modelling rail noise & vibration - acoustics · basic concepts -noise noise source from...

Modelling Rail Noise & Vibration

Daniel Lloyd

Lloyd Acoustics

Basic Concepts - Noise

� Noise Source from

� Wheel/Rail Interaction

� Propulsion System – Accelerating/High Speed

� Brakes

� Wheel Squeal – On tight bends

Modelling Considerations

� Spatial

� Distance from Train to Receiver

� Ground Elevations

� Barriers – Natural/Structural

� Source

� Train Properties –� Length

� Speed

� Source Height

� Specified Criteria

Modelling Process - Noise

� Develop Digital Terrain Model

� 3D Land Contours -DLI

� Rail Alignment (x,y,z) at 10m Centres

� Receiver Locations (x,y,z)

� Often required visual survey to identify houses, schools, care facilities, sheds, etc

� Existing Barriers – Fences, Safety Barriers

� Height, condition, location


� Input Noise Source

� Source Height – Affects Barrier Performance

� Train Length

� Ground Absorption

� Movements during Daytime/Night-time period

� Train Speed along Track Section

� Ignore Stations

Modelling Process –Example Layout


� Select Algorithm

� Nordic Railway Prediction Method (Kilde Report 130)

� Gives both LAeq Day/night and LAmax

� Calibration

� Compare against criterion (Initial)

� Compare against measured data (Final)


� Data Input


� Running The Model

Modelling - Noise

� Results

1 3

8

8

6

5

3

3

2

2

2

2

2

1 2

11

1 1

BS

FH

FH

FH

FH

FH

FH

FH

BS

FH

13

65

3

2

2

SB

FH

FH

FH

FH

FH

Noise levelLrDin dB(A)

<= 4040 < <= 4545 < <= 5050 < <= 5555 < <= 6060 < <= 6565 < <= 7070 < <= 7575 < <= 8080 < <= 8585 <

Modelling - Noise

� Results

2

2

2

FH

SB

FH


<= 4040 < <= 4545 < <= 5050 < <= 5555 < <= 6060 < <= 6565 < <= 7070 < <= 7575 < <= 8080 < <= 8585 <

Modelling - Noise

� Results

Modelling Process –Example Layout


� Running The Model

Modelling - Noise

� Results

2

2

2

FH

SB

FH


<= 4040 < <= 4545 < <= 5050 < <= 5555 < <= 6060 < <= 6565 < <= 7070 < <= 7575 < <= 8080 < <= 8585 <

Basic Concepts - Vibration

� Vibration Source from� Wheel/Rail Interaction� Feelable Vibration: Frequency range 4 Hz to 80 Hz. Has a low rate of attenuation with distance and is perceived as whole-body vibration in buildings near to the line.

� Ground-borne Noise: Frequency range 30 Hz to about 200 Hz. Ground vibration may excite bending resonances in the floors and walls of buildings which then radiate a rumbling noise directly into the rooms.

Modelling - Vibration

� Predictions are extremely unreliable unless ground composition and conditions known between source and receiver.

� Better to measure

Modelling - VibrationAnalysis of Vibration Levels From Train Pass-by's a t

Approximately 100 km/h

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.500

1

1.3

1.6 2

2.5

3.1 4 5

6.3 8

10

12.5 16

20

25

31.5 40

50

63

80

10

0

12

5

16

0

20

0

25

0

31

5

40

0

50

0

63

0

80

0

100

0

125

0

160

0

200

0

250

0

315

0

400

0

500

0

630

0

800

0

100

00

125

00

160

00

200

00

Frequency

RM

S V

eloc

ity m

m/s

RMS Velocityat 3m RMS Velocity at 10m RMS Velocity at 15m Curve 1.4 Curve 2


� From measured results, develop an algorithm for predictions based on distance and train speed.

� Use CAD programs to determine distance of each receiver from rail

� Apply algorithm.


� ResultsPredicted Vibration Levels from the Narrows Bridge to Mt Henry Bridge

90919293949596979899

100101102103104105106107108109110111112113114

A1

A2

A3

A4

A5

A6

A7

A8

A9

A1

0

A1

1

A1

2

A1

3

A1

4

A1

5

A1

6

A1

7

A1

8

A1

9

A2

0

A2

1

A2

2

A2

3

A2

4

A2

5

A2

6

A2

7

A2

8

A2

9

A3

0

A3

1

A3

2

A3

3

A3

4

A3

5

A3

6

A3

7

A3

8

A3

9

A4

0

A4

1

A4

2

Receiver Number

Pea

k V

ibra

tion

Leve

l dB

v

Predicted Peak Vibration Level Curve 1.4 Curve 2.0

modelling rail noise & vibration - acoustics · basic concepts -noise noise source from...

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