This synthesis will be of interest to highway environmental engineers, noise analysts, design engineers, maintenance personnel, planners, administrators, and others responsible for the design, selection, and maintenance of noise barriers or other traffic noise abatement policies. Information is provided on current state practice associated with noise abatement techniques and on the various products that are used. This synthesis describes the state of the art with respect to traffic noise abatement procedures, especially noise barriers. This report of the Transportation Research Board provides information on the design, construction and maintenance of both new (Type I) and retrofit ( Type II) noise barriers. The design elements that are addressed include materials, the selection process, service life, foundations, drainage, aesthetics, and safety. The construction section covers technical problems related to surface effects, durability, snow damage, and costs. Other noise abatement measures such as insulation and highway design alternatives are also addressed. The issue of public demand and availability funding is included, and recommendations are made to improve the situation.