Appendix E: Glossary
In the following list, MUTCD refers to definitions taken from Section 4A.02 Definitions Relating to Highway Traffic Signals of the Manual on Uniform Traffic 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 traffic 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 traffic 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 differentiated from the WALK interval indicator (tones).
Controller unit. That 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. The time required for one complete sequence of signal indications. (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 (flashing mode). A mode of operation in which a traffic signal indication is turned on and off repetitively. (MUTCD)
Full-actuated operation. A type of traffic 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 different highways that join at any other angle may come into conflict; (b) the junction of an alley or driveway with a roadway or highway shall not constitute an intersection. (MUTCD)
Interval. The part of a signal cycle during which signal indications do not change. (MUTCD)
Interval sequence. The order of appearance of signal indications during successive intervals of a signal cycle. (MUTCD)
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, reflective surface.
Major street. The street normally carrying the higher volume of vehicular traffic. (MUTCD)
Minor street. The street normally carrying the lower volume of vehicular traffic. (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 flashing 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)
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 (flashing 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 traffic at a traffic control signal. (MUTCD).
Pedhead. See Pedestrian signal head.
Permissive mode. A mode of traffic 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 traffic. (MUTCD)
Preemption control. The transfer of normal operation of a traffic control signal to a special control mode of operation. (MUTCD)
Pretimed operation. A type of traffic 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 modified. (MUTCD)
PROWAAC. Public Rights of Way Access Advisory Committee of the U.S. Access Board, that includes advocates, engineers, architects, and public works officials.
Protected mode. A mode of traffic control signal operation in which left or right turns may be made when a 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 traffic 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. The illumination of a signal lens or equivalent device. (MUTCD)
Signal phase. The right-of-way, yellow change, and red clearance intervals in a cycle that are assigned to an independent traffic movement or combination of movements. (MUTCD)
Signal section. The assembly of a signal housing, signal lens, and light source with necessary components to be used for providing one signal indication. (MUTCD)
Signal timing. The amount of time allocated for the display of a signal indication. (MUTCD)
Signal warrant. A threshold condition that, if found to be satisfied as part of an engineering study, shall result in analysis of other traffic conditions or factors to determine whether a traffic control signal or other improvement is justified. (MUTCD)
Steady (steady mode). The 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.
Traffic control signal (traffic signal). Any highway traffic signal by which traffic 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)
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)
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