Bridges, ferry terminals, and other structures constructed over water commonly have driven pile foundations. Driving piles in water may produce intense underwater sound that can negatively impact aquatic animals. State DOT's, harbor districts and others must be able to reasonably predict the acoustical properties of sound generated by a project to forecast and mitigate the possible impacts to aquatic animals. There is little scientific knowledge on noise characteristics produced in relation to variables in pile driving such as pile material, pile shape, hammer characteristics and so on. Understanding the acoustical properties of pile driving will help government and private entities select the proper materials and methods and noise reduction strategies for pile driving to economically ensure proper structural integrity while minimizing the adverse impacts of underwater noise.

1. To investigate how modifications in pile materials, pile shape, hammer characteristics, the nature of the substratum into which the pile is driven, water depth, the depth to which the pile is driven into the substratum, the load-bearing objective of the pile and other variables influence the properties of noise generated during pile driving. 2. To develop and validate acoustical source models of pile driving based on pile materials, pile shape, hammer characteristics and other variables. 3. To develop and validate sound field models of the effects of sound attenuation systems on the sound field close to piles. This includes defining the limits of the near field for different physical conditions (that is, size and shape of pile, depth of water, wavelengths of interest). 4. Develop guidance for DOT's and other entities to select appropriate materials, methods and noise reduction strategies for pile driving projects. 5. To identify additional ranked research topics necessary to address regulatory or other concerns as necessary to adequately address practical application solutions.

A technical committee of representatives from participating states will identify common research needs, select projects for funding and oversee implementation of results. Specific research activities addressed within the program will include, but not be limited to: · investigating how the characteristics of sound produced during pile-driving are influenced by modifications in pile materials, pile shape, hammer characteristics and other variables, · investigating means to effectively reduce underwater sounds close to the piles during pile driving with attenuation systems, · validating the predictive models during actual construction, · synthesizing information from this project with other efforts notably NCHRP Project 25-28 Predicting and Mitigating Hydroacoustic Impacts on Fish from Pile Installation and other pertinent research, and · developing a guidance document for practitioners.

Pooled fund participation is planned for a minimum of 10 States at initial commitment of $30,000 from each State. The additional $20,000 will be funded by each State at the beginning of the 2nd year of the project.