When and how often the APS installation should be checked
As with any complex device, an APS has many features that could malfunction or fail in the course of its operation. If features such as WALK indication, locator tone, or signal interaction fail to work correctly, the resulting lack of information or misinformation for pedestrians who are blind can be dangerous. It is important that municipalities who have taken steps to install these devices also take steps to ensure correct functioning through the years.
The overseeing agency should conduct an audit or checkup of the APS installations on a regular basis. Checkups should be conducted frequently if factors such as harsh weather may have affected the devices. At the very least, the APS should be checked:
- Every 6 months
- After any repairs to the intersection signals, poles or controller
- After any changes to signal timing
What should be checked
On each regular visit to conduct a checkup of the APS units, the evaluator should recheck each of the items on the original post-installation checklist (see previous section). To add more specific items to the list, the following list comprises some of the most common failures that have been observed on installed APS devices. These items should be checked specifically, since some may not be obvious on a cursory glance:
- Vibrating arrow/button: may stop working or have very weak vibration
- WALK indication: tone or speech message may have stopped working or be delayed in sounding after the WALK interval begins
- Raised arrow: may be missing or pointing in the wrong direction
- Pushbutton: may be jammed or malfunctioning
- Ambient noise response: may be slow to respond or have ceased responding at all
Other operation and maintenance issues
Repairing an APS after a crash
Figure 7-13. APS was temporarily replaced on the pole, but the tactile arrow points to the center of the intersection, rather than being aligned with the direction of travel on the crosswalk.
It is essential that all maintenance personnel understand the functioning of the APS and consider it during repairs.
One municipality had a problem when the pole of the APS was knocked down in an accident and the repair team replaced the pole with the APS oriented toward the wrong street (see Figure 7-13). The speech message and arrow did not match up; the speech was saying "WALK sign is on to cross Harford Road" (at the correct time) but the arrow on that device pointed toward Taylor Avenue.
In another instance, an APS was damaged by a car that left the roadway. The APS was just strapped back onto the pole with no attention to the alignment of the tactile arrow. The APS continued to function, but was pointing to the center of the intersection, rather than being aligned with the appropriate crosswalk.
Lessons Learned from APS Installations
Not unlike any new technology, the first installation of new types of APS devices does not always operate flawlessly. There are issues to resolve with some of the devices. In addition, reports from older installations have brought up recurring problems that need to be addressed in installation. All of the issues were easily solvable. The following should provide information to prevent these problems from reoccurring. Some issues include:
- Wiring to pedhead and/controller
- Pushbutton installation
- Signal phasing
- Volume adjustment
- Use and wording of speech messages
- Pushbutton and pole location
- Tactile arrow location and position
- Speaker positioning and volume
- Braille signage and correct installation
Some minor problems have been experienced with wiring and color code.
- Prisma, a Swedish company, uses a European wire color standard. Since this standard is not consistent with the U.S. NEMA color code standards, some wiring problems were created. Care should be taken by installers of these products to be certain the devices are wired correctly.
- Prisma APS have also drawn concern from signal technicians over the voltage (120 VAC) sent to the pushbutton location. Technicians are concerned about pedestrian safety if the pushbutton is damaged or the pushbutton is taken off by a passing vehicle, and a pedestrian comes in contact with the live wires or electrically charged metal pole. Step-down transformers for mounting in the pedhead are provided upon request for U.S. installation.
Other problems may be related to incorrect wiring of the pushbutton units:
- In one location, the technician attached the vibration wire to the speech WALK indication. Instead of the speech WALK indication that was expected, there was a rapid buzzing sound from the unit during the WALK and no vibration of the arrow as expected. This was easily corrected by switching the wires, once the problem was noticed and diagnosed.
- At another location, wires from the parallel crosswalks were switched when attached to the control unit in the controller. Those units were programmed for the extended button press to call audible beaconing on the crosswalk, but the sound came from the APS on the parallel crosswalk, rather than from the other end of the called crosswalk. This problem might lead blind pedestrians to cross the intersection diagonally.
Pushbutton installation and vibrotactile indication
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.
A problem was experienced when two pushbuttons were on the same pole with no vibratory insulation (Figure 7-14). Pedestrians were unable to determine which pushbutton was vibrating, since it appeared both were. Proper insulation of the pushbutton will prevent this problem from occurring.
- An installation had a problem when the signals went into flash mode and the APS device remained in WALK mode. This scenario presented an unsafe condition and message for pedestrians. This problem was resolved by correctly wiring the APS device into the controller/signal system so the controller logic and conflict monitor detected and changed the pedheads to the appropriate indications.
Although current standards call for the APS volume to only be 2 to 5 dB above ambient sound and for the locator tone to be heard from 6 to 12 feet from the pushbutton, volume is often set much louder than that.
- Installers are used to devices using audible beaconing and think that APS are supposed to be loud enough to hear across the street.
- Another issue is that there is no easy way to measure the volume of locator tone and WALK indication, because of the short duration of the tones or messages, the requirement to measure in relation to ambient sound, and the signal's quick response to ambient sound.
- 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.
One installation experienced a different problem in adjusting the volume of an APS unit.
- They had used the pushbutton control units that install in the cabinet (as opposed to those that install in the pedhead).
- The wiring was too small of a gauge to drive the speaker to provide a loud enough message (compounded by the pole and speaker being more than 10 feet back from the crosswalk).
- Manufacturer's guidelines and specifications should be followed for proper operation. Speakers can be provided for each control unit.
The speech messages used for the WALK indication, as well as the descriptive pushbutton message, must be understandable.
- Poorly recorded WALK messages, by an individual with a strong accent, made the street names indistinguishable ["Pratt" and "Calvert"].
- Using a standard message, "WALK sign is on" at locations with two pushbuttons on the same pole. A pedestrian waiting to cross, who is unable to see the WALK signal, cannot distinguish which WALK is displayed from that message.
- A speech message that does not have additional information that clarifies which street the pushbutton applies to can be confusing to pedestrians unfamiliar with the intersection. For example, at the intersection of Harford and Taylor Streets, the pushbutton information message said "Harford and Taylor" for all devices. If the pedestrians do not know which street they are facing, the speech WALK message "WALK sign is on for Taylor" is unclear.
- One jurisdiction wanted to use a male voice for one crossing direction and a female voice for the other to distinguish crossing directions and add to the safety of the crossing. Most APS devices provided a male voice only, however, all APS devices use messages recorded on speech chips. A different voice can be specified. Most devices provide self-recording message capabilities now. However, care should be taken to provide clear and understandable messages.
- Speech WALK indications should be in the form, "Maple, WALK sign is on to cross Maple". Some problems have resulted from using a different message wording.
Pushbutton and pole location
Some problems have been observed in locations of pushbuttons and poles of APS devices:
- Poles that are more than 10 feet from the curb line create real problems for blind pedestrians who must find the pushbutton and then realign to cross the street
- Pushbuttons are often placed in positions that are not reachable from the sidewalk area, or in the bushes, or behind a fence
Tactile arrow and position
The tactile arrow is supposed to point in the direction of pedestrian travel on the crosswalk and the face of the device is supposed to be parallel to the crosswalk it controls.
Some installation issues:
- If the pole is in a poor location, the arrow may be pointing at the street and crosswalk direction but may not be within the crosswalk area.
- If installers do not understand the purpose of the arrow, they may install it angled in the wrong direction. For example, if they use the holes from a previous pushbutton, the arrow may be pointing diagonally across the intersection rather than in line with the crosswalk.
Pedestrian head mounted speakers in existing installations are often mounted in positions that make the messages more ambiguous. See examples in Chapter 6 in "APS Microphones and Speakers" and also earlier in this chapter.
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.
As shown in Figure 7-15, the pushbuttons are installed incorrectly, so the APS is too far from the crosswalk it signals and the sound for the other crosswalk at the intersection comes from a speaker that is closer to the crosswalk.
In Figure 7-16, the APS are installed correctly (close to the crosswalk they signal) and provide accurate information through proximity to the crosswalk.
Braille signing and location
Braille indications on the pedestrian signals have sometimes been mounted backwards or with the braille label for the wrong street.
- Manufacturers ship them with a label to clarify positioning for non-braille-readers. However, technicians might later make adjustments to the sign and reverse or mix up the braille plaques.
- Adding the braille makes it so the sign cannot be turned around without reversing the braille. The braille must remain raised to the touch. If the original specification was not correct, this limits the arrow direction and location.
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