Audible Traffic Signals: The Technology, the Reality, and the Possibilities

by Curtis Chong

From the Editor: Curtis Chong is probably best known for his technical expertise and his long service as the chairperson of the computer science division. But he is not so easily pigeonholed. He has many interests, and almost everything he writes I find intriguing. He has a good sense of history, a good sense of what is going on in the present, and is very willing to offer his thoughts about what we should do in the future. Here is what he has to say about audible pedestrian signals:

Audible traffic signals (now called accessible pedestrian signals) have generated a lot of discussion (if not controversy). There are differing opinions about where and under what circumstances these signals should be installed. However, given the increasing complexity of traffic patterns in our cities today and the improvements in accessible pedestrian signal technology, one would be hard-pressed to find anyone who would say that accessible pedestrian signals provide absolutely no benefit to the nonvisual pedestrian. The problem with these devices seems to be a lack of consistency as to how they behave and where they are placed. Should accessible pedestrian signals provide information using buzzers, beeps, clicks, recorded speech, vibrations, or some combination of the above? Should they generate a locator tone to help the blind pedestrian to find the signal pole? Does the nonvisual indication that the walk sign is on need to be generated all the time or only when requested? If the blind pedestrian must activate the nonvisual walk sign indicator, is it appropriate to require the pedestrian to press and hold the activation button or should a simple press be sufficient? Is it sufficient for the signal to indicate only that the walk signal has been activated or would blind pedestrians be well served if more information was provided during the crossing, for example, an audible homing signal on the other side of the street which tells the pedestrian in what direction to walk? At any given corner, where should the signal poles be placed for easy crossing, and at what height should the activation button be positioned? Should accessible pedestrian signals be installed at every signalized intersection or only at those intersections which are difficult or impossible to negotiate nonvisually?

The earliest audible traffic signals used loud buzzers or alarm bells to alert the blind pedestrian that the light was green. Later versions alternated between the sound of a chirping bird or a cuckoo clock, depending on what intersection had a green light. Other models generated repeating clicks to indicate the state of the walk signal: slow clicks when the signal was off and rapid clicks when it was on.

Accessible pedestrian signals with more modern technology generate a beep tone every second that (in theory) is meant to be heard only when the pedestrian is within ten or twenty feet of the signal, thus enabling the pedestrian to determine the location of the signal pole. The volume of the beep tone is supposed to vary depending on the level of ambient sounds. This type of accessible pedestrian signal continually beeps every second unless or until the pedestrian presses and holds the arrow-shaped button on the signal pole. Then, the signal will say something like, "Wait…wait to cross street name a at street name b." Then, when the walk signal comes on, the signal will say something like, "The walk signal is now on to cross street name a." On some accessible pedestrian signals, you will hear a voice counting down the number of seconds remaining before the walk sign will be turned off; on others, you will hear a louder series of tones which is supposed to serve as an audible homing beacon to guide the blind pedestrian to the other side of the intersection; and there are still others which remain silent during the walk phase. Some accessible pedestrian signals have Braille symbols on them to indicate which street is to be crossed using the signal; other signals do not. Some signals vary the volume of the locator beeps depending on the volume of ambient traffic noise; others do not.

Municipalities around the country have developed their own local policies and procedures relating to accessible pedestrian signals. Ideally, these policies and procedures are developed in cooperation with state affiliates and local chapters of the National Federation of the Blind; however, more often than not, cities make their own decisions about when and where to install accessible pedestrian signals and how they will be configured. When this happens, decisions are too often made based on what we in the National Federation of the Blind would call outdated stereotypical thinking about the characteristic of blindness. For example, some traffic engineers believe that accessible pedestrian signals should be installed near agencies for the blind where blind people are likely to cross the street. It never occurs to them to think that perhaps the agencies are encouraging their students to learn to cross streets where no accessible pedestrian signals are installed.

In the cities of Aurora, Colorado; Albuquerque, New Mexico; Des Moines, Iowa; Baltimore, Maryland; and Minneapolis, Minnesota (cities where I have lived), there are accessible pedestrian signals at some street crossings with locator tones for each signal pole along with speech to tell you when the walk signal is on. I don't know how these cities determined where to install these accessible pedestrian signals. I often found these signals at four-way crossings which would ordinarily not pose a problem for a blind pedestrian with decent independent travel skills.
In San Diego, California, I encountered accessible pedestrian signals which beeped and talked, similar to the ones in Denver. I appreciated the count-down timer which would tell me how many seconds were left as I crossed the street.

In the city of Honolulu, Hawaii, I remember that within a few blocks from the local agency for the blind, there were accessible pedestrian signals at a busy intersection which generated slow or rapid clicks to tell the blind pedestrian when the walk signal was on. Slow clicks meant that you were not supposed to cross; rapid clicks meant that the walk signal was on and that it was theoretically safe to cross. Moreover, while crossing, the blind traveler could hear clicking on the opposite side of the street which served as a homing beacon. There was no controlling mechanism to activate the nonvisual indicators; they were on all the time.

The majority of signalized intersections that we are likely to encounter today will not be equipped with accessible pedestrian signals of any type. We cannot know where, in specific cities, accessible pedestrian signals might be operating, let alone how each signal will work. Thus, as I see it, the best course of action for the savvy blind pedestrian to take is to assume that most of the time, street crossings will not be equipped with accessible pedestrian signals and plan accordingly. Agencies who provide independent travel training services to the blind should help their students to understand this reality and train them to be confident enough in their travel skills that they can cross all but the most complex intersections they encounter, regardless of the presence or absence of accessible pedestrian signals. We, the organized blind, should work with local governments so that nothing about us is done without us. Local chapters of the National Federation of the Blind should understand the local policies and ordinances that determine how, when, and where accessible pedestrian signals are installed, and we should all work with our local governments to establish uniform standards for accessible pedestrian signals that consider our real needs and avoid outdated stereotypical thinking about the characteristic of blindness.
Ideally, the installation, deployment, and operation of accessible pedestrian signals would be governed by a national standard which everyone agrees with. But, given the past history of this technology, I am doubtful that this will occur.