Environmental noise barriers : a guide to their acoustic and visual design

Contents Preface ix Acknowledgements xiii Locations of photographs xv 1 Introduction 1 Background 1 Environmental noise barrier terminology 4 Noise is a landscape issue 5 Barrier use: a contrast in provision 7 References 11 2 Defining the need for barriers 13 Legislation and policy 13 Introduction 13 The Land Compensation Act, 1973 14 The Noise Insulation Regulations, 1975 14 The Highways Act, 1980 15 National Government policy 15 Local government policy 17 Alternative European approaches 17 The Noise Insulation (Railways and Other Guided Transport Systems) Regulations, 1996 19 European Union directives 20 Risk to health 21 Design process 22 Acoustic assessment 23 Landscape decision-making process 24 Landscape assessment 24 Assessment of visual intrusion 25 vi Contents DMRB assessment, consultation and design process 29 Summary of mitigation design strategies 31 References 33 3 Acoustic performance of barriers 35 Introduction 35 Barrier theory 35 Sound insulation 38 Barrier placement 39 Barrier length 40 Bunds versus screens 40 Dealing with reflections from barriers 42 Reflections from high-sided vehicles 43 Improving the acoustic performance of a screen 45 Introduction 45 Cantilevered barriers 45 Tunnels 46 Galleried barriers 46 Louvred covers 46 Diffracting-edge modifications 46 Noise leakage through gaps 51 Varying longitudinal profiles 52 Noise screening by vegetation 52 Acoustic performance testing 53 References 54 4 Barrier morphology and design 57 Anatomy of barriers – elements and characteristics 57 Top section and top edge 58 Middle section 59 Bottom section and bottom edge 60 Barrier façades 61 Ends 62 Vertical profile – angled and cantilevered barriers 65 Support structures, transitions and foundations 72 Fixings 74 Other considerations 76 Viewing at speed 76 Two-faced barriers 76 Barriers: Vertical or horizontal landscape elements? 78 Repetition 79 Pattern 81 Texture 82 Colour 82 Light and shade 87 Profiling 87 Materials and design 89 Choosing materials – visual neutrality and compatibility 92 Reference 93 Contents vii 5 Types of barrier and barrier materials 95 Introduction 95 DMRB guidelines 97 Noise barrier types 99 Earth mounds 99 Earth mounds and planting 104 Timber barriers 106 Sheet-metal barriers 109 Concrete barriers 115 Brick barriers 117 Plastic, PVC and fibreglass barriers 119 Transparent barriers 119 Cantilevered barriers 127 Thatch barriers 131 Bio-barriers 131 Integrated barriers 138 Barrier materials on bridges 139 Barriers and solar panels 141 Tunnels 142 Escape routes 148 Planting and barriers 148 References 150 6 Engineering, safety, environmental and cost considerations 151 Introduction 151 Engineering considerations 151 Environmental considerations 153 Costs 155 References 156 Appendix I – Index of manufacturers, installers and suppliers 157 Author index 161 Subject index 163