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