Wiring needs and availability should be considered before ordering devices because some devices and features require additional wires between the pedestrian signal head, the pushbutton, and the controller. APS typically require an additional control board in the pedestrian signal head or in the controller cabinet.
Manufacturer's instructions should be reviewed, as wiring may be more complex than expected due to additional features such as the vibrotactile WALK indication (vibrating surface) and additional messages or tones. Other potential wiring issues are as follows:
- May need wire in addition to what is provided with the APS
- Wire types may range from phone type wire to stranded wire
- APS that require four wires may need to have extra wiring installed at the pushbutton poles.
- Some manufacturers provide a 2-wire APS model that uses the existing wiring from previously installed standard pushbuttons. For that installation a control unit is installed in the controller cabinet. Wiring this device requires correct connection of wires from pedestrian signal heads, particularly where two parallel crosswalk do not operate concurrently to provide accurate messages. In addition, replacing standard pushbuttons with APS may not be as easy as it appears. In some cases, new holes will have to be drilled and the APS mounted in a correct position if the previous pushbutton was not positioned correctly (e.g., previous pushbutton angled toward center of intersection instead of parallel to crosswalk).
- APS that provide audible beaconing from the far side only (opposite end of crosswalk from where button was pressed) may require additional wiring to provide the proper signals between the pedestrian signal and controller for the beaconing.
APS control units
As mentioned above, APS often have control units that must be installed in the pedhead or in the traffic signal controller. An example of a control board being installed in the pedhead is shown in Figure 7-2. As can be seen in the photo, the technician found that a bungee cord was helpful in holding the pedhead lens while he was installing and adjusting the APS control unit. Additional photos and information on control units can be found in Chapter 6 in "Mounting and Wiring Issues."
Traffic signal controllers
As stated earlier, APS devices work with current controllers used in the U.S. While Malfunction Management Unit (MMU) problems seem to have been solved by manufacturers, functioning of the intersection and devices should be carefully checked after installation.
Pushbuttons, tactile arrows, vibrating surfaces and signs
Height of pushbuttons
Figure 7-3. This pushbutton may be 42 inches from the bottom of the pole, but it is almost 60 inches above the landing, not accessible to a wheelchair user and not likely to be located by a person who is blind.
Figure 7-4. Not only is the pushbutton in the bushes and out of reach range from the sidewalk, construction barriers have been stored against the pole, preventing all pedestrians from reaching the pushbuttons.
The pushbutton must be within accessible reach range of a level landing for use from a wheelchair and MUTCD recommends a mounting height of approximately 3.5 feet but no more than 48 inches above the sidewalk. This also meets the reach ranges specified by Proposed PROWAG.
Proposed PROWAG (R404, R406) requires operable parts (APS pushbuttons) to be installed within specified reach ranges of a defined “clear space” . A “clear space” is defined as a surface with a slope consistent with the slope of the pedestrian access route and no more than 2% cross slope .
Reach ranges in Proposed PROWAG are described as forward reach or side reach . Forward or side reach refers to the position in relation to a level surface and whether the pushbutton can be approached from the directly (forward) or must be approached from the side. Obstructed or unobstructed describes whether the wheelchair can be pulled immediately next to the pushbutton mounting surface or whether an obstruction, such as a wall, pole base, or an uneven or dirt surface, must be reached over in order to reach the pushbutton from a wheelchair. Obstructions are not allowed for forward reaches while an obstruction of up to 10 inches is allowed for side reaches.
For forward or side reach, Proposed PROWAG allows pushbuttons to be mounted between 15 in and 48 in above the level surface.
Locations that are "convenient" to the installer may not be usable by all pedestrians.
Vibrotactile WALK indication should be provided during the associated WALK interval by each APS . The vibrating surface which is the tactile arrow will be usable only if it is installed within the width of the crosswalk or very near the crosswalk, and near the curb line. Pedestrians must be able to wait to cross while keeping a hand on the vibrating surface.
When two APS pushbuttons with vibrotactile indications are installed on the same pole, they may require insulation and a rubber gasket to eliminate vibrations generated from the other pushbutton.
Shape and type of mounting pole
Figure 7-6. A mounting bracket or shim is needed on this square pole to orient the arrow properly. Without it, the arrow points to the center of the intersection.
Municipalities in the U.S. use a great variety of poles for mounting pedheads and pushbuttons. When the tactile arrow is part of the pushbutton and located on the face of the pushbutton integrated device, the orientation of the device on the pole determines whether the tactile arrow is aligned with the crosswalk. A new mounting hole may need to be drilled for the pushbutton, in order to be sure the arrow points in the correct direction. A person who is blind may attempt to determine their heading for crossing based on the arrow. The arrow should point toward the destination corner.
Most pushbutton-integrated devices are designed to be installed on round poles. Poles that are not round may require a special mounting bracket or shim to orient the arrow correctly.
Location and orientation of tactile arrows
Before devices were ordered, the pushbutton and tactile arrow (vibrating surface) location should have been determined and specified. Any adjustment from the intended design must be carefully considered. If poles are located too far away from the center of the intersection, outside the extension of the crosswalk lines, the pedestrian who is blind may attempt to cross at a location that is not within the crosswalk area. See an example of a poorly placed pole in Figure 6-14 in Chapter 6. Pushbuttons should be within reach from a level landing, within 5 feet of the crosswalk lines extended and within 10 feet of the curb. Specifications on pushbutton location are provided in Chapter 6.
The tactile arrow must be oriented parallel to the direction of travel on the crosswalk controlled by the pushbutton. It may be helpful to stand behind the unit and look across the street to check the orientation before and after installation. The arrow should point to a location within the crosswalk along the opposite curb. Arrows on several manufacturers' devices can be turned or repositioned by the installer. However, with some devices, the direction of arrow is specified when ordering the units. Pole location in relation to the crosswalk can affect the arrow direction.
Where speech messages are used for the WALK indication or where there is a pushbutton information message, installer should check that arrow direction and speech messages agree. APS have accidentally been installed with the message providing notification about the wrong street.
The fluted pole in Figure 7-7 made correct alignment more difficult. The installer said he had to put it that way because he did not have any shims. The specifications given to the manufacturer for this unit should have included shims to allow for the necessary angle adjustment.
In areas where pushbuttons are installed on wooden poles, the wiring usually runs in a conduit on the outside of the pole. A mounting bracket, which needs to be ordered with the APS, is needed on some devices for wiring the pushbutton. Other options are discussed in Chapter 6 in "Mounting and Wiring Issues."
Braille labels and signs
Figure 7-8. At this location, the faceplate was mounted backwards, with the Braille indented rather than raised and the small paper label, intended only to translate the Braille, is on the outside rather than the inside.
The direction of the face plate and associated arrow is determined when the raised dots of braille are added. Braille is generally just punched into the metal plate. Print street names may not be provided on the APS, since print street signs may be available at the intersection already. Typically, the faceplate can be flipped to show a right arrow or a left arrow, and the manufacturer includes a print label on the faceplate to translate the braille for installers so they will install the sign at the appropriate location. The print label should be installed on the inside of the faceplate (facing the pole), not on the outside (see Figure 7-8). If the braille sign has been installed correctly, the braille dots will be raised to the touch after installation.
APS microphones and speakers
Some APS require installation of microphones to monitor the ambient sound; this is part of the automatic sound adjustment feature. The microphones are measuring the sound levels to adjust the volume at the waiting location and are usually mounted in the pedhead or are part of the pushbutton unit. If the microphone is mounted too far from the intersection, it will not adequately sample and adjust the volume levels resulting in a WALK indication that is too quiet for a pedestrian to hear above the sound of traffic.
Speakers for APS may be mounted on the pedhead or located in the pushbutton unit. There are different issues to be considered, depending on the speaker location. If possible, APS devices should have speakers oriented toward the street as well as the sidewalk and pedestrian waiting location. In locations with audible beaconing, a speaker oriented toward the middle of the crosswalk is needed. The addition of a pedhead-mounted speaker may need to be considered in that situation; some manufacturers sell optional add-on speakers. One manufacturer provides baffles to better control the direction of sound.
An H-frame is used for mounting pushbuttons in some northwestern states. The design of the frame makes it difficult to hear the sound of the locator tone from both the approach direction and the crossing direction.
Sound from pedhead-mounted speakers
Unless audible beaconing is needed, speakers should be aimed down toward the pedestrian waiting location. Speakers may be aimed toward the center of the street at crosswalks where audible beaconing is needed. For pedhead-mounted speakers, sound will travel farther the more nearly horizontal the radiation pattern of the speaker is.
Installation of speakers and microphones
Confirming speaker location and orientation
Speaker location and orientation need to be checked against the specifications. Installers should make no change in speaker location or orientation without checking with the responsible signal engineer. Poorly located speakers can result in:
- Ambiguous information about which crosswalk has the WALK interval;
- Failure of blind pedestrians to begin or end crossings within the crosswalk; and
- Veering of blind pedestrians outside the crosswalk, possibly into conflicting traffic.
See discussion and examples in Chapter 6 for more information on the effects of speaker location and orientation.
Incorrect speaker location can make a difference in ability of pedestrians who are visually impaired or blind to discern which APS is sounding.
- Each APS speaker at a corner must always be closest to the crosswalk it signals.
- For pedhead-mounted APS, speakers should not be automatically located on the pedhead that signals the same crosswalk. The pedhead closest to one crosswalk may signal the perpendicular crosswalk. In this case, speakers must be mounted on the pedhead for the perpendicular crosswalk.
The speakers should be adjusted so the pushbutton locator tone can be heard by a pedestrian approaching the corner from both the sidewalk side and the street. However, it is most critical that the WALK indication can be heard at the beginning of the crosswalk.
Precise orientation of the APS speaker is especially critical at locations with audible beaconing. If a speaker or transmitter is oriented even a few degrees out of alignment with the associated crosswalk, pedestrians may inadvertently travel out of the crosswalk, perhaps into the path of vehicular traffic.
Pedhead-mounted speakers in existing installations are often mounted in positions that make the messages more ambiguous. See more information on correct mounting of pedhead speakers in Chapter 6 in "APS Microphones and Speakers."
For pushbutton integrated devices, the speaker is in the pushbutton housing. Location of the pushbutton and orientation of the speaker can be critical to hearing the WALK indication at the crosswalk. If the speaker is located too far from the crosswalk location, pedestrians who are blind may not hear the WALK indication.
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