Achieving consensus: addressing noise issues when planning for mass transit

Transit innovations and expansions are a central part of constructing more livable communities, but the potential for increased noise is often a major concern. How can technology be used to win the support of community stakeholders and decision makers? By Dr. Ahmed El-Aassar, INCE, ASA, senior acoustical consultant, Gannett Fleming, Inc.

When a change is planned for a community, it is easy for stakeholders to make inaccurate assumptions. Early and ongoing public involvement allows organisations to be aware of potential issues, problems and impacts, and it allows for comprehensive discussions to address the public's concerns. Generally, the public welcomes infrastructure improvements, but the potential for increased noise is often met with opposition. During a transit alternatives analysis of the 85-mile, 28-city, South Florida East Coast Corridor in the United States, multiple transit and transportation technologies were evaluated. The planning process required extensive public outreach to address community and decision maker concerns, ranging from environmental impacts, station locations, and transit alternatives. For one controversial component - the sound impact - the client required an innovative solution to convey transit sound samples.

In response to this need, Gannett Fleming designed a powerful, technology tool called 'Sounds of Transit' to present information about noise in the environment. Using this tool, Gannett Fleming developed a library of recorded and calibrated sound levels collected from transit and rail sites with similar corridor characteristics. This first-of-its-kind audio-visual tool was used to clearly and accurately convey the impact of actual sound levels to the public and decision makers.

One feature of the programme that was particularly suited for community interaction was the ability to modify the distance from the listener to the source with appropriate distance attenuation. This made 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 passing events.

For the first time, communities in the path of infrastructure improvements can accurately experience the auditory effect of a proposed project by using 'Sounds of Transit'. A key feature of this original solution is that it conveys sound information in a format that requires no special technical knowledge of noise management strategies. There is global potential for this precedent-setting technology as it is a powerful, scalable tool that can be customised for any type of infrastructure improvement where noise concerns exist, such as high-speed rail, highways, airports and military operations. In the Middle East, where development of new transportation systems is underway, the 'Sounds of Transit' application could help agencies and communities to make informed choices related to sound.

Another future application for 'Sounds of Transit' is to apply 3-D noise mapping, a technique that uses specific map locations to illustrate sound scenarios. By selecting a location on a map, a user could experience aurally and visually how real audio of a particular transportation mode will sound at any given specific location. 3-D noise mapping could be implemented on a large scale to include all existing and alternative transportation modes within a city.

This tool can be utilised without difficulty at locations throughout the world and has been designed to be independent of both the language in which presentations are made and the noise metric systems being illustrated. 'Sounds of Transit' makes complex abstract sound scenarios very simple for users in a single realistic demonstration. It is intuitive, using standard point and click conventions. For public workshops, no special equipment is required other than a computer, a quality audio system and a data projector. Because the program works from a database, additional information can be added and custom programmes can quickly be developed to address many different situations by simply adding more sound and audio samples to the database.

About

Dr. Ahmed El-Aassar serves as a project manager for noise and air quality projects with Gannett Fleming, Inc. He develops and implements all phases of acoustical analyses, including noise monitoring, impact and mitigation analyses, and noise barrier design. El-Aassar also designed the innovative audio-visual tool 'Sounds of Transit' for use during public involvement meetings.