Other concerns and needs

Engineering concerns

Noyce & Barlow (2003) investigated problems reported with the interface between APS devices and signal controllers to determine whether there were systemic problems with the APS/controller interface. Most problems were found to be installer errors, or wiring problems that had already been corrected by the manufacturer by the time research was conducted.

While the adjustment of the volume of the APS is critical for neighborhood acceptance and for usability by pedestrians who are blind, it continues to be an issue in many jurisdictions. In NCHRP 3-62 research on effect of device features (NCHRP 3-62 Final Report) researchers found that it was not possible to adjust all devices to have the same perceived loudness, despite extensive efforts and adjustments and involvement by manufacturers' representatives. Perceived loudness is not amenable to objective measurement, and is influenced by conditions such as wind, humidity, precipitation, and nearby reflective surfaces.

APS devices, as with much new technology, have continued to generate maintenance and engineering concerns. As part of NCHRP 3-62 research, devices that were installed for human factors testing were monitored for a year by signal maintenance staff (see NCHRP 3-62 Final Report, Chapter 7). Concerns were expressed about more failures than expected, particularly of the vibratory feature of the devices. Manufacturers were said to be responsive to concerns and were continuously modifying devices to provide better durability.

Case studies of devices installed in cold weather areas were also developed as part of Project 3-62 (see NCHRP 3-62 Final Report, Chapter 6).

Training needs

In NCHRP 3-62 Research in Tucson and Charlotte, experimenters observed that some participants did not have adequate information or techniques for using pushbuttons and APS devices in crossing streets and many did not have good information and understanding about the complexity of intersection signalization. Of concern to researchers were comments from some participants (prior to any explanation or training in the use of APS) who seemed to be trying to use the fact that the locator tone was sometimes louder in response to ambient sound as a WALK indication. These participants generally did not look for or push the pushbutton, but heard the audible locator tone and without knowledge of locator tones and their function, and made an assumption that it was some kind of WALK indication. This misunderstanding of ambient sound adjustment and the locator tone could lead to dangerous crossings. Where APS with locator tones are installed, it may be necessary to make a concerted effort to provide information about the devices to individuals in the community.

The major reason for the tactile arrow is to enable users to identify which street the pushbutton controls. Many participants in NCHRP 3-62 research and in NEI research needed to be shown the arrows on the devices to understand which way the arrow pointed. Use of the tactile arrow and the incorrect pushbutton presented a very different picture in Charlotte than in Tucson. In Tucson, participants who looked at the arrow on the incorrect pushbutton always correctly rejected the incorrect pushbutton. However, in Charlotte, even following familiarization, participants looked at the arrow on the incorrect pushbutton and failed to reject it on 20% of trials. This confusion in using the correct pushbutton seemed to be related to participants' lack of strategies to maintain their orientation; some would completely turn to face the street parallel to their travel path, while examining the arrow on the device, then push the button and line up to cross the parallel street. Strategies for looking for pushbuttons and aligning to cross need to be taught.

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