《Bridge engineering handbook桥梁工程手册-62隔音墙和栏杆》.pdf

62 Sound Walls and Railings 62.1 Sound Walls Introduction • Selection Of Sound Walls • Design Considerations • Ground-Mounted Sound Walls • Bridge-Mounted Sound Walls • Independent Sound Wall Structures Farzin Lackpour 62.2 Bridge Railings Parsons Brinckerhoff-FG, Inc. Introduction • Vehicular Railings • Bicycle Fuat S. Guzaltan Railings • Pedestrian Railings • Structural Parsons Brinckerhoff-FG, Inc. Specifications and Guidelines for Bicycle and Pedestrian Railings 62.1 Sound Walls 62.1.1 Introduction 62.1.1.1 Need for Sound Walls Population growth experienced during past decades in metropolitan areas has prompted the expansion and improvement of highway systems. As a direct result of these improvements, currently 90 million people in the United States live close to high-volume, high-speed highways. Rush-hour traffic on a typical high-volume, high-speed urban highway generates noise levels in the 80 to 90 dBA range. Within 50 to 100 yd (45 to 90 m) from the highway, due to absorption by the ground cover, the noise level dissipates to about 70 to 80 dBA. This ambient noise level, in comparison with a 50 to 55 dBA noise level in an average quiet house, is very intrusive to the majority of people, and should be further reduced to at least 60 to 70 dBA level by implementing noise abatement measures. 62.1.1.2 De