vibration

RIVAS Training Workshop 23/5/213, Die Schmiede, Berlin, Germany "Reducing railway induced ground vibration by interventions on the transmission path" Railway induced ground vibration Geert Lombaert, Stijn