X02.5.1.1 General. Where new traffic signals with pedestrian controls are installed, they shall comply with this section.
X02.5.1.2 Features. Push buttons shall have the following features.
(A) Size. Push buttons shall be a minimum of 2 inches (51mm) across in at least one dimension.
(B) Maximum force. The force required to activate push buttons shall be no greater than 3.5 pounds (15.5N).
(C) Operation. Push buttons shall be operable with a closed fist.
(D) Locator tone. There shall be a locator tone complying with X02.5.1.5.
(E) Visual contrast. Push buttons shall have a visual contrast with the body background of at least 70 percent.
(F) Indicator. There shall be a visible and audible indicator that the button press has occurred.
Advisory: A long button press (e.g., 3 seconds) may bring up the accessible features or additional accessibility features of the individual device. An additional button should not be used to bring up additional accessibility features. All accessible features available are to be actuated in the same way. Thus, for a given signal, a long button press could request more than one additional feature. Possible additional features include: 1) sound beaconing by increasing the volume of the WALK tone and the associated locator tone for one signal cycle, so a blind pedestrian might be able to use the sound from the opposite side of the street to provide alignment information; 2) sound beaconing by alternating the audible WALK signal back and forth from one end of the crosswalk to the other; 3) providing extended crossing time; and 4) providing a voice message with the street names at the intersection.
(G) Signage. Signage accompanying push buttons shall comply with Section X02.5.1.4.
Discussion: These specifications are intended to make pedestrian push buttons accessible. The recommended change to a reduced maximum operating force is based in part, on the preamble to proposed ADAAG309 Operable Parts (p 62262, 2nd col): "Information indicates that most control buttons of keys can meet a 3.5 maximum pounds of force and a maximum stroke depth of 1/10 inches." The closed fist requirement is based on the Access Board's design guidelines: "Devices that can be operated by a closed fist acting on any point on the surface will be most usable by pedestrians who have mobility impairments." The provision of visual contrast and a locator tone enable blind or visually impaired pedestrians to locate the push button. The visible and audible indicator informs both visually impaired and sighted individuals that the request for a walk signal has been received.
X02.5.1.3 Push button location. The location of push buttons shall be in accordance with the following minimum requirements.
(A) Adjacent to landing. The push button shall be mounted adjacent to a clear ground space or a landing on the pedestrian access route leading to the crosswalk. The clear ground space shall be at least 32 inches by 54 inches (815 by 1370mm), shall slope no more than 1:48 in any direction, and shall be provided with a stable, firm and slip resistant surface from which to operate controls. This clear ground space may overlap entirely with the pedestrian access route.
(B) Proximity to approach. Where a parallel approach to the push button is provided, controls shall be within 10 inches (255 mm) of the clear ground space, measured horizontally, and centered on it. Where a forward approach is provided, controls shall abut and be centered on the clear ground space.
(C) Direction of control face. The control face of the push button shall be parallel to the direction of the crosswalk controlled by the push button, and no closer than 30 inches (760mm) to the curb line.
(D) Mounting height. The centerline of the push button shall be mounted 42 inches (1070mm) above the clear ground space for approach.
(E) Close to crosswalk. The push button shall be mounted no further than 5 feet (1.5m) from the extension of the crosswalk lines, and within 10 feet (3m) of the curb line, unless the curb ramp is longer than 10 feet (3m).
(F) Proximity to curb or transition ramp. When located at a curb ramp, the push button shall be placed within 24 inches (610mm) of the top corner of the curb ramp, on the side furthest from the center of the intersection of the roadway. When located at a transition ramp, the push button shall be placed adjacent to the lower landing.
Advisory: It should be noted that for information in vibrotactile format to be useable, the pole must be located so the user is able to keep a hand on the button while aligned at the top of the curb ramp or at the crosswalk. Note: vibrotactile information alone is not allowed.
(G) Separation. Where there are two accessible pedestrian signals on the same corner, the push buttons shall be mounted on poles separated by at least 10 feet (3 meters).
EXCEPTION: If the requirement for separation cannot be met due to location requirements (A) through (G), two accessible pedestrian signal-related push buttons may be installed on a single pole. If installed on the same pole, the APS must be equipped to provide speech-transmitted data or other technology that delivers an unambiguous message about which crosswalk has the walk signal indication.
Curb ramps at an intersection with APS zones indicated in plan.
Transition ramps at an intersection with APS zones indicated in plan.
Shared ramp at an intersection with APS zones indicated in plan.
Discussion: Requirements for push button location were discussed in detail by the subcommittee and are essentially the same as requirements proposed by FHWA for inclusion in the Manual on Uniform Traffic Control Devices (MUTCD) in December 1999. The committee's intent is to standardize some elements of pedestrian push button location to make the push button more accessible to pedestrians who are blind or who have vision impairments. Locating the pedestrian push buttons at some distance from the crosswalk, which is common now, makes it difficult for a pedestrian, particularly a blind pedestrian or a pedestrian using a mobility aid, to push the button and return to the crosswalk location in time for the walk phase. Users of wheelchairs and mobility aids need to be able to push the button from a level surface. The control face of the push button or the push button housing will include a tactile arrow to inform a blind pedestrian about the direction of the crosswalk, so the location and direction of the control must be aligned with the crosswalk. Since the APS will provide an audible indication of the walk interval from the pedestrian push button, the blind pedestrian must be able to discern which signal is sounding at each phase. This is much harder if both APS are on the same pole, since using only different tones to distinguish the directions is prohibited in Section X02.5.2.2 (A). The separation is intended to allow the blind pedestrian to determine which APS is sounding through sound localization while standing at the curb preparing to cross the street. While the separation is not required for call buttons that are not associated with an APS or locator tone, routinely separating the call buttons will result in a more uniform and predictable location, and will facilitate future APS and/or locator tone installation.
(A) Tactile arrow. Where there is a push button, there shall be a tactile arrow pointing in the direction of pedestrian travel controlled by the button. The arrow shall be raised at least 1/32 inch (0.8 mm), 1 1/2 inches (38mm) in length. Stroke width shall be between 10 percent minimum and 15 percent maximum the length of the arrow. The arrowhead shall be open and at 45 degrees to the shaft. The arrowhead shall be no more than 33 percent of the length of the arrow shaft.
Advisory: If the curb ramp is not aligned with the crosswalk, the arrow will point in the direction of travel, not in the direction of the curb ramp orientation.
Diagrammatic view of arrow illustrating proportional relationships.
(B) Universal symbol. Controls are to include a universal tactile and visual symbol (if established by the Access Board) that will go on or at the push button indicating the presence or absence of an accessible pedestrian signal at a crosswalk.
Diagram of three Braille dots forming an equilateral triangle centered on the face of a 2" push button.
Discussion: For the universal tactile and visual symbol, the committee suggests application of three dots in a triangle on the button as close to the center as practicable.
(C) Street name. Street name information shall be provided at pedestrian push buttons. The accessible street name information provided at a pedestrian push button shall include the street name (or a reasonable abbreviation) in grade 2 Braille and in tactile raised letters complying with Section X02.3 and Section X02.5.1.4. The sign shall be located immediately above the push button mechanism and parallel to the crosswalk controlled by the button. The street name shall be the name of the street whose crosswalk is controlled by the push button.
Advisory: While this is in contrast to the convention in visual street naming, where the street name is parallel to the street itself in order to be visible to drivers and pedestrians, it is not in contrast to visual signs adjacent to pedestrian push buttons which indicate which street is controlled by the push button.
Audible signage may be provided in addition to Braille and tactile signage. Audible signage can provide auxiliary information about the intersection, which can be of great value to persons with visual impairments and to persons benefiting from redundancies.
Discussion: The arrow and street name information at the push button will provide information accessible to blind pedestrians, now typically provided to sighted pedestrians by signage, to clearly indicate which crosswalk is controlled by the push button. The arrow must be oriented parallel to the crosswalk to give this information clearly; the specifications of the arrow are to make it more easily distinguishable by touch.
(D) Crosswalk mapping. Where a map of a crosswalk is associated with a push button, the map shall be visual and tactile. Maps shall have at least 70 percent visual contrast, light-on-dark or dark-on-light. The characters and/or symbols shall be raised 1/32 inch (0.8mm) minimum. The crosswalk shall be represented by a vertical line, with the departure end of the crosswalk at the bottom of the map. The map shall be on the side of the push button housing that is furthest from the street to be crossed.
Advisory: The above elements should be arranged at a push button as follows : symbol on the push button, arrow on or immediately above the push button, and signage above the arrow.
X02.5.1.5 Locator tone. Where provided, locator tones shall meet the following requirements.
(A) Volume. Volume of the locator tone shall be at least 2 dB and no more than 5 dB greater than the ambient noise level and shall be responsive to level changes. At installation, signal system is to be adjusted to be audible at no more than 5 to 12 feet (1.5 - 3.7m) from the system or at building line, whichever is closer.
EXCEPTION: At locations with audible beaconing, in response to a long button press, the locator tone loudness may increase during the pedestrian clearance interval to allow the user to hear the tone on the opposite side of the intersection (see Section X02.5.2.3 (B)).
(B) Repetition. The locator tone shall be 0.15 seconds maximum in duration and repeat at one second intervals. Sound shall operate during the DON'T WALK and flashing DON'T WALK pedestrian clearance interval of the signal.
(C) Availability. The locator tone shall be audible whenever people are in the vicinity.
Advisory: The locator tone may be initiated by a passive detector such as an infrared detector, and therefore sound only when pedestrian presence triggers the device.
(D) Deactivation. The locator tone shall be deactivated during periods in which the pedestrian signal system is inactive.
Discussion: A locator tone notifies pedestrians who are blind or visually impaired of the need to push a button to request a WALK signal. It also indicates the location of the push button. These specifications are the same as the specifications in the proposed MUTCD for the locator tone.
Research need: A variety of tones are currently utilized as locator tones. The above specifications describe the repetition rate of the tone, however the exact nature of the tone is not specified. Research is recommended to determine the most localizable tone in the presence of traffic sounds.
X02.5.2.1 General. Where new traffic signals are installed, accessible pedestrian signals (APS) shall be provided when any of the following conditions are present:
(A) Actuation. An accessible pedestrian signal shall be provided where the timing of pedestrian phases is affected by push button actuation.
(B) Lead pedestrian interval. An accessible pedestrian signal shall be provided where the signal includes a leading pedestrian interval (LPI).
Advisory: Without an accessible pedestrian signal, a blind pedestrian listening for a parallel traffic surge at a crosswalk with LPI may miss the walk interval and enter the crosswalk without enough time to complete the crossing before the signal changes.
(C) Pretimed signal. An accessible pedestrian signal that is available at the option of the user shall be provided where there is a pretimed traffic signal that presents pedestrian signal indication information. In this instance, a push button shall be provided that actuates the accessible pedestrian signal.
Discussion: The primary technique that people who are blind or visually impaired have used to cross streets at signalized locations is to initiate their crossing when they hear the traffic alongside them begin to move, corresponding to the onset of the green interval. The effectiveness of this technique has been reduced by several factors including: increasingly quiet cars, the availability of right turn on red (which masks the beginning of the through phase), complex signal operations and wide streets. Further, low traffic volumes make it difficult for pedestrians who are blind or visually impaired to discern signal phase changes. The increasing use of actuated signals, at which the pedestrian must push a button and cross during the pedestrian phase, requires blind pedestrians to locate the pedestrian push button and to cross only at the proper time during that phase. These changes in signalization make it necessary to provide the pedestrian signal information in an accessible format. In responding to a request for an accessible pedestrian signal at an existing intersection, the jurisdiction may find it useful to work closely with the blind pedestrian(s) who will be using the intersection and with an orientation and mobility specialist.
X02.5.2.2 Required features. Where accessible pedestrian signals are provided, they shall comply with the following requirements.
(A) Crosswalk indication. Accessible pedestrian signals shall clearly indicate which crosswalk has the walk interval. The use of two different tones as sole indication of which crosswalk has the walk interval is not permitted.
Advisory: When walk interval information is broadcast from the push button housing, then separation of the push buttons combined with the required signage is a good means to provide crosswalk-specific information. A speech message may also be used to provide this information. The MUTCD specifies the wording of such a speech message. Remote infrared audible signs (RIAS), which are inherently directional, are another good way to clearly indicate which crosswalk has the walk interval. Additional strategies that may provide unambiguous information are an alternating audible signal or an audible signal from the far end of the crosswalk; however, this type of beaconing is not generally recommended; see X02.5.2.3 (B), Audible Beaconing.
(B) Walk indication. When indicating the walk interval, the accessible pedestrian signal shall deliver the indication in audible and in vibrotactile format. Signals providing accessible information in vibrotactile format only are not permitted.
(C) Locator tones. Where an accessible pedestrian signal is controlled by a push button, there shall be an associated locator tone.
(D) Walk interval tone. When an APS uses audible tones, it shall have a specific tone for the walk interval. If the same tone is used for the push button locator tone, the walk interval tone shall have a faster repetition rate than the associated locator tone. The two signals shall be distinguishable either by tone and/or by repetition rate. A voice message may be used for the WALK indication.
Where the APS provides signal information using tones, the tone shall consist of multiple frequencies with a large component at 880 Hz. The walk tone shall have a repetition rate of 5 Hz minimum and a duration of 0.15 seconds maximum.
Advisory: Frequencies above 1 kHz are difficult for persons with an age related hearing loss to detect. Multiple frequencies will assist a larger population group of vision and hearing impaired persons.
(E) Operating period. Under stop-and-go operation, APS shall not be limited in operation by time of day or day of week.
Advisory: Information access must not be abridged by day or time. Rather than disconnect a device for periods of time, volume should modulate in response to ambient levels.
(F) Activation. Actuating a single APS on an intersection is not intended to activate all other devices at all other crosswalks.
(G) Volume. Tones shall be at least 2dB and no more than 5dB greater than the ambient noise level and shall be sensitive to level changes. The walk tone shall be no louder than the locator tone. At installation, the signal system should be adjusted to be audible at no more than 5 to 12 feet (1.5 to 3.7m) from the system or at building line whichever is closer. If an audible tone is provided, the audible tone(s) shall be audible from the beginning of the associated crosswalk. Audible information shall be provided at the departure curb only.
EXCEPTION: Where audible beaconing is provided, the opposite beacon may be audible at the departure curb. A louder walk interval audible tone and subsequent pedestrian clearance interval tone may be provided after a long button press at intersections where audible beaconing is needed.
Advisory: The APS specifications and sound levels recommended here are intended to provide precise information about the onset of the walk interval. Using special actuation as specified below, they may also function as audible beacons, giving assistance in alignment and crossing within the crosswalk.
(A) Prolonged push button press. Additional features which may be required to make a specific intersection accessible shall be brought up by a prolonged press of the push button.
Advisory: A long button press (e.g.,pushing the pushbutton for 3 seconds) may bring up the accessible features or additional accessibility features of the individual device. An additional button should not be used to bring up additional accessibility features. All accessible features available are to be actuated in the same way. Thus, for a given signal, a long button press could request more than one additional feature. Possible additional features include: 1) sound beaconing by increasing the volume of the WALK tone and the associated locator tone for one signal cycle, so a blind pedestrian might be able to use the sound from the opposite side of the street to provide alignment information; 2) sound beaconing by alternating the audible WALK signal back and forth from one end of the crosswalk to the other; 3) providing extended crossing time; and 4) providing a voice message with the street names at the intersection.
(B) Audible Beaconing. Where provided, audible beaconing signals shall be provided during the walk interval. Audible beaconing may be provided during the pedestrian clearance interval, if no conflicting traffic movements are permitted.
Advisory: Audible beaconing is usually not needed. Beaconing may be needed at intersections that are wide, have low parallel traffic volume, or have skewed crosswalks. Where beaconing is desired as an additional accessibility feature, it should be actuated by depressing the push button for a longer period of time.
Where beaconing is provided, it will be most effective if it functions only for that crosswalk where the push button was actuated. The area of definite audibility in the direction of travel should be detectable within one-third of the width of the crosswalk from the entrance to the crosswalk. Beaconing may be provided by the increase in the locator tone (see Section X02.5.1.5 (A.)).
Discussion: The technology of accessible pedestrian signals has developed in recent years. There are now four types of APS available in the United States. Overhead signals mounted on the pedestrian signal indication have been most commonly used, but problems noted include: difficulties identifying which signal is associated with which crosswalk and which signal is associated with which intersection; noise complaints from neighbors; and difficulty by blind pedestrians in hearing traffic above the loud sound of the APS.
Signals in which sound comes from the pedestrian push button and include a locator tone and vibrotactile information, are used extensively in Europe and Australia and are now available in the United States. There are also signals that are vibrotactile only, but that system is not recommended by the committee. Sound transmitted to a receiver carried by the blind pedestrian, using RIAS or Light Emitting Diode (LED) technology, has also been used to provide information about the status of the walk signal and to provide additional information about the location and the nature of the intersection. RIAS systems provide a beaconing effect by means of the directional sensitivity of the receiver units.
The features and specifications listed above are currently appropriate given the technology and research available. Future technological developments may lead to additional alternatives. The committee wished to open the door to new technologies, but was interested in clarifying some features that most members considered essential in an APS. The committee did not want travelers to be required to carry a single, function-specific receiver in order to access intersection information.
While sound beaconing is an alternative that may assist a blind pedestrian in aligning at a difficult crosswalk, the committee did not feel that the use of beaconing at all intersections is necessary. There are concerns that loud overhead APS may mask traffic sounds that are useful to the blind pedestrian, and subject residents who live near the APS to unacceptable noise levels. Nearby residents have objected to audible signals in the past where they used two different sounds in a beaconing manner to alert users. By providing tones with volume that modulates to ambient noise levels, noise intrusion beyond the intended hearing range is minimized and termination of the tone during night hours is unnecessary.
Research need: A variety of tones, speech messages, or melodies are currently utilized to indicate the walk interval. Research is recommended to determine the most localizable tone in the presence of traffic sounds. The committee felt there was enough information to provide basic specifications for the walk interval tones. Research now being conducted by the National Institutes of Health on accessible pedestrian signals will compare usability of overhead and pedestrian button mounted speakers for orientation and alignment and provide additional information regarding the use of tones, speech messages, or alternating signals for localization.
X02.5.3.1 Other pedestrian signals and timing controls not specifically described elsewhere shall comply with the requirements of this section.
Advisory: When a dedicated phase for left-turning auto traffic precedes the through movement and the walk interval, it increases the difficulty for persons using auditory cues to accurately determine the appropriate time to start crossing. It is easier to determine the appropriate time to start when the through movement occurs first and the left-turning movement afterward.
X02.5.3.2 Mid-block crosswalks. Reserved.
Research need: The committee had a lengthy discussion about how best to notify blind and visually impaired pedestrians of the availability of a mid-block crosswalk. The committee discussed requiring a push button with a locator tone at mid-block unsignalized crosswalks. The button would initiate a speech message notifying the user of the unsignalized condition. However, the committee was concerned about diluting the meaning of a locator tone. The committee decided that a guidance surface would be preferable to a locator tone. However, at this time the information necessary to fully specify the texture, placement, material, contrast or other characteristics of guidance surfaces is not available. As this research is completed, requirement for a detectable surface may be appropriate.
X02.5.3.3 Near side pedestrian signals. Reserved.
Discussion: Providing pedestrian signal indication on the near side of the crosswalk is of direct benefit to persons with low vision and to persons benefited by redundancies. Use of larger devices and signage which is visible at near side curbs is encouraged.
X02.5.4.1 General. Where provided, crosswalks shall comply with the following requirements.
X02.5.4.2 Cross slope. The cross slope of crosswalks, at either marked or unmarked locations, shall be not more than 1:48 measured perpendicular to the direction of pedestrian travel.
X02.5.4.3 Running grade. The running grade of crosswalks, at either marked or unmarked locations, shall be not more than 1:20 (5 percent) in the direction of pedestrian travel in the crosswalk.
Discussion: It is not uncommon for streets to be constructed with constant profile grades up to 9 percent or 10 percent. This standard requires reduction of these profile grades to 2 percent at both marked and unmarked crosswalks. It applies wherever applicable law defines a crosswalk. Street design will need to include a "tabled" area at locations of crosswalks (generally at intersections) that provides 2 percent or less grade at the intersection. Transitions into and out of the intersection can be accomplished with vertical curves in the street profile.
In addition, superelevation (or banking) can result in steeper cross slopes. These grades and cross slopes create street crossing conditions that are very difficult for persons in wheelchairs and persons with other mobility limitations. Limiting these street cross slopes (which are the running grade in the crosswalk) to 5 percent creates a manageable crossing condition.
Cross slope increases the difficulty and amount of energy expended by a person in a wheelchair. Often cross slope is harder to negotiate than running grade. At more than 1:48, a person in a manual wheelchair will be pushing forward on the downhill wheel and braking with the uphill wheel to keep the chair from turning downhill. A study by the Veterans Administration published in the Journal of Rehabilitation Research and Development in 1986 (Vol. 23, no. 2) indicates that a person on a level, smooth surface in a good quality chair with precision bearings will expend four times as much energy traveling 100 feet as a person walking the same distance, and that a 3 percent cross slope requires 50 percent more effort than a 2 percent cross slope.
X02.5.4.4 Markings. Crosswalks at signalized intersections shall be marked on the roadway with pavement markings.
Advisory: Crosswalk markings are especially important to pedestrians with low vision and pedestrians with cognitive disabilities. Consider marking crosswalks at unsignalized locations in any case where pedestrians and/or motorists need additional cues about the safest location for crossing.
Discussion: The committee would have liked to recommend requiring crosswalk markings at every crosswalk, whether signalized or not, but some research indicates that crosswalk markings at unsignalized crosswalks can reduce safety for pedestrians. Although it seems likely that safety would be increased if all crosswalks were marked, the committee concluded that putting this requirement in the recommendation would be likely to generate an undesirable level of controversy.
X02.5.4.5 Width. Crosswalks shall be at least 8 feet wide
Advisory: The minimum width of the crosswalk should be measured from inside edge to inside edge in the case of parallel crosswalk markings or any markings that use parallel bordering lines, and from outside edge to outside edge in the case of piano key crosswalk markings or any other markings that do not use parallel bordering lines.
Discussion: The MUTCD requires a minimum of 6 feet of width for a crosswalk. Since blind, visually impaired and wheelchair users must pass each other in a crosswalk in an environment that demands rapid crossing times in vehicular controlled spaces, it is important for crosswalks to provide adequate width so quick and easy passing occurs without delaying clearance of the crosswalk.
X02.5.5.1 General. Pedestrian crossing intervals shall be calculated in compliance with the following requirements.
X02.5.5.2 Pedestrian walk speed. All pedestrian signal phase timing shall be calculated using a pedestrian walk speed of 3.5 feet per second (1.1 m/s) or less.
Advisory: Designers should consider extending the time for pedestrian crossing beyond the calculated requirement if any of the following factors are present: running grade of the crosswalk greater than 1:20; cross slope of the crosswalk greater than 1:48; or crosswalk length greater than 50 feet with no intermediate pedestrian refuges.
Extended time for pedestrian crossing may be initiated by passive detection of pedestrian movement in the crosswalk, provided that the detection system is designed to include detection of people using wheelchairs. Use of passive detection for this purpose is encouraged. Extended time may also be initiated by a long (e.g., greater than 3 seconds) button press.
Discussion: The committee recognized that the current standard for rate of pedestrian travel in a crosswalk is 4 feet per second, but was unconvinced that this rate is representative of the general population, particularly persons with disabilities. Many people with mobility impairments can move at only very slow speeds; a rate of about 1.5 feet per second on level ground. The committee understood that some jurisdictions are considering changing the rate used for calculating crossing timing from 4 feet per second to 2.5 feet per second. Recognizing that extending crossing times for pedestrians will have impacts on traffic flow, the committee wishes to encourage the use of flexible systems that respond to demand for extended crossing times, either through passive detection or the use of a long button press.
X02.5.5.3 Length of crosswalk defined. The total crosswalk distance used in calculating pedestrian signal phase timing shall include the entire length of the crosswalk plus the length of one curb ramp.
EXCEPTION: If the crosswalk has an APS signal, the starting point of the overall crosswalk length used for timing calculation is to extend to the vibrotactile signal pad or to the top of the curb ramp, whichever results in the longer distance.
Discussion: One reason for providing a level landing at the top of a curb ramp is so that pedestrians using wheelchairs or other mobility aids can safely wait for the walk interval, since waiting on the running grade of the curb ramp is not safe. It follows that this additional distance must be included in the length of the crosswalk used in calculating the pedestrian crossing interval.
X02.5.6.1 General. Raised medians and pedestrian refuge islands in crosswalks shall be cut through level with the street or have curb ramps complying with Section X02.4 at both sides. If cut through, there shall be a flush landing within the cut and the edges of the cut shall be aligned perpendicular to the street being crossed, or parallel to the direction of the pedestrian access route if the pedestrian access route is not perpendicular to the street. Where curb ramps are used there shall be a landing at the top of the curb ramp in the part of the island intersected by the crosswalks.
Partial plan view of an island with a landing 60 inches by 60 inches.
Discussion: Adequate stopping, queuing and passing places are necessary in mid-street pedestrian refuge locations. A five foot by five foot space is the minimum required for two persons traveling opposite directions to wait, out of the street, for opportunities to continue crossing the street.
X02.5.6.2 Detectable Warnings. Curb ramps at medians and refuge islands, and locations where medians and refuge islands are cut through level with the street at crosswalks, shall have detectable warnings complying with Section X02.5.7.
X02.5.7.1 General. Where required, detectable warnings shall comply with Section X02.5.7.
X02.5.7.2 Application. Detectable warnings shall be provided only at the following locations:
(A) Where a sidewalk crosses a vehicular way, excluding unsignalized driveway crossings.
Illustrates 24" deep detectable warning located near the street edge of the curb ramp.
Shows detectable warning at a transition ramp.
Figure X02.5 I Shared Curb Ramp with Detectable Warning
Shows detectable warning at a shared curb ramp.
Figure X02.5 J Detectable Warning at Blended Curb
Shows detectable warning at blended curb.
Plan view of a multi-use path and road intersection. Detectable warnings are indicated at the intersection.
(B) Where a rail system crosses pedestrian facilities that are not shared with vehicular ways.
Plan view of detectable warnings at a railroad crossing.
(C) At reflecting pools within the public right-of-way, which have no curb or rim protruding above the walking surface.
(D) At islands and medians that are cut through level with the roadway.
Plan view of pedestrian passage that cuts through a refuge island at the same level as the street. Detectable warnings are shown at each end of the cuts.
Advisory: Where islands or medians are less than 4 feet wide, the detectable warning should extend across the full length of the cut through the island or median.
(E) Where required by proposed ADAAG Chapter 10.
Discussion: The detectable warning is a unique and standardized surface intended to function much like a stop sign to alert pedestrians who are blind or visually impaired to the presence of hazards in the line of travel. The truncated dome surface should not be used for wayfinding or directional information. The removal of curbs, which provided a clearly defined indication of the location of the edge of the street, has caused difficulty for individuals who are blind or visually impaired. The locations above were identified by the committee as being appropriate for the installation of detectable warnings. Detectable warnings are not required at unsignalized driveways based on comments to the committee that installation at driveways would make it harder to truly identify the streets.
(A) Size. Detectable warnings shall be 24 inches (610mm) in the direction of travel and extend the full width of the curb ramp or flush surface.
Discussion: Research has confirmed that for persons who are visually impaired, there is a high level of risk of inadvertent street entry associated with the presence of curb ramps, particularly those having slopes of 1:12 or less (Bentzen, B. & Barlow, J., 1995; Hauger, S., Rigby, J., Safewright, M. and McAuley, W., 1996). It has been demonstrated that detectable warnings complying with existing ADAAG Section 4.29.2 are highly detectable by persons with visual impairments, and can provide an effective stop signal for persons who are blind or visually impaired which can be used to determine the end of the sidewalk and the beginning of the vehicular way. Research has also demonstrated that 24 inches of detectable warning material is sufficient to enable persons who are blind or visually impaired to stop on 90 percent of approaches (Peck, A. & Bentzen, B., 1987).
Research has now been conducted which addresses concerns about safety of detectable warnings for individuals with mobility impairments, indicating that detectable warnings on slopes have minimal impact on the safety and ease of travel for persons having physical disabilities (Bentzen, B., Nolin, T., Easton, R., Desmaris, P., and Mitchell, P., 1994; Hauger, et al, 1996). On the basis of this research, the committee voted to recommend the installation of detectable warnings at sidewalk/street transitions.
A few committee members did not fully support this recommendation, feeling there might be a significant adverse impact on safety and ease of travel for wheelchair users. The committee discussed threshold ramp grade requirements where only the gentlest ramps (1:15 and flatter) would have detectable warnings. Nonetheless, because such a requirement would tend to confuse both designers and builders and would give inconsistent information to individuals who are visually impaired, the committee voted to require detectable warnings on all sidewalk/street transitions regardless of slope.
(B) Location. The detectable warning shall be located so that the edge nearest the curb line or other potential hazard is 6 to 8 inches (150 to 205mm) from the curb line or other potential hazard, such as a reflecting pool edge or the dynamic envelope of rail operations.
Discussion: Placement of the detectable warnings a maximum of 6 to 8 inches back from the curb line gives some latitude in placement of the detectable warning. Where curbing is embedded at the sidewalk/street junction, this will not need to be replaced. In addition, allowing 6 to 8 inches of ramp (or curb) surface beyond the detectable warning will give pedestrians who are blind an additional stopping distance before they step into the street. It will also enable some persons having mobility impairments to make a smoother transition between the street and the curb ramp.
(C) Dome size and spacing. Truncated domes shall have a diameter of 0.9 inch (23 mm) at the bottom, a diameter of 0.4 inch (10 mm) at the top, a height of 0.2 inch (5 mm) and a center-to-center spacing of 2.35 inches (60 mm) measured along one side of a square arrangement.
Section of dome from a detectable warning. Drawing shows height, top and bottom dimensions.
Plan and section views of detectable warning domes and their relative spacing on the x and y axis.
Discussion: The size and spacing of the domes affect detectability by pedestrians who are blind. This specification is much more detailed than that in the current ADAAG, and offers much less latitude in dimensions and spacing. It ensures that the dome spacing is the maximum currently known to be consistent with high detectability. The diameter measurement in the present ADAAG is ambiguous if the user of these guidelines is not told whether the diameter is to be measured at the bottom or the top of the truncated domes. As currently implemented by most US manufacturers, it is the bottom diameter that measures 0.9 inch, and the top diameter varies widely. The diameter of the dome where it touches the sole of the shoe affects detectability, and the top diameter of 0.4 inch, in the suggested language, is based on current research (see below).
A few members of the committee felt that there needed to be more flexibility in the size and shape of the domes. Some suggestions were that the domes be a semi-spherical shape using a 1-inch base, or a "butte" design with a larger top diameter (0.6 inch). Wider spacing, up to 3 inches, between domes was also suggested. It was felt that the wider gaps or lanes between the domes would better accept the wheel path of most wheelchairs so that users would not need to "bump" over the domes. However, there was no evidence that either of these alternatives would be better or worse than the proposed standard in terms of ease of traversal by wheelchair users and detectability for individuals who are blind or visually impaired. The proposed standard is supported by research on spacing and detectability completed in Japan in 1998. The committee voted to recommend the parallel alignment of domes as well as the two-foot depth of the detectable warning, in consideration of minimizing bumpiness for wheelchair users.
(D) Dome alignment. Domes shall be aligned on a square grid in the predominant direction of travel to permit wheels to roll between domes.
Plan view of a detectable warning surface showing domes aligned in rows, not skewed diagonally.
Discussion: This specification ensures the greatest degree of safety and negotiability for persons with mobility impairments. It requires square alignment, to give persons using wheeled mobility aids the greatest chance of being able to avoid the truncated domes.
(E) Visual Contrast. There shall be a minimum of 70 percent contrast in light reflectance between the detectable warning and an adjoining surface, or the detectable warning shall be "safety yellow". The material used to provide visual contrast shall be an integral part of the detectable warning surface.
Advisory. Both domes and the underlying surface must meet the contrast requirement. Visual contrast shall be measured in accordance with existing ADAAG, A220.127.116.11, appendix.
Discussion: For pedestrians with low vision, a visual contrast will provide information about the location of the detectable warning and the street edge. Safety yellow is a color that is standardized for use as a warning in the pedestrian/highway environment. It has been demonstrated to be highly detectable when used as a detectable warning in contrasts as low as 40 percent (Bentzen, B.L., Nolin, T.L & Easton, R.D. (1994) Detectable warning surfaces: Color, contrast and reflectance. Final report, US Department of Transportation, Federal Transit Administration, Volpe National Transportation Systems Center. VNTSC-DTRS 57093-P-80546.) ADAAG currently recommends a 70 percent contrast, dark-on-light or light-on-dark.
There was concern on the part of some members that it may be impossible to develop and maintain a minimum 70 percent visual contrast with the materials commonly used in construction of public street improvements, such as Portland cement concrete. The committee agreed that visual contrast was essential but some members suggested that a lesser level of contrast could be as effective and more economical to provide than a minimum 70%.
Some members of the committee noted that safety yellow is not conspicuous to many persons with low vision, and that therefore high visual contrast should be the sole measure of whether detectable warnings are visible.
Research need: The committee encourages the transportation industry to broaden its testing of color and contrast of typical construction materials and to include pedestrians with vision impairments in the development of standards. Work performed at The Lighthouse in New York City and research by Bentzen et al. (1994) can provide a useful basis for future research.
X02.5.8.1 General. Where pedestrian overpasses and underpasses are provided to cross public rights-of-ways, each shall meet the requirements set forth in this section.
X02.5.8.2 Pedestrian access route. Where pedestrian overpasses and underpasses are provided as a primary means to cross a street, they must have continuous pedestrian access routes and shall provide an accessible connection to adjacent pedestrian facilities. When the continuous pedestrian access route of an overpass or underpass requires a ramp (i.e. with a grade greater than 1:20) and the vertical rise is greater than five feet, an elevator complying with proposed ADAAG Section 407.2 is required.
X02.5.8.3 Stairs. Stairs, when provided, shall comply with proposed ADAAG Section 504.
X02.5.8.4 Signs. Signs, where provided, shall be both tactile and visual and shall comply with proposed ADAAG Section 703.2.
X02.5.8.5 Lighting. Reserved.
Advisory: When artificial lighting is used to illuminate a pedestrian underpass, variable level lighting should be considered to maximize accessibility for persons with low vision. The difference between external lighting conditions and those in the overpass or underpass should be limited. Extreme differences in illumination levels can result in temporarily blinding individuals whose eyes adapt slowly to lighting changes.
Discussion: Elevators are being required when an elevation difference of more than five feet must be accomplished with grades of 5 percent or greater because lengthy travel along ramps to accomplish greater elevation changes results in very limited accessibility for many users.
The committee discussed the problems associated with current overpass/underpass designs. Although they may be designed in compliance with proposed ADAAG Section 405, the length of travel required uphill is simply beyond many users' abilities.
X02.5.9.1 General. Where marked or unmarked pedestrian crosswalks are provided at roundabouts, each shall meet the requirements set forth in this section.
(A) Separation. Continuous shrubbery, planters, landscaping, guardrails or other barriers shall be provided along the street side of the public sidewalk where pedestrian crossing is prohibited. Where railings are used they shall have a bottom rail no more than 15 inches (380mm) above the pedestrian access route so as to be detectable by cane in time to prevent street entry.
(B) Cues. A cue shall be provided to allow blind and visually impaired pedestrians to locate each crosswalk.
Advisory: The locator tone of an accessible pedestrian signal may be used to indicate the presence of the crosswalk.
(C) Signals. A pedestrian actuated traffic signal complying with Section X02.5.2 shall be provided for each segment of the crosswalk, including at the splitter island. Signals shall clearly identify which crosswalk segment the signal serves.
Advisory: If allowed by MUTCD, the signal system may provide for permissible crossings without activating the signal and without violating a DON'T WALK pedestrian signal. In addition, the accessible symbol shown in proposed ADAAG Section 703.7.2.1 may be displayed on the activation button to discourage use by pedestrians not needing the additional protection.
Discussion: Modern roundabouts are defined by two basic operational and design principles, 'yield-at-entry' and 'deflection for entering traffic'. The principle of 'yield at entry' requires that vehicles in the circulatory roadway have the right-of-way and all entering vehicles on approaches have to wait for a gap in the circulating flow. The entry control is a yield sign. Modern roundabouts are not designed for weaving movements. The principle of 'deflection for entering traffic' dictates that no traffic stream gets a straight movement through the intersection. Entering traffic points to the central island, which deflects vehicles to the right, thus causing low entry speeds. While this traffic pattern has been an asset to traffic planners in controlling and slowing the flow of traffic at intersections in lieu of having a signalized intersection, the absence of stopped traffic presents a major problem for blind and visually impaired pedestrians when crossing.
Barriers or similarly distinct elements are needed to prevent blind persons from inadvertently crossing a roundabout roadway in an unsafe location. The 15-inch dimension on the bottom rail, if a guardrail is used, was selected to allow the use of standard roadside guardrail, while maximizing cane detectability.
Because the pedestrian crosswalk is generally placed at least one car length from the entry point, in a location that is not immediately apparent to a blind or visually impaired pedestrian, a cue is needed for crosswalk location.
Pedestrians report that vehicles at roundabouts, right slip lanes, and other unsignalized pedestrian crosswalks often do not yield for pedestrians. Pedestrians with disabilities are particularly vulnerable in these situations. People who are blind or visually impaired are unable to make eye contact with drivers Ð making it impossible to 'claim the intersection.' The driver's view of people using wheelchairs is often blocked by other vehicles. Pedestrians with slower than normal mobility may hesitate when entering the street. All of these situations may result in drivers misinterpreting the pedestrian's intention to cross. For these reasons, pedestrians with disabilities must have the ability to reliably halt traffic when they are crossing. It is recognized, however, that the purpose of these types of unsignalized crosswalks is to keep traffic moving as continuously as possible. Traffic flow can be achieved, while still affording pedestrians with disabilities the opportunity to cross safely, with the use of pedestrian actuated technologies that halt traffic only while the pedestrian is in the crosswalk. An advantage of passive detectors is that, when pedestrians cross slowly, more time can be automatically provided. When a pedestrian crosses quickly, the traffic is stopped only during the time the pedestrian is crossing, thereby eliminating the problem of traffic being held up when no pedestrian is in the crosswalk.
Recommended question: The committee distinguished between a roundabout (typically a larger, total intersection design) and a neighborhood traffic circle (typically a small circle installed within the confines of an existing intersection). The committee limited its recommendations to roundabouts, since those traffic configurations appear to be the most complex and provide the most difficulty for pedestrians with disabilities to cross. However, the committee recommends that the Board ask a question inquiring whether the same mobility problems that are present at large roundabouts also pose similar problems at smaller neighborhood traffic circles.
X02.5.10 Turn lanes at intersections.
X02.5.10.1 General. Where marked or unmarked pedestrian crosswalks are provided at right or left turn slip lanes, each shall meet the requirements set forth in this section.
(A) Cue. A cue shall be provided to allow blind and visually impaired pedestrians to locate the crosswalk.
Advisory: The locator tone of an accessible pedestrian signal can be used to indicate the presence of the crosswalk.
(B) Signal. A pedestrian-activated traffic signal complying with Section X02.5.2 shall be provided for each segment of the pedestrian crosswalk, including at the channelizing island. Signals shall clearly identify which crosswalk segment the signal serves.
Advisory: If allowed by MUTCD, the signal system may provide for permissible crossings without activating the signal and without violating a DON'T WALK pedestrian signal indication. In addition, the accessible symbol shown in proposed ADAAG Section 703.7.2.1 may be displayed on the activation button to discourage use by pedestrians not needing the additional protection.
Discussion: Because crosswalks at roundabouts are typically located so they would not be immediately apparent to a blind or visually impaired pedestrian, a cue is needed for crosswalk location.
X02.6 Vehicular Ways and Facilities