In our ever expanding quest for an improved environment, we are concerned with the evaluation and control of transportation noise. For several years, Federal, State, and local attention has been directed toward operational noise impacts resulting from the operation and movement of transportation vehicles. Recently, considerable concern, particularly in urban areas, has been focused on the construction noise associated with the development of the transportation facility. This manual deals specifically with the measurement, prediction, and mitigation of highway construction noise.
In order to evaluate and control highway construction noise, the following information must be known:
The first three items are used to evaluate the noise associated with the construction of the highway to see if a noise impact does exist. If a noise impact does exist, the last item provides mitigation strategies that can be used to control construction noise.
Section 1.1 indicated that criteria were needed before construction noise impacts could be quantified in terms of human response. While progress is being made in this area, criteria for evaluating construction noise have not been developed. It appears that several years will elapse before such criteria are established. In the interim, the user of this manual must select his own criteria. In selecting such criteria, the following factors should be considered:
While it is not possible to provide criteria for evaluating construction noise impacts, a noise metric must be selected which can be used to describe noise levels. A noise metric to describe construction noise should meet the following criteria:
The metric chosen for use in this manual is the hourly, A-weighted equivalent sound level (energy basis), Leq(h). This metric satisfies the first four requirements. It may also satisfy the fifth requirement, but there is not enough information presently available to select any metric on this basis.
Chapter 2 discusses noise measurements. Unfortunately, only limited measurements of highway construction noise have been made. The data available in the literature are often quite vague on what noise levels were measured and how they were measured. While measurement procedures are being developed, they have not yet evolved to the point where they have been standardized.
In Chapter 3, a prediction procedure is presented. The prediction procedure describes a method that can be used to calculate the noise levels resulting from a construction operation. It also permits the evaluation of alternative strategies to control the noise level.
Chapter 4 discusses mitigation methods and techniques. Methods of lessening the impacts of noise produced by construction activities are outlined, ranging from equipment modification to community awareness. Included in this chapter are examples of regulations or specifications that may be used in controlling construction noise. The sample specifications have been devised and used by various agencies to abate construction noise. In some cases, the construction noise specifications are not strictly highway related, but may be applicable in many situations.
Appendix A lists noise levels for various types of construction machinery. This section gives the reader a very basic indication as to the wide range of noise levels produced by different individual pieces of equipment. It should be noted that the levels provided in Appendix A are peak values based on limited data. Users of this manual are encouraged to supplement, refine, and update these values.
Appendix B provides the measurement procedures referenced in the manual.