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Effect on APS An APS that is audible from the wrong crossing location may lead a visually impaired pedestrian to begin to cross at the incorrect time and place. Geometry such as unsignalized and signalized right turn lanes, and medians have been recognized as situations of concern in language in the MUTCD. The type of APS may not be as important as the location of the sound source and volume of the APS WALK indication. These issues must be considered in the design phase in determining type of device and location. Also, careful adjustment of APS volume after installation is essential. Unsignalized right turn lanes and splitter islands An unsignalized right turn lane can pose a problem if the APS for crossing the center of the intersection is too loud. Pedestrians who are unaware of the existence of an unsignalized right turn lane may reach the curb, hear the APS sounding and cross the unsignalized lane, thinking that it is signalized. This concern is the reason MUTCD 4E.06 urges careful selection of tones at locations with free right turns. However, tone selection does not really provide a solution; volume of the sound and placement of the speaker are the important issues. The APS must be adjusted so it is only heard from the location where the pedestrian is waiting to cross and only audible for the crosswalk being signaled. It is generally not appropriate to use audible beaconing where there are splitter islands because the volume cannot be controlled precisely enough; there will always be occasions when a signal for one crossing will be audible from another. As discussed in the section on split phasing, volume and placement of the sound source are critical considerations in designing and installing the APS. Signalized right turn lanes Where crosswalks from corners to splitter islands are signalized, the signals to cross to the island may not be concurrent with parallel traffic movements. Those signals should be located precisely by the associated crosswalks and should be equipped with pushbutton integrated APS with careful volume adjustment. Pedestrians waiting on the island must not confuse the WALK indication for the turn lane with the WALK indication for the through lanes of the intersection. Pedestrians approaching the corner need guidance to the crosswalk location, which can be provided by the locator tone combined with curb ramp location. Because signalized right turn lanes are relatively uncommon, and because blind pedestrians can create gaps in traffic by actuating such signals, installation of APS at signalized right turn lanes should be given high priority. APS in locations with signalized turn lanes are quite common in Sweden and Australia. See International Practice for photos of international installations. Medians If the pedestrian clearance time is sufficient only to cross to a median having an additional pushbutton, it is very important that the pushbutton on that median be an APS with a locator tone. This may inform the pedestrian who is visually impaired that a second button press is needed to complete the crossing, and will aid in location of the median and the pushbutton. If only one APS device is on the median, the pushbutton should have a double-ended arrow. If pedestrian phases for the two halves of the street are timed separately, two pushbutton-integrated APS are needed on the median, separated by as much distance as possible, and located as close to each crossing departure location as possible. In addition to the locator tone of an APS, a fence and offset crosswalks are used in European and Australian cities to alert all pedestrians about the need to stop on the median and wait for the next pedestrian phase.
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