Acoustical Design Recommendations for New York City Railway Stations: Improving Accessibility for Hearing and Visually Impaired Patrons
Robert Nichols, Nichols Design Associates, Inc., Washington, DC, USA
Objectives of the Acoustical Design Recommendations Research Project
The purpose of the research project is called "Acoustical Design Recommendations for New York City Railway Stations: Improving Accessibility for Hearing and Visually Impaired Patrons." This project is a universal design research and suggestion for the 129th Meeting and Journal of The Acoustical Society of America, which was published in May 1995.
An acoustical design of the New York Railway Stations is proposed to improve the acoustical accessibility for persons with hearing and visual impairments. The acoustical design includes methods and materials for reducing reverberation times in the stations. Reducing reverberation times increases the capability for auditory communication by: (1) lowering interfering reverberant noise levels generated by people and trains, and (2) increasing the clarity of speech from people and audio systems proficing railway information. The universal design research in which we had presentation for the ASA conference included videotape and slides for the Penn Station and Columbus Station, design and methods, and popular version of invited paper.
Research Universal Design & Methods
The two New York City underground railway stations are Columbus Circle and Penn Station with their similar materials, concrete and steel, which are generally highly reverberant spaces. Coupled with noise from trains and people, auditory communication in the stations is difficult for people with normal hearing and extremely difficult for people with hearing impairments. In the reverberant train stations determining directions from which sound is emanating, used in particular by people with vision impairments to locate sound sources and get around, is also difficult.
With sound-absorptive materials, the reverberation in the New York City underground railway stations can be substantially reduced. Reducing the reverberation increases the capability for auditory communication by: (1) lowering interfering reverberant noise levels generated by people and trains, and (2) increasing the clarity of speech from people and audio systems providing railway information. Reducing the reverberation also improves the capability for acoustically locating sound sources.
Ideally, the entire ceiling area and one-half of the wall area (including the area of the side walls below the platform near the tracks) of a typical station should be covered with sound-absorptive materials. However, a sound-absorptive surface area equivalent to roughly 65-100% of the ceiling area will substantially improve the acoustical accessibility. The proper sound absorption can be achieved with various materials 1-5 in. (2.5-12.7 cm) in thickness with cementitious spray-on, plain white or light gray color. The sound- absorptive materials are most effective when distributed on both wall and ceiling areas of the station.
Following these guidelines with considerations for practical sound-absorptive material locations, a cost-effective design for a typical station with three platforms and four tracks consists of some sound-absorptive materials on the ceiling above the platforms and some on or between the columns separating the two adjacent middle tracks.
Sound-absorptive materials in the New York City underground railway stations must not only be acoustically effective, but meet other requirements as well. Depending on the specific location, other requirements may include ruggedness, vandal-resistance, washability, fire resistance, and resistance to damage from water leaks at the Penn Station and Columbus Circle Station. To be economically viable, the materials should also be relatively inexpensive. Certain cementitious spray-ons 1 in. (2.5 cm) thick meet the above requirements and are suitable for the Columbus Circle and Penn Station including the low ceilings [typically less than 8 ft. (2.4 m)] above the platforms where a rugged material is required. For the high ceilings [typically higher than 15 ft. (4.6m)] above the platforms, other sound-absorptive material options are available with better low frequency sound absorption characteristics. These include 1-1/2 - 2 in. thick (3.8-5.1 cm) perforated metalfaced polyethylene-enclosed fiberglass panels, certain faced or closed-cell foams, and fiberglass baffles with suitable facings such as aluminum-vinyl coated fiberglass cloth.
The cementitious spray-ons and special foams are suitable for installation on the columns between tracks which are inaccessible by the general public. Alternatively, the sound absorption could be achieved with baffles between these columns at a height of 8 ft. (2.4m) above the tracks. Appropriate baffles include perforated metal-faced polyethylene-enclosed fiberglass panels and fiberglass baffles covered with aluminum-vinyl coated fiberglass cloth.
Data and Analysis Procedures
Surveys of the underground railway stations at Columbus Circle and Penn Station were conducted on April 24, 1995. The operations of the stations were observed, photographed, and videotape recorded. Noise levels generated by arriving and departing trains were measured. The configurations and finishes of the stations were inspected. Physical dimensions of relevant architectural components of the stations were measured. Operation and effectiveness of the sound reinforcement systems were evaluated.
Based on the survey results, the reverberation time characteristics of the stations were estimated and evaluated. Sound reflection paths were analyzed to facilitate determination of the best locations for sound absorptive treatments. Calculations were performed to determine the amounts of sound absorptive treatments required to achieve a substantial improvement in the accessibility for people with hearing and visual impairments.
Significance and Uses of Results
Columbus Circle and Penn Stations should have both acoustical absorptive panels and ceilings installed over the train tracks (See Figure 1 and Figure 2). Acoustical treatment should also be applied over all platform and mezzanine area which are high enough to be well out of reach by the public. The two different absorptive panel designs for both stations should be installed between adjoining train tracks and the colonnade columns. The square absorptive panels should be placed above the bean between the colonnade columns at Columbus Circle at height of 16 feet above the platform. The size of the square panel should be roughly 4 by 4 square feet (See Figure 3 and Figure 4).
The colonnade which is running below the square panels should be view between the platforms for public. The vertical absorptive panels should be placed between the colonnade columns at height of 9 feet above the platform. The size of the vertical panel should be roughly 3 by 8 square feet with cable connected between the metal grommet on its four corner and columns. The two colors for the absorptive panels at both stations should be orange and yellow which should be painted in rhythm. These colors are an abstract of existing dull painted structures which aid people with vision impaired to see bright in glow (See Figure 3, Figure 4, Figure 5 and Figure 6).
The new absorptive panels at both stations should be placed within two car lengths beyond the entrance and exit of the station. Because the exhausted and air pressure wind from the tunnels cause high turbulent against the colonnade on the entrance and exit. The lengths of track at Columbus Circle and Penn Stations should be assigned to support the absorptive panels in between the colonnade columns.
The new acoustical absorptive panels and ceilings will make a large contribution toward reestablishing New York's subways as a premium system among the great metropolises of the world.
Images
Figure 1 - Columbus Circle Station: Plan, Section & Absorptive Panel Drawings.
Figure 2 - Penn Station: Plan, Section & Absorptive Panel Drawings.
Figure 3 - Columbus Circle Station: Model of visually impaired and wheelchair patrons viewing absorbtive panels.
Figure 4 - Columbus Circle Station: Model of visually impaired and wheelchair patrons viewing absorbtive panels.
Figure 5 - Penn Station: Model of visually impaired and wheelchair patrons viewing absorbtive panels.
Figure 6 - Penn Station: Model of visually impaired patron viewing absorptive panels.
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