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Suggested Citation:"Appendix E - Glossary ." National Academies of Sciences, Engineering, and Medicine. 2011. Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010). Washington, DC: The National Academies Press. doi: 10.17226/22902.
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Page 332
Suggested Citation:"Appendix E - Glossary ." National Academies of Sciences, Engineering, and Medicine. 2011. Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010). Washington, DC: The National Academies Press. doi: 10.17226/22902.
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Page 332
Page 333
Suggested Citation:"Appendix E - Glossary ." National Academies of Sciences, Engineering, and Medicine. 2011. Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010). Washington, DC: The National Academies Press. doi: 10.17226/22902.
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Page 333
Page 334
Suggested Citation:"Appendix E - Glossary ." National Academies of Sciences, Engineering, and Medicine. 2011. Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010). Washington, DC: The National Academies Press. doi: 10.17226/22902.
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Page 334

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Accessible Pedestrian Signals: A Guide to Best Practice E - 331 Appendix E: Glossary In the following list, MUTCD refers to defi nitions taken from Section 4A.02 Defi nitions Relating to Highway Traffi c Signals of the Manual on Uniform Traffi c Control Devices. Accessible pedestrian signal (APS). A device that communicates information about pedestrian timing in nonvisual format such as audible tones, verbal messages, and/or vibrating surfaces. (MUTCD) Actuated operation. A type of traffi c control signal operation in which some or all signal phases are operated on the basis of actuation. (MUTCD) Actuation. Initiation of a change in or extension of a traffi c signal phase through the operation of any type of detector. (MUTCD) Actuation indicator. Either a light, a tone, a voice message, or both audible and visual indicators that indicate to pedestrians that the button press has been accepted. Alert tone at onset of WALK interval. A very brief burst of high frequency sound, rapidly decaying to a 500 Hz WALK tone, to alert pedestrians to the exact onset of the WALK interval. APS. See Accessible pedestrian signal. Audible beacon. Use of a sound source to provide directional orientation and alignment information. Automatic volume adjustment. An APS volume control that is automatically responsive to ambient (background) sound; automatic gain control. Braille street name. Provision of the name of the associated street in Braille above the APS pushbutton. Button actuated timer (BAT). See Extended button press. Clearance interval indicator. Tones sounding during the pedestrian clearance interval that are diff erentiated from the WALK interval indicator (tones). Controller unit. Th at part of a controller assembly that is devoted to the selection and timing of the display of signal indications. (MUTCD) Crosswalk. (a) that part of a roadway at an intersection included within the connections of the lateral lines of the sidewalks on opposite sides of the highway measured from the curbs or in the absence of curbs, from the edges of the traversable roadway, and in the absence of a sidewalk on one side of the roadway, the part of a roadway included within the extension of the lateral lines of the sidewalk at right angles to the centerline; (b) any portion of a roadway at an intersection or elsewhere distinctly indicated for pedestrian crossing by lines or other markings on the surface. (MUTCD) Crosswalk map. See Tactile map. Cycle Length. Th e time required for one complete sequence of signal indications. (MUTCD)

E - 332 Appendix E: Glossary Locator signal. See Pushbutton locator tone. Long button press. See Extended button press. Long cane. A cane individually prescribed to provide safety and orientation information to persons who are blind or visually impaired; typically much longer than a support cane and not intended for support; typically has a white, refl ective surface. Major street. Th e street normally carrying the higher volume of vehicular traffi c. (MUTCD) Minor street. Th e street normally carrying the lower volume of vehicular traffi c. (MUTCD) Passive pedestrian detection. A feature that uses sensors (piezo-electric, infrared, microwave, or video camera serving remote sensor software) to trigger, cancel, or lengthen pedestrian timing, or to trigger the pushbutton locator tone when the pedestrian enters the detection zone. Pedestrian. People who travel on foot or who use assistive devices, such as wheelchairs, for mobility. Pedestrian change interval. An interval during which the fl ashing UPRAISED HAND (symbolizing DONT WALK) signal indication is displayed. When a verbal message is provided at an accessible pedestrian signal, the verbal message is “wait.” (MUTCD) Pedestrian clearance time. The time provided for a pedestrian crossing in a crosswalk, after leaving the curb or shoulder, to travel to the center of the farthest traveled lane or to a median. (MUTCD) Detectable warning. A standardized surface feature built in or applied to walking surfaces or other elements to warn visually impaired people of hazards on a circulation path. Detector. A sensing device used for determining the presence or passage of vehicles or pedestrians. (MUTCD) Extended button press. On APS, holding the ped button down between 1-3 sec. may activate special features, including audible beaconing and extended pedestrian clearance interval. Fixed time operation. See Pretimed operation. Flashing (fl ashing mode). A mode of operation in which a traffi c signal indication is turned on and off repetitively. (MUTCD) Full-actuated operation. A type of traffi c control signal operation in which all signal phases function on the basis of actuation. (MUTCD) Intersection. (a) the area embraced within the prolongation or connection of the lateral curb lines, or if none, the lateral boundary lines of the roadways of two highways that join one another at, or approximately at, right angles, or the area within which vehicles traveling on diff erent highways that join at any other angle may come into confl ict; (b) the junction of an alley or driveway with a roadway or highway shall not constitute an intersection. (MUTCD) Interval. Th e part of a signal cycle during which signal indications do not change. (MUTCD) Interval sequence. Interval sequence. Th e order of appearance of signal indications during successive intervals of a signal cycle. (MUTCD)

Accessible Pedestrian Signals: A Guide to Best Practice E - 333 left or right GREEN ARROW signal indication is displayed. (MUTCD) Pushbutton. A button to activate pedestrian timing. (MUTCD) Pushbutton locator tone. A repeating sound that informs approaching pedestrians that they are required to push a button to actuate pedestrian timing and that enables pedestrians who have visual disabilities to locate the pushbutton. (MUTCD) Pushbutton message. A speech message that provides additional information when the APS pedestrian pushbutton is pushed. Remote activation. A handheld pushbutton device allowing a pedestrian to send a message over a short distance to call the ped phase. Semiactuated operation. A type of traffi c control signal operation in which at least one, but not all, signal phases function on the basis of actuation. (MUTCD) Signal head. An assembly of one or more signal faces together with the associated signal housings. (MUTCD) Signal indication. Th e illumination of a signal lens or equivalent device. (MUTCD) Signal phase. Th e right-of-way, yellow change, and red clearance intervals in a cycle that are assigned to an independent traffi c movement or combination of movements. (MUTCD) Signal section. Th e assembly of a signal housing, signal lens, and light source with necessary components to be used for providing one signal indication. (MUTCD) Pedestrian phase (or ped phase). The cycle of pedestrian timing consisting of three parts: (1) The WALK interval (WALK sign); (2) the pedestrian clearance interval (f lashing DONT WALK); and the pedestrian change interval (steady DONT WALK). Pedestrian signal head. A signal head, which contains the symbols WALKING PERSON (symbolizing WALK) and UPRAISED HAND (symbolizing DONT WALK), that is installed to direct pedestrian traffi c at a traffi c control signal. (MUTCD). Pedhead. See Pedestrian signal head. Permissive mode. A mode of traffi c control signal operation in which, when a CIRCULAR GREEN signal indication is displayed, left or right turns may be made after yielding to pedestrians and/or oncoming traffi c. (MUTCD) Preemption control. Th e transfer of normal operation of a traffi c control signal to a special control mode of operation. (MUTCD) Pretimed operation. A type of traffi c control signal operation in which none of the signal phases function on the basis of actuation. (MUTCD) Priority control. A means by which the assignment of right-of-way is obtained or modifi ed. (MUTCD) PROWAAC. Public Rights of Way Access Advisory Committee of the U.S. Access Board, that includes advocates, engineers, architects, and public works offi cials. Protected mode. A mode of traffi c control signal operation in which left or right turns may be made when a

E - 334 Appendix E: Glossary WALK interval. An interval during which the WALKING PERSON (symbolizing WALK) signal indication is displayed. When a verbal message is provided at an accessible pedestrian signal, the verbal message is “WALK sign.” (MUTCD) Signal timing. Th e amount of time allocated for the display of a signal indication. (MUTCD) Signal warrant. A threshold condition that, if found to be satisfi ed as part of an engineering study, shall result in analysis of other traffi c conditions or factors to determine whether a traffi c control signal or other improvement is justifi ed. (MUTCD) Steady (steady mode). Th e continuous illumination of a signal indication for the duration of an interval, signal phase, or consecutive signal phases. (MUTCD) Tactile. An object that can be perceived using the sense of touch. Tactile arrow (aligned in direction of travel). A raised (tactile) arrow in an APS pushbutton that helps users know which crosswalk is actuated by the pushbutton. Tactile map. A raised schematic map (located on an APS pushbutton housing) that shows what will be encountered as the pedestrian negotiates the crosswalk controlled by that push button. Traffi c control signal (traffi c signal). Any highway traffi c signal by which traffi c is alternately directed to stop and permitted to proceed. (MUTCD) Vibrotactile pedestrian device. A device that communicates, by touch, information about pedestrian timing using a vibrating surface. (MUTCD)

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TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 150: Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010) provides an introduction to accessible pedestrian signals (APS) and highlights issues related to the design, installation, operation, and maintenance of APS.

The report also addresses public education, U.S. case studies, and international practice related to APS. In addition, the report explores issues related to travel by pedestrians who are blind or who have low vision, and examines traffic signals and modern intersection design.

NCHRP Web-Only Document 150 is designed to serve as a companion resource document to a one-day training course on accessible pedestrian signals. For information on the training program, contact Stephan Parker of TRB at SAParker@nas.edu.

NCHRP Web-Only Document 150 is a reformatted edition of and replaces NCHRP Web-Only Document 117A: Accessible Pedestrian Signals: A Guide to Best Practice.

On July 20, 2011, TRB co-sponsored a web briefing or "webinar" that explored information about the project. As a part of the webinar, panelists provided information about how to host a free APS workshop offered through NCHRP. Details about the webinar can be found on our website.

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