I
LIST OF CONTENTS
1 INTRODUCTION ..........................................................................................................................1
2 BASIC TERMINOLOGY .............................................................................................................5
3 BRIEF FACTS ABOUT SOUND AND NOISE ........................................................................ 11
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
SOUND AND NOISE ...................................................................................................................................... 13
SOUND PRESSURE ........................................................................................................................................ 13
SOUND PRESSURE LEVEL AND THE DECIBEL (DB) ............................................................................. 14
LOUDNESS AND LOUDNESS LEVEL ......................................................................................................... 14
HOW AN INCREASE OR DECREASE IN SOUND IS PERCEIVED ........................................................... 14
SOUND INTENSITY AND SOUND INTENSITY LEVEL ........................................................................... 14
FREQUENCY, WAVELENGTH AND SPECTRUM ..................................................................................... 16
FREQUENCY WEIGHTING AND THE DB(A) "UNIT" .............................................................................. 17
TIME WEIGHTING AND THE EQUIVALENT SOUND LEVEL, LAEQ ................................................... 18
ADDITION OF SOUND SOURCES ............................................................................................................... 19
SOUND IN AIR AND IN OTHER MEDIA OR MATERIALS....................................................................... 19
EFFECTS OF NOISE ....................................................................................................................................... 20
3.12.1
3.12.2
3.12.3
3.12.4
3.12.5
3.12.6
3.12.7
General ................................................................................................................................................................ 20
Fatal or damaging effects .................................................................................................................................... 20
Extra-auditory effects (health) ............................................................................................................................. 20
Sleep disturbance ................................................................................................................................................ 20
Interference with communication and intellectual performance .......................................................................... 20
Annoyance........................................................................................................................................................... 21
Monetary effects .................................................................................................................................................. 21
4 HISTORICAL PERSPECTIVES ............................................................................................... 23
4.1
4.2
4.3
4.4
4.5
4.6
NOISE PROBLEMS IN ANCIENT TIMES .................................................................................................... 25
GENERAL NOISE CONTROL ....................................................................................................................... 25
TYRE/ROAD NOISE ISSUES IN EARLIER TIMES ..................................................................................... 27
EARLY POLISH VEHICLE NOISE STUDY ................................................................................................. 28
MEASURING METHODS .............................................................................................................................. 32
DEVELOPMENT OF VEHICLE NOISE EMISSION - AN I-INCE STUDY ................................................ 33
4.6.1
4.6.2
4.6.3
4.6.4
4.6.5
4.6.6
4.6.7
4.6.8
4.6.9
4.6.10
4.6.11
4.6.12
4.7
The I-INCE Initiative .......................................................................................................................................... 33
Background ......................................................................................................................................................... 33
Extent of the Study .............................................................................................................................................. 34
Review of Change in Limits ................................................................................................................................ 34
Type of Tests - Review of Measuring Procedure ................................................................................................ 34
Results - Annoyance and Community Noise Changes ........................................................................................ 36
Results - Change of Vehicle Noise Emission Values Measured During Type Approval .................................... 36
Results - Noise Changes in Actual Traffic .......................................................................................................... 36
Results - Comparison of Japanese with Other Experiences................................................................................. 37
Reasons for the Limited Effectiveness ................................................................................................................ 38
Recommendations from the study ....................................................................................................................... 39
Concluding remarks ............................................................................................................................................ 40
THE DEVELOPMENT OF NOISE EMISSION FROM TYRES DURING THE 20TH CENTURY............. 40
5 TYRE/ROAD NOISE AS PART OF VEHICLE NOISE ......................................................... 43
5.1
5.2
5.3
VEHICLE NOISE - GENERAL CHARACTERISTICS .................................................................................. 45
VEHICLE NOISE SOURCES .......................................................................................................................... 46
RELATION BETWEEN POWER UNIT NOISE AND TYRE/ROAD NOISE .............................................. 50
5.3.1
5.3.2
5.3.3
General relation ................................................................................................................................................... 50
Passenger cars ..................................................................................................................................................... 51
Trucks and busses ............................................................................................................................................... 52
II
5.4
SOURCES DIFFICULT TO DISTINGUISH FROM TYRE/ROAD NOISE .................................................. 55
6 BASIC INFORMATION ABOUT TYRES AND ROAD SURFACES ................................... 57
6.1
TYRES.............................................................................................................................................................. 59
6.1.1
6.1.2
6.1.3
6.1.4
6.1.5
6.1.6
6.1.7
6.2
6.3
Early history of wheels and tyres......................................................................................................................... 59
Refinement of pneumatic tyre construction ......................................................................................................... 59
Tread pattern types .............................................................................................................................................. 61
Tyre components, markings, terminology and standards..................................................................................... 67
Retreaded tyres .................................................................................................................................................... 68
Studded tyres ....................................................................................................................................................... 72
Speculations about the future .............................................................................................................................. 73
ROAD SURFACES .......................................................................................................................................... 74
6.2.1
Historical notes ................................................................................................................................................... 74
6.2.2
Basic construction features of the most common road surface types................................................................... 78
6.2.3
Some less common surface types ........................................................................................................................ 84
6.2.4
Some notes about bitumen binders ...................................................................................................................... 86
6.2.5
The most commonly used surfaces in various situations ..................................................................................... 87
6.2.6
Standard specifications for road surfaces ............................................................................................................ 88
6.2.7
Discussion of some basic road surface terms ...................................................................................................... 88
6.2.8
What is a "Low Noise Road Surface" .................................................................................................................. 88
ROAD SURFACE TEXTURE TERMINOLOGY AND CHARACTERISATION ......................................... 89
6.3.1
The use of texture profile curve data ................................................................................................................... 89
6.3.2
The use of three-dimensional surface data .......................................................................................................... 93
6.3.3
Other surface characterisation methods and further reading ............................................................................... 93
7 TYRE/ROAD NOISE SOURCES AND GENERATION MECHANISMS............................ 95
7.1
GENERATION MECHANISMS ..................................................................................................................... 97
7.1.1
7.1.2
7.1.3
7.1.4
7.1.5
7.1.6
7.1.7
7.1.8
7.1.9
7.1.10
7.1.11
7.1.12
7.1.13
7.1.14
7.1.15
7.1.16
7.1.17
7.1.18
7.1.19
7.1.20
7.1.21
7.1.22
7.1.23
7.1.24
7.1.25
7.2
7.3
General ................................................................................................................................................................ 97
Exploration methods ........................................................................................................................................... 97
Examples: Early studies of noise-texture and vibration-noise relations .............................................................. 97
Wave types in tyres ........................................................................................................................................... 103
The impact mechanism: Vibrations induced by tyre tread or surface texture impact ........................................ 104
Tread band versus sidewall vibrations............................................................................................................... 107
Tyre structural resonances ................................................................................................................................. 107
Tyre/rim bending waves .................................................................................................................................... 109
Radiation of sound from rim vibrations ............................................................................................................ 109
Tangential stick-slip motions (scrubbing) ......................................................................................................... 109
Adhesion stick-snap .......................................................................................................................................... 111
Summary of the stick-slip and stick-snap mechanisms...................................................................................... 112
Torus cavity resonance in the tyre tube ............................................................................................................. 113
Air turbulence ................................................................................................................................................... 114
Air pumping ...................................................................................................................................................... 115
Air resonant radiation (Helmholtz resonators) .................................................................................................. 119
Pipe resonances in channels formed in the foot-print........................................................................................ 120
Amplification effect by the acoustical horn between tyre tread and road surface.............................................. 122
Mechanical impedance influence ...................................................................................................................... 123
Sound radiation from the road? ......................................................................................................................... 123
Effect of the moving medium on acoustic radiation .......................................................................................... 124
Crossover frequencies ....................................................................................................................................... 124
Wet surface generation mechanisms.................................................................................................................. 124
Studded tyre generation mechanisms ................................................................................................................ 126
The remarkable peak at 700-1300 Hz................................................................................................................ 126
THE LOCATION OF THE MAJOR SOURCES AND RADIATION AREAS ............................................. 127
7.2.1
In general about methods, etc ............................................................................................................................ 127
7.2.2
Measurements utilising sound intensity technique ............................................................................................ 128
7.2.3
Measurements utilising the vibrational mapping technique .............................................................................. 133
7.2.4
Measurements utilising the near-field holography (NAH) technique ................................................................ 133
7.2.5
Measurements utilising the spatial transformation of sound fields (STSF) and time
domain holography (TDH) techniques .............................................................................................................. 135
DIRECTIVITY ............................................................................................................................................... 138
III
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
7.3.6
7.4
7.5
Introduction ....................................................................................................................................................... 138
Sound radiation to front, side and rear positions ............................................................................................... 138
Directivity in the horizontal plane ..................................................................................................................... 141
Directivity in the vertical plane ......................................................................................................................... 142
Three-dimensional directivity ........................................................................................................................... 143
Conclusions ....................................................................................................................................................... 143
SOURCE LOCATION AND RADIATION - CONCLUSIONS .................................................................... 144
MODELS ........................................................................................................................................................ 145
7.5.1
Introduction ....................................................................................................................................................... 145
7.5.2
Simple, empirical models .................................................................................................................................. 145
7.5.3
More complicated, theoretical and semi-empirical models ............................................................................... 148
7.5.4
"Complete" models............................................................................................................................................ 151
7.5.5
Input data .......................................................................................................................................................... 152
7.5.6
Commercial models ........................................................................................................................................... 153
7.5.7
Ongoing and expected model development ....................................................................................................... 154
8 TYRE/ROAD NOISE EMISSION - GENERAL INFLUENCES AND
TYPICAL DATA.........................................................................................................................155
8.1
8.2
INTRODUCTION .......................................................................................................................................... 157
TYRE INFLUENCE IN GENERAL TERMS ................................................................................................ 157
8.2.1
8.2.2
8.3
8.4
8.5
8.6
8.7
8.8
Range ................................................................................................................................................................ 157
Typical differences between types of tyres ........................................................................................................ 158
ROAD SURFACE INFLUENCE IN GENERAL TERMS ............................................................................ 159
TYPICAL TIME HISTORIES ....................................................................................................................... 161
TYPICAL SOUND LEVELS (LAMAX) VERSUS SPEED .......................................................................... 162
TYPICAL SOUND LEVELS WITH A CLOSE-PROXIMITY METHOD - PLUS MORE ON
THE TYRE INFLUENCE .............................................................................................................................. 164
TYPICAL FREQUENCY SPECTRA ............................................................................................................ 165
NOISE INCREASE FOR WET ROAD .......................................................................................................... 167
9 DRIVER INFLUENCE ON TYRE/ROAD NOISE EMISSION ............................................169
9.1
SPEED ............................................................................................................................................................ 171
9.1.1
9.1.2
9.1.3
9.1.4
9.1.5
9.1.6
9.2
9.3
Introduction ....................................................................................................................................................... 171
General noise-speed relationship ....................................................................................................................... 171
The A+B logV relationship .............................................................................................................................. 172
The very useful A and B constants .................................................................................................................... 175
Local irregularities and tonal components......................................................................................................... 177
Noise-speed relations for interior noise ............................................................................................................. 179
TANGENTIAL FORCES ............................................................................................................................... 182
9.2.1
Driving and braking forces (longitudinal slip) .................................................................................................. 182
9.2.2
Side forces (lateral slip)..................................................................................................................................... 189
9.2.3
Possible mechanisms responsible for the tyre slip effects ................................................................................. 193
9.2.4
Influence of road crossfall ................................................................................................................................. 195
TYRE LOAD AND INFLATION .................................................................................................................. 195
9.3.1
Various investigations ....................................................................................................................................... 195
9.3.2
Polish study ....................................................................................................................................................... 198
9.3.3
Bridgestone study .............................................................................................................................................. 201
9.3.4
Discussion of mechanisms ................................................................................................................................ 202
9.3.5
Influence on interior noise ................................................................................................................................ 203
9.3.6
Conclusions ....................................................................................................................................................... 204
10 INFLUENCE ON NOISE EMISSION OF VARIOUS TYRE-RELATED
PARAMETERS ...........................................................................................................................205
10.1
10.2
NUMBER OF TYRES.................................................................................................................................... 207
WIDTH AND OTHER DIMENSIONAL INFLUENCES ............................................................................. 208
10.2.1
10.2.2
10.2.3
General considerations ...................................................................................................................................... 208
Brief review of earlier investigations ................................................................................................................ 209
Results obtained at TUG for a large number of tyres ........................................................................................ 210
IV
10.2.4
10.2.5
10.2.6
10.2.7
10.2.8
Results obtained for specific tyre brands ........................................................................................................... 212
A wider look at the width relation ..................................................................................................................... 213
Truck versus car tyre sizes................................................................................................................................. 214
The use of oversized tyres and wheels .............................................................................................................. 215
Conclusions ....................................................................................................................................................... 215
10.3 INFLUENCE OF INNER TYRE STRUCTURE ........................................................................................... 215
10.4 TYRE RUNOUT, UNBALANCE AND OTHER NON-UNIFORMITIES ................................................... 216
10.5 RUBBER HARDNESS AND OTHER MATERIAL PROPERTIES ............................................................. 217
10.5.1 Introduction ....................................................................................................................................................... 217
10.5.2 Empirical data ................................................................................................................................................... 218
10.5.3 Model calculations ............................................................................................................................................ 220
10.5.4 Conclusions ....................................................................................................................................................... 222
10.6 TREAD PATTERN ........................................................................................................................................ 222
10.6.1 Randomisation .................................................................................................................................................. 222
10.6.2 Ventilation......................................................................................................................................................... 226
10.6.3 General layout of grooves and block shapes in the tread pattern....................................................................... 228
10.7 DIRECTION OF ROTATION AND ASYMMETRIES BETWEEN SIDES ................................................ 229
10.8 CONDITION (WEAR AND AGEING) ......................................................................................................... 233
10.9 RETREADED TYRES ................................................................................................................................... 238
10.10 STUDDED TYRES ........................................................................................................................................ 242
10.10.1 Overall characteristics ....................................................................................................................................... 242
10.10.2 Specific studies.................................................................................................................................................. 243
11 ROAD SURFACE INFLUENCE ON NOISE EMISSION .....................................................245
11.1
11.2
11.3
11.4
11.5
INFLUENCING PARAMETERS .................................................................................................................. 247
SOME BASICS OF ROAD SURFACE CONSTRUCTION .......................................................................... 247
MACRO- AND MEGATEXTURE: INFLUENCE ON OVERALL NOISE LEVELS ................................. 248
MACRO- AND MEGATEXTURE: MORE SOPHISTICATED TEXTURE DESCRIPTORS .................... 249
MACRO- AND MEGATEXTURE: RELATIONS BETWEEN SPECTRAL LEVELS
OF NOISE AND TEXTURE .......................................................................................................................... 249
11.6 ISOTROPIC AND ANISOTROPIC (ORIENTATED) TEXTURES ............................................................. 253
11.7 EFFECT OF JOINTS IN BRIDGES AND CEMENT CONCRETE SURFACES......................................... 253
11.8 BRIDGE DECK SURFACES ......................................................................................................................... 253
11.9 SURFACE COLOUR ..................................................................................................................................... 254
11.10 UNEVENNESS .............................................................................................................................................. 255
11.11 MICROTEXTURE AND FRICTION ............................................................................................................ 255
11.11.1
11.11.2
11.11.3
11.11.4
11.11.5
11.11.6
11.11.7
11.11.8
11.12
11.13
11.14
11.15
11.16
Basic and derived properties ............................................................................................................................. 255
Noise-friction relations measured in field experiments and using conventional wet friction descriptors .......... 256
Field experiments at VTI considering the texture-friction interaction .............................................................. 257
Comparison of tyre/road noise on pairs of surfaces with similar macrotexture but different microtexture ....... 259
Laboratory tests with talcum injection .............................................................................................................. 262
Other observations ............................................................................................................................................ 263
Conclusions regarding microtexture and friction influence............................................................................... 265
Implications for road surface construction ........................................................................................................ 266
POROSITY ..................................................................................................................................................... 266
11.12.1 Terminology - What is a porous surface? .......................................................................................................... 266
11.12.2 Modelling of Acoustical Reduction Properties ................................................................................................. 267
11.12.3 Effects ............................................................................................................................................................... 267
11.12.4 Noise reduction principles................................................................................................................................. 267
11.12.5 The Importance of Air Voids and Thickness Considered Together .................................................................. 269
11.12.6 Modified Bituminous Binders ........................................................................................................................... 270
STIFFNESS .................................................................................................................................................... 271
AGE AND WEAR OF THE SURFACE ........................................................................................................ 272
AMOUNT OF WATER ON THE SURFACE ............................................................................................... 273
OVERALL EFFECT ...................................................................................................................................... 275
V
12 INFLUENCE OF ENVIRONMENTAL PARAMETERS ON TYRE/ROAD
NOISE EMISSION ....................................................................................................................277
12.1
TEMPERATURE ........................................................................................................................................... 279
12.1.1
12.1.2
12.1.3
12.1.4
12.1.5
12.1.6
12.1.7
12.2
12.3
Introduction ....................................................................................................................................................... 279
Some Examples of Measured Effects ................................................................................................................ 279
Relation between air, road and tyre temperatures.............................................................................................. 282
Standardisation considerations - Summary of observations .............................................................................. 282
Possible model for noise - temperature relation based on tyre material properties ........................................... 283
Temperature corrections currently applied in standards or regulations ............................................................. 284
Road surface colour effect ................................................................................................................................. 284
HUMIDITY .................................................................................................................................................... 284
WIND ............................................................................................................................................................. 285
13 INFLUENCE OF VEHICLE CONSTRUCTION ON NOISE EMISSION ..........................287
13.1
13.2
13.3
13.4
13.5
SUMMARY OF VEHICLE EFFECTS .......................................................................................................... 289
VEHICLE GEOMETRY ................................................................................................................................ 291
RIM EFFECT ................................................................................................................................................. 292
EFFECT OF WHEEL HOUSING AND ABSORPTION ............................................................................... 294
PROPAGATION AND SCREENING EFFECTS .......................................................................................... 295
14 STANDARDS AND METHODS FOR VEHICLE AND TYRE/ROAD
NOISE MEASUREMENT .........................................................................................................297
14.1
OVERVIEW AND SUMMARY .................................................................................................................... 299
14.1.1
14.1.2
14.1.3
14.1.4
General .............................................................................................................................................................. 299
Advanced methods for research purposes (NAH, STSF, LDV, etc.)................................................................. 299
Measurements aimed at comparing tyres ........................................................................................................... 299
Measurements aimed at comparing road surfaces ............................................................................................. 300
14.2 THE ACCELERATION PASS-BY METHOD (ISO 362 AND SIMILAR) .................................................. 301
14.3 THE COAST-BY METHOD.......................................................................................................................... 302
14.4 REFERENCE SURFACE (ISO 10844) .......................................................................................................... 304
14.5 THE CONTROLLED PASS-BY METHOD (CPB)....................................................................................... 305
14.6 THE STATISTICAL PASS-BY METHOD (SPB) ........................................................................................ 306
14.7 THE CLOSE-PROXIMITY METHOD (CPX) .............................................................................................. 307
14.7.1 Description of the method ................................................................................................................................. 307
14.7.2 Subjective assessment of advantages and disadvantages ................................................................................... 313
14.8 THE TRAILER COAST-BY METHOD ........................................................................................................ 313
14.8.1 Description of the method ................................................................................................................................. 313
14.8.2 Subjective assessment of advantages and disadvantages ................................................................................... 314
14.9 LABORATORY DRUM METHOD .............................................................................................................. 315
14.9.1 Description of the method ................................................................................................................................. 315
14.9.2 Subjective assessment of advantages and disadvantages ................................................................................... 316
14.9.3 Replica road surfaces for drums ........................................................................................................................ 317
14.9.4 Separation of tyre/road contributions by synchronisation ................................................................................. 320
14.10 GENERAL ASSESSMENT OF THE TEST METHODS .............................................................................. 321
14.11 SOUND ABSORPTION MEASUREMENTS ............................................................................................... 321
14.12 ROAD SURFACE MEASUREMENTS ......................................................................................................... 323
15 MEASURING METHODS – DISCUSSION OF SOME MAJOR TOPICS .........................325
15.1
BASIC OBJECTIVE MEASURES ................................................................................................................ 327
15.1.1
15.1.2
15.1.3
15.1.4
15.1.5
15.1.6
15.2
Time-history-based overall levels...................................................................................................................... 327
Choice of measure - Microphone distance effect (7.5 or 15 m) ........................................................................ 329
Average levels for steady-state sound ............................................................................................................... 329
Speed correction ................................................................................................................................................ 330
Time and frequency weighting .......................................................................................................................... 330
Frequency spectra .............................................................................................................................................. 331
SOME FACTORS AFFECTING TYRE/ROAD NOISE MEASUREMENTS .............................................. 333
VI
15.2.1
15.2.2
15.2.3
15.2.4
15.2.5
15.2.6
15.2.7
15.2.8
15.2.9
15.2.10
15.2.11
15.2.12
15.2.13
15.3
15.4
15.5
Vehicle .............................................................................................................................................................. 333
Load and inflation influence ............................................................................................................................. 333
Wind noise around the vehicle .......................................................................................................................... 333
Transmission (axle) noise .................................................................................................................................. 334
Background noise – in general .......................................................................................................................... 335
Background noise – Pass-by methods ............................................................................................................... 336
Background noise – CPX method ..................................................................................................................... 337
Some basics of sound propagation and reflections ............................................................................................ 340
Sound propagation and reflection problems for the CPX method ..................................................................... 342
Meteorological conditions and climate ............................................................................................................. 342
Choice of microphone position ......................................................................................................................... 343
Microphone distance ......................................................................................................................................... 345
Influence of drum curvature when using the Drum method .............................................................................. 350
REFERENCE SURFACES............................................................................................................................. 353
15.3.1 Introduction ....................................................................................................................................................... 353
15.3.2 Reference for road surface "noisiness" comparison .......................................................................................... 353
15.3.3 Standard surface(s) for vehicle testing .............................................................................................................. 353
15.3.4 Standard surface(s) for tyre testing .................................................................................................................... 353
TEST TYRES OFTEN REFERRED TO IN THIS BOOK ............................................................................ 356
REFERENCE TYRES .................................................................................................................................... 357
15.5.1 General principles ............................................................................................................................................. 357
15.5.2 Reference tyres for various purposes currently available .................................................................................. 357
15.5.3 Reference tyres in the CPX method .................................................................................................................. 358
15.5.4 Storage and preservation of tyres ...................................................................................................................... 360
15.5.5 Reference tyres - Recommendation ................................................................................................................... 360
16 MEASURING INSTRUMENTS AND OTHER EQUIPMENT .............................................361
16.1
16.2
16.3
16.4
16.5
16.6
16.7
16.8
BASIC MEASURING INSTRUMENTS ....................................................................................................... 363
EQUIPMENT USED BY THE AUTHORS ................................................................................................... 363
VEHICLES USED WORLDWIDE FOR CONDUCTING CPX MEASUREMENTS .................................. 364
EXAMPLES OF VEHICLES FOR TRAILER COAST-BY MEASUREMENTS ......................................... 370
EXAMPLES OF LABORATORY DRUM FACILITIES .............................................................................. 371
EXAMPLE OF SOUND ABSORPTION MEASURING EQUIPMENT ...................................................... 374
ISO TEST TRACK SURFACES .................................................................................................................... 374
MANUFACTURING OF REPLICA ROAD SURFACES FOR DRUMS ..................................................... 374
16.8.1
16.8.2
"Drum Paving" .................................................................................................................................................. 374
"Drum Segment Moulding" ............................................................................................................................... 376
17 RELATIONSHIPS BETWEEN THE METHODS .................................................................381
17.1
17.2
17.3
17.4
17.5
GENERAL CONSIDERATIONS .................................................................................................................. 383
RELATIONS BETWEEN THE SPB, CPB AND CPX METHODS ............................................................. 383
RELATIONS BETWEEN THE COAST-BY, CPX AND DRUM METHODS ............................................ 384
CPX VS DRUM METHOD ........................................................................................................................... 387
CONCLUSIONS ............................................................................................................................................ 389
18 LOW NOISE COMPROMISING SAFETY OR OTHER IMPORTANT
PARAMETERS? .........................................................................................................................391
18.1
18.2
THE IMPORTANCE OF STUDYING POTENTIALLY CONFLICTING REQUIREMENTS ................... 393
FRICTION ...................................................................................................................................................... 393
18.2.1
18.2.2
18.2.3
18.2.4
18.2.5
18.3
Introduction ....................................................................................................................................................... 393
Studies before 1997 ........................................................................................................................................... 393
The VTI-TUG experiments ............................................................................................................................... 393
The TÜV/UBA Experiments in Germany ......................................................................................................... 395
Discussion and conclusions............................................................................................................................... 396
ROLLING RESISTANCE .............................................................................................................................. 397
18.3.1 Introduction ....................................................................................................................................................... 397
18.3.2 Experimental work ............................................................................................................................................ 398
18.3.3 The VTI-TUG experiments ............................................................................................................................... 399
VII
18.3.4
18.4
The TÜV/UBA Experiments in Germany ......................................................................................................... 400
TYRE WEAR ................................................................................................................................................. 401
19 TYRE/ROAD NOISE ISSUES RELATED TO METHODS AND MODELS ......................403
19.1
TREAD PATTERN - ANALYSIS AND DESIGN METHODS .................................................................... 405
19.1.1
19.1.2
19.1.3
19.1.4
19.2
19.3
General considerations ...................................................................................................................................... 405
Mathematical representation of a tread pattern ................................................................................................. 405
Tread randomisation by simple algorithms ....................................................................................................... 407
Tread randomisation by complicated algorithms ............................................................................................... 408
TYRE/ROAD NOISE ISSUES IN TRAFFIC NOISE PREDICTION MODELS .......................................... 409
19.2.1 Road surface correction - General ..................................................................................................................... 409
19.2.2 The use of road surface corrections in the Nordic prediction model ................................................................. 409
19.2.3 The current use of road surface corrections in other prediction models ............................................................ 410
19.2.4 Road surface correction - New advanced table ................................................................................................. 412
19.2.5 Wet road, winter tyres or studded tyres ............................................................................................................. 414
MODEL FOR PREDICTION OF ROAD SURFACE INFLUENCE ON NOISE.......................................... 414
19.3.1 General structure of the model .......................................................................................................................... 414
19.3.2 Submodel based on macro- and megatexture influence .................................................................................... 414
19.3.3 Submodel based on age influence ..................................................................................................................... 414
19.3.4 Submodel based on porosity influence .............................................................................................................. 415
19.3.5 Submodel for road surface influence on noise from heavy vehicles based on influence on noise from
cars .................................................................................................................................................................... 415
19.3.6 Combining the submodels ................................................................................................................................. 418
20 NOISE REDUCTION MEASURES RELATED TO TYRES ................................................419
20.1
20.2
20.3
20.4
20.5
20.6
20.7
INTRODUCTION .......................................................................................................................................... 421
TYRE REQUIREMENTS IN GENERAL...................................................................................................... 421
LOW NOISE TYRES ..................................................................................................................................... 422
SELECTION OF TYRES FROM THE EXISTING POPULATION ............................................................. 422
THE MOST QUIET TYRE AVAILABLE .................................................................................................... 423
SELECTION OF TYRES WITH RESPECT TO SECTION WIDTH ........................................................... 424
TREAD PATTERN DESIGN GUIDELINES ................................................................................................ 425
20.7.1
20.7.2
20.7.3
20.8
20.9
20.10
20.11
20.12
20.13
20.14
20.15
20.16
20.17
20.18
Potential influence............................................................................................................................................. 425
General considerations ...................................................................................................................................... 425
Guidelines ......................................................................................................................................................... 425
IMPROVING THE TYRE TORUS CAVITY................................................................................................ 427
FILLING THE TYRE WITH SOME SOLID MATERIAL ........................................................................... 427
TYRE INTERNAL CONSTRUCTION ......................................................................................................... 428
RUBBER COMPOUND................................................................................................................................. 429
TYRE INTERACTION WITH THE RIM AND VEHICLE .......................................................................... 430
AFFECTING THE ACOUSTICAL IMPEDANCE CLOSE TO THE SOURCE .......................................... 430
TYRE SCREENING AND OTHER VEHICLE MEASURES ....................................................................... 430
LOW-NOISE ALTERNATIVE TO STUDDED TYRES ? ........................................................................... 430
THE TRIAS MODEL ..................................................................................................................................... 431
SOME LOW NOISE TYRE EXPERIMENTS ............................................................................................... 431
20.17.1 The German program of the 1980's ................................................................................................................... 431
20.17.2 The TINO project .............................................................................................................................................. 433
20.17.3 Quiet truck tyre at Continental .......................................................................................................................... 433
A VEHICLE MANUFACTURER'S TYRE NOISE REQUIREMENTS ....................................................... 433
21 DESIGN GUIDELINES FOR NOISE REDUCTION RELATED TO
ROAD SURFACES .....................................................................................................................435
21.1
21.2
21.3
21.4
WHAT IS A "LOW NOISE ROAD SURFACE"? ......................................................................................... 437
TEXTURE OPTIMISATION FOR LOW NOISE ......................................................................................... 437
GENERAL GUIDELINES FOR NOISE REDUCTION RELATED TO ROAD SURFACES...................... 438
DESIGN GUIDELINES FOR LOW NOISE ROAD SURFACES ................................................................. 438
VIII
21.4.1
21.4.2
21.4.3
21.4.4
21.4.5
21.4.6
21.4.7
21.4.8
21.4.9
21.4.10
21.4.11
21.4.12
21.5
21.6
21.7
Introduction ....................................................................................................................................................... 438
Guidelines with respect to Microtexture and Adhesion..................................................................................... 438
Guidelines with respect to Macrotexture ........................................................................................................... 438
Guidelines with respect to Megatexture ............................................................................................................ 439
Guidelines with respect to Texture of Porous Surfaces ..................................................................................... 441
Summary of texture design: Desirable texture spectrum ................................................................................... 441
Guidelines with respect to Binder ..................................................................................................................... 442
Guidelines with respect to Colour ..................................................................................................................... 442
Guidelines with respect to Porosity ................................................................................................................... 442
Guidelines with respect to the Use of Rubber ................................................................................................... 443
Guidelines with respect to Special Treatment of Cement Concrete Surfaces .................................................... 444
Maintenance of low noise characteristics .......................................................................................................... 444
POSITIVE VERSUS NEGATIVE SKEW ..................................................................................................... 445
SPECIAL MEASURES TO REDUCE NOISE ON CEMENT CONCRETE SURFACES ........................... 445
21.6.1 General .............................................................................................................................................................. 445
21.6.2 Randomisation and dimensions of grooves or tines .......................................................................................... 445
21.6.3 Appropriate orientation of the texture (longitudinal texturing) ......................................................................... 446
21.6.4 Grinding ............................................................................................................................................................ 446
21.6.5 Exposed aggregate cement concrete .................................................................................................................. 447
21.6.6 Texture optimisation in general ......................................................................................................................... 448
21.6.7 Topping with a surface dressing with small chippings ...................................................................................... 450
21.6.8 Topping with a rubberised mix (GPUX) ........................................................................................................... 450
21.6.9 Porous cement concrete ..................................................................................................................................... 451
21.6.10 Cement concrete block pavements .................................................................................................................... 451
BRIDGE DECK SURFACES ......................................................................................................................... 452
22 LOW NOISE ROAD SURFACES - A STATE-OF-THE-ART REVIEW ........................453
22.1
22.2
22.3
DISTINCTION BETWEEN THIS CHAPTER AND CHAPTER 21 ............................................................ 455
LOW NOISE SURFACES IN HISTORY ...................................................................................................... 455
NON-POROUS LOW NOISE ROAD SURFACES ....................................................................................... 455
22.3.1
22.3.2
22.3.3
Surface treatments ............................................................................................................................................. 455
Thin surfaces ..................................................................................................................................................... 458
Expanded clay ................................................................................................................................................... 459
22.4 POROUS LOW NOISE ROAD SURFACES ................................................................................................. 459
22.4.1 Terminology ...................................................................................................................................................... 459
22.4.2 Some historical notes ........................................................................................................................................ 460
22.4.3 Literature ........................................................................................................................................................... 460
22.4.4 Construction: Grading ....................................................................................................................................... 460
22.4.5 Construction: Binders ....................................................................................................................................... 460
22.4.6 Summary of Noise Reduction Mechanisms....................................................................................................... 462
22.4.7 Porous Cement Concrete ................................................................................................................................... 462
22.4.8 Rejuvenation of porous surfaces ....................................................................................................................... 464
22.4.9 Clogging and Restoration of Clogged Surfaces ................................................................................................. 464
22.4.10 The Double-layer Concept ("Twinlay")............................................................................................................. 467
22.4.11 Various remarks ................................................................................................................................................ 468
22.5 COMBINATION OF POROUS SURFACE AND NOISE BARRIERS ........................................................ 469
22.6 EXAMPLES OF CURRENT USE AND EXPERIENCE OF POROUS SURFACES ................................... 469
22.7 CURRENT USE OF OTHER SURFACES WITH LOW NOISE CHARACTERISTICS ............................. 470
22.8 FUTURISTIC SURFACES ............................................................................................................................ 471
22.9 INCENTIVES FOR USING LOW NOISE ROAD SURFACES ................................................................... 471
22.9.1 Economic compensation in the Netherlands ..................................................................................................... 471
22.9.2 HAPAS in the U.K. ........................................................................................................................................... 471
22.9.3 Other incentives ................................................................................................................................................ 472
22.10 CASE STUDY: UNITED KINGDOM ........................................................................................................... 472
22.10.1 Delugrip ............................................................................................................................................................ 472
22.10.2 Colsoft ............................................................................................................................................................... 473
22.11 CASE STUDY: NEW ZEALAND ................................................................................................................. 473
22.12 CASE STUDY: DENMARK .......................................................................................................................... 474
IX
22.13 CASE STUDY: THE NETHERLANDS ........................................................................................................ 477
22.13.1 General .............................................................................................................................................................. 477
22.13.2 The Noise Pilot project and its road surface ideas ............................................................................................. 477
22.13.3 The Modular Road Surface project ................................................................................................................... 477
23 POTENTIAL NOISE REDUCTION BY CHANGED DRIVING BEHAVIOUR ................479
23.1
23.2
23.3
23.4
GENERAL INFORMATION ......................................................................................................................... 481
SPEED CONTROL ........................................................................................................................................ 481
CONTROL OF ACCELERATIONS AND DECELERATIONS ................................................................... 482
CONTROL OF SIDE FORCES ...................................................................................................................... 483
24 OTHER TYRE/ROAD NOISE REDUCTION METHODS ...................................................485
24.1
SCREENING OF TYRES BY ENCLOSURES OR DISCS ........................................................................... 487
24.1.1
24.1.2
24.1.3
24.1.4
24.2
The Akustikbyrån/VTI projects 1974-77 .......................................................................................................... 487
Screening by means of discs and absorbers ....................................................................................................... 490
Screening by means of partial wheel covers ...................................................................................................... 491
Conclusions ....................................................................................................................................................... 491
ACTIVE NOISE CANCELLATION ............................................................................................................. 492
25 FUTURISTIC TYRE DESIGNS ...............................................................................................493
25.1
THE COMPOSITE WHEEL .......................................................................................................................... 495
25.1.1
25.1.2
25.1.3
25.1.4
25.1.5
25.2
Introduction ....................................................................................................................................................... 495
Swedish trials in 1988-89 .................................................................................................................................. 495
Trials in 1991 .................................................................................................................................................... 497
Trials in 1999-2001 ........................................................................................................................................... 499
Conclusions ....................................................................................................................................................... 500
THE POROUS TREAD.................................................................................................................................. 500
26 FUTURISTIC ROAD SURFACE DESIGNS ...........................................................................501
26.1
THE POROELASTIC ROAD SURFACE ...................................................................................................... 503
26.1.1
26.1.2
26.1.3
26.1.4
26.1.5
26.1.6
26.1.7
26.1.8
26.2
26.3
What is a poroelastic surface? ........................................................................................................................... 503
History and early trials in Sweden ..................................................................................................................... 503
Trial in Norway ................................................................................................................................................. 505
Tests with mixes of rubber and sand ................................................................................................................. 506
Ongoing projects at PWRI, Japan, and VTI, Sweden........................................................................................ 506
Potential use of poroelastic surfaces.................................................................................................................. 509
Conclusions ....................................................................................................................................................... 510
Potential use of scrap tyres ................................................................................................................................ 511
THE "EUPHONIC ROAD" ............................................................................................................................ 511
OTHER IDEAS .............................................................................................................................................. 511
27 ASPECTS OF HUMAN PERCEPTION AND SOUND QUALITY RELATED TO
TYRE/ROAD NOISE .................................................................................................................513
27.1
27.2
27.3
SOUND QUALITY ASPECTS ...................................................................................................................... 515
TONAL NOISE .............................................................................................................................................. 515
RESULTS OF STUDIES OF SUBJECTIVE PERCEPTION OF TYRE/ROAD NOISE .............................. 516
27.3.1
27.3.2
27.3.3
27.3.4
27.3.5
27.3.6
27.4
VTI results......................................................................................................................................................... 516
Results of various studies attempting to relate objective and subjective measures ........................................... 517
Results of a study in Japan ................................................................................................................................ 518
Results of a study by TRL ................................................................................................................................. 518
Study in Copenhagen concerning double-layer porous asphalt ......................................................................... 520
Conclusions ....................................................................................................................................................... 520
SPECIAL REACTIONS OF RESIDENTS .................................................................................................... 521
28 THE EU DIRECTIVE ON TYRE/ROAD NOISE EMISSION .............................................523
28.1
28.2
28.3
28.4
HISTORY OF ATTEMPTS TO INTRODUCE TYRE/ROAD NOISE EMISSION REQUIREMENTS ..... 525
THE NOISE REQUIREMENT IN EU DIRECTIVE 92/23/EEC .................................................................. 525
LIMITATIONS OF THE DIRECTIVE .......................................................................................................... 528
ESTIMATED EFFECT OF THE DIRECTIVE ............................................................................................. 529
X
28.5
28.6
28.7
28.8
TYRE/ROAD NOISE LIMITATION INDIRECTLY IMPOSED BY THE VEHICLE NOISE EMISSION
LIMITS ........................................................................................................................................................... 530
SOME VIEWS EXPRESSED WITH REGARD TO THE DIRECTIVE ....................................................... 530
FUTURE LIMITS FOR FRICTION AND ROLLING RESISTANCE? ........................................................ 531
THE EXCEPTIONAL SPEED REQUIREMENTS ....................................................................................... 532
29 COSTS & BENEFITS OF LOW NOISE TYRES AND ROAD SURFACES .......................535
29.1
29.2
29.3
29.4
INTRODUCTION .......................................................................................................................................... 537
NOISE DAMAGE COSTS ............................................................................................................................. 537
ESTIMATION OF TYRE NOISE COSTS .................................................................................................... 537
ESTIMATION OF COSTS AND BENEFITS APPLIED TO LOW NOISE ROAD SURFACES AND
NOISE BARRIERS ........................................................................................................................................ 538
30 OVERVIEW OF STANDARDS, REQUIREMENTS AND ENVIRONMENTAL
LABELLING SYSTEMS ...........................................................................................................541
30.1
INTERNATIONAL STANDARDS AND REQUIREMENTS ...................................................................... 543
30.1.1
30.1.2
30.1.3
30.2
30.3
Overview ........................................................................................................................................................... 543
Measuring standards.......................................................................................................................................... 543
International regulations.................................................................................................................................... 544
NOISE DECLARATION OF TYRES AND ENVIRONMENTAL LABELLING ........................................ 545
30.2.1 Noise declaration ............................................................................................................................................... 545
30.2.2 Environmental labelling .................................................................................................................................... 545
LIMITS WITH REGARD TO ROAD SURFACE INFLUENCE .................................................................. 547
31 TYRE/ROAD SOUND - USEFULNESS OF THE SOUND EMISSION ..............................549
31.1
31.2
31.3
31.4
31.5
31.6
31.7
31.8
INTRODUCTION .......................................................................................................................................... 551
INDICATION OF TYRE USEAGE ............................................................................................................... 551
INDICATION OF ROAD HOLDING............................................................................................................ 551
SAFETY IN THE ROAD ENVIRONMENT - IS QUIET TOO QUIET? ..................................................... 552
INDICATION OF ROAD CONDITION FOR DRIVERS ............................................................................. 553
ROAD CONDITION MONITORING ........................................................................................................... 554
RUMBLE STRIPS FOR APPROACH WARNING ....................................................................................... 555
SOUND MESSAGE AND MUSIC FROM THE ROAD ............................................................................... 558
31.8.1
31.8.2
Talking pavement .............................................................................................................................................. 558
Music road in Villepinte, France ....................................................................................................................... 559
32 SEARCHING THE LITERATURE .........................................................................................561
32.1
THE "TRN-BIBL" DATABASE .................................................................................................................... 563
32.1.1
32.1.2
32.1.3
32.1.4
32.1.5
32.1.6
32.2
32.3
History............................................................................................................................................................... 563
General outline of the Bibliography .................................................................................................................. 563
Special features ................................................................................................................................................. 563
Change of interest in certain topics with time ................................................................................................... 565
Conclusions ....................................................................................................................................................... 566
Final remarks ..................................................................................................................................................... 566
OTHER DATA BASES .................................................................................................................................. 566
MAJOR INTERNATIONAL CONFERENCES............................................................................................. 567
33 CONCLUDING DISCUSSION .................................................................................................569
34 REFERENCES ............................................................................................................................573
ANNEX 1 ......................................................................................................................................603
INDEX ..........................................................................................................................................611