AU2005203742B2

AU2005203742B2 - Conflict monitor for road traffic control equipment

Info

Publication number: AU2005203742B2
Application number: AU2005203742A
Authority: AU
Inventors: Malcolm Young
Original assignee: ALDRIDGE TRAFFIC CONTROLLERS Pty Ltd
Current assignee: ALDRIDGE TRAFFIC CONTROLLERS Pty Ltd
Priority date: 2004-08-19
Filing date: 2005-08-19
Publication date: 2010-03-25
Anticipated expiration: 2025-08-19
Also published as: AU2005203742A1

Description

Regulation 3.2 Revised 2/98 AUSTRALIA Patents Act, 1990 ORIGINAL COMPLETE SPECIFICATION TO BE COMPLETED BY THE APPLICANT NAME OF APPLICANT: Aldridge Traffic Systems Pty Limited ACN 001 678 557 ACTUAL INVENTOR: Andrew Bull ADDRESS FOR SERVICE: Peter Maxwell and Associates Level 6 60 Pitt Street SYDNEY NSW 2000 INVENTION TITLE: CONFLICT MONITOR FOR ROAD TRAFFIC CONTROL EQUIPMENT DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO: 2004 904 743 - 19 August 2004 Australia The following statement is a full description of this invention including the best method of performing it known to us: m:\docs\20051039\084420.doc 2 The present invention relates, at least in some embodiments, to a conflict monitor for road traffic control equipment and, in particular, to a load switching system in a conflict monitor for the safer operation of electronic road traffic control equipment. Any discussion of the prior art throughout the specification should in no way be 5 considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. Since electronic road traffic control equipment was first introduced, it became apparent to both road users and traffic controllers that certain failures of the equipment, such as wiring faults, at a road intersection or pedestrian crossing where such 10 equipment was being used could permit or cause conflicting or confusing signals to be displayed to road users and pedestrians, with the consequence that the road users and pedestrians were put at risk of danger through collisions. Clearly, there was a high risk of danger if a driver of a vehicle responded to a faulty signal, say, a green signal, when travelling through an intersection and another green signal simultaneously welcomes 15 other drivers to drive their vehicles in an intersecting direction into the intersection. An early attempt to address this problem involved road traffic control equipment that used electro-mechanical relays to switch power to the lamps of traffic control lanterns. The equipment was safeguarded against faulty operation of the relays by means of extra contacts used in a method known commonly as interlocking. This 20 method did not, however, protect against faults in the external wiring to the lanterns. Subsequently, with the advent of solid state switching of the lamps, the nature of the solid state switching devices did not permit interlocking to be carried out. Rather, conflict monitors were introduced to safeguard the road traffic control equipment against certain failures. Conflict monitors undertake monitoring of the operation of the control 25 equipment and, in the event of detecting that a faulty signal is being displayed, will act to switch off the control equipment or otherwise cause safer signals to be displayed by the lanterns than the conflicting signals resulting from the failure. However, as conflicting signals can presently only be visualised through display by the lanterns, the checking of their operation can only be achieved by repair and installation personnel in 30 circumstances that require road users and pedestrians to ignore the conflicting signals whilst their operation is being checked, and supplementary traffic control equipment of a mobile nature to be used. Furthermore, from the time when the failure occurs to the time when the conflict monitor acts for the safer operation of the traffic control equipment, a short or fleeting 35 period of time may elapse when conflicting signals are being displayed, thus presenting a high risk of danger to road users and pedestrians.

3 It is an object of the embodiments of the present invention to overcome, or at least substantially ameliorate, the disadvantages and shortcomings of the aforementioned prior art. According to an embodiment of the present invention there is provided a load 5 switching system in a conflict monitor for road traffic control equipment, said system including a plurality of load switches for operating respective traffic control signals, means for transmitting information about the traffic control signal operated by a first load switch to one or more of the other switches, means for preventing the said other switches from operating their respective traffic control signal when the information 10 received by the said other switches represents that the first load switch is operating its traffic control signal, and means for displaying that the transmitted information has been received by the said other switches whereby an active status of the conflict monitor can be confirmed. According to another embodiment, there is provided a load switching system in 15 a conflict monitor for road traffic control equipment, said system including: a plurality of load switches for operating a respective one or more traffic control signals; means for transmitting information about a green traffic control signal operated by a first load switch to one or more of the other switches; 20 means for preventing the said other switches from operating their respective green traffic control signals when the information received by the said other switches represents that the first load switch is operating its green traffic control signal; and means for displaying that the transmitted information has been received by the said other switches whereby an active status of the conflict monitor can be confirmed. 25 Preferably, information about the operating traffic control signal is transmitted from the first load switch.

4 It is preferred that the information is transmitted to the said other load switches when the first load switch is instructed to operate by a programmable controller. Preferably, the displaying means comprises a monitoring circuit for the 5 load switches. The information may be transmitted to the said other load switches when the first load switch is operating through the monitoring circuit. Preferably, the preventing means includes electronic gates. In a preferred form, a first load switch transmits information about a 10 green traffic control signal that it is operating to one or more of the other switches which are prevented from operating their respective green traffic control signals when the first load switch is transmitting said information. In the above embodiment, the one or more of the other switches operate a red traffic control signal when the first load switch is transmitting said 15 information. In a further preferred form, the operation of the red traffic control signal is prolonged by the preventing means. Preferably, each load switch operates green, amber and red signals of a respective road traffic lantern, whereby a first load switch transmits information 20 about a green signal of the lantern it is operating to one or more of the other switches which are prevented from operating the green signal of their respective road traffic lanterns when the first load switch is transmitting said information. Preferably, the one or more of the other switches are prevented from 25 operating the green signal of their respective road traffic lanterns by means adapted to prolong the operation of the red signal of their respective road traffic lanterns. I AMA/90AA 5 In a further preferred form, the load switches are instructed to operate by a centralised programmable controller of the conflict monitor. Alternatively, the load switches are instructed to operate by a decentralised remote controller of the conflict monitor. 5 As an example, a first load switch responsible for turning on or operating a green signal transmits information about which other load switches are not permitted to operate when it is operated. This information is transmitted to the other load switches when the first load switch is instructed to operate or when it appears, by means of a monitoring circuit, to already be operated. Each load 10 switch, by means of electronic gates or otherwise, will not operate its green signal if any other load switch transmits information or notifies that this is not permitted. In addition, the operation of a red signal of a load switch can be forced to continue if operating the green signal would be dangerous. Additionally, the information transmitted to each load switch from the other load 15 switches can be displayed on the systems, thus confirming to service personnel that the conflict monitoring is active and correct. The above system, while described in terms of centralised, programmable control equipment, may be easily used in situations where load switching is carried out in a remotely controlled, decentralised manner. 20 In order that the invention may be readily understood and put into practical effect, reference will now be made to the accompanying drawing of Fig. 1, which schematically depicts a preferred load switching system in a conflict monitor device of the invention. Items al, a2 and a3 represent the load switches for potentially 25 conflicting lamps. These are generally green lamps. For clarity of presentation, obvious power and control and timing signals are not shown. The load switches send data to co-incidence detector g via time division i A/AAI/AAA 6 multiplexed signals e and f. The operation is as follows. The time division multiplexing uses, in this case, three time intervals 1, 2 and 3. During interval N, where N can represent 1, 2 or 3, load switch aN will send an active signal on signal line e if the load switch recognizes that it is displaying a green signal. 5 Also during interval N, load switches that would conflict with aN send an active signal on signal line f if they are currently displaying a green signal. The signal lines e and f are fed to co-incidence detector g which produces an active output only if inputs from both signal lines e and f are active during the same time interval. The output of the co-incidence detector is fed on signal line h to 10 latching memory device j, causing j to change state to a conflict detected state if the signal on line h is active. Latching memory device j can only be returned to its normal state by a signal on line r which may come from an external manual or automatic resetting means (not shown). The latching memory device output on signal line q is fed to a control means k which can render the 15 entire system safe by forcing the lamps to assume a safe display which is typically red or flashing yellow. The details of this are well understood and omitted for clarity. In constructing a conflict monitor device as shown in Fig. 1, item g could conveniently be a AND gate. Typical commercially available AND gates, such 20 as SN74HCO8, are made by the Texas Instrument company. The latching memory device j could conveniently be a SN74HC76 used in its asynchronous SR mode. This device is also made by the Texas Instrument company. The interconnection of these devices is simple and well understood. The multiplexing arrangement for signals e and f could conveniently be done using 25 tri-state drivers or open collector drivers on the load switches. Although only three load switches are shown here, the system is to be understood to be applicable with obvious changes to any number of load switches. 1QinolonnA 7 It will be understood by persons skilled in the art that various modifications may be made in details of design and construction of the above described load switching system in a conflict monitor device for road traffic control equipment without departing from the scope and ambit of the invention. 5 i ln/lInn A

Claims

1. A load switching system in a conflict monitor for road traffic control equipment, said system including: 5 a plurality of load switches for operating a respective one or more traffic control signals; means for transmitting information about a green traffic control signal operated by a first load switch to one or more of the other switches; means for preventing the said other switches from operating their respective 10 green traffic control signals when the information received by the said other switches represents that the first load switch is operating its green traffic control signal; and means for displaying that the transmitted information has been received by the said other switches whereby an active status of the conflict monitor can be confirmed.

2. The load switching system of claim 1 wherein information about the operating is traffic control signal is transmitted from the first load switch.

3. The load switching system of claim 2 wherein the information is transmitted to the said other load switches when the first load switch is instructed to operate by a programmable controller.

4. The load switching system of any one of claims 1 to 3 wherein the displaying 20 means comprises a monitoring circuit for the load switches.

5. The load switching system of claim 4 wherein the information is transmitted to the said other load switches when the first load switch is operating through the monitoring circuit.

6. The load switching system of claim 1 wherein the preventing means includes 25 gates.

7. The load switching system of any preceding claim wherein one or more of the other switches operate a red traffic control signal when the first load switch is transmitting said information.

8. The load switching system of claim 7 wherein the operation of the red traffic 30 control signal is prolonged by the preventing means. 9

9. The load switching system of claim 1 wherein each load switch operates green, amber and red signals of a respective road traffic lantern, whereby a first load switch transmits information about a green signal of the lantern it is operating to one or more of the other switches which are prevented from operating the green signal of their 5 respective road traffic lanterns when the first load switch is transmitting said information.

10. The load switching system of claim 9 wherein one or more of the other switches are prevented from operating the green signal of their respective road traffic lanterns by means adapted to prolong the operation of the red signal of their respective road traffic lanterns. 10

11. The load switching system of claim 1 wherein the load switches are instructed to operate by a centralised programmable controller of the conflict monitor.

12. The load switching system of claim 1 wherein the load switches are instructed to operate by a decentralised remote controller of the conflict monitor.

13. A load system substantially as herein described with reference to any one of the 15 embodiments of the invention illustrated in the accompanying drawings and/or examples.