This report was developed with the assistance derived from the Federal Transit Act, as amended, through a Cooperative Agreement with the U.S. Department of Transportation, Federal Transit Administration and Project ACTION of the National Easter Seal Society.

Doc No: 95-0051

This project was supported by the Federal Transit Administration, Project ACTION of the National Easter Seal Society and by The Smith-Kettlewell Eye Research Institute's Rehabilitation Engineering Research Center. We are indebted to our collaborating institutions for their full support; the San Francisco Municipal Railway (Muni), the Bay Area Rapid Transit (BART), and the Living Skills Center of San Pablo, CA. The project received direct support from the Director of Muni's Accessible Services, Ms. Annette Williams; BART's Supervisor for Access Planning, Mr. Harley Goldstrom; the BART Access Planning Department officer, Mr. Ron Brooks; and the BART Technical Projects Services Department Manager, Mr. George Rohrback.

Significant technical assistance was provided by Smith-Kettlewell engineers, Mr. William Gerrey and Mr. Albert Alden. Smith-Kettlewell illustrator, Mr. Jim Brodale produced the figures for this document. The staff of Talking Signs, Inc. and Microcomputer Systems (of Baton Rouge, LA.) provided hardware to the project at a reduced cost.

Mr. David Steed of the Steed Group and C. Ward Bond of Talking Signs, Inc. provided information about the managerial and contractual components of a successful commercial Talking Signs implementation.

The project's Steering Committee, composed of a number of blind persons who regularly use public transit, administrators of agencies providing services to blind persons and accessibility officials from Muni and BART, assisted in guiding the project at key points in its evolution and decided important policy issues.

We appreciate the valuable information provided by and the cooperation received from the 36 persons who participated as research subjects in the study.

This guide is one of three documents that resulted from the project entitled "Transit Accessibility Improvement through Talking Signs^R Infrared Remote Signage: A Demonstration and Evaluation" (W. Crandall, Smith-Kettlewell RERC) funded by Project ACTION. The main activity of the project was installing Talking Signs in a tri-level transit station in San Francisco and testing their effectiveness in providing wayfinding information to people who are visually impaired. The project's two companion documents are: Bentzen, B., Myers, L., and Crandall, W. " Talking Signs^R System: Guide for Trainers." Project ACTION, 1995, and Crandall, W., Bentzen, B., Myers, L., and Mitchell, P. "Transit Accessibility Improvement through Talking Signs^R Infrared Remote Signage: A Demonstration and Evaluation." Project ACTION, 1995.

The guide is designed to provide the scope of information needed by transit property managers to evaluate, specify, purchase and install Talking Signs^R remote infrared signs in transit facilities for use by passengers who are visually impaired or print handicapped.

The activities of this project were guided, in part, by a Steering Committee comprised of administrators of agencies providing services to blind persons, blind persons who regularly use public transit, and the accessibility officials from the San Francisco Municipal Railway (Muni), and the Bay Area Rapid Transit (BART). At the conclusion of the project, the Steering Committee unanimously approved the following final recommendation to be presented to Project ACTION.

"Having noted that the Talking Signs system enables users who are print handicapped to travel independently throughout a complex transit station, that even users who receive minimal training benefit from this system, and that transit operators experienced no operational hardships as a result of this system, we recommend that remote infrared audible signage (specifically Talking Signs^R) is the preferred technology enabling print handicapped persons to travel independently in transit facilities."

Talking Signs^R Remote Infrared Signage:

The Need for Signage

Rationale:

Everyone's effective mobility depends upon proper orientation; for mainstream society this is accomplished by printed signs. People who are print disabled, are blind, or have other visual impairments are at a disadvantage for the lack of labels and signs. For sighted travelers, signs mainly provide identification. However, in the broadest sense, signs comprise a menu of choices for travelers; they confront them with the options available at any given point in their travels. In a sense, signs act as a form of memory for travelers; signs "remind" travelers about important characteristics of the environment.

Currently, persons with severe visual impairments most often require extensive assistance from strangers in order to travel in unfamiliar areas. In the best case, the information they receive is accurate, concise, and in the appropriate language. Such an ideal source of information is not always available. In urban areas, one may have safety concerns about approaching a stranger for assistance. Finally, blind people just do not like to be dependent upon others for information -- especially if there are suitable alternatives.

The National Center for Health Statistics estimated that 4.3 million people in the US have difficulty reading the newspaper with their corrected vision -- a functional definition of perceived limitations termed Severe Visual Impairment as defined by Nelson and Dimitrova in the American Foundation for the Blind's Journal of Visual Impairment and Blindness of March, 1993. Importantly, an additional 2.3 million people have a disability that involves the loss of intermediate or distant vision only. From these statistics, we may conclude that a total of 6.6 million people are unable to read printed signs at normal viewing distance. Data from the Bureau of the Census put the figure for this same level of impairment at 9.7 million people (McNeil, 1993). There is another important way of looking at the demographics of blindness. Estimates of tested acuity classify 1.1 million people as Legally Blind which is defined as corrected acuity of 20/200 or less and a visual field of < 20 ⁰ (Chiang, et al, The Milbank Quarterly, Vol. 70, No. 2, 1992).

Many other disabilities prevent persons from reading print. In addition to people who are blind or have low vision and may not be able to see the print, there are many stroke, head-injured, autistic and dyslexic (or even just educationally impaired) persons who may not be able to assimilate printed language even though they can see the page. Many people can accept this information through speech -- having print read aloud to them.

Problems Encountered by Blind Travelers in the Transit System

Transit facilities present a unique challenge to a person who has a visual dysfunction; such transit patrons must visit specific points along a potentially crowded and complex path of travel having no signs which are perceptible to them, in order to successfully navigate from street entrances to the proper train. Braille and raised letter signs are alternatives for printed information and are a required accommodation to transit facilities under the Americans with Disabilities Act (ADA Accessibility Guidelines for Buildings and Facilities, 1991). There is substantial interest in providing signage that is more appropriate for large, open areas where these tactile signs may be difficult for providers to install and/or difficult for users to locate. Transit facilities are such a setting. A large concourse may contain multiple turnstiles entrances, stairways, escalators and elevators -- all or some of which may be stand-alone within the space where such signs cannot be installed. In addition, there may be multiple corridors leading to other modes of transit, telephone booths, entrances to shops, and designated boarding areas on platforms. If you are blind and looking for an elevator, you do not find a tactile sign identifying the elevator until you are already at the elevator.

Other transit system challenges for persons who are unable to read print signs are identifying approaching buses, trains or trams, locating bus stops, and identifying and safely crossing streets en route to transit facilities. These challenges are being addressed in ongoing demonstration and evaluation projects in which Talking Signs^R transmitters are being used to label transit vehicles, bus stops, and crosswalks.

Perhaps the most difficult part of traveling for the visually impaired person is being able to identify an approaching bus, tram or train. Often several buses pull into a bus stop simultaneously and depart after a brief stay. This does not allow a visually impaired person enough time to find his or her bus using the current method of serially asking bus drivers to identify the bus route number. Because trains and subways going to different destinations often use the same platforms and tracks, they are even more difficult to identify. In addition, the driver might be several cars away from where the passenger is standing or there may be no driver at all. Talking Signs are being installed as a means for print handicapped passengers to identify transit vehicles.

Visually impaired persons travel a great deal by walking. Knowing which street they are crossing is very important for their orientation. Knowing when the pedestrian signal indicates the walk period is important for safety. Talking Signs transmitters at intersections in downtown San Francisco identify streets, blocks, and the pedestrian's direction of travel. When a Talking Sign user is within the crosswalk, the current status of the traffic cycle is announced.

Bus stops are notoriously inconsistent in some locales. A stop may be at the beginning, middle or end of a block, and it may or may not have any physical marker such as a shelter or distinctively shaped post which is readily locatable by non-visual means, and which positively identifies a bus stop. Talking Signs transmitters are being evaluated on bus stops in San Francisco.

Thus, the Talking Signs system can be a comprehensive transit wayfinding system providing the information necessary for independent decision making at intersections, transit facilities and transit vehicles.

Remote Infrared Signage

Remote Infrared Signage:

Remote infrared signs allow people who are print disabled to directly know not only what, but where. Just as non-disabled people visually scan the environment to acquire both label and direction information, remote infrared signs directly orient disabled people to the labeled goal and constantly update them as to their progress to that goal. That is, unlike Braille, raised letters, or voice signs which passively label some location or give instructions to some goal, the remote signage technology developed at The Smith-Kettlewell Eye Research Institute (Talking Signs^R) provides a repeating, directionally selective voice message which originates at the sign and is transmitted by infrared light to a hand-held receiver some distance away. The directional selectivity is a characteristic of the infrared message beam; the intensity and clarity of the message increases as the sign is "pointed at" or approached. This ensures that the people using the Talking Signs^R system can choose to get feedback about their relative location to the goal as they move towards it. Talking Signs^R are light and small, easy to install, consume very low power, and are easy to program with human voice or synthesized voice messages. Talking Signs^R conform to the ADA guidelines which stipulate that an accommodation must also be "refusable." Talking Signs^R has been subjected to rigorous human factors testing in several settings as reviewed below (see "Background").

The information for this guide was based primarily upon a demonstration and evaluation project for accessible signage at Powell Station in downtown San Francisco. This demonstration was sponsored by the Department of Transportation through Project ACTION. Other important experiences came through working with property owners, architects and contractors at installations for the New Main Library, Yerba Buena Gardens and the Dept. of Public Works in San Francisco and from the Lighthouse for the Blind in New York City and the Washington, DC Metro.

Station Configuration:

The demonstration and evaluation project was carried out at the Powell Street transit station. The top level of this underground, tri-level, multi-modal San Francisco station is a concourse serving the San Francisco Municipal Railway Metro (Muni, light rail) and Bay Area Rapid Transit (BART, rapid rail) as well as retail establishments. Trains for Muni and BART are boarded from the two lower levels of center-loading platforms. Along the main concourse are faregates, stairs, escalators and elevators up to the street level and down to the platforms, shops, restrooms, change machines, telephones, and corridors to other parts of the station.

Talking Signs:

The Talking Signs^R installation at Powell Station is a distributed system where each transmitter contains its own recording circuit and light emitting diode (LED) array. These stand-alone transmitters are connected to remote, modular power supplies located throughout the station at places convenient to the 110 volt mains.

Figure 2. Transmitter and receiver of the type used in the demonstration.

1. Each transmitter/LED array sends a light message to the receiver. The transmitter is adjusted to have a range of from 10 feet (3.1 m) to 60 feet (18 m), depending upon the function of that sign. The prerecorded human speech frequency modulates (FM) a 25 kilohertz carrier.
1. Twenty-eight small, "wall mounted", 12 volt modular power supplies are distributed throughout the station at locations convenient to 110 volt mains. The low voltage wire runs connecting the power supplies to the transmitters are typically 20 (6 m) to 80 feet (24 m) in length. Multiple transmitters are often serviced from one power supply.
1. The receiver consists of a small hand-held box [(4"x2"x1") or (10.1 mm x 5.1 mm x 2.5 mm)] containing a battery, photodetector, FM discriminator, amplifier, and internal speaker. Participants hear the digitally recorded message whenever the sensor aperture of the receiver is pointed in the direction of the infrared transmitter while the receiver is activated.

Powell Station sign placement:

In the demonstration, ninety-three (93) transmitter "signs" are located throughout the three levels of the station.

Signs were placed at an elevation of approximately ten feet, either on a wall or suspended from the ceiling. Transmitters were strategically placed and messages optimized to enhance travel efficiency regardless of the direction from which users might be moving through the station. In general, it has been found appropriate to place Talking Signs in the vicinity of printed signs. However, Talking Signs should also label amenities such as telephones and drinking fountains which are quickly identified by sight but are often not labeled with printed signs. Figure 4 shows a user locating the exit from the concourse level up to Market Street using Talking Sign # 12.

Figure 4. A transit patron approaching the Talking Sign transmitter located above the printed sign indicating the exit up to Market Street.

Typical travel situation for demonstration system users:

Figure 3 also shows the route transit patrons at Powell Station take when changing from the Muni inbound train (near Talking Sign #13, Muni level) to the BART Richmond-bound train. In order to complete this route, visually-impaired travelers need first to locate the stairs. They can scan to find a sign which says "Stairs and escalator up to concourse level." At the top of the stairs or escalator they need to find a way to exit the Muni system. One of several signs in this vicinity says "Muni faregates." They then need to locate a faregate through which they can enter the BART system. One sign in the vicinity, but some distance away, says "BART faregate." After negotiating this faregate, they need to find out how to get to the BART platform. By scanning, they are able to find a sign saying "Stairs and escalator down to all BART trains." At the bottom of the stairs or escalator, they can scan to find a sign saying "Main boarding area for Concord, Fremont and Richmond further down this platform." Continuing down this side of the platform, they eventually come to the destination, a sign saying "Main boarding area for Concord, Fremont and Richmond" (Talking Sign #14, BART level).

Results of recent evaluations:

An evaluation of Talking Signs in a campus environment (indoor and outdoor) has recently been completed at San Francisco State University (Crandall, 1994). An analysis of testing the ability of sixteen blind subjects to navigate six routes (six on each of two visits or a total of twelve trials) indicates that, in addition to other positive outcomes, significantly more routes were successfully completed with the use of Talking Signs (with minimal verbal travel instructions) than without Talking Signs (but with longer verbal travel instructions). We believe that the results favorably demonstrated the efficacy of Talking Signs in wayfinding when compared to verbal travel instructions alone. As subjects proceeded through the trials, they learned, by their own use, many important characteristics of the system which we did not specifically teach them in the short training preceding test trials.

The Powell Station evaluation:

Ease of use, learning to scan, ease of picking up messages, and following signs to destinations are thought to be related to the level of training. Therefore, training requirements for effective and safe use of Talking Signs were evaluated at Powell Station. The present transit study (Crandall, Bentzen, & Myers, 1995) focused on the question: "What is the minimum amount of training required for a person to effectively and safely use the Talking Signs system?" Subsidiary to this main question are ones concerning the proper mix of instruction and hands-on experience. To answer these questions, we evaluated the travel characteristics of 36 visually impaired people who used the Talking Signs system as an aid to navigation through this complex subway station in downtown San Francisco. The broad cross section of subjects were divided into three groups, each group matched for familiarity with Powell Station, use of BART, use of Muni,, degree of residual vision, method of travel (guide dog or cane), presence of hearing impairment, and varying levels of mobility skills. Each group received a different amount of training on the proper use of the system.

The most highly trained group received one to two hours of training, until they reached a predetermined criterion of successful independent travel on six practice routes in one end of the station. The next group training level was 15 to 30 minutes, or until two practice routes were completed with verbal assistance only. Prior to coming to Powell Station for testing, participants in the minimally trained group received verbal instructions regarding the use of Talking Signs in their preferred reading medium, a receiver, and a pseudo-transmitter which provided a beeping signal for practice.

All groups were tested for one hour on their ability to travel routes of increasing complexity in the station. No verbal instructions were given to participants, and they were not permitted to request assistance or information. Easy routes required the use of two transmitters which could always be located, when needed, by scanning with the receiver. Medium routes required the use of three transmitters, and traveling a short distance when there was no relevant transmitter to provide direct guidance. Hard routes required the use of five to seven transmitters, were considerably longer than medium routes, and required longer travel distances between transmitters (see, above section Typical travel situation for demonstration system users for description of a "hard" route).

Within the time limit of the one hour test session, 35 of 36 participants succeeded in traveling at least two easy routes, and 24 of the 36 participants succeeded in traveling some medium and hard routes. Differences in amount of training did not significantly affect route completion. Participants in the group which had no personal instruction, however, did not demonstrate as high a level of proficiency in using the Talking Signs system as participants in the other two groups. A manual for trainers is available under this project (Bentzen, Myers & Crandall, 1995). Candidate training (if requested by the user) could be on-site or off-site, provided by a transit property or an organization providing services to persons who are print handicapped.

Focus Group

Following testing and four months of unsupervised use of the Talking Signs system in Powell Station, eight former subjects participated in focus groups to help researchers evaluate the total program. Focus group participants were very enthusiastic about the benefits of increased independence, confidence, and decreased stress they experienced in this transit facility. They remarked about their pleasure in being able to glance around with their receivers and discover alternative routes and features of the transit station such as telephones, an automated teller machine, and a number of shops which were located along the concourse. They particularly liked being able to independently discover which side of a platform to wait on, and where the main boarding area on each side of each platform was located. One participant remarked that in Powell Station he was "truly equal" to sighted travelers. Each member expressed a strong opinion that individual training should be available to all persons who wish to use the Talking Signs system, but that no particular level of training should be required.

Steering Committee

The activities of this project were monitored by a Steering Committee comprised of administrators of agencies providing services to blind persons, blind persons who regularly use public transit, and accessibility officials from the San Francisco Municipal Railway (Muni) and the Bay Area Rapid Transit (BART). They assisted in guiding the project at key points in its evolution and decided important policy issues.

Elements of a typical installation

A typical Talking Signs installation has three major elements:

1. Hardware
1. Sign placement
1. Messaging

1. Hardware

Hardware for a centralized Talking Signs system of the type currently being installed elsewhere has four components. Figure 5 shows the transmitter chassis, transmitter cards, LED array bezels and receiver.

Figure 5. Hardware components of centralized Talking Signs system are the transmitter cards, a transmitter chassis, LED array and receiver.

a. A transmitter card containing the message unit and transmitter driver electronics. Each transmitter is adjusted to have a range of from 5 feet (1.5 m) to 100 feet (30.5 m), depending upon the function of that transmitter. The prerecorded human speech frequency modulates (FM) a 25 kilohertz carrier.

b. An electronics chassis for housing ten transmitter cards and a power supply. The chassis is typically housed in an equipment room near the signs it will serve (within 1000 ft. or 305 m).

c. A light emitting diode array (LED array) which sends light messages to the receiver. The LED array is housed in a standard electrical box (J-box) which has a cover (bezel) compatible with architectural requirements. The LED array is connected to the transmitter chassis by low voltage signal wires.

d. The hand held receiver which consists of a small [(4"x2"x1") or (10.1 mm x 5.1 mm x 2.5 mm)] box containing a battery, photodetector, FM discriminator, amplifier, and internal speaker. Users hear the digitally recorded message whenever the front of the receiver is pointed in the direction of the infrared transmitter and the receiver is turned on.

2. Sign Placement

Determining the location and messaging of conventional print signs in a transit setting is a technical profession. Selecting the appropriate sites and messaging for Talking Signs is an even more specialized role. Visually impaired travelers require much more precise information to efficiently navigate a route because they lack the visual context provided sighted users. Talking Signs, Inc. can recommend an experienced technical group composed of Orientation and Mobility Specialists and an engineer to coordinate the exact placement of the signs. Each member of the team understands the Talking Signs technology and how blind people travel. This team will have the necessary knowledge to make subtle modifications in transmitter power, direction, and angular dispersion to reduce problems of reflections, conflicting interference from other signs, and confusing messages. Accuracy and uniformity are essential.

The purpose of Talking Signs is to provide orientation by labeling the environment and providing an effective and accurate path of travel. Following is a list of recommended areas which should be included:

1. Portals: Entrances/exits (faregates and streets).
1. Vertical transportation: Escalators, stairs, ramps, and elevators.
1. Access points: Platform area (exits, boarding areas), bus stops.
1. User facilities: restrooms, public telephones, water fountains, agent booths or information kiosks, and change and ticket machines.
1. Path of travel: From each entrance to the boarding areas and from the transit vehicle to each exit.
1. Commercial facilities: Businesses, shops, vending stands, and ATM machines.

3. Messages

It is important that the message be accurate from every point from which the sign can be picked up. Talking Signs messages do not strictly correspond to print sign messages. The team which decides on the exact sign placement will also write the message schedule.

Reading signs is a relatively new skill for most blind individuals. It may be helpful to have available a list (in accessible format) of the locations which are signed at each site.

Talking Signs provide two types of messages:

1. LABEL MESSAGES indicate specific locations and are the names of things. Examples are "Public telephone", "Faregate" and "Stairs down to all trains."
1. DIRECTIONAL MESSAGES are like arrows and contain more abstract information as to the location of a destination. Examples are, "To exits for Stockton and Ellis ', and "Main boarding area for Daly City further down this platform."

Because Talking Signs are a public utility, they should not be used for advertising other than the naming of business. To do so would decrease the efficiency of the system by adding messages which are irrelevant to the wayfinding task.

Elements of a typical transit property/user group

1. Transit property development team (transit property/administrator, accessible services, architect, electrical engineer, etc.).
1. Funding / capital resources development team.
1. Community blind services organization involvement to help in system assessment, training (if requested by a user of the system) and distribution of receivers (if appropriate).

Steps in implementing a Talking Signs project

1. Assemble the transit property/user group
1. Develop support for the project.
1. Development of a scope of work/budget forecast
1. Wayfinding needs assessment
1. System design
1. Hardware procurement
1. System installation
1. System validation
1. Distribution of receivers
1. Training

2. Assemble the transit property/user group.

Bring transit property and disabled transit users together to assess the need for enhanced accessibility to signage.

2. Develop support for the project

Secure support of Disabilities Committees of the Transit System and local government and local universities or colleges. Secure support of the blind consumer groups and blind services agencies in the community including, if applicable, the Lighthouse for the Blind, rehabilitation agencies, Living Skills Centers and Lions Clubs.

3. Development of a scope of work/cost proposal

The contracting project manager works with transit property/user group to outline a scope of work/cost proposal. This becomes the basis for all contract documents.

4. Wayfinding needs assessment

The Talking Signs project manager works with the transit property/user group and the technical group to develop a wayfinding needs assessment for the facility as a planning guide for the specification of design development. This consists of a message schedule index of all signs keyed to a location plan. The technical group is composed of Orientation and Mobility [O&M] Specialists and an engineering personnel who analyzes the facility in terms of sign placement, power, dispersion and messaging.

5. System specification

Using parameters approved in the wayfinding needs assessment, all system specifications are developed and finalized by the project manager for every sign location. Blueprints specify the location, power and dispersion for each sign.

6. Hardware procurement

A final cost quotation is issued based on the final approved project documentation and a purchase order is issued for hardware and installation.

7. System installation

The system is installed from the specifications in the final approved project documentation. Installation occurs in two phases:

The Talking Signs message is transmitted on a cone-shaped beam of infrared light to the receiver. As with ordinary light, infrared light from transmitters will illuminate not only the receiver, but other objects in its path. Messages may therefore be reflected off of nearby surfaces, such as columns or walls. Careful tuning of the various transmitter and LED array parameters minimizes reflections.

• The power setting of the transmitter determines the maximum distance at which the Talking Sign message will be received.
• The direction in which the LED array is pointing determines the part of the environment the infrared light message illuminates.
• The dispersion of the cone-shaped infrared beam determines the message's area of coverage.

8. System validation

All aspects of the installed system's function and use are tested and reviewed. This can include transit property-user team, project manager, technical group, and members of the transit agency's disability community.

9. Distribution of receivers

For the system to have a meaningful impact upon the community, a mechanism for getting receivers into the hands of passengers who want them should be established. The extent to which this may or may not directly involve the transit property is a function unique to each setting. Except in cases of privately purchased receivers, the community may have to establish a policy concerning distribution of receivers purchased through public or private grants.

10. Training:

Talking Signs are a signage system meant to augment printed signs so that equivalent signage information is available to visually-impaired travelers. It is not meant to enhance the safety of the user. It is not a mobility aid, nor is it meant to replace the need for any of the mobility skills of the traveler.

The project's Focus Group expressed a strong opinion that individual training should be available to all persons who wish to use the Talking Signs system, but that no particular level of training should be required.

As stated in the Forward, the project's Steering Committee made the following formal recommendation to be presented to Project ACTION:

Each transit situation is unique, as are the desires and resources of each community. Therefore, issues involving training should be a local consideration.

Cost Analysis

There are five costs areas:

Management Technical Design Hardware

Installation Maintenance

1. Management fees are for the Talking Signs, Inc. approved project manager.

Management functions are the coordination of contracts between the owner and all other parties, and overseeing the design, installation and system validation. The number of hours necessary for the management of a particular project will vary according to project size, complexity of the project, completion of contracts, etc.

2. Technical design fees are for the Talking Signs, Inc. approved Talking Signs technical consultants. Technical design functions are the application of Talking Signs principles to the determination of Talking Signs messaging, location, range, direction, height, angle and as well as the arc of coverage that describes the sign. The technical team is responsible for adjustment of the transmitters ("tuning" the system) and system validation.

3. Hardware costs include the transmitters and bezels for the diode arrays. The rack-mounted transmitters come as a set of 10 transmitter cards per electronics chassis (card rack). The electronics chassis is typically located in an electrical, telephone, or utility closet. The actual "sign", then, is composed of a light emitting diodes array (LED arrays) located at some distance from the electrical box and connected to it through low power signal wires similar to telephone wires. Transmitter costs for interior installations (including electrical box) average $300 per sign. Hardware costs may also include some receivers at $250 per unit.

Talking Signs LED arrays can be built directly into ceiling and wall furnishings such as light fixtures, illuminated signs or tactile displays. Within the past year, a bezel has been produced which integrates tactile labels and LED arrays for doorway identification plates mounted at shoulder height. Another bezel has been produced in the form of a truncated pyramid for flush mounting on ceiling and walls.

4. Installation costs are a total of the electrical work required to locate the transmitter electronics chassis, mount the bezel for the LED arrays and run the low power signal wire. These costs are equivalent to those incurred in telephone system installation since both require pulling low powered wire from a utility closet to remote locations. As the signal wires (simple, stranded, six-conductor, and approximately 20 gauge) are for conducting low voltage, code considerations are minimal. New construction has the advantage over retrofitting existing structures in that the low power signal wires can be run with the other cables, thereby minimizing installation costs. New construction also allows maximum flexibility for LED arrays bezels to be designed into the locations most appropriate for maximizing navigation efficiency.

5. Maintenance costs for Talking Signs is considered to be minimal because they are manufactured with components estimated to operate for twenty years without failure.

A collateral consideration is vandalism. The majority of signs in installed or planed systems (Lighthouse for the Blind in New York, New Main Public Library and Public Works Department in San Francisco) have centralized transmitter units with the diode arrays either mounted flush with the wall or ceiling at a height of approximately ten feet or integrated into tactile name plates (at doorways). Even in the most vulnerable installation (Powell Station) there has been only one incident of a missing transmitter since the demonstration began seven months ago. This is a surprising outcome as the discrete transmitters (rectangular black plastic box measuring [(4"x2"x1") or (10.1 mm x 5.1 mm x 2.5 mm)] and containing the electronics as well as the LED arrays) are, for the demonstration, attached to ceiling and wall-mounted aluminum brackets with Velcro. None of the approximate one-half mile of low voltage power wiring (which was largely exposed) was disturbed.

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