AU2003257865B1 - Traffic speed control - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: Details of Associated Provisional Application No: YALLONGA PTY LTD COLIN ALWYN OLSSON

INTELLEPRO

Patent Trade Mark Attorneys Level 7 102 Adelaide Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) TRAFFIC SPEED CONTROL Australian Patent Application No 2002952254 filed 25 October 2002.

The following statement is a full description of this invention, including the best method of performing it known to me: 9- 3-04:11 !35AM INTELLEPRO :61732214762 5/ 33 2 TRAFFIC SPEED CONTROL FIELD OF THE INVENTION THIS INVENTION relates to traffic speed control and in particular but not limited to control of the speed of motor vehicles from a telemetric signal from traffic speed signs erected along highways and other roads.

BACKGROUND TO THE INVENTION Speed causes accidents and it has been proposed to limit speeds locally by governing speeds to the prevailing speed limit when a vehicle enters a speed zone. Examples include US6166658; DE19701432; FR2792445; DE 29901283; US6,285,943; GB 2179824 and EP1096457. However, none of these proposals takes into account other variable local factors apart from the normal speed limit that might under certain conditions increase the probability of accidents at speeds under the limit, for example during rain, bush fires or similar which factors may make it desirable to reduce the speed limit in a dynamic way to a figure below normal. On the other hand US 5,771,484 describes an automotive positive control system for weather and Is primarily for use in relation to small pockets of dense fog by notifying drivers in advance of the need to alter speed.

This system is based on persuasion and monitored traffic flow according to prevailing weather conditions rather than speed limiting as such and relies on the discretion of drivers to control speed as recommended within a traffic flow. This is due to the systems ability to advise accurately in advance of the severe conditions being encountered. The system recommends a set speed to individual drivers in the traffic flow thus taking into account leading and trailing COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04;11 !35AM:INTELLEPRO :;61732214782 6/ 33 3 vehicles in the flow. The recommended speed is not a limit speed but a regulated speed relative to other vehicles to prevent primarily following vehicles colliding with vehicles in front. Vehicle speed may be overridden but driver discretion is completely removed and vehicle speed is regulated to the recommended speed. This system has specific application to severe conditions and is generally not applicable to general application In circumstances where the present invention is envisaged.

OUTLINE OF THE INVENTION In one broad aspect there is provided a variable speed telemetric traffic control system for local speed control whereby a receiver or transceiver on a motor vehicle Interacts with a transmitter ortranscelver located along a roadside where the speed limit changes Into a limited speed zone having a controlled upper speed limit being either a normal fixed speed limit for that zone for normal conditions or a variable speed limit for that zone for abnormal conditions so that the speed of the vehicle is controlled automatically to not exceed the controlled upper speed limit when the vehicle is in the limited speed zone, the speed below the controlled speed limit being at the discretion of the driver, the variable speed limit at which the vehicle is controlled being less than the normal speed limit for that zone and being determined by local safety factors determined according to predetermined variable criteria.

The speed is typically controlled by a control unit, adjacent or before the sign. Typical telemetric systems Include those employing optical telemetry as well as information processing. The vehicle could simply have a speed COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:11!35AM; INTELLEPRO :61732214762 7/ 33 4 recognition receiver involving optical recognition of a visual speed indication.

This may be in the visible spectrum.

The predetermined criteria may include the prevailing visibility as determined by government authorities and input as an index of safety factor reducing speed in accordance with that factor. A typical example would be in circumstances involving reduced visibility or unsafe weather conditions arising through wet roads. The index or safety factor may be input manually by a traffic controller at a central control station to say reduce speeds to a maximum of of the sign speed allowed in optimum driving conditions. Alternatively, the index or safety factor may be determined automatically by local sensors, say a visibility sensor that reduces the speed proportionally in response to sensed reductions in visibility. Clearly other factors may give rise to reductions below the usual speed.

Preferably, the vehicle includes a speed governor able to govern the speed to any one of a selected number of governed speeds according to a received signal from the control unit. Typically vehicle maximum speeds of 40, 50, 60, 70, 80, 90, 100, 110 kilometres may be employed.

A scanner or other receiver or transceiver mounted in or on the vehicle responds to a signal from the control unit and sends a signal to a computer or other mechanism which typically controls the fuel supply to constrain the vehicle to only achieve the speed indicated by the traffic sign. Therefore, speed governors according to the present invention will be utillised in all types of known vehicles including petrol, diesel, autogas, electric and so on. This Includes road COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04;11:35AM:INTELLEPRO :61732214782 8/ 33 vehicles intended to be registered but typically excludes emergency vehicles such as police and ambulance. Typically, the control unit has limited range and is directional or has suitable range finding equipment to detect whether or not a vehicle Is entering the speed zone or whether or not a vehicle is leaving the speed zone. Alternatively, the unit is multi-directional but employs a directional sensor or is able to identify a vehicle according to a known ID to progressively determine the direction in which a vehicle is travelling and thereby determine whether or not it is entering a particular speed zone or leaving that zone. In a further alternative form, the said scanner provided in or on the vehicle may be adapted to read a language, signature or code such as a bar code indicative of zone speed limit being provided on, or alternatively adjacent or before the traffic speed sign so as to obviate the need for use of a control box to control the speed of the vehicle.

Typical methods may include reflection measurement or absorption measurement to determine visibility. The predetermined criteria is typically the prevailing visibility to a Visibility Metre which calculates a Visibility Index for which there is a corresponding maximum speed, data is communicated to a Traffic Speed Control Unit and causes it to override the sign posted speed replacing it with a speed determined from the measured Visibility Index. This is used to set a Visibility Metre (VM) at a certain Index for which there is a corresponding maximum speed. The VM is directly coupled to a Traffic Speed Control Unit and causes it to override the sign posted speed replacing it with a speed determined by a VT calculated index. In some cases it may be preferable COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:11 35AM: INTELLEPRO ;61732214762 9/ 33 6 to have the VT send a signal to a passive receiver which responds back to the VT with a Visibility Index The system may include a manual override where operators may set vehicle speeds outside the normal calculated speeds. For example police vehicles may be equipped to set vehicle speeds directly for individual vehicles or zones. This may be useful if there is an accident or roadworks in progress in terms of the local factors.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present Invention may be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings which illustrates preferred embodiments of the invention and wherein:- Figure 1 is a plan view illustrating a typical roadway system according to the invention; Figure 2 is an alternative embodiment; Figure 3 is a block diagram illustrating application of the present invention to a vehicle having a carburettor as the fuel dispenser; Figure 4 is a block diagram illustrating application of the present invention to a vehicle having a carburettor as an alternative to the Figure 3 embodiment; Figure 5 is a block diagram illustrating application of the present invention to a fuel injector; Figure 6 is an alternative to Figure 5 as applied to diesel; Figure 7 is application of the present invention to an LP and natural gas driven vehicle; Figure 8 is a block diagram illustrating the overall control of the system; COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:1135MM1INTELLEPRO :61732214762 10/ 33 7 Figure 9 is a block diagram illustrating a preferred traffic control centre; Figure 10 is a block diagram illustrating a preferred road side unit; Figure 11 is a block diagram illustrating a preferred arrangement for an onboard unit on a vehicle; and Figure 12 Is a schematic block diagram of a control unit that may be mounted on a police or other traffic authority vehicle.

METHOD OF PERFORMANCE Referring to the drawings and initially to Figure 1 there is illustrated a speed control system 10 employing speed signs 11 and 12 between respective speed zones for 60 kilometres per hour in the direction of arrow 13 and kilometres per hour in the direction of arrow 14. As can be seen car 16 is leaving the 80 kilometre zone and entering the 60 kilometre speed zone whereas car 16 is travelling in the opposite direction, leaving the 60 kilometre zone and entering the 80 kilometre zone. Each of the sign units i 11 and 12 is equipped with a transmitter delivering a directional beam shown at 17 and 18 respectively that actuates speed governing in each of the vehicles according to the speed zone being entered. The second beams 19 and 20 confirm passage of the vehicle into the new zone and at the correct speed and prevent interference between the controls and also prevent undetected passage between the speed zones.

An alternative is illustrated in Figure 2 where the speed zone signs are spaced along the roadway. This Is illustrated at 21, speed zone signs 22 and 23 with vehicle 23 entering the 80 zone and vehicle 24 entering the 60 zone defined COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-()4,'11!35AM:1NTELLEPRO ;61732214762 11/ 33 8 by the broken line at the boundary between the zones at 25. In this case the transmission signal covers both lanes of the road but uses a range finder or doppler to detect vehicle direction. Each of the vehicles 23 and 24 include an identification transceiver and a coded signal particular to that vehicle is initiated and sent to the vehicle in case two vehicles are within the zone and are on opposite sides of the road atthe same time. The different direction distinguishes between the vehicles and the signal is particular to and encoded for the vehicle identification received from the vehicle transceiver.

Referring to the other drawings, various arrangements for controlling fuel delivery to the vehicle engine are illustrated. In relation to the embodiment of Figure 1 the communication between the control unit and the vehicle is one way from the control unit to the vehicle. In the case of the embodiment of Figure 2 there is two-way communication. The drawings illustrate the options of receiver/transceiver on the vehicle but it will be understood that both options are possible in alternative versions of the present invention. Likewise satellite control and vehicle positioning to govern speed in the speed zones by GPS is also contemplated.

Figure 3 illustrates application of the invention to the carburettor family of fuel control in vehicles, a fuel metre capable of accurately dispensing a given amount of fuel and able to be actuated to any of ten settings required to allow the vehicle to achieve maximum speed Indicated by the traffic sign, would be fitted before the carburettor. The fuel pump would be fitted with a by-pass system so that a pre-determined maximum fuel pressure Is maintained to COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04;1:35AMINTELLEPRO :61732214762 12/ 33 9 achieve the accurate delivery of the required amount of fuel for the setting of the fuel metre.

Alternatively, in Figure 4 a fuel metre which has a pre-determined number of jets capable of dispensing a given amount of fuel and able to be actuated for any of the ten settings required to allow the vehicle to achieve the maximum speed indicated by the traffic sign would be fitted before the carburettor. The fuel pump will be fitted with a by-pass system so that a pre-determined maximum fuel pressure is maintained to achieve the accurate delivery of the required amount of fuel for the setting of the fuel metre.

Figures 5 and 6 Illustrate application of the present invention to a vehicle where fuel is delivered by fuel injectors. Early petrol injector systems such as the K jetronlc are mechanically activated and need an additional system to be Installed after the injectors, such system to be Controlled electronically. While this system is quite old there are not many vehicles fitted with it today. All other Injecting systems are controlled by sensors reporting to an engine management system. Such an engine management system can be activated to control the amount of fuel required to achieve the desired speed by variations in the control software. These could therefore be governed by a governor independent of the vehicle driver.

Figure 6 is another injection system but typically utilised in diesel injection.

Most diesel engines have a governor, are controlled mechanically, which can be changed to an electronic control system. Such a system would be designed to COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:11 !35AM:INTELLEPRO :61732214762 13/ 33 allow the correct amount of fuel to be injected so that the vehicle could only achieve the speed required by the traffic sign.

Figure 7 illustrates application of the present invention to liquid petroleum gas and natural gas family of engines. These units have a supply of liquid gas in a special fuel tank. From the tank the fuel is fed under pressure to a convertor which heats the liquid and converts it to gas. The gas is delivered to the carburettor by either a mechanically controlled or computer controlled gas valve.

The present invention envisages modification of such a system to receive a signal sent by the traffic speed control unit which activates the fuel metre controlling the amount of fuel delivered, or the computer, so the veh icle can only achieve the speed required by the traffic sign.

Since the above description deals with the maintenance of governed speed the prevailing safety conditions may then be superimposed on the normal vehicle speed for optimum conditions which is considered a maximum safe speed. Traffic authorities are of the view that in certain conditions speed should be lower than the sign speed. In the present example each of the signs is equipped with a Visibility Transceiver (VT) which uses infrared, radio, microwave or other signal measuring visibility. Typical methods may include reflection measurement or absorption measurement to determine visibility. This Is used to set a Visibility Metre (VM) at a certain index for which there is a corresponding maximum speed. The VM is directly coupled to a Traffic Speed Control Unit and causes it to override the sign posted speed replacing it with a speed determined by the VT calculated Index. In some cases it may be COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04,*1135AM:INTELLEPRO :61732214762 14/ 33 11 preferable to have the VT send a signal to a passive receiver which responds back to the VT with the Visibility Index(VI).

Typical examples of the relationship between VI and speed are given below for nominal 100 110 km and 60 km speed zones.

index VI (relative to clear) Speed (km/hr) Nominall00/110 Speed zone 100/110 9 8 7 6 4 3 2 1 Nominal 60 speed zone 6 5 4 3 2 1 The following description is in relation to drawing Figures 8 to 12 which illustrate the relationship between the various elements of the system and the overall control algorithm.

The system featured below uses technology which is currently available in existing products and would achieve the outcome of limiting the speed of a vehicle according to the zone speed and local safety factor (Visibility). It also provides methods by which the system can be monitored and enforced.

COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04;1135AM,INTELLEPRO :61732214762 15/ 33 12 Figure 8 breaks the system up into four major parts as shown namely, a "traffic control centre"; a "roadside unit"; a "vehicle unit" and "a police unit". These units are depicted in the Figures 9 to 12 and described below.

Traffic Control Centre The traffic control centre is where all collected data will be stored and any speed changes suggested by the roadside units confirmed or rejected. It will have to house the facilities to receive all the incoming messages and provide facilities for the operators to respond to all speed change requests.

Roadside Unit The roadside unit has the job of calculating the current VI and deciding on whether a speed change is required. When the unit believes a speed change Is required it requests a confirmation of the change from the Traffic Control Centre. On receiving the command back from the Traffic Control Centre the unit implements the command received. It also has the job of catching any vehicle that passes by with the wrong previous speed or could not be contacted in cases where speed limitation avoidance has or is occurring.

Vehicle Unit The vehicle unit captures the speed limit as transmitted by the road side unit and limits the car accordingly. It is also capable of receiving a speed limitation command from a police car. Additional to that it will transmit the last speed setpoint and a vehicle ID to the roadside unit on passing the unit.

COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:11 35AM; INTELLEPRO ;61732214762 16/ 33 13 Police Unit A high powered transmitter which is able to send a disabling or speed limiting signal to a vehicle within a certain range. It will also have the capability of transmitting a signal to a specific vehicle if the ID is known.

Data Transceiver The Traffic Control Centre of Figure 9 includes a data transceiver a device allowing data to be sent and received by the Control Centre to and from the road side Central Processing Unit. An Operator Interface comprises a user interface which shows the operator the sites which suggested a speed change and enables the operator to view a picture of current weather conditions at the site and make a decision on whether to accept, postpone, discard or mark the site as faulty and needing repair.

The Road Side Unit of Figure 10 will now be described.

Communication The five parts that make up the road side unit will be connected using the standard RS232 interface and USB connections. Communication will be controlled by the Central Processing Unit in all communication links except for the Data Transceiver to Central Processing Unit where by the Data Transceiver will be able to open the port communication port. This would be to allow control personnel to connect to the unit to check the status and/or request any required data.

Communication between the Road Side Unit and the Traffic Control Centre will be done using the existing GSM/CDMA/GPRS network as much as possible.

COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:1135AM,INTELLEPRO 961732214762 17/ 33 14 This will eliminate the requirement to build a totally new communication network.

In areas where neither of these networks are available a dedicated radio network will have to be introduced which will then feed back to a collection point.

RS232 Interfaces will be used between the Central Processing unit and Visibility metre, Data transmission Unit and Roadside Transmitter. The communication link to the camera will be USB to allow for higher data transfer rates.

Communication between the Road Side Unit and the Vehicle will be done using the existing 5.8GHz allocation for road side to vehicle communication and will encompass the IEEE 802.11 a protocol standard. Such devices are readily available on the market today and are well proven.

Visibility Metre Using a forward scatter detection method the relative visibility may be detected to within a 10 percent error range. Due to the complexity and design cost to develop a forward scattering visibility metre it is suggested to use an existing product such as the Vaisala PWD11. The PWD1I has a RS232 output which can be used to connect in to the rest of the system and allow the Central Processing Unit to collect the required data Central Processing Unit There are many possible Micros that could do this Job, however, the micro to be finally chosen should have a wider operating temperature (-40 to 85 0 C) and low energy usage. One example would by the MSP430 made by TEXAS Instruments.

COMB ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:1135AM: INTELLEPRO :61732214762 18/ 33 Data Transceiver Unit The Data Transceiver unit would in most cases be a GSM/CDMA/GPRS modem; however where there is neither GSM or CDMA coverage a radio network will have to be put in its place. This part of the system would allow the monitoring system to send data back to a control centre where all the speed changes are monitored by an operator.

Camera This is to be a digital camera which is able to be triggered to take a photo and upload the photo via a USB port. The camera need not be a super high resolution camera as its main function will only be to confirm the speed changes suggested by the system. However installing a better camera may allow it to be used as a method of apprehending those who have tampered with their Vehicle Unit and can not be contacted.

Roadside Transceiver The 5.8GHz radio band has been set aside for exactly what the system is trying to do. There are also a number of products that may be purchased off the shelf to do this job. This is the proffered method as it reduces the cost of the prototype and the systems available have been proven over time to work and be reliable. These systems allows for two way communication between the road side and the passing vehicle. It has a downlink of up to 500kbps and an uplink of 250kbps. It has a RS232 port which will link into the Central Processing Unit.

Using this link, data can be uploaded or downloaded to a vehicle unit. The major COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 9- 3-04:1135AM;INTELLEPRO :61732214762 19/ 33 16 draw back of the technology is the 10 metres reception distance limitation and the need for a metal free path between the Roadside and Vehicle Unit.

The Vehicle Unit will now be described with reference to Figure 11.

Transceiver This will use the same technology as the Roadside Transceiver.

Controller Receiving once off data from the Transceiver and continual data from the speedometer the controller will action the engine governing system as required to limit the vehicle speed via a predetermined algorithm. The control algorithm is something that will need to be calculated for each individual make of car.

Vehicle Speed The input to the controller which indicates the vehicle speed will depend on the existing speedometer and thus will vary from vehicle to vehicle. The two most common methods will be an analogue input and a pulsing digital input which will both be proportional to speed.

Engine Governina System There will need to be three major different versions of the Engine Governing System made for the three major different types of cars. These types are; Mechanical control, Electrical control and Computerised control.

Mechanical Control This will be an electromechanical controller which allows the controller to cut the fuel and air received by the motor irrespective of accelerator position.

COMS ID No: SMBI-00654886 Received by IP Australia: Time 12:49 Date 2004-03-09 Resend 9- 3-04:11 46AM INTELLEPRO :61732214762 20/ 33 17 Electronic This controller will have to adjust the electrical signals received by the motor as to control it.

Computerised Control In the case of a fully computerised engine management system it may be possible to implement the control code to the existing control system and get the existing control system to collect the data from the transceiver. If this is not possible then the signal received by the engine management system will have to be altered accordingly.

Finally, the Police Control Unit of Figure 12 includes a high powered transmitter which is able to send data to a Vehicle unit on command and a user interface which allows a Police officer to reduce the maximum speed of a particular vehicle or all vehicles within the reception area via the transmitter.

The following tabulation represents the chosen technologies that are suitable for implementing the present invention according to the control and described above.

Traffic Speed Controller Data Transceiver This would be combination of the following communication systems such that all terrains and possibilities are covered.

1. Dedicated mobile radio 2. GSM 3. CDMA COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04;11:46AM;INTELLEPRO ;61732214762 21/ 33 18 4. Land line Optical Fibre Computer Database 1. Computer Operator Interface 1. Computer Roadside Unit Visibility Detector 1. Forward Scattering Controller 1. Microprocessor Data Transceiver This would be combination of the following communication systems such that all terrains and possibilities are covered.

1. Dedicated mobile radio 2. GSM 3. CDMA 4. Land line Optical Fibre Camera 1. Digital Roadside Transceiver 1. Dedicated Short Range Communications (DSRC) 5.8GHz COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04;11:46AM INTELLEPRO :61732214762 22/ 33 19 Speed Sign 1. LED Vehicle Unit Transceiver 1. Dedicated Short Range Communications (DSRC) 5.8GHz Controller 1. Microprocessor Vehicle Speed Indicator 1. Analogue 2. Pulsing input Engine Governing System 1. Electro-mechanical 2. Electronic 3. Engine Management system integration Police Unit Transmitter 1. Dedicated Short Range Communications (DSRC) 5.8GHz User Interface 1. Laptop COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04:11 !46AM:INTELLEPRO :61732214762 23/ 33 The roadside unit continually checks the visibility factor of the local area.

It also checks all passing cars were set to the correct speed for the previous speed zone and sends the current speed for the new speed zone. Also photographs any passing car which could not be contacted.

On a change in the visibility factor the unit compares this with the predetermined maximum allowable speed of a vehicle. If the current set speed is higher than the speed found In the comparison chart then a request for a speed change is sent to a Traffic Control Centre along with photo of the current weather conditions. Using the photo an operator in the Traffic Control Centre will accept or reject the speed change. Other options would be to postpone or mark that site as faulty and needing repair. On receiving the final command from the Traffic Control Centre the Roadside unit follows the orders given (ie make the change or ignore).

If a car passes with the wrong speed limit set for the previous section of road the vehicle ID is recorded and stored for transmission after a certain amount of time, when the next speed change is requested or if memory fills up.

This data can then be used to later investigate the reason for the wrong speed being present in the vehicle.

If a vehicle passes that can not be contacted a photo is taken and sent to the Traffic Control Centre such that the reason for the vehicle not being contactable can be investigated.

COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04:11!46AM: INTELLEPRO ;61732214762 24/ 33 21 The vehicle unit is responsible for taking the speed limit set by the Traffic Control Centre via the road side unit and ensuring the vehicle doesn't go faster than it is allowed to.

The Traffic Control Centre operators are responsible for checking any speed changes requested by the road side units. They would also have the job of investigating any incorrect vehicle speed settings and also investigating those which could not be contacted via the roadside unit.

Whilst the above has been given by way of illustrative example of the present invention many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as herein set forth, for example, electronic speed control units which perform the function envisaged by the present invention could be utilised for the control of electric motors In electric car engines once those become popular.

COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09

Claims (12)

1. A variable speed telemetric traffic control system for local speed control whereby a receiver or transceiver on a motor vehicle interacts with a transmitter or transceiver located along a roadside where the speed limit changes into a limited speed zone having a controlled upper speed limit being either a normal fixed speed limit for that zone for normal conditions or a variable speed limit for that zone for abnormal conditions so that the speed of the vehicle is controlled automatically to not exceed the controlled upper speed limit when the vehicle is in the limited speed zone, the speed below the controlled speed limit being at the discretion of the driver, the variable speed limit at which the vehicle is controlled being less than the normal speed limit for that zone and being determined by local safety factors determined according to predetermined variable criteria.

2. A telemetric system according to claim 1 wherein the speed is controlled by a control unit, adjacent or before the sign.

3. A telemetric system according to claim 1 wherein the predetermined criteria is the prevailing visibility.

4. A telemetric system according to claim 1 wherein the predetermined criteria is the prevailing visibility as determined by government authorities and Input as an index of safety factor reducing speed in accordance with that factor.

5. Atelemetric system according to claim 1 wherein the safety factor is input manually by a traffic controller at a central control station.

6. A telemetric system according to claim 1 wherein the safety factor is determined automatically by local sensors. COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04;11!46AM:; INTELLEPRO :61732214762 26/ 33 23

7. A telemetric system according to claim 1 wherein the vehicle includes a speed governor able to govern the speed to any one of a selected number of governed speeds according to a received signal from a control unit.

8. A telemetric system according to claim 1 wherein a control unit sends a control signal to vehicles, the control unit has limited range and Is directional or has suitable range finding equipment to detect whether or not a vehicle is entering a limited speed zone or whether or not a vehicle Is leaving the limited speed zone.

9. A telemetric system according to claim 1 wherein a control unit sends a control signal to vehicles, the control unit is multi-directional but employs a directional sensor or is able to identify a vehicle according to a known ID to progressively determine the direction in which a vehicle is travelling and thereby determine whether or not it is entering a particular limited speed zone or leaving that zone.

10. A telemetric system according to claim 1 wherein the predetermined criteria is the prevailing visibility determined by reflection measurement or absorption measurement to determine visibility.

11. A telemetric system according to claim 1 wherein the predetermined criteria is the prevailing visibility to a Visibility Metre which calculates a Visibility Index for which there Is a corresponding maximum speed, data Is communicated to a Traffic Speed Control Unit and causes it to override the normal speed limit replacing It with a lower speed determined from the measured Visibility Index.

12. A telemetric system according to claim 1 where police vehicles or other COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09 Resend 9- 3-04 11 :46AM; lTELLEPRO :61732214762 27/ 33 24 traffic control vehicles are equipped to set vehicle speeds by transmitting control signals to a target vehicle. DATED this 8th day of March 2004 YALLONGA PTY LTD By Its Patent Attorneys INTELLEPRO COMS ID No: SMBI-00654900 Received by IP Australia: Time 12:57 Date 2004-03-09