TRAFFIC SURVEILLANCE AND CONTROL SYSTEM

• US 3,626,413 A
• Filed: 02/02/1970
• Issued: 12/07/1971
• Est. Priority Date: 02/02/1970
• Status: Expired due to Term

• Current Assignee: Howard C. Zachmann
• Original Assignee: Howard C. Zachmann
• Inventors: Zachmann, Howard C.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US05/007,586
• Time in Patent Office: 673 Days
• Field of Search: 343/6A,8,9 235/150.24
• US Class Current: 342/104
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions

Abstract

An all-weather system utilizing doppler radar devices for monitoring traffic on highways to provide warnings and diversionary information to motorists. Radar equipment mounted on gantries at selected locations along the highways provides traffic information on the number, type and velocity of vehicles and together with complementary equipment such as a data-linked computer develops information on traffic density and required clear distance for trailing vehicles, continuously taking into account local environmental conditions. The latter '"'"''"'"''"'"''"'"'tailgate'"'"''"'"''"'"''"'"' information as well as velocity and diversionary information is provided at the gantries as a visual display. Counting of vehicles by class is performed both by doppler pulse amplitude and interval at a monitored speed techniques and two alternate configurations for providing the tailgate function are disclosed, one being completely self-contained at the gantry.

Claims

1. A traffic control system for developing information of existing traffic conditions comprising means responsive to the movement of vehicles along a roadway for producing a series of signals indicative of such traffic, one of said signals being representative of the velocity of a vehicle, means responsive to said one signal for generating a time interval having a duration related to said one signal, means for sensing the condition of the production of a second one of said signals within such time interval, and means responsive to said sensing means for providing an indication of such condition.

2. The control system as set forth in claim 1 wherein said indication means comprises a device for presenting information in visual form, said device being disposed near the roadway being monitored for viewing from the vehicles.

3. The control system as set forth in claim 2 wherein said time interval generating means comprises a computer programmed to develop an output as a function of the velocity of the vehicle, said output being operative to condition said sensing means for receipt of said second signal.

4. The control system as set forth in claim 3 further including means responsive to said signal producing means for discriminating among signals representative of the type of vehicles, said discriminating means being operative to modify the output of said computer.

5. The control system as set forth in claim 3 further including means for registering environmental conditions in the area of the traffic, said registering means being operative to modify the output of the computer.

6. A system for monitoring the movement of vehicles along a roadway comprising means for directing a train of signals at a predetermined location of the highway which signals are intercepted and reflected by moving vehicles, means for receiving the reflected signals from the vehicles, doppler frequency sensing means coupled to said receiving means for providing an indication of the velocity of said vehicles, discriminating means coupled to said sensing means for categorizing the types of reflected signals into various classes of vehicles, means responsive to said doppler means and said discriminating means for determining a time interval having a duration related to the velocity and class of vehicles, means operative within such time interval for sensing the receipt of a reflected signal at said receiving means, and indicator means responsive to said sensing means for registering such condition.

7. The system as set forth in claim 6 wherein said indicator means comprises a display proximate to the roadway in the line of sight of operators of the vehicles.

8. The system as set forth in claim 7 wherein said discriminating means comprises a first detector coupled to said receiving means for monitoring the amplitude of the reflected signals and for providing output signals representative thereof.

9. The system as set forth in claim 8 wherein said discriminating means further comprises a second detector coupled to said receiving means for monitoring the interval of the reflected signals, said second detector being responsive to said doppler means for providing output signals representative of classes of vehicles, and means for combining the outputs of said first and second detector means to provide a further classification of the vehicles.

10. The system as set forth in claim 9 further including means for monitoring environmental conditions in the area of the roadway and for providing a signals representative thereof, said time interval determining means being further dependent upon said monitoring means.

11. The system as set forth in claim 10 wherein said time interval determining means comprises a computer programmed to combine thE indications of velocity, vehicle class and environmental conditions to provide an indication of a time interval related thereto, said sensing means being operative in response to said computer indication.

12. The system as set forth in claim 11 further including a second computer operatively connected to receive the indications of velocity and vehicle class from said doppler means and said discriminating means respectively, said second computer being programmed to accumulate such indications and compute density of vehicles and flow rates for the roadway.

13. A system for monitoring vehicular traffic comprising a radar system for producing sequential echo signals from the moving vehicles, means responsive to the echo signals for indicating the velocity of the vehicles, means responsive to the echo signals for indicating the class of vehicles, means operatively connected with said class means and said velocity means for detecting sequential indications within a time interval determined by such indications, and means operatively connected with said detecting means for providing a visual display representing such sequential indications.

14. The system as set forth in claim 13 wherein said detecting means comprises a variable time delay circuit, said circuit being triggered into operation by receipt of a first indication, a gate responsive to operation of said circuit and a second indication for providing a signal to said display means, and means for varying the delay of said circuit as a function of the indications.

15. The system as set forth in claim 14 wherein said delay circuit is a one-shot circuit and said varying means comprises a variable impedance element operatively connected to control the discharge time of said one-shot circuit.

16. The system as set forth in claim 14 wherein said delay circuit is a digital counter and said varying means comprises a computer operatively connected to control the maximum count of said counter, said computer being operative in the interval between sequential indications.

17. The system as set fourth in claim 13 wherein said detecting means comprises an information register for storing the indications of said class means and said velocity means, a sequence circuit for interrogating said register, a computer connected to said sequence circuit for developing an interval instruction as a function of the information in said register, a circuit responsive to said interval instruction and a sequential indication to provide an output signal to said display means, and means for synchronizing said computer with the receipt of the sequential indications.

18. The system as set forth in claim 17 wherein said synchronizing means comprises a clock source operatively connected with said information register and said computer and operative to determine the magnitude of the interval instruction.

19. A system for classification of vehicles comprising means for developing a pulse group of echo signals from a moving vehicle, said signals having amplitude related to frontal reflective surface of the vehicle, doppler frequency related to velocity and duration related to length and velocity, means for sensing amplitude of the signals and for providing output signals representative of the frontal reflective surface of the vehicles, doppler frequency detector means for determining the velocity of the vehicles, means for sensing the duration of the signals to provide indications proportional thereto, means for combining the indications of said duration sensing means and said doppler detector means to provide output signals representative of the length of the vehicles, and means for combining the output signals to provide a combined classification of the frontal surface and length of the vehicles.

20. The system as set forth in claim 19 wherein said first named means comprises a radar unit located above a lane of traffic to be monitored and directed at a small angle below a horizontal line toward oncoming traffic to provide both frontal and lOngitudinal reflection from the vehicles.