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Synthesis on the Legibility of Variable Message Signing (VMS) for Readers with Vision Loss


(Abstracts were excerpted from referenced article or were written by Philip Garvey.)

Bentzen, B.L. (In Progress).Accessible pedestrian signals. Draft Report to U.S. Architectural and Transportation Barriers Compliance Board under Contract No.PD-97-0772.

Abstract:The Transportation Equity Act for the 21st Century - TEA-21, the successor to ISTEA - directs the pedestrian safety considerations, including the installation of audible traffic signals, where appropriate, be included in new transportation plans and projects. The bill was signed into law on June 9, 1998.

Bentzen, B.L., Crandall, W.F., and Myers, L. (1999). Wayfinding system for transportation services: Remote infrared audible signage for transit stations, surface transit, and intersections.Transportation Research Record.No. 1671, p19-26.National Academy Press, Washington, D.C.

Abstract:People who are print-disabled, who are blind, or who have other visual impairments are restricted in their ability to participate in public life because of lack of labels and signs in the environment. Currently, persons with severe visual impairments often require extensive assistance from strangers to travel in unfamiliar areas. Many other types of disabilities can prevent people from reading print. In addition to people who are blind or who have low vision, there are many people with head-injuries, autism, and dyslexia, along with persons who have had a stroke, who are not able to assimilate printed language even though they can see the page. Many people can accept the information through speech–that is, having print read aloud to them. Some human factors evaluations of a signage system specifically developed to aid people who have visual impairments or a print-reading disability gain information that is available to sighted people through print are described in this paper. This remote, infrared audible signage system–Talking Signs–is composed of a small infrared transmitter that emits a repeating voice message over a directional light beam to a handheld receiver carried by a blind pedestrian. The infrared system greatly reduces the need for travelers to remember distances, directions, and turns, thereby enhancing independence and efficiency in travel. Results show that remote infrared audible signage provides effective wayfinding information for using transit stations, surface transit, and intersections, enhancing independent use of public transit by people with visual impairments or cognitive disabilities.

Bentzen, B.L., and Easton, R.D. (1996). Specifications for transit vehicle next stop messages.Final Report to Sunrise Systems, Inc.,Pembroke, MA.

Abstract:This project was undertaken to determine optimum characteristics to promote legibility of LED next stop message signs by persons with varying visual acuities, including persons having no visual impairment as well as persons who are legally blind. (Persons who are legally blind have visual acuities of 20/200 or less, in the better eye, with correction, or visual fields of 20 degrees or less in the better eye.) Characteristics of LED next stop message signs considered were color, font, inter-character spacing, streaming vs. paging, change rate, and separation distance between next stop messages and advertising or public information messages. The project obtained both objective data on legibility of messages displayed as 84 participants were riding buses, and subjective data on legibility of messages displayed to three focus groups seated in a room.

Bentzen, B.L.,Easton, R.D., Nolin, T.L., and Mitchell, P.A. (1994). Signage specification for transit vehicles: Human factors research.Prepared for the American Foundation for the Blind. New York, New York.

Abstract:This research was undertaken to identify characteristics of signs in the mass transportation environment, particularly signs identifying transit vehicles, which promote the greatest legibility for persons with visual impairments. Persons having visual impairments are particularly dependent on mass transportation, as their visual status renders them ineligible for drivers’ licenses. As such, these persons may be likely to be disproportionately represented in transit ridership, as compared to their representation in the general population. It was the function of this research to obtain human performance data regarding factors affecting legibility of transit signs, including print signs and changeable message signs (CMS), for persons having various amounts of vision.

Colomb, M. and Hubert, R. (1991).Legibility and contrast requirements of variable-message signs. Transportation Research Record.No. 1318, p137-141. National Academy Press, Washington, D.C.

Abstract:New technologies such as optic fibers and light-emitting diodes are now used for information matrix signs. A field study was carried out to evaluate the best conditions for the legibility of these signs during the day and at night. For legibility criteria, the contrast between the letters and the sign background is chosen for daylight conditions and the luminance of the letters for night conditions. The performance of some commercially available signs is compared with the study results.

Colomb, M., Hubert, R., Carta, M., and Dore-Picard. (1991). Variable-message signs: Legibility and recognition of symbols.Proceedings of the Conference Strategic Highway Research Program and Traffic Safety on Two Continents, in Gothenburg, Sweden.p45-62.

Abstract:A laboratory study of the understanding of six types of signs was conducted using transparencies produced by the EDGAR graphic software developed for the purpose. The signs were presented to observers for a limited time. The influences of the number of points in the matrix and of the shape of the symbol were investigated. This study raises the problem of specifying matrix symbols. It should be continued in an attempt to arrive at simple recommendations for the main symbols. It would be best to discuss this question at the international, or at the European level, since the symbols on road signs should be the same in all countries.

Crandall, W., Bentzen, B.L., and Myers, L. (1996). Remote infrared signage for people who are blind or print disabled: A surface transit accessibility study. The Smith-Kettlewell Eye Research Institute, San Francisco, CA. Report No. 95-0111, 16p.

Abstract:Remote infrared audible signage provides wayfinding information forboth transit stations and surface transit, thereby enhancing independent use of public transit by persons having visual impairments. The focus of this study is to provide the basis for successful transfer of remote infrared signage technology to widespread use. The study had five goals: Determine whether infrared remote signage enhances accessibility to buses and bus stops by patrons who are blind; determine the optimal configuration for the transmitter units for buses and bus stops; provide transit patrons a direct opportunity to determine the usefulness of infrared remote signage in the context of buses and bus stops; provide information regarding the usefulness of infrared remote signage vs. tactile signs to regulatory agencies, so that resources for accessibility to public accommodations can be wisely spent; and, provide for the publication and distribution of information useful to transit officials aboutthe proper implementation of infrared remote signage technology for buses and bus stops.

Daily, K., McGee, H., and Garvey, P. (2000).Optimizing changeable message sign design and use.Final Report for DTFH61-96-R-00061.U.S. DOT Federal Highway Administration,Washington, D.C.

Abstract: Unlike other traffic control devices, there are no nationally recognized specifications regarding the appearance of Changeable Message Signs (also known as Variable Message Signs). This absence of guidelines has resulted in CMSs that display any number of colors, shapes, sizes, fonts, borders, and spacings, all of which affect the signs’ visibility. The goal of this research was to develop sample specifications that would address these issues by providing guidance that, if followed, will maximize portable CMS visibility while keeping costs down. Because of the inherent variability in portable CMS usage, particularly with regard to travel speed and sight distance, this document refrains from setting fixed requirements for portable CMS visibility, but instead lists and discusses CMS visibility elements. Lookup tables are provided to give users the information required to decide forthemselves what values to use when filling in the blanks in the specifications for their particular application.

Dudek, C.L. (1991).Guidelines on the use of changeable message signs.Final Report - DTFH61-89-R-00053. 269p. U.S. DOT Federal Highway Administration, Washington, D.C.

Abstract:The 1986 FHWA publication “Manual on Real-Time Motorist Information Displays” provides practical guidelines for the development, design, and operation of real-time displays, both visual and auditory. The emphasis in the Manual is on the recommended content of messages to be displayed in various traffic situations; the manner in which messages are to be displayed–format, coding, style, length, load redundancy, and number of repetitions; and where the messages should be placed with respect to the situations they are explaining. This report is intended to provide guidance on 1) selection of the appropriate type of Changeable Message Sign (CMS) display, 2) the design and maintenance of CMSs to improve target value and motorist reception of messages, and 3) pitfalls to be avoided, and it updates information contained in the Manual. The guidelines and updated information are based on research results and on practices being employed by highway agencies in the United States, Canada and Western Europe. CMS technology developments since 1984 are emphasized. Since the use of matrix-type CMSs, particularly light-emitting technologies, has increased in recent years,matrix CMSs have received additional attention in this report. The report concentrates on design issues relative to CMSs with special emphasis on visual aspects, but does not establish specific criteria to determine whether to implement displays. The intent is to address display design issues for diverse systems ranging from highly versatile signing systems integrated with elaborate freeway corridor surveillance and control operations to low cost, less sophisticated surveillance and signing systems intended to alleviate a single specific problem.

Dudek, C.L. (1997).Changeable message signs.NCHRP Synthesis of Highway Practice 237.National Academy Press, Washington, D.C.

Abstract:This synthesis will be of interest to traffic engineers in Federal, state, provincial, and local transportation agencies who are responsible for the design and operation of safe and efficient highway systems. It will also be useful to consulting traffic engineers, sign manufacturers, and vendors in the private sector who assist governmental clients in the application of changeable message sign (CMS) and other intelligent transportation systems (ITS) technology. It is an update of NCHRP Synthesis No. 61 (1979). It describes the various types of permanently mounted CMSs in use in the United States and Canada. This technology, also referred to as “variable message signs” or “motorist information displays”, is in widespread use in North America. This report of the Transportation Research Board provides information on the various CMS types in use, their typical characteristics, including the technology types, the character (letters and numbers) types and size, and conspicuity. The synthesis presents a discussion on the types of messages used when there are no incidents. Other aspects, such as procurement, maintainability, and warranties are also discussed.

Earnhart, G.A. (1996).Guidelines for transit facility signing and graphics.Transit Cooperative Research Program (TCRP) Report 12. Transportation Research Board, National Research Council, National Academy Press. Washington, D.C.

Abstract: This report documents and presents the results of a research project to develop a graphics design manual describing the use of signs and symbols which provide for the safe, secure, and efficient movement of passengers to and through transit facilities. During the course of this 18-month project, existing signs and symbols were reviewed worldwide; compliance with ADAAG (Americans with Disabilities Act Accessibility Guidelines) was determined for existing signs; new signs and symbols were developed in five functional categories, namely, Identification, Directional, Processing, Regulatory, and Warning; the key signs were tested by focus groups representing major types of disability, as well as transit users and non-users; a standard design manual of signs and symbols was developed that could be used by transit agencies nationwide; and a plan was developed to achieve maximum dissemination of the guidelines nationwide to transit entities. The project was performed in two phases, with Phase I structured to reviewand document the “state-of-the-practice” of signage in the transit industry. More than thirty properties nationwide, representing a broad cross section of the industrywere surveyed and their signage practices documented. Signage information from both international and domestic transit providers were reviewed, and the information needs of transit users that could be satisfied by signs and symbols were identified. Phase II efforts involved the design of candidate symbols and signs and their evaluation by a broad cross-section of transit riders and non-riders, graphics designers, and transit personnel. The evaluation results were factored into the development of these graphics design guidelines incorporating the best of those signs, symbols and graphics design standards for the transit industry.

Garvey, P.M. and Mace, D.M. (1996).Changeable message sign visibility.Publication No.FHWA-RD-94-077.Federal Highway Administration, Federal Department of Transportation Washington, D.C.

Abstract:This research began with a detailed critical review of the literature to determine the factors that most affect CMS visibility. Those variables determined to have the greatest impact on visibility were selected for a three-level analysis. Level One consisted of a laboratory study using a computer simulation of a CMS. During this stage, 11 variables were assessed regarding their effects on minimum observable letter size. These variables were: character width-to-height ratio (W:H), stroke-width-to-height ratio (SW:H), matrix density, font, color, contrast orientation, character luminance, word-length, inter-word spacing, inter-letter spacing, and inter-line spacing. Level Two was a static field study in which a mock-up CMS, an actual CMS, and the observers were stationary. This second level of analysis measured the effects of time of day, sun position, character height, inter-letter spacing, font, and distance from the observer on minimum character luminance required for CMS legibility. Level Three involved a dynamic field study using actual trailer-mounted CMS’s on public roadways. An assessment was made on the effects of seven variables on the distance at which the signs could be found and read. These variables were: sun position, sign type, character luminance, contrast orientation, inter-letter spacing, character height, and character W:H.

Garvey, P.M., Pietrucha, M.T., & Meeker, D. (1997).Effects of font and capitalization on legibility of guide signs. Transportation Research Record, No. 1605, p.73-79. National Academy Press, Washington, D.C.

*Abstract: **The research objective was to improve highway guide sign legibility by replacing the 40-year-old guide sign font with a new font called Clearview. It was believed that the current guide sign font’s thick stroke design, made with high-brightness materials and displayed to older vehicle operators, exhibited a phenomenon known as irradiation or halation. Irradiation becomes a problem if a stroke is so bright that it visually bleeds into the character’s open spaces, creating a blobbing effect that reduces legibility. The Clearview font’s wider open spaces allow irradiation without decreasing the distance at which the alphabet is legible. Results are presented of two daytime and two nighttime controlled field experiments that exposed 48 older drivers to high-brightness guide signs displaying either the current or the Clearview font. The Clearview font allowed nighttime recognition distances 16% greater than those allowed by the *Standard Highway SeriesE(M) font, without increasing overall sign dimensions.

Garvey, P.M., Pietrucha, M.T., & Meeker, D. (1998).Development of a new guide sign alphabet.Ergonomics in Design, 6 (3), p.7-11.

Abstract: To address issues of legibility and visibility of road signs from a distance and at night, a new font, named Clearview, was developed by Meeker & Associates and tested by the Pennsylvania Transportation Institute (PTI) at **Pennsylvania State University. After creating initial versions of the fonts, the authors subjected them to an iterative design process based on the results of subjective field evaluations, objective tests of the typefaces’degradability, and objective laboratory studies using computer simulation. The steps in this evaluation process are described here.

Garvey, P.M., Thompson-Kuhn, B. & Pietrucha, M.T. (1995). Sign visibility literature review. United States Sign Council (USSC) Research Project, Final Report.

Abstract:The main objective of this research was to present a synthesized review of literature pertaining to sign visibility. The table of contents lists the following major subject headings. 1. Introduction; 2. Basic Definitions - Lighting, Signs,The Driver; 3. Sign Ordinance Restrictions - Permitted and Prohibited Signs, General Physical Restrictions, Restrictions by Specific Sign Type; 4. Sign Visibility Literature Review - Federal Traffic Sign Regulation, Sign Visibility Research; 5.Understanding Driver Limitations - Visual Acuity, Glare Sensitivity, Reading Time; 6.Sign Visibility and Traffic Safety; Appendix A. Visibility Guidelines for On-Premise Signs; Appendix B. Annotated Bibliography.

Howett G.L. (1983). Size of letters required for visibility as a function of viewing distance and observer visual acuity.National Bureau of Standards. Report No.HS-037 967; NBS TN 1180 Final Report. 72p.

Abstract:A formula is derived giving the letter stroke-width needed for legibility of words on a sign at any given distance by an observer with any given visual acuity. The stroke width, in turn, determines the letter size, depending upon the characteristics of the type face used. The derivation is strictly mathematical and is based on the assumption that beyond a distance of a few meters, a person’s visual acuity is specifiable by a fixed visual angle, independent of the distance. The information implicit in the formula is also presented graphically, in four plots that apply to four different combinations of length units for measuring stroke width and viewing distance. Also presented are formulas and graphs for correcting the critical stroke width for nonstandard contrast or background luminance. These correction formulas are based on a body of data on visual acuity as a function of contrast and background luminance, and a formula fitting the mid-ranges of the data, both published recently by other researchers.

Hunter-Zaworski, K. (1994).Accessing public transportation: New Technologies Aid persons with sensory or cognitive disabilities.TR News, 175, p24-29.

Abstract:The Americans with Disabilities Act of 1990 requires that transit systems ensure effective communication with persons with disabilities, including those with sensory and cognitive impairments. The legislation has stimulated the development of a number of new technologies to help those with disabilities access public transportation systems by maximizing the independence and dignity of these passengers. A number of the new and advanced technologies are currently under development, undergoing demonstration, or in early use. When fully implemented, it is anticipated that these innovations will make the transit trip as seamless and pleasant as possible for all travelers, not just for those with disabilities. This article examines some of these new technologies, including the following: For Trip Planning - tactile maps, telecommunication devices for the deaf, hearing aid-compatible telephones, facsimile equipment, “Smart” traveler systems, handyline, and busline; For Getting to and from Transit Facilities - bus stop and transit station access, electronic speech information equipment, auditory pathways, route cards, verbal landmark systems, and talking buses; For Fare Collection - smart cards and the Fahrsmart system (Germany); For Navigating the System - visual signs and electronic information systems (descriptions of systems operating in San Diego, California, St. Saulve, France, Montreal, Quebec, Canada, Rotterdam and Utrecht, Netherlands, and London, England); Technologies Under Development - automatic speech recognition systems, radio frequency fare cards, and GIS (geographic information system) and AVL (automatic vehicle location) technologies; and Future Concepts.

Hunter-Zaworski, K., and Hron, M.L. (1999).Bus accessibility for people with sensory disabilities.Transportation Research Record.No. 1671, p40-47.National Academy Press, Washington, D.C.

Abstract:With the passage of the Americans with Disabilities Act (ADA) it has become a civil rights violation to deny access to public transportation to people with disabilities. The ADA requires transit agencies to provide accessible buses or equivalent services to people with mobility, sensory, or cognitive impairments. Issues concerning people with sensory impairments, and their access to fixed-route transit services, are examined in this study. The literature concerning access to public transit by people with sensory disabilities is summarized in this paper, along with exemplary training programs and technologies that have improved transit accessibility for people with sensory disabilities. A major conclusion of this study is that technological solutions may not increase bus accessibility for people with sensory impairments. One-on-one interaction is needed to solve many individual access problems of the transit users. Training for transit personnel is needed so personnel can become aware of, and more sensitive to, the needs of all transit users. Training for the transit user is necessary so that use of the transit system is accomplished with grace, speed, efficiency, and dignity. Training for those who train people with disabilities is necessary so that transit travelers will be informed about all the available services offered by transit agencies. Visual signage must be consistent and highly legible to be effective and includes sign and information location, lighting, contrast, and content.

Hunter-Zaworski, K.M. and Watts, D. (1994).Development of ergonomic guidelines for electronic customer information systems. Federal Transit Administration Report Number: FTA-OR-26-7000-94-1, 117pp.

Abstract: This study examines issues concerning persons with sensory and cognitive impairments and their access to public transit. The research focuses on the development of ergonomic performance guidelines for visual electronic customer information systems. It is the first attempt to provide direction for the specification and installation of these devices. The guidelines were influenced by the particular needs of persons with sensory or cognitive disabilities. The approach kept the guidelines general to accommodate the particular needs of persons with sensory disabilities in a number of language formats and electronic media. The first part of this report provides a compendium of current state-of-the-art in electronic customer information systems, including a list of model installations and summary descriptions of exemplary and currently operating systems. The second part of the report provides draft guidelines for the ergonomic performance of the man-machine interface of the visualcomponent of electronic customer information systems. The guidelines incorporated the comments and suggestions received from more than 50 reviewers around the world. These reviewers represent transit agencies, groups of persons with disabilities, researchers, manufacturers, and government officials. The final section of this report includes a brief discussion of a number of controversial issues that arose out of the research activities and suggestions for further investigation. It is anticipated that the guidelines will form the basis of international standards to be developed as a cooperative effort between the United States, Canada, Australia, and the European Community as well as the basis for work related to the ITS/APTS program.

Iannuzziello, A.S. (2001) Communicating with persons with disabilities in a multimodal transit environment: A synthesis of transit practice. Transit Cooperative Research Program (TCRP) Synthesis 37. Transportation Research Board, National Research Council, National Academy Press. Washington, D.C.

Abstract:* This synthesis will be of interest to transit agency professionals and the consultants who work with them in dealing with travelers with disabilities. These are travelers with sensory, vision, hearing, and cognitive impairments who need alternative methods for accessing and processing the transit information that is now being commonly provided to the general public. The report describes current North American transit practice in information and communication technologies, as well as operations, implementation, and human factor issues. Attention is given to information and communication technologies related to planning, customer service, marketing, and training that can improve the travel experience for all persons traveling in a transit environment. The focus is on the communication techniques and technologies for persons with sensory and cognitive disabilities. This document from the Transportation Research Board integrates information from a literature review, survey responses from 19 transit agencies, and extensive telephone interviews with seven specific providers.*

Joffee, E. (1995).Transit vehicle signage for persons who are blind or visually impaired. Journal of Visual Impairment and Blindness, 89(5), Research Notes, p461-469.

Abstract:The purpose of this research project was to identify factors associated with the readability of conventional print and electronic signs used on transit vehicles, specifically buses, in the dynamic transit environment by persons with visual impairments. The subjects were individuals with visual impairments whose visual acuities ranged from 20/70 to 20/400. Conventional and Changeable Message Signs were evaluated.

Abstract:As people age, a number of visual functions such as acuity, visual field, and night vision deteriorate. This decline in vision is associated in part with an increase in vehicular accidents per mile driven by the elderly. Four age-related occular conditions - cataract, macular degeneration, open-angle glaucoma, and diabetic retinopathy - are primarily repsonsible for the decline in visual acuity and visual field in the elderly. Few epidemiologic data are available about these diseases, and at present they cannot be prevented. There is need for more information about visual decline and how it affects driving performance and for development of pragmatic approaches for detecting and assessing the elderly driver with functional visual deficits.

Levinson,M. (1996).Brighter benefits from VMS.Traffic Technology International ‘96.Annual Review Issue, p.201‑2.

Abstract:This article discusses recent experiences of installation of variable message signs (VMSs) in **Israel and the Netherlands. Although VMS systems have been used worldwide for more than ten years, they have suffered from display technology limitations and other problems until very recently. Improvements in technology, including the use of light‑emitting diodes (LEDs) have now made the applications of VMS to road traffic beneficial to drivers and government departments responsible for road safety. A pilot project was recently conducted in Haifa, Israel, to evaluate the efficiency of VMS units in an urban area. Four VMS units were tested, each displaying two 24‑character lines of text with 25cm height. Drivers were interviewed while waiting for traffic lights to change at intersections displaying the units. It was found that drivers prefer to have traffic information, even if they do not use it. Most drivers could read the VMSs and think that VMSs reduce traffic anxiety. The Dutch Ministry of Traffic recently began roadside testing of an LED VMS mounted on a mobile trailer. It was found that only 4.4% of cars were speeding past a roadworks sign, displaying very bright yellow‑white LEDs visible in daylight, even in direct sunlight. Thirty-four LED lane control signs have recently been installed in Jerusalem.

Lewis, D.J. (2000).Photometric requirements for arrow panels and portable changeable message signs. Proceedings of the Ninth Maintenance Management Conference, Juneau, Alaska, July 16-20. National Academy Press, Washington, D.C.

Abstract:Arrow panels and portable changeable message signs are often used in work zones to inform drivers of the need for a lane change or caution. The “Manual on Uniform Traffic Control Devices” (MUTCD) requires that Type C arrow panels have a minimum legibility distance of 1.6 km (1 mile). However, the MUTCD does not provide a subjective means for determining whether an arrow panel meets this criterion. Nor are there industry photometric standards for message panels. The purpose of this project is to develop a reliable and repeatable objective method for measuring the photometrics of arrow and message panels to ensure adequate performance. The research project tasks include a review of the state of the art, reviews of existing pertinent specifications, development of initial test methods, evaluations of arrow and message panel visibility and the effectiveness of the test methods, revisions and modifications of the test methods, and documentation of research activities and findings. The research findings will be described in a research report and a project summary report. The recommended test methods will be included in both documents.

Marin-Lamellet, C., Pachiaudi, G., and Le Breton-Gadegbeku, B. (2001).Information and orientation needs of blind and partially sighted people in public transportation.BIOVAM project. Transportation Research Record, No. 1779, 203-208.National Academy Press, Washington, D.C.

Abstract:Presented are the results of the BIOVAM project in **France concerning the problems experienced individuals with vision impairments who use public transportation, such as buses, subways, and trains. The project focused on information gathering and orientation processes in the public transportation context. The BIOVAM approach uses a questionnaire survey to identify the main difficulties that public transportation users with visual impairment must manage. The approach includes a review of promising devices that could reduce these difficulties,such as personal information systems and tactile pavements. An overview of the results obtained from the survey is presented, addressing the use of buses and subways. The main technical solutions considered by the project are described, and the research protocols that are to be used in the field experiments are presented. The results of the BIOVAM project could be used to make concrete recommendations to include the specific needs of travelers with visual impairments in the design of a public transport infrastructure.

Marston, P.P. (1993). Changeable message signs: avoiding design and procurement pitfalls.Public Roads, 57(2), p27-34.

Abstract:The use of changeable message signs (CMS), which display real-time information to motorists, has assisted in efforts to improve roadway operations and safety of existing facilities. Some of the difficulties that currently exist with the procurement and implementation of CMS are due to several major issues including inadequate specifications, insufficient definition of protocols, low bid acceptance practices, and no industry standards. This article describes the various CMS technologies and their uses, explains some of the challenges inherent with their use, and recommends solutions to the problems. The key to producing a specification that addresses the needs of the public agency without compromising any one company or technology lies in creating a performance-based specification considering the agency’s goals and objectives. Guarantees, warranties, performance/liquidated damages bonds, and independent testing and certification can be successful tools in helping the agency acquire and maintain an efficient and safe CMS network, avoiding the design and procurement pitfalls associated with CMS. The Arizona Department of Transportation provides a good example of the way that a transportation agency can approach CMS.

Miller, J.S., Smith, B.L., Newman, B.R., and Demetsky, M.J. (1995). Final Report: Development of manuals for the effective use of variable message signs. Virginia Department of Transportation, Report No.VTRC 95-R15.

Abstract:A comprehensive research effort to develop operator’s manuals for variable message signs (VMSs) was undertaken to improve the operations of both portable and permanent (fixed-site)VMSs in Virginia. This report describes the development of two manuals, the “Permanent VMS Operator’s Manual” and the “Portable VMS Operator’s Manual.”

Miller, J.S., Smith, B.L., Newman, B.R., and Demetsky, M.J.(1995). Effective use of variable message signs: lessons learned through development of users’ manuals.Transportation Research Record, 1495, p1‑8.

Abstract:* In an effort to improve the operations of both portable and permanent (fixed‑site) variable message signs (VMSs) in Virginia, a comprehensive research effort to develop operational guidelines was undertaken. These guidelines, presented in the form of users’ manuals, were based on information obtained from the literature, VMS operators, and motorists. Issues addressed by the manuals include whether to use a VMS, where to place a portable VMS, and how to design a VMS message. The manuals are not simply a list of predefined messages; instead, they are composed of concise, readable modules designed to guide an operator through the thought process required to use a VMS effectively. An operator follows a logical decision tree as each module is completed, allowing effective use of the VMS as well as training the operator for use of the device. Key lessons learned in developing two such manuals for portable and permanent VMSs are highlighted. On the basis of theoretical calculations and motorists’ experiences, it is strongly recommended that a VMS use no more than two message screens. A single message screen is preferred. VMSs should be used only to advise drivers of changed traffic conditions and to convey specific traffic information concisely. Because of limited information capabilities, VMSs should be used in conjunction with other means of communication such as highway advisory radio and static signs. Most importantly, it is crucial that credibility be maintained. Incorrect information can have disastrous consequences on VMS effectiveness.*

MUTCD 2000: Manual on Uniform Traffic Control Devices Millennium Edition.(2000).U.S. DOT, Federal Highway Administration.

Abstract:The Manual on Uniform Traffic Control Devices (MUTCD) defines the standards used by road managers nationwide to install and maintain traffic control devices on all streets and highways. The MUTCD is incorporated by reference in 23 Code of Federal Regulations (CFR), Part 655, Subpart F. Although the MUTCD is routinely updated to include amendments that clarify new standards and incorporate technical advances, it has been more than 20 years since the manual was entirely rewritten, and the most recent edition was published in 1988. The new MUTCD is published in 3-ring binders for easy updating, on CD-ROM, and on the Internet. Redesigned text format will help users identify STANDARDS – “shall” conditions; GUIDANCE – “should” conditions; OPTIONS – “may” conditions; and SUPPORT – descriptive and/or general information for designing, placing, and applying traffic control devices. Measurements are presented in both metric and English units. This hard copy version contains the following sections: Introduction; Part 1 - General; Part 2 - Signs; Part 3 - Markings; Part 4 - Highway Traffic Signals; Part 5 - Traffic Control Devices for Low-Volume Roads; Part 6 - Temporary Traffic Control; Part 7 - Traffic Controls for School Areas; Part 8 - Traffic Controls for Highway-Rail Grade Crossings; Part 9 - Traffic Controls for Bicycle Facilities; Part 10 - Traffic Controls for Highway-Light Rail Transit Grade Crossings; Appendix A1 - Congressional Legislation; and an Index.

Proffitt, D.R., Wade, M.M., and Lynn, C. (1998).Creating effective variable message signs: Human factors issues. Final Contract Report, Proj No. 9816-040-940, VTRC 98-CR31.25p.Virginia Department of Transportation, Richmond, VA.

Abstract:This report addresses the human factors issues related to the reading and comprehension of variable message sign (VMS) messages. A review of the literature was conducted on factors that affect how people read VMSs. Several topics were reviewed. The first topic was literacy. Since reading literacy is not a requirement for obtaining a driver’s license, VMS composition should reflect the varied reading competence levels of motorists. It was found that about 25% of Virginians over the age of 16 are weak readers and will likely encounter problems reading VMSs. The second topic addressed how people read. Reading is an interactive process that derives much of its speed and accuracy from implicit knowledge acquired through familiarity. This implies that VMS messages should present familiar, standardized content whenever possible. A review of the literature on warning signs was the third topic. This review found that effective warning signs should have several properties: short, concise messages are both easier to read and more likely to be read; and signal words, such as CAUTION, are not effective. Finally, areas for further research were identified. Symbolic messages and abbreviations are worthy of further investigation as they have the potential for easy recognition, provided they are familiar to motorists and can be accommodated by the VMS. In addition, although the Manual on Uniform Traffic Control Devices (MUTCD) advises angling the VMS away from the roadway to reduce headlight glare, angling the VMS toward the roadway could be desirable for increasing readability. In both these areas, theoretical and practical work is needed. The report recommends that these human factors characteristics and limitations be taken into consideration in the deployment of VMSs and in the composition of their messages.

Public Rights-of-Way Access Advisory Committee. (2001). Final Report: Building a true community. U.S. Architectural and Transportation Barriers Compliance Board. Washington, D.C.

Abstract:Public rights-of-way harbor many transportation activities, including walking and rolling, bicycling, transit, freight movement, and automobile travel. They house the hardware, such as traffic signals and street lights, that supports those activities. In many cases they contain public and private utilities. With so many diverse functions to be supported, the streetscape within the public right-of-way is often created over a period of time by a variety of minds and hands. This report has been prepared to address access to public rights-of-way for people with disabilities. The report is a recommendation for a new national set of guidelines that define the details necessary to make the streetscapes in public rights-of-way accessible to all users. Accessibility is not an afterthought. The design of a coherent corridor of accessible travel should be the starting point for every project in the public right-of-way.

Simon, R.M. (1993). Americans with disabilities act of 1990: Mandate for full accessibility.Transportation Research News, 168, p17-23.

Abstract:The Americans with Disabilities Act of 1990 (ADA), a comprehensive civil rights law that removes barriers to equal opportunity and provides full societal access for all individuals with disabilities, extends the basic framework of Titles II and VI of the Civil Rights Act of 1964 for coverage and enforcement and Section 504 of the Rehabilitation Act of 1973 for a definition of discrimination. For the first time in history, persons with disabilities are guaranteed sweeping protection against discrimination in both public and private services. The ADA has become what no other Federal transportation legislation has ever been: a mandate for full accessibility in the transportation industry. Its accessibility requirements cover all modes of public and private transportation except air travel, which is covered by the Air Carrier Access Act of 1986 and related U.S. Department of Transportation regulations. This systems-change legislation affects Federal highways, transit systems, private transportation providers, rail transportation, airports, and water transportation. This article provides an overview of the transportation provisions of ADA and related regulations and progress made in their implementation. The primary focus is on public transit.

Stainforth, R.W. and Kniveton, P.E. (1996). Display technologies for VMS.Traffic Technology International ‘96.Annual Review Issue, p.208‑13.

Abstract: Two years after an original review of display technologies for variable message signs (VMSs), the authors of this article reconsider the new technologies for collective driver information, and argue that improved light‑emitting diodes (LEDs) could become the dominant and cost‑effective light source. The following VMS technologies are compared: (1) rotating planks and prisms; (2) roller blinds; (3) electromagnetic reflecting flip disk; (4) lamp matrices; (5)fibre optics; (6) LEDs; and (7) liquid crystal displays (LCD). Fibre optic signs and LEDs perform best. Fibre optic displays have excellent visibility in all weather conditions, although they can be difficult to read in direct sunlight. The fibre optic reflective disk combines the qualities of fibre optics and the reflective disk to be exceptionally visible in direct sunlight. The advantages and disadvantages of first‑generation technology are listed. R‑R Industrial Controls has developed a new generation of LEDs for transport and traffic applications. Its high intensity yellow LED, Rigel, has greatly increased optical efficiency and reduced power consumption. Its technology has been chosen for several British VMS projects.

Swinea, J.D. (1998).Secrets of selection.Traffic Technology International, Annual Review, p163-165.

Abstract:This article presents criteria that should be considered in selecting variable message sign (VMS) systems. It discusses types and sizes of displays, reliability, software, and service considerations. It also offers general criteria for selecting a VMS company.

Upchurch, J. Armstrong, J.D., Baaj, M.H., and Thomas, G.B. (1992). Evaluation of variable message signs: Target value, legibility, and viewing comfort.Transportation Research Record. No. 1376, p. 35-44. National Academy Press, Washington, D.C.

Abstract:Three different technologies for variable message signs were evaluated in terms of target value, legibility distance, and viewing comfort. The technologies evaluated were flip disk, light-emitting diode (LED), and fiber optic. For comparison purposes, conventional overhead guide signs were also evaluated. Twelve signs were evaluated in the field in a human factors study; hired observers measured target value and legibility distance from a moving vehicle on the freeway and subjectively evaluated viewing comfort. Observations were madeunder four lighting conditions: midday, night, washout, and backlight. For target value, legibility distance, and viewing comfort, fiber-optic signs performed better than LED signs in most conditions. However, both types have acceptable performance overall. The effects of observer age were identified and documented. Both fiber-optic and LED signs are recommended as acceptable for the freeway management system in the Phoenix, Arizona, urban area.

Uslan, M.M., Peck, A.F., and Waddel, W. (1988). Audible traffic signals: How useful are they?ITE Journal, 58(9). p43.

Abstract:This is a report of a controlled study of 27 blind persons who attempted to cross three intersections outfitted with audible pedestrian signals and one without. The legally blind persons were selected to provide a range of visual impairment, type of mobility aid, and age. Details of the method used are described. Details are given of the four study intersections that represented differing degrees of complexity and a variety of challenges to pedestrians with vision impairments. The results of the study are presented and discussed. The study found that audible signals aid blind pedestrians at complex intersections, but also pointed out the limitations associated with audible signals. It is noted that blind pedestrians have difficulty locating the proper pedestrian signal pole and push button. At complex intersections, audible signals require intensified listening, and the full advantage of audible signals can only be realized through instruction and practice in their use.

Wourms, D.F., Cunningham, P.H., Self, D.A., and Johnson, S.J. (2001). Bus signage guidelines for persons with visual impairments: electronic signs. Federal Transit Administration Report FTA-VA-26-7026-02.1.

Abstract:This report focuses on the adequacy of the ADA destination signage guidelines for visual technologies used to improve the dissemination of public transit information individuals with vision impairments. Specifically, this document is concerned with the use of LED and LCD signs in and on the transit vehicle to present destination and route information. The content is derived from relevant standards, guidelines, and research literature identified during extensive government and commercial database searches, as well as a comprehensive search ofworld wide web resources. To the extent available, input from subject-matter experts and industry points-of-contact is also included.

The objective of this on-going research is to update the FTA bus signage guidelines for reflective disk changeable message signs (CMS) (FTA-MD-26-0001-98-1) to include light-emitting CMS technologies (LED and LCD). In task 1 the researchers conducted a literature and document review to identify current CMS guidelines and research related to bus signage for individuals with vision impairments. In task 2 the researchers conducted two user surveys, one with transit authorities and one with users of transit systems with vision impairments. The preliminary results of the transit authority survey indicated that most authorities used ADA regulations as a minimum starting point, but specified larger letter heights. In general, the specifications that the authorities are using are broad-based and often lack specific target values for sign characteristics. The preliminary results from the survey of transit users with visionimpairments indicate that the major problems these individuals have with external bus CMS are: bright daylight (glare); poor use of color; and vehicle motion (vibration). Problems they have with internal bus CMS are: bright daylight (glare); letters that are too small; and text scrolling speed that is too fast. Task 3 will result in a research plan based on the findings of the first two tasks that will be using to determine guidelines to optimize the visibility of light emitting CMS for travelers with vision impairments.


(Abstracts are from PsycINFO database record.)

Bowers, A.R. and Reid, V.M. (1997). Eye movement and reading with simulated visual impairment. Ophthalmology and Physiological Optics, 17(5), p492-402.

Abstract:Investigated the effects of simulated visual impairment on the reading speed and reading eye movements of young, normally-sighted observers (18-35 yrs old). Afocal diffusing filters (Ryser occlusion foils) were used to create 3 levels of impairment and eye movements were recorded using a spectacle-mounted, infra-red limbal reflection system. **Reading speed decreased significantly as the level of impairment increased. Eye movement analysis revealed the main contributory factors to be increased fixation durations shorter saccades (resulting in increased numbers of forward saccades per line) and, to a lesser extent, increased time required for page navigation. The results suggest that in order to achieve optimal reading speeds, print size should be at least 4 times the acuity threshold and that print contrast should be at least 20 times contrast threshold.

Fine, E.M. and Peli, E. (1996). Visually impaired observers require a larger window than normally sighted observers to read from a scroll display. Journal of the American Optometric Association, 67(7), p390-396.

Abstract:Examined the optimal window size for proportionally spaced fonts when reading from a scroll display. Twenty-four visually impaired and 44 normally sighted subjects aged 50+ years were asked to read either sentences or random words scrolled across a computer screen. The window size was varied sothat from 1-12 characters were visible, on average, at any one time. Each subject read with 6 different window sizes within the range of 1-12 characters visible. Results showed that for the normally sighted group, a window of 4-5 characters was necessary to read at maximal rates. Subjects with vision impairments required a significantly larger window of 6-7 characters to reach maximal reading rates. The larger window size requirement for subject with vision impairments could result from the additional stimulation available with a larger window to entrain the eyes’ motion when reading from a passively scrolled display.

Fine, E.M. (1995). Reading dynamically displayed text with visual impairments. Dissertations Abstracts International: Section B: The Sciences and Engineering Vol. 56(6B).

Abstract:With normal vision, about 20% of reading time is consumed by eye movements.(Rayner, 1978; Just & Carpenter, 1980). RSVP and scrolled text display formats both require eye movements different from normal reading, and were previously shown to increase reading rates for observers with vision impairments. Because eye movements are either reduced (central field loss–CFL) or eliminated (no CFL and normal vision) when reading from an RSVP display, reading should be faster than when reading from a scroll display. As expected, normally sighted observers read faster from the RSVP display. Readers with vision impairments did not. The remaining experiments explored this unexpected finding. Experiment 2 used a comparison of the ratio of reading rates for sentences and random word strings (sentence-gain) across the display formats to determine if readers use information available from the word to the right of their current fixation. If they do, sentence-gain will be different when reading from the two displays. Normally sighted readers showed less sentence-gain when reading from the scroll display, suggesting they use the available extra-fixational information. Persons with CFL did not. Experiment 3 (young subjects) and Experiment 4 (older subjects) used cataract simulating lenses, and showed that severely reduced acuity does not eliminate the benefit of the single locus presentation of the RSVP display. As with the subjects in Experiment 2, it does eliminate the use of extra-fixational information in the scroll display. In the presence of CFL, reading behavior differs substantially from that of observers with no CFL, regardless of acuity. The fact that these subjects derive no benefit from the reduced eye movement requirements of the RSVP display lends support to the belief that the scroll display entrains their otherwise unstable eye movements (Whittaker et al., 1993; Legge et al., 1985a), thus providing a more visible image. The number of characters usable during a fixation is smaller.

Fine, E.M., Peli, E., and Reeves, A. (1995). Simulated cataract does not reduce the benefit of RSVP.Vision Research, 37(18), p2639-2647.

Abstract:Thirteen younger and 12 older (mean age 71 years) normally sighted subjects read sentences and random lists of words from a rapid serial visual presentation (RSVP) display and a scroll display using their normal vision and through two levels of cataract simulators. Unlike subjects with central field loss, there was no decrease in the benefit of RSVP with reduced vision due to the cataract simulators. However, the usefulness of sentence-level context was reduced as visual acuity was reduced. In addition, older readers did not benefit as much from RSVP as youngerreaders, and many in the older group were unable to read using the more severe cataract simulators from either display format. The data indicate that the benefits of RSVP are not reduced with reduced acuity and contrast sensitivity, and that there are age-related changes in reading rates from dynamic text displays not related to acuity.

Kang, T.J. and Muter, P. (1989). Reading dynamically displayed text. Behaviour and Information Technology 8(1), p33-42.

Abstract: Two experiments with 48 college students were carried out to find an optimal electronic text display method given limited space. The display formats tested were in 2 categories: times square (TS), in which text is scrolled from right to left; and rapid, serial, visual presentation (RSVP), in which text is presented one or several words at a time to a fixed location in the display. In Experiment 1, a comparison was made between multiple-word RSVP and 3 versions of the TS format, differing in the size of steps by which the display was scrolled. Except for the largest step-size, comprehension was as high in the TS conditions as in the RSVP condition. Subjects expressed a significant preference for smooth-scrolling TS over any other condition. Experiment 2 showed that comprehension for smooth scrolling TS was at least as high as that for RSVP at presentation rates ranging from 100 to 300 words/min. TS reading is discussed in terms of optokinetic nystagmus.

Krischer,C.C. and Meisser, R. (1983).Reading speed under real and simulated visual impairment.Journal of Visual Impairment and Blindness 77(8), p386-388.

Abstract:Simulated 2 types of visual impairment–cataracts and deteriorated retinas–in normally sighted subjects (aged 20-45 yrs) with average reading speeds. Three groups of partially sighted persons (N = 72; average age 28 yrs) were also studied: those with normal visual fields, those with defects in peripheral fields, and those with defects in the central field. Results for these 3 groups were similar to those obtained under conditions of simulated visual impairment. The authors conclude that reading speed depends on visual acuity.

Legge, G.E., Ahn, S.J., Klitz, T.S., and Luebker, A. (1997).Psychophysics in reading - XVI.The visual span in normal and low vision.Vision Research, 37, p1999-2010.

Abstract: The visual span in reading is the number of characters that can be recognized at a glance. The shrinking visual span hypothesis attributes reading speed deficits in low vision, and slow reading in normal vision at low contrast, to a reduction in the visual span. This hypothesis predicts that reading time (msec/word) becomes increasingly dependent on word length as text contrast decreases. We tested and confirmed this prediction using the rapid serial visual presentation (RSVP) method. Estimates of the visual span ranged from about 10 characters for high-contrast text to less than two characters for low-contrast text. Eye movement recordings showed that longer reading times at low contrast are partitioned about equally between prolonged fixation times and an increased number of saccades (presumably related to a reduced visual span). RSVP measurements for six out of seven low-vision subjects revealed a strong dependence of reading tome on word length, as expected from reduced visual spans.

Legge,G.E. and Rubin, G.S. (1986).Psychophysics of reading. IV. Wavelength effects in normal and low vision.Journal of the Optical Society of America A 3(1), p40-51.

Abstract: Examined whether color of text influenced its legibility, using psychophysical methods to measure the effects of wavelength on the reading performance of 4 normal observers, 2 dichromats, and 25 low-vision observers (aged 21-71 yrs). Reading rates were measured for text scanned across the face of a TV monitor. Performance was compared under 4 luminance-matched conditions in which sets of neutral-density and Wratten color filters were placed in front of the TV screen–blue, green, red, and gray. Under photopic conditions, the reading rates of normal subjects were independent of wavelength, with the exception of characters near the acuity limit. At lower luminances, wavelength effects could be explained by the shift from photopic to scotopic vision. It was hypothesized that light scatter or absorption in eyes with cloudy ocular media would result in depressed performance in the blue. Only 1 of 7 subjects demonstrated this effect, which was traced to wavelength-specific absorption. Subjects with advanced photoreceptor disorders tended to read blue text faster than red text. It is suggested that wavelength only occasionally plays a significant role in reading. When it does, performance tends to be depressed either in the red or the blue and to be nearly optimal for green or gray.

Lovie-Kitchin, J.E., Bowers, A.R., and Woods, R.L. (2000).Oral and silent reading performance with macular degeneration.Ophthalmology and Physiological Optics, 20(5), p360-370.

Abstract: Investigated whether reading rate for large print sizes shown to be a predictor of oral reading rate with low vision devices (LVDs), would apply using large print sizes more readily available in clinical situations (e.g. 2 degrees, 1.4 logMAR character size) for subjects with macular degeneration. For 22 14.3-88.4 year olds with either juvenile (mean age 36 yrs) or age-related (mean age 76 yrs) macular degeneration, the authors assessed rauding rates (reading for understanding). A combination of near-word visual acuity and large-print reading rate (without LVDs) provided the best prediction of oral rauding rates (with LVDs). However, near-word visual acuity alone was almost as good. Similarly, silent rauding rate was predicted best by near-word visual acuity alone. Near visual acuity limits are suggested as a clinical guide to expected oral and silent reading performance with LVDs for patients with macular degeneration.

Raasch,T.W. and Rubin, G.S. (1993).Reading with low vision.Journal of the American Optometric Association, 64(1), p15-18.

Abstract: Most subjects with low vision express a desire to read standard print as easily and as quickly as possible. There are a multitude of visual factors that can interfere with reading, yet we hove only an incomplete understanding of these factors. These include the relationship between acuity, magnification, and reading performance, the role of eye movements in low vision reading, and the effect of central scotomas on reading performance. We describe current research in each of these areas, and discuss their potential clinical implications.

Yager, D., Aquilante, K., and Plass, R. (1998). High and low luminance letters, acuity reserve, and font effects on reading speed.Vision Research, 38, p2527-2531. Abstract: Compared reading speed in 46 normally sighted high school and optometry students with two fonts, Dutch (serif) and Swiss (sans serif). Text was displayed on a computer monitor, white letters on black, with the RSVP method. Luminance of the letters was either 146.0 or 0.146 cdm2. Lower-case x-height of the fonts was approximately 5.5 times as large as letter acuity. At the high luminance, there was no difference between reading rates. There was a significant advantage for the Swiss font at the low luminance. The acuity reserve for Swiss was higher than for Dutch at the low luminance, which may account for the difference in reading speeds.