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| Version 4.0 July 9, 2001 |
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| Basics of Accessible Design | © Edward Steinfeld and Danise Levine, 2001 | |||||
| Contents | 7. Communications in Buildings | |||||
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Visual
Impairments
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The bulk of barrier-free design recommendations and regulations focus on the needs of people with walking and other movement impairments. But, the needs of people with impairments of vision and hearing are also a major concern. The architectural environment is not only a spatial realm but it is also a communications media. Accessibility issues for people with sensory disabilities center on this function of buildings. Communications plays a role in wayfinding, work, entertainment, life safety and other important human activities. Hazard protection devices, sign systems, telecommunications, amplification systems, and emergency alarms are key design elements for communication in buildings. There are also some additional design issues such as orientation and direction finding and the avoidance of noise and information overload. Visual Impairments
The “non-visual traveler” uses two principal techniques for independent navigation: dog guides and long cane technique. New technology is available that promises to provide significant improvements in non-visual travel in the future. These devices include laser canes and sonar style devices that provide a sonic or tactile “picture” of the path up ahead. Currently, however, these devices are expensive, awkward and have reliability problems. They serve best as a supplement to the two principle methods of traveling. There are no specific design requirements for those people who use dog guides. All that is necessary is that building management acknowledge the right of their owners to bring the guides inside and that other occupants do not interfere with the guide’s job. For a cane user, on the other hand, a potentially hazardous object must be within the range of canes. Thus the design of the environment must take cane technique and anthropometrics into account. The most serious problems for the cane user are hazards caused by objects that overhang the path above the point at which the cane is held and thus are not detected with cane technique and walking surfaces that drop off suddenly without warning. In addition to canes and guide dogs, visually impaired people utilize many other sources of information to navigate. These include tactile information sensed by feet as well as air movements, changes in air temperature, smell, and most importantly sound. The sound of doors opening and closing, the arrival of elevators, variations of background noise, conversation and traffic noises (both vehicular and pedestrian) all create non-visual “landmarks.” It should be noted that dog guides do not help their owners orient themselves in space. Although they can be taught to find their way to places that they have been before, their owner has to do the training. Thus, for all people with visual impairments, regardless of mobility technique used, the environment provides a great deal of non-visual information that is critical for orientation. An important factor in finding one’s way around in a building is the ability to read signs and other graphic information. Only a small percentage of totally blind individuals read Braille. This is because most people lose their sight late in life and find it hard to learn or never had the opportunity to learn. They can read tactile letters, however, provided that they are large enough. Braille is more complicated than most people realize. There are three “grades” of Braille, 1,2 and 3. Grade 1 Braille is the most basic and includes all characters. Grade 2 and 3 are progressively more abbreviated. Most Braille users find Grade 1 annoying and awkward. To the partially sighted person, the visual environment is even more important than to the sighted person. Partially sighted individuals require high-quality visual information, including good contrast between information and its background, the avoidance of visual noise, the elimination of glare, higher illumination levels, larger font sizes for the same sight distance, and legible proportions for letters and signs. The size of signs is not very critical when people can move closer to read small characters. However, it is critical where signs cannot be approached or where decisions must be made at a designated distance from the sign. Hearing Loss For the most part, physical access to buildings is not impaired by loss of hearing. However, in the use of telecommunications, audio systems, and emergency warning systems, there are, of course, serious limitations. Lack of access to the information used and transmitted through these systems is, effectively, the same thing as lack of physical access. There are many ways to create access to information that is transmitted through communications systems. In general, these strategies involve boosting sound levels, the use of visible alternatives to sound, the provision of interfaces for assistive devices and personal assistance. Two well known assistive devices are hearing aids that amplify sound and text telephones (TTYs) that allow text messages to be transmitted through the telephone system. Hearing aids convert sound to an electrical signal, amplify it and re-transmit the signal to the ear. The TTY looks like a computer keyboard with a small LED. The TTY is connected to the telephone wiring with a jack or it is acoustically coupled to the headset. It sends telephone signal tones to other TTYs which convert the signal to text that is printed out on the LED. Contemporary TTYs can be small enough to carry in a pocket or purse. Two common types of assistance are the use of interpreters and relay operators. Sign language interpreters listen to someone speaking and translate the speech into Sign. Lip reading interpreters listen to the speaker and, with careful lip formations, repeat what they have heard to their clients. They may also translate the speech of their clients for others if necessary but usually lip readers can communicate effectively on their own. The ADA requires that all states have toll free relay services. Relay operators work for telephone service companies. If individuals who use a TTY want to talk to people who don’t have one, they call the relay number. The relay operator answers on a TTY and obtains the number of the calling party. The operator then calls the other party on a regular phone and relays the TTY side of the call. The operator also relays the verbal side of the conversation on the TTY line. The privacy of relay calls, is of course, limited. The quality of the acoustic environment is critical in places where many individuals with hearing impairments will spend a considerable amount of time. In addition, good lighting, furniture arrangement, proper sight lines, and other aspects of design contributing to visibility become even more important to the hearing impaired person than to the person with normal hearing. Tactile
Warning Signals There are many locations where it is difficult to provide protection through barriers and still maintain the degree of accessibility needed for general use. For example, it is impossible to build walls around all the edges of intersections because no one would be able to cross the street. Or, stairways obviously need to be open at the top even though they are hazardous. In such locations, there are several countermeasures that can maintain usability and provide a reasonable degree of safety for the visually impaired traveler. First, hazardous areas within the path of travel should be minimized. Stairways should not be located directly in a path of travel. They can be perpendicular to it or off to the side. Second, “orientation edges” should be provided where there are no barriers. For example curbs serve to warn cane travelers that they have come to an intersection. They are used to “squaring off” perpendicular to the street to facilitate a straight crossing. Thus, curb ramps for wheelchair access should be off to the side of street crossing areas rather than right in the middle. This will leave a stretch of curb for orientation. Third, where extreme hazards exist, warning devices should be employed to notify pedestrians that there is a hazard. One method of warning visually impaired people of a hazardous area is the use of a “detectable tactile surface treatment” or tactile warning signal. This consists of a texture on the area of a walkway immediately preceding the hazard and bounding the edge of the hazardous area. The signal should cover the entire area of curb ramps. In other places, it should be at least three feet deep. This depth has been found to be easily perceived by even fast-moving people. A heavily textured surface such as a stamped metal plate (with a non slip coating), metal grate or artificial turf must be used for easy identification. Contrast in resiliency with surrounding surfaces improves detection. A significant sound difference helps even more. Grooves in the walking surface are not satisfactory because they can be easily confused with construction joints or cracks. There have been several research studies that examined the ability of visually impaired people to detect and discriminate tactile warning signals. Both issues are important. Any material used as a warning signal must be detectable from the surrounding background material. In addition, it must be a material that can be reliably recognized as a warning signal as opposed to simply another material in the path. Research to date has demonstrated that certain materials are detectable and others are not. “Truncated domes” have been used with reported success in many applications. They are used widely in Europe and in Japan. But, the only research study that examined a complex discrimination task rather than simple detection trials concluded that few generally available materials are easy to discriminate from others in the vicinity. The most recognizable are materials such as artificial turf that are not acceptable as a walking surface in many locations. Thus, the need for tactile warning signals is well established but methods to provide reliable fail-safe signals have not been developed. At present, we can use detectable materials and hope for the best. Tactile warning signals should be used wherever there are drop-offs, both indoors and outdoors, that are not protected by guardrails or walls. An example of such an application would be along the edge of a rapid transit boarding platform. Another very important application for tactile warning signals is at the top of stairs found directly in the path of travel. There is no need for a tactile warning signal at the bottom of such stairways because the stairway itself can be located with the cane. It is extremely important that tactile warning signals are not used for unnecessary reasons because indiscriminate applications will reduce their usefulness. Some design recommendations have promoted their use to mark the location of telephones, water fountains, and other amenities. In Japan, pathways are marked by “tracks” of specially designed tiles. The use of too many signals, however, can make it impossible for the non-visual traveler to identify hazardous areas. Thus, throughout a building, the texture used for warning signals should be consistent and, if serious hazards exist, the number of surface textures used on walking surfaces should be reduced to a minimum to help in discrimination of warning signals. Although some codes require truncated domes or other surface materials, they are now being reconsidered because of questions surrounding their effectiveness. Although they appear to work at transit station platforms where people are aware that they are present, they are not as effective in places where one may not expect to find a hazard. Moreover, their usefulness can be completely negated by deposits of snow and ice and damage by street maintenance equipment. One major advocacy organization for people with visual impairments is vehemently opposed to any warning signals because they believe that non-visual travelers will become dependent on them. They argue that the individual should develop better navigational skills to avoid the need for such devices. The other major advocacy group supports the tactile signal concept. It is safe to say that at the present time a search for other technologies and perhaps a more focused application of tactile warnings would be useful. Audible Beacons and Talking
Signs Talking signs are a new technology that could provide an alternative to tactile warnings, tactile/Braille signage and audible beacons. One type of talking sign has a radio receiver and transmitter. When a transmitter in the vicinity carried by a person sends a signal, the receiver in the sign picks up the signal and another transmitter responds with a message that can be received by the person over a headset or through an audible message. The portable device can be set up to transmit and receive constantly or only when activated by a switch on the unit. Such devices not only can be used to warn individuals who need such assistance of hazards, they can also be used to convey many kinds of direction finding and orientation information. This can be a potential benefit to all people, even those who have no visual impairments. Access codes do not require these devices but they may be considered by some authorities as a preferable alternative to tactile warnings or tactile room identification. Protection from
Overhanging Objects Sign Systems Signs can be used for many purposes in a building: identification, warnings, instructions for direction finding and labeling. Access codes require that tactile signage be present wherever visual signs are used for identification of rooms and spaces, direction and information signs. Tactile room identification in buildings can help visually impaired people find locations, but they are only useful if people know that such signage is present and where it is located. Since access codes have required tactile signage for many years in new buildings and in renovations, it is becoming far more common and expected. Codes have standardized the location of room identification signs at the latch side jamb of doors, 5 ft. above the floor. There has been little research on the detectability or readability of tactile signage but codes do not allow recessed types under the premise that they can easily get filled with dirt and excess cleaning supplies. Recessed signs may make sense, however, in outdoor recreational settings where signs are often made by routing into wood. Recessed signs made like this have large characters and are easy to read tactually. Raised characters should be at least 5/8 in. high but no higher than 2 in. If they are too large, they become awkward to read easily. The height off the surface should be 1/32 inch. Grade 2 Braille should be provided in addition to the raised character. It should be placed below the character so that it doesn’t get in the way. Not only does signage have to be readable in tactile mode but, of course, it must also be easy to read with vision. The proportions of characters should be as follows: 1) a width height ratio between 3:5 and 1:1, and 2) a stroke-width height ratio between 1:5 and 1:10. Characters and symbols that contrast with their background, either light characters on a dark background or dark characters on a light background, are easiest to read. Although some codes specify light on dark, the difference between the two is insignificant in normal building use. Signs should have a non-glare finish. Overhead signs cannot be approached so characters on such signs should be large. The ADAAG requires a minimum height of 3 in. but larger characters may be more appropriate if the sign has to be read from a great distance. There are several pictograms that are used to identify the availability of accessible facilities. The most common is the International Symbol of Access which is used to identify accessible parking spaces, passenger loading areas, entrances (when not all are accessible) and toilet and bathing facilities. Since the ISA implies wheelchair access, there are other symbols to indicate the presence of TTYs and telephones equipped for the hard of hearing. Use of elevators requires finding and processing information about the control panel. People with severe visual impairments have a very difficult time determining which call buttons to press. Tactile floor numbers and Braille should be provided to the left of all call buttons. Tactile characters on the buttons themselves are not effective because most elevator call buttons are so sensitive that the elevator would stop at every floor touched. To make it easier to find specific floor buttons on the elevator panel, the entry floor should be marked with a star. Tactile floor numbers with Braille also should be placed at both door jambs of each hoistway entrance so that visually impaired people can verify that they have arrived at their floor before leaving the elevator. Such numbers must have a standardized location to be useful. A height of 5 feet is recommended because it is close to eye level and is therefore most beneficial to partially sighted and fully sighted people. The numbers should be large but no larger than 2 in. high. Elevator manufacturers are introducing new technologies that may make the need for tactile buttons unnecessary. With the new “destination oriented” systems, passengers enter the destination through a standard touch keypad (same as a touch tone telephone) in the elevator lobby and a computer determines which elevator will stop and pick that passenger up. When the passenger gets on the elevator, he or she does not have to enter a floor number because the car already “knows” which floor the passenger wants. People with visual impairments should have no trouble using a standard touch keypad without tactile labels. Audible signals for elevators are important to people with visual impairments. Such signals are needed, in addition to visible signals, in the elevator lobby to note, in advance, which elevator cars are arriving and their direction or travel. They should sound once for the up direction and twice for the down direction or have verbal enunciators that say “up” or “down.” Within the car itself, there should be a sound at least 20 decibels loud to mark the passing of each floor that is served by an elevator. Or, the elevator can announce which floor it stops at with a recorded message. It is not necessary that elevators serving a zone, e.g. only the upper ten stories of a 20-story building, have the signal operative except within the zone. An alternative to this sound would be a verbal message that announces the actual number of the floor at which an elevator stops. Telecommunications
There are many hearing impaired people whose hearing loss is not severe enough to require hearing aids and others whose hearing aids are not supplied with an inductive pick-up. These individuals can benefit from amplification of sound. Pay telephones can be equipped with variable volume devices that amplify the sound of the transmission. Variable-volume control could be specified for at least one telephone in every bank of telephones. For those individuals who cannot hear well enough to understand conversation, there are a variety of text telephones available (TTYs). Public telephones equipped with TTYs are now available. They have sliding drawers where the TTY is stored when not in use. When the phone is activated, the drawer automatically slides out. Telecommunications technology and service is evolving rapidly. In many locations one can find public telephones with multiple features including a keyboard for TTY calls and computer network access, a fax machine and the standard headset. “Electronic kiosks” are a generic name for communication devices that allow a consumer to make business transactions and access information. The most common form of an electronic kiosk is the ATM. these have proven to be very difficult to use by people with severe visual impairments. Several useful approaches to accessibility have been devised for these machines including Braille labels for the controls, Braille output, standardized input and output sequences, and verbal instructions and information through a headset. Accessibility regulations are currently in a state of flux in this area. ATM machines have turned out to be only the first rung on an evolutionary ladder of electronic kiosks. New systems are being introduced that require much more sophisticated access because they fulfill many functions beyond cash transfers including accessing public information databases like University course schedules, making travel reservations, buying tickets, sending and receiving e-mail. A promising new technology that provides a single interface that anyone can use is the touch screen with audible “textures.” As an individual passes their hand along the surface of the screen, sounds are emitted that mark the boundaries of touch screen “buttons.” These buttons can be used in visual mode or the audible mode can be turned on by a standard hand swipe along the top of the screen. Sound “signatures” and digitized speech can be used to navigate from screen to screen and get feedback for input. Research has demonstrated that people with visual impairments can learn how to use these touch screens very quickly. It should be noted that security and privacy are important secondary design issues related to the use of electronic kiosks by people with visual impairments. They can easily be victimized without their knowledge when using such equipment. Alarm Systems To be effective, alarm systems must be perceivable in all areas of a building where people may be. There are audible alarms, even smoke detectors, that come equipped with visual signals. Although corridor locations alone may be satisfactory for an audible alarm, visual systems have to be located in all spaces where people with hearing impairments might be working or living alone. Codes have spacing and mounting requirements for large rooms to insure full coverage. A high enough flashing rate must be used to attract attention but certain flashing frequencies can cause people with epilepsy to have seizures. Thus, the flashing rate required by ICC/ANSI A117.1 (1992) is .33 - 3 Hz. There are two modes for visible signaling appliances, “awake” and “sleep”. There is no disagreement about the effective illumination in awake mode. Codes and standards have tables that identify the minimum illumination output levels based on spacing of the lamps. But, current research raises significant questions about the usefulness of visual signals in sleep mode. The available research results suggest that there are no devices currently manufactured that are effective. Other methods for awakening people with hearing impairments should be considered. One of the most effective is a vibrating device like a pager that can be placed under a pillow or carried on the body. Such devices would have to be linked to a building’s emergency alarm system using a transmitter. Amplification Systems
Earphone jacks with variable volume controls can benefit only those people who have slight hearing losses but do not help people with hearing aids. Audio-loop devices consist of a transmitter and a receiver with a wire loop. The loop surrounds an area of floor or a number of seats. Within the loop, people who have hearing aids with inductive pick-ups can hear the transmitted signal. The loop can surround a large area or can be small and portable and, thus, moved easily from place to place. They can be permanently installed under carpets or in walls. However, loops do not help people who do not use hearing aids. A third type of device is a radio frequency (FM) system , which can be extremely effective and inexpensive. People without hearing aids can use them. However, people who use hearing aids may require custom-designed equipment for some FM units. A fourth type is the infrared (IR) system. This provides the highest quality sound but requires carefully located reflectors and special head sets. They are more expensive than FM systems. If listening systems serve individual fixed seats, those seats should be within 50 feet of stages or performing areas so that people with hearing impairments will be close enough to see performers’ faces. Visual Environment
Acoustic Environment
Summary
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