Noise control is a major factor in the planning, design, and construction of transportation corridors. Architects, acoustical engineers and transportation planners are searching for creative ways to eliminate or greatly reduce noise levels. The challenge lies in attaining desired sound levels while simultaneously maintaining or enhancing the visual environment.
Environmental architecture, a new and evolving discipline, can provide solutions. Approaching the challenge with a global outlook, we define environmental architecture as "planning for the future through the environment."
When transportation systems must be located in densely populated areas, a challenge we are facing now in the Puget Sound region, conflicts arise over community land use issues. Avoiding conflict is possible when inherent problems, like noise pollution, become the criteria for planning an area, whether it is a subdivision near a freeway or a regional master plan.
As early as 1969, Ian McHarg wrote in his classic "Design With Nature" that the criteria for selecting transportation routes must extend far beyond traditional cost-benefit analysis to include social elements, such as a community's values and history, and the potential costs of increased nuisance "from toxic fumes, noise, glare, and dust."
Environmental architecture agrees with this wide range of elements, while including design in balance with the natural terrain.
No one would deny that transportation systems design is fraught with complex and controversial issues. To resolve them we must look closely, recognizing that within the challenge lies exciting opportunities to apply new (or even ancient) architectural technologies in new ways.
Stepping back from community reactions that focus on the threat of increased traffic and noise (which has clouded local transportation projects like Burlington Northern's proposed regional transfer hub in Auburn or the Third Runway at Sea-Tac), we can examine an environmental design approach to noise control in three scenaria:
Planning for New Communities
"Clean slate" transportation planning, which addresses noise control from the earliest phases of a development, is an ideal scenario for environmental design solutions.
Highways, rail corridors, airports, transit hubs, and industrial areas can be strategically placed to take maximum advantage of natural features that reduce noise. Techniques include:
Locally, examples of these techniques appear in selected planned unit and suburban housing developments, in which planning and design work with the topography to reduce noise for residents. In the future, global opportunities for environmental architecture will exist in developing and newly industrialized countries as communities evolve.
Noise Control in the Built Environment
Today, the most intensive exploration of new technologies for transportation noise control is in sound barrier research. According to "Highway Traffic Noise," published by the Federal Highway Administration, effective noise barriers can reduce noise levels by 10 to 15 decibels, cutting the loudness of traffic noise in half.
This is often true initially. However, a common problem arises when the abatement effect "wears off" over time, leading to renewed community complaints. Seattle acoustical engineers Towne, Richards & Chaudiere note that noise barriers seldom achieve 10 dB of noise reduction, and typically achieve about one-half that much.
They add that barriers are designed for ground floors only; upper floors receive little or no benefit. "It all depends on location," says Martin Palmer, Assistant Environmental Program Manager for the Washington Dept. of Transportation. "The reduction is heard only by the residents closest to the wall." He adds that benefits are variable, at best.
In addition to mainstream research, which is delving into new materials and sound deadening techniques, a discovery in the Mexican ruins at Chichen Itza may yield exciting possibilities.
Martin Palmer notes that California engineer Frank Hodgson of the Kilo Foundation is investigating these ancient Mayan ruins, in which the configuration of some stone stairways appears to convert the frequencies of impinging sound waves upward.
Departments of Transportation in several states, including Washington, are looking closely at Hodgson's research because it seeks to change noise patterns altogether, rather than imperfectly reflecting, deflecting, or absorbing the sound waves. Current techniques in use include:
This solution is very expensive, however, and may not compete well with other needs for scarce transportation funding.
Sound Isolation in the Heavily Built Environment
Airport noise affects millions of people throughout the United States.
Significant reduction in aircraft noise, itself, rests with airplane engine manufacturers. Through aggressive abatement, however, sound isolation is an area in which environmental architecture can play an important role. By analyzing the environmental impact of noise to an existing structure, appropriate remedies can be tailored and designed.
Railroad noise impacts present special challenges associated with high levels of low-frequency noise, pure-tone squeals, vibration, and impulsive sounds that occur during impact when train cars are coupled together. Careful land use planning is especially important to ensure that railroad corridors are compatible with neighboring land uses.
Architectural noise controls, such as selection of exterior wall types, windows, and door treatments, should give special attention to vibration and low frequencies.
Planning for a 20-mile rail corridor has been completed in the greater Los Angeles area. This project provides an excellent opportunity to implement environmental architecture in heavily developed communities. Portland's light rail system also takes advantage of careful land use planning to help reduce noise impacts.
Innovative applications of environmental architecture in transportation corridors holds great promise. As the state of research in noise control evolves, we will see more collaborative ventures between architects, engineers, and planners.
Environmental architecture and visionary community land use planning go hand-in-hand. Still in its infancy, environmental architecture holds the key to some of the most exciting developments we will see in years to come -- not only in the Northwest, but worldwide.
Susan L. Baker is director of client services for Meng, a Seattle architectural firm involved in design and research. Baker is doing research on innovative applications of environmental architecture in transportation corridors.
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