Are you listening?

By Dr. Ahmed El-Aassar, INCE, ASA, senior acoustical consultant, Gannett Fleming, Inc.

There aren’t many places left in the world where only the sounds of nature exist. We’re expanding cities, building upon land that was once vacant, and developing all of the areas in between.

As part of developing livable communities and attracting business to these growing regions, planning for mass transit is a critical component of the equation. But, development can lead to concern by stakeholders and decision makers alike, including a multitude of environmental impacts, such as the impact of noise created by new transit modes and locations.

Transit corridors can include residential areas, employment centers, recreational facilities, educational centers, hospital complexes, tourist destinations, and major retail developments. With the potential of affecting thousands of residents and businesses, the environmental noise impact of future transit is one of the most controversial aspects of the planning process. Public concerns range from public welfare issues, such as potential for future hearing impairment, to how the transit noise would impact someone's home, to the overall general annoyance levels in the community, to the impact of noise on future property values. While the economic impacts from noise pollution are very difficult to model, public concerns about exposure to sound levels as it relates to wellness, stress, and hypertension related to high noise levels can be alleviated.

To deal with these concerns the public participation process is essential. Public outreach can save countless resources and address objections to, and questions about, noise scenarios.

Achieving Consensus

Achieving consensus about transit enhancements is possible with the help of technology developments, such as an application called Sounds of Transit designed by Gannett Fleming. This Interactive Sound Information System (ISIS) is used to present information about noise in the environment. This first-of-its-kind audio visual tool clearly and accurately conveys the impact of actual sound levels to the public and decision makers. Because the program works from a database, this tool is easily customized with libraries of recorded and calibrated sound levels collected from transit and rail sites. Sounds of Transit has a graphic user interface designed for quick learning and ease of use. It is intuitive, using standard point and click conventions. The system uses readily available equipment -- a computer, a quality audio system, and a data projector.

Sounds of Transit addresses public concerns in an accurate, convenient way. As a result, community members could shift their focus to the importance of the overall project and the social benefits that the new transportation will bring to their area.

One feature of the program that is well-suited for community interaction is the ability to modify the distance from the listener to the source with appropriate distance attenuation. This makes it possible to deliver transit comparisons tailored to individual locations. In addition, the listener can experience the transit vehicle passing by inside or outside. The user can even set the volume on a radio or television program to a comfortable listening level to appreciate the relative disturbance potential of the passby events. Sounds of Transit also allows participants to experience various mitigation proposals during public workshops. For example, the placement of sound barriers at various heights and locations, as well as the impact on proposed transit alternatives.

This system is also capable of applying 3-D noise mapping, a technique that uses specific map locations to illustrate sound scenarios within a large city, where the shielding factor of tall buildings must be considered. 3-D noise mapping also provides the ability to animate the movement of mass transit within the city while showing the changing noise level as the vehicle passes by a location. By selecting a location on a map, a user can experience aurally and visually how real audio of a particular transportation mode will sound at any given specific location. 3-D noise mapping can be implemented on a large scale to include all existing and alternative transportation modes within a city.

Hearing is Believing

When a change is planned for a community, it is easy for residents to make inaccurate assumptions based on their own experiences and impressions. Generally, accessibility improvements are welcomed by the public, but concerns about transit noise can quickly stifle initiatives. Early and ongoing public involvement allows organizations to be aware of potential issues, problems, and impacts, and it allows for comprehensive discussions to address the public's concerns. While most public involvement strategies yield positive results, Sounds of Transit has provided a powerful resource for engaging the public and navigating the community's impression of new transit modes that are to come.

Copyright © Gannett Fleming, Inc., 2011. All rights reserved.