Method and a circuit arrangement for modifying control information in a traffic signal system, particularly a street traffic signal system

• US 4,352,086 A
• Filed: 05/01/1980
• Issued: 09/28/1982
• Est. Priority Date: 06/06/1979
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Hunziker, Walter
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/145,710
• Time in Patent Office: 880 Days
• Field of Search: 340/35, 340/36, 340/40, 340/32, 340/33, 340/34, 340/38 R, 340/38 L, 340/37, 340/41 R, 11/11, 364/436, 364/437, 364/438
• US Class Current: 340/906
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles
• CPC Class Codes: G08G 1/081 Plural intersections under common control

Abstract

A method and a circuit arrangement for modifying central control information commands forming signal programs in traffic signal systems in particular street traffic signal systems, the central control information commands being output from a central station to intersection devices of the system in order to control signal generators assigned to the intersection devices. This modification is to occur through the use of traffic information which are determined in the traffic areas whose traffic flows are to be controlled by the signal generators of the intersection devices. In order to be able to undertake a modification of the signal program sequencing in the respective intersection devices, modification time areas are determined in the form of partially overlapping central control information commands, in particular binary "1'"'"'s" transmitted from the central station to the respective intersection device. Within these modification time areas, separate local control information commands can become effective for setting the signal generators.

Claims

1. A circuit arrangement for controlling and modifying central control information commands in a traffic signal system comprising:

a central control station for transmitting central control information commands and at least one intersection device for receiving the central control information commands, and signal generators connected to said intersection device;

an evaluation circuit in said intersection device for evaluating the central control information commands and emitting command signals for controlling the signal generators in response thereto;

a command recognition circuit connected to receive the same central control information commands as said evaluation circuit and responsive to overlapping control information commands to produce an output signal;

local control information commands input means for receiving local control information commands concerning the traffic conditions at the intersection; and

a control circuit connected between said evaluation circuit and said signal generators and connected to said command recognition circuit and to said local control information commands input means and responsive to the output signal from said command recognition circuit to block operation of said signal generators in response to the overlapping control information commands transmitted by said central station and to permit operation of said signal generators in accordance with the local control information commands supplied to said intersection device, including means for operating said signal generators in accordance with said local control information commands.

2. The circuit arrangement of claim 1, wherein said local control information commands input means comprises:

traffic detector means connected to said control circuit

for providing traffic flow information thereto.

3. The circuit arrangement of claim 2, and further comprising:

logic means in said local control information commands input means connected to said command recognition circuit and to said traffic detector means and to said control circuit for logically linking output signals from said command recognition circuit and local control information commands.

4. The circuit arrangement of claim 3, and further comprising:

inhibiting means connected between said command recognition circuit and said local control information commands input means, and said evaluation circuit, for disabling operation of said evaluation circuit in response to specific control information or combinations of control information.

5. The circuit arrangement of claim 4, wherein said inhibiting means comprises:

an EXCLUSIVE OR gate having inputs connected to said local control information commands input means and an output; and

an AND gate including inputs connected to said EXCLUSIVE OR gate and said command recognition circuit, and an output connected to said evaluation circuit.

6. The circuit arrangement of claim 1, wherein said evaluation circuit comprises:

a pair of bistable circuits for receiving respective control information commands.

7. The circuit arrangement of claim 1, wherein:

said traffic signal system operates on a time division multiplex basis and includes a plurality of said circuit arrangements each comprising an input demultiplexer including first and second ouputs connected to said evaluation circuit.

8. The circuit arrangement of claim 7, wherein:

said command recognition circuit comprises an AND gate having inputs connected to respective first and second outputs of said demultiplexer.

9. In a method of modifying central control information commands forming signal programs, which includes the steps of transmitting the central control information commands from a central station to an intersection device of a traffic signal system which controls traffic signal generators connected thereto, and by transmitting local control information commands obtained from traffic information from an area whose traffic flow is controlled by the signal generators, the improvement comprising the steps of:

transmitting control information commands from the central station to the intersection device with periods of overlapping control information commands, said periods defining permission time for controlling said signal generators only by said local control information commands; and

detecting such periods of overlapping control information commands; and

transferring operational control of said traffic signal generators from said control information commands transmitted from said central station to said local control information commands.