Next time you stand at a road crossing with pedestrian lights, and you press that conveniently-positioned button and wait for the lights to change and the familiar alteration in the sound that alerts you that you can "walk", be proud of Australian scientists and technicians.
Yes, Australians.
This button is called the PB/5, and it is a particular type of ATPD (Audio-Tactile Pedestrian Detector). It was patented and has spread around the world since 1984. Not only is this a marvellous use of high-technology, but it is an example of how scientific research progresses from one iteration of an idea to a better one when things don't go quite right the first time. Or the second. Or even maybe the third.
To stop yourself being bored, take another moment while you are waiting and closely observe other functions of the pedestrian button that make it convenient for you, and also for others with different levels of disability, to safely negotiate our traffic.
Important and practical features
Have you noticed the following features of this button: it has no sharp edges (they are all rounded and smooth); it is firmly bolted to the post (you never see them vandalised); it has both sound and vibrations co-ordinated with the visual displays of the red and green "men", to aid those with handicaps of sight and/or hearing (if you touch the small arrow, you will feel it vibrate, and you will also feel a Braille message embedded there).
The large arrow makes it clear which direction to walk; the sound adjusts itself to the background noise of traffic; the change of sound makes it clear when you can start walking; and last but not least, the press-button is very large and easy to use (and it doesn't matter if someone presses it many times, the first push is the only one that registers ).
Some of these things, particularly the different sounds and other aspects that help both able and disadvantaged pedestrians, have been developed after much consultation with users and various different trials that didn't work out so well.
For example, as far back as the 1960s, a simple change in tone between a bell sound and a buzzer was trialled. This turned out to be confusing "in the field" as it was not consistent from place to place, and it was not obvious which was the "walk" signal. In 1976, a firm of consultants was asked to redesign the sytem, and came up with the three-phase tones we hear today. The change to a fast-paced rhythm, after a sudden alert-sound, intuitively prompts people to "walk".
But there is MORE: clever electronics inside
The three sounds, plus a microphone that detects ambient noise and adusts the volume, and the vibrator on the small arrow, are all controlled by the one transducer. This makes the design, manufacture and maintenance very efficient. A transducer is an electronic device that translates one type of energy (eg electrical energy) into another form (in this case, the three different sounds and the vibration, on different circuits of the one device).
There is also a clever trick embedded in the switch on the push button. The movement of the button is physically isolated from the switching mechanism. The button actually floats on a sliding shaft, and the only contact made with the switch is via a magnet. Once the magnetic force inside the mechanism has triggered the switch, then no further pushing of the button does anything except slide it up and down on the shaft, not touching any electronics.
It is therefore easy to disable the switch entirely at busy intersections, or at busy times of day, when the pedestrian lights are co-ordinated with the traffic lights, and no pushing of the button will make them change to "walk" any quicker than they are programmed to do.
The designers actually paid attention to human behaviour, and designed a "fail safe" mechanism instead of expecting people to change! So push the button over and over if it helps your frustration – it won't make the lights change, but it won't hurt the device either.
Continual and future improvements
Yes, it is a great design that has been commercialised and exported to cities around the world. But no, it isn't perfect. Ongoing questions from users about positioning, the height of the button for cyclists, and whether or not you know if the button has already been pressed, are a few more issues that could be addressed in the next version of the design. Many different consultants and groups of researchers are involved in this ongoing process.
Colossians tells us how important perseverance is: "being strengthened with all power according to his glorious might so that you may have great endurance and patience, and giving joyful thanks to the Father, who has qualified you to share in the inheritance of his holy people in the kingdom of light."
As mentioned in some of my previous articles, science and technology progress stepwise and slowly, over a long time frame. We need to remember this if we are going to ensure our technology keeps up with the times and our scientists and engineers continue to be able to help our society move forward.
More detailed information, in an easy-to-read format, can be found from:
Miles Park from UNSW: and Dr Karl.