Support:
The primary technique that pedestrians who have visual disabilities use
to cross streets at signalized intersections is to initiate their crossing
when they hear the traffic in front of them stop and the traffic alongside
them begin to move, corresponding to the onset of the green interval.
This technique is effective at many signalized intersections. The existing
environment is often sufficient to provide the information that pedestrians
who have visual disabilities need to operate safely at a signalized intersection.
Therefore, many signalized intersections will not require any accessible
pedestrian signals.
Guidance:
If a particular signalized intersection presents difficulties for pedestrians
who have visual disabilities to cross safely and effectively, an engineering
study should be conducted that considers the safety and effectiveness
for pedestrians in general, as well as the information needs of pedestrians
with visual disabilities.
Support:
The factors that might make crossing at an intersection difficult for
pedestrians who have visual disabilities include: increasingly quiet cars,
right turn on red (which masks the beginning of the through phase), continuous
right-turn movements, complex signal operations, traffic circles, and
wide streets. Further, low traffic volumes might make it difficult for
pedestrians who have visual disabilities to discern signal phase changes.
Local organizations, providing support services to pedestrians who have
visual and/or hearing disabilities, can often act as important advisors
to the traffic engineer when consideration is being given to the installation
of devices to assist such pedestrians. Additionally, orientation and mobility
specialists or similar staff also might be able to provide a wide range
of advice. The U.S. Access Board’s Document A-37, “Accessible
Pedestrian Signals,” provides various techniques for making pedestrian
signal information available to persons with visual disabilities.
Accessible pedestrian signals provide information in non-visual format
(such as audible tones, verbal messages, and/or vibrating surfaces).
Information regarding detectors for accessible pedestrian signals is found
in Section 4E.08.
Standard: When used, accessible pedestrian signals shall be used in combination
with pedestrian signal timing. The information provided by an accessible
pedestrian signal shall clearly indicate which pedestrian crossing is
served by each device.
Under stop-and-go operation, accessible pedestrian signals shall
not be limited in operation by the time of day or day of week.
Guidance:
The installation of accessible pedestrian signals at signalized intersections
should be based on an engineering study, which should consider the following
factors:
A. Potential demand for accessible pedestrian signals.
B. A request for accessible pedestrian signals.
Traffic volumes during times when pedestrians might be present; including
periods of low traffic volumes or high turn-on-red volumes.
C. The complexity of traffic signal phasing.
D. The complexity of intersection geometry.
Support:
Technology that provides different sounds for each non-concurrent signal
phase has frequently been found to provide ambiguous information.
Standard: When choosing audible tones, possible extraneous sources of sounds
(such as wind, rain, vehicle back-up warnings, or birds) shall be considered
in order to eliminate potential confusion to pedestrians who have visual
disabilities.
Guidance:
Audible pedestrian tones should be carefully selected to avoid misleading
pedestrians who have visual disabilities when the following conditions
exist:
A. Where there is an island that allows unsignalized right turns across
a crosswalk between the island and the sidewalk.
B. Where multi-leg approaches or complex signal phasing require more than
two pedestrian phases, such that it might be unclear which crosswalk is
served by each audible tone.
C. At intersections where a diagonal pedestrian crossing is allowed, or
where one street receives a WALKING PERSON (symbolizing WALK) signal indication
simultaneously with another street.
Standard: When accessible pedestrian signals have an audible tone(s), they
shall have a tone for the walk interval. The audible tone(s) shall be
audible from the beginning of the associated crosswalk. If the tone for
the walk interval is similar to the pushbutton locator tone, the walk
interval tone shall have a faster repetition rate than the associated
pushbutton locator tone.
Support:
A pushbutton locator tone is a repeating sound that informs approaching
pedestrians that they are required to push a button to actuate pedestrian
timing, and that enables visually-impaired pedestrians to locate the pushbutton.
Guidance:
The accessible walk signal tone should be no louder than the locator tone,
except when there is optional activation to provide a louder signal tone
for a single pedestrian phase.
Automatic volume adjustment in response to ambient traffic sound level
should be provided up to a maximum volume of 89 dB. Where automatic volume
adjustment is used, tones should be no more than 5 dB louder than ambient
sound.
Standard: When verbal messages are used to communicate the pedestrian interval,
they shall provide a clear message that the walk interval is in effect,
as well as to which crossing it applies.
The verbal message that is provided at regular intervals throughout the
timing of the walk interval shall be the term “walk sign,”
which may be followed by the name of the street to be crossed.
A verbal message is not required at times when the walk interval
is not timing, but, if provided:
A. It shall be the term “wait.” B. It need not be repeated for the entire time that the walk interval
is not timing.
Option:
Accessible pedestrian signals that provide verbal messages may provide
similar messages in languages other than English, if needed, except for
the terms “walk sign” and “wait.”
Support:
A vibrotactile pedestrian device communicates information about pedestrian
timing through a vibrating surface by touch.
Standard: Vibrotactile pedestrian devices, where used, shall indicate that
the walk interval is in effect, and for which direction it applies, through
the use of a vibrating directional arrow or some other means.
Guidance:
When provided, vibrotactile pedestrian devices should be located next
to, and on the same pole as, the pedestrian pushbutton, if any, and adjacent
to the intended crosswalk.
top Section 4E.08 Accessible
Pedestrian Signal Detectors
Support:
An accessible pedestrian signal detector is a device designated to assist
the pedestrian who has visual or physical disabilities in activating the
pedestrian phase.
Option:
Accessible pedestrian signal detectors may be pushbuttons or passive detection
devices. Pushbutton locator tones may be used with accessible pedestrian
signals.
Standard: At accessible pedestrian signal locations with pedestrian actuation,
each pushbutton shall activate both the walk interval and the accessible
pedestrian signals.
Guidance:
At accessible pedestrian signal locations, pushbuttons should clearly
indicate which crosswalk signal is actuated by each pushbutton. Pushbuttons
and tactile arrows should have high visual contrast (see the Department
of Justice’s Americans with Disabilities Act Standards for Accessible
Design, 1991). Tactile arrows should point in the same direction as the
associated crosswalk. At corners of signalized locations with accessible
pedestrian signals where two pedestrian pushbuttons are provided, the
pushbuttons should be separated by a distance of at least 3 m (10 ft).
This enables pedestrians who have visual disabilities to distinguish and
locate the appropriate pushbutton.
Pushbuttons for accessible pedestrian signals should be located as follows:
A. Adjacent to a level all-weather surface to provide access from a wheelchair,
and where there is an all-weather surface, wheelchair accessible route
to the ramp;
B. Within 1.5 m (5 ft) of the crosswalk extended;
C. Within 3 m (10 ft) of the edge of the curb, shoulder, or pavement;
and
D. Parallel to the crosswalk to be used (see Figure 4E-2).
If the pedestrian clearance time is sufficient only to cross from the
curb or shoulder to a median of sufficient width for pedestrians to wait
and accessible pedestrian detectors are used, an additional accessible
pedestrian detector should be provided in the median.
Standard: When used, pushbutton locator tones shall be easily locatable,
shall have a duration of 0.15 seconds or less, and shall repeat at 1-second
intervals.
Guidance:
Pushbuttons should be audibly locatable. Pushbutton locator tones should
be intensity responsive to ambient sound, and be audible 1.8 to 3.7 m
(6 to 12 ft) from the pushbutton, or to the building line, whichever is
less. Pushbutton locator tones should be no more than 5 dB louder than
ambient sound.
Pushbutton locator tones should be deactivated during flashing operation
of the traffic control signal.
Option:
At locations with pretimed traffic signals or nonactuated approaches,
pedestrian pushbuttons may be used to activate the accessible pedestrian
signals.
The audible tone(s) may be made louder (up to a maximum of 89 dB) by holding
down the pushbutton for a minimum of 3 seconds. The louder audible tone(s)
may also alternate back and forth across the crosswalk, thus providing
optimal directional information.
