1. Field of the Invention
This invention relates to a 2-wire control system which communicates with pole mounted push button stations of the kind found at a traffic light controlled intersection via existing pairs of underground wires over which power and data signals are transmitted to enable a visually impaired pedestrian to receive both audible and tactile signals in response to depressing a push button head at a push button station when it is intended for the pedestrian to cross the intersection once vehicular traffic has been halted.
2. Background Art
It has long been known to combine a visual display with a series of traffic lights that are located at an intersection to control vehicular traffic and thereby enable pedestrians to enter the intersection once vehicular traffic has been halted. That is to say, the usual visual display conveys both a written message (i.e., WALK or DON'T WALK) as well as a color sensitive message (i.e., red, green or white) to instruct pedestrians when to cross the intersection. However, such visual warnings are of little value to those pedestrians who are visually impaired. Consequently, a visually impaired pedestrian who activates the push button of a traffic signal will have no way to accurately know when the intersection has been cleared of traffic so that it is time to cross.
In order to come into compliance with federal guidelines, such as the Americans With Disabilities Act, cities are required to increase the number of accessible signals that are available to pedestrians at the pole mounted push button stations associated with a traffic light controlled intersection. In particular, to accommodate the needs of visually impaired pedestrians, audible and/or tactile signals are generated at each push button station by which an audible message, a vibration, or the like, is generated when a push button is depressed by one wishing to cross an intersection. In this way, not only will the usual visual message be displayed to sighted pedestrians, but other sensory messages will also become available to coincide with the aforementioned visual message so as to alert visually impaired pedestrians when it is time to cross the intersection after the signal light has changed to halt vehicular traffic.
In the past, the pedestrian accessible signaling means has typically been powered at each corner of an intersection by the 115 VAC available at each existing pedestrian lighted sign. Although this approach does not require that additional wires be pulled from each push button station to the traffic control cabinet, the resulting disadvantage is that each push button station operates independently of the others so that sounds cannot be coordinated or synchronized for optimum audible and vibro-tactile presentation to visually impaired pedestrians.
The labor costs and the interruption in both vehicular and pedestrian movement at each intersection can be significant as a result of having to install new underground wiring to the push button stations in order to enable the additional signal function to be generated and made accessible to visually impaired pedestrians following the depression of a push button. However, most intersections already contain previously installed pairs of wires that run underground from the existing push button stations to a remote traffic light control box.
In this regard, cost sensitive cities would be able to avoid many of the expenditures and inconveniences of having to pull additional wires or even dig trenches and lay new field wires in order to install the new push button stations for each intersection if a control system were available that could incorporate the existing underground wire pairs to transmit power and data signals in order to generate the accessible signal functions for both sighted and visually impaired pedestrians.
Reference may be made to U.S. Pat. No. 5,241,307 issued Aug. 31, 1993 for a microprocessor operated sound signaling and optical signaling generation device that is activated by means of a pedestrian depressing a push button at a traffic light controlled intersection.