Emergency vehicle traffic controller

• US 3,881,169 A
• Filed: 06/01/1973
• Issued: 04/29/1975
• Est. Priority Date: 06/01/1973
• Status: Expired due to Term

• Current Assignee: Henry G. Malach
• Original Assignee: Henry G. Malach
• Inventors: Malach, Henry G.
• Primary Examiner(s): Cooper, William C.
• Application Number:
  US05/366,089
• Time in Patent Office: 697 Days
• Field of Search: 340/32,34,36
• US Class Current: 340/906
• CPC Class Codes: G08G 1/087 Override of traffic control, e.g. by signal transmitted by an emergency vehicle

Abstract

Controlled street intersections are equipped with an audio detector and emergency controller for automatically regulating the intersection traffic signals to initiate a predetermined traffic flow pattern at the approach of an emergency vehicle. The detector is responsive to a multiple tone audio frequency signal having predetermined frequency and time characteristics emitted by the emergency vehicle. Equipment in the controller determines when the detector is presented with a signal in which predetermined frequencies occur within an established time period. When these conditions are met, the emergency controller automatically provides the desired traffic signal to assist the emergency vehicle through the intersection. When the emergency vehicle'"'"''"'"'s audio signal is out of range of the detector for a predetermined length of time, normal operation of the traffic signal is automatically reinitiated. Phase detecting means are included in the controls so that the normal red, amber and green cycles follow with normal duration after the emergency control system is deactivated. A plurality of controllers may be employed to regulate traffic flow in all directions at any multi-street intersection.

Claims

1. A traffic controller for regulating traffic flow through a traffic intersection equipped with a traffic signal comprising:

a. detector means responsive to an audible, transmitted audio frequency warning signal which has been transmitted through the atmosphere from an emergency vehicle;

b. frequency selective means connected with said detector means for determining the presence of a plurality of selected audio frequencies in the transmitted signal;

c. timing means connected with said frequency selective means for determining whether all of said plural selected signals occur within a selected time interval; and

d. control means connected with said timing means and said frequency selective means and operable upon the occurrence of said plural selected signals within said selected time interval to operate said traffic signal in a non-normal, predetermined manner.

2. A traffic controller as defined in claim 1 further including second timing means connected with said controller for reinitiating normal operation of said traffic signal when said plural selected signals are absent as inputs to said traffic controller for a predetermined period of time.

3. A traffic controller as defined in claim 2 further including:

a. a normal controller for normal operations and adapted to cyclically produce different color lights in a predetermined color sequence; and

b. phase detecting means connected with said second timing means for reinitiating normal operations following termination of said non-normal, predetermined operation whereby the first color change of lights in said traffic signal following termination of said non-normal operation is from the color during non-normal operation to the next color in said predetermined sequences of colors.

4. A traffic controller for regulating traffic flow through a traffic intersection equipped with a traffic signal as defined in claim 3 wherein:

a. said normal controller includes means for regulating the duration of light production from each of said different color lights whereby each of said different color lights respectively produces light for a predetermined time period; and

b. said phase detecting means includes means for reinitiating control by said normal controller at the beginning of the respective time period for said next color in said predetermined seQuence.

5. A traffic controller as defined in claim 1 wherein said selected audio frequency signals include signals of approximately 600Hz and 900Hz.

6. A traffic controller as defined in claim 4 wherein said selected audio frequency signals include signals of approximately 600Hz and 900Hz.

7. A traffic controller as defined in claim 5 wherein said selected time interval is approximately 2 seconds.

8. A traffic controller as defined in claim 6 wherein said selected time interval is approximately 2 seconds.

9. A traffic controller as defined in claim 1 wherein said non-normal predetermined manner comprises flashing red lights signaling all streets in said traffic intersection.

10. A traffic controller as defined in claim 1 further including selectively operable means for providing a plurality of non-normal modes of operation of said traffic signal.