EP0303848A2 - Traffic-monitoring device - Google Patents

Abstract

A device for the photographic monitoring of traffic contains a sensor, for example an induction loop laid in the carriageway for traffic light monitoring or a Doppler radar, which reacts to passing vehicles. It is determined by means of a signal evaluation whether a detected vehicle has infringed a traffic regulation, for example has exceeded the maximum permissible speed. In the case of such an infringement, a camera is automatically triggered and the monitored vehicle photographed. In order to permit the data produced by such systems and relating to the traffic incident to be utilised for statistical purposes, a memory is provided in which events detected by the device, which are not only restricted to the infringement of traffic regulations, can be stored.

Description

Technical field

• (a) einen auf durchfahrende Fahrzeuge ansprechenden Sensor,
• (b) Mittel zur Feststellung einer Übertretung von Ver­kehrsregeln durch das durchfahrende Fahrzeug und
• (c) eine Aufnahmeeinrichtung zur Aufnahme eines solchen Fahrzeugs, die von den besagten Mitteln zur Fest­stellung einer Übertretung von Verkehrsregeln ge­steuert ist

The invention relates to a device for traffic monitoring, comprising

• (a) a sensor responsive to passing vehicles,
• (b) means for determining a violation of traffic rules by the passing vehicle and
• (c) a recording device for recording such a vehicle, which is controlled by said means for determining a violation of traffic rules

This can be a device for photographic traffic monitoring, in which a photograph of the vehicle is taken when a violation of a traffic rule is determined. Examples of such devices are traffic light monitoring systems or photographic speed monitoring systems operating with Doppler radar.

Underlying state of the art

Devices for the automatic photographic monitoring of traffic light-controlled intersections are known. A sensor, such as an induction loop installed in the road, gives a signal when a vehicle enters an intersection monitored by traffic lights. Another signal is provided by the traffic light when the traffic light goes into its blocking phase. If the vehicle enters the intersection during the blocking phase, a photograph is taken, which records the vehicle and its license plate. This enables the vehicle to be identified and the violation to be documented. In order to improve the evidential value of the photographic registration, several shots are usually triggered one after the other.

Such devices are described for example in DE-PS 683 658, US-PS 2 871 088, AT-PS 225 077, DE-AS 1 078 797, an essay in "Police, Technology, Traffic" Issue 8 (1965 ), 269-272, DE-PS 23 65 331.

It is also known to measure the speed of a vehicle and to trigger a photographic recording which exceeds the permissible maximum speed, by means of which the vehicle is held with its license plate.

The already mentioned AT-PS 225 077 describes, in one embodiment, a traffic monitoring system with two sensors arranged at a fixed distance from one another in the paint path. A camera is triggered and the vehicle is photographed when the time interval between the two sensors being passed is less than a predetermined value. A similar arrangement is given by the AT-PS 246 617 known.

It is furthermore known to trigger two recordings at fixed time intervals if the exceeding of the permissible maximum speed is signaled by the two sensors arranged in the roadway and the evaluation circuit acted upon by their signals. A further measured value for the speed can be obtained from the positions of the vehicle on the two recordings.

It is also known to determine the speed of a vehicle to be monitored using a Doppler radar. Such a speed monitoring system is described, for example, in US Pat. No. 2,683,071, Swiss Pat. No. 414,210 or Swiss Pat. No. 470,674. With conventional photographic speed monitoring systems with Doppler radar, the measured speed is displayed. If the permissible maximum speed is exceeded by the vehicle to be monitored, the vehicle is photographed and the display of the measured speed is reflected in the recording (e.g. DD-PS 66 974).

Practically all of the above-mentioned devices for traffic monitoring contain devices for generating time information, that is to say a clock for displaying the time and a date generator which displays the date. This time information is registered together with the recording of the vehicle to be monitored, usually reflected in the recording (DD-PS 66 974).

It is also known to use a Doppler radar to generate a sequence of speed measurements while a vehicle to be monitored is generated by the radar beam passes through. These speed measurement values are stored in a classified manner in such a way that a histogram is obtained, that is to say a frequency distribution of these speed measurement values. From such a histogram, conclusions about overtaking processes or the like can be drawn. to be pulled. It is also possible to use the histogram to infer the type of vehicle passing through, i.e. whether it is a car or a truck.

It is also known to use sensors for traffic counters e.g. in the form of induction loops in the carriageway and the number of vehicles passing through for statistical purposes.

Disclosure of the invention

The invention is based on the knowledge that, in traffic monitoring systems of the type mentioned above, a large amount of information about the traffic situation is obtained as "waste products", which are interesting for traffic planning and traffic statistics and possibly also for the assessment of a single registered violation, but which are not recorded in the known systems. This information is particularly interesting because such traffic monitoring systems are usually used at traffic foci where statistical documents on traffic density, temporal distribution of traffic and frequency of violations of traffic rules are of particular importance for traffic planning and control.

The invention is accordingly based on the object of making it possible to use such additional information which is obtained in traffic monitoring devices.

The invention is further based on the object of facilitating the evaluation of the detected violations by means of electronic data processing.

According to the invention, this object is achieved by an electronic memory in which processes recorded by the device can be stored for later evaluation.

It is not only possible to detect the vehicles which violate a traffic rule and are photographed, but also all vehicles passing through the device. The vehicle density can therefore be determined and, with the help of the clock and date provided anyway, the temporal distribution of the vehicle density can also be determined. The number of violations can be related to the vehicle density, or the time distribution of the violations can be determined. If the device can differentiate between cars and trucks based on a histogram, then this can also be statistically evaluated.

The statistical analysis can also be used to draw conclusions about the traffic situation at the time of a particular violation. For example, one can determine whether there was heavy traffic or the road was empty during the period in which, for example, a monitored vehicle was driving at excessive speed.

The electronically stored data of the detected violations can also be used to, for example, the form with the help of electronic data processing moderate processing (writing an advertisement) of the registration. Then only the stored data (e.g. date, time, location and speed) need to be identified by a number that also appears on the recording. The evaluating official only needs to enter the vehicle registration number recognizable in the recording in a form which has been filled or written by a computer after the memory. This can significantly relieve the police of routine paperwork.

Embodiments of the invention are the subject of the dependent claims.

Brief description of the drawings

• Fig.1 ist eine schematisch - perspektivische Darstellung einer ampelgeregelten Kreuzung mit einer Vor­richtung zur photographischen Überwachung dieser Kreuzung
• Fig.2 ist ein Blockdiagramm einer Vorrichtung zur Über­wachung einer ampelgeregelten Kreuzung mit einem Speicher zur Registrierung der erfaßten Vorgänge.
• Fig.3 ist eine schematische Darstellung einer mit Doppler - Radar arbeitenden Geschwindigkeits - ­Überwachungsvorrichtung.
• Fig.4 ist ein Blockdiagramm der Geschwindigkeits - ­Überwachungsvorrichtung von Fig.3.

Embodiments of the invention are explained below with reference to the accompanying drawings.

• 1 is a schematic - perspective illustration of a traffic light-controlled intersection with a device for photographically monitoring this intersection
• Fig. 2 is a block diagram of a device for monitoring a traffic light-controlled intersection with a memory for registering the detected processes.
• 3 is a schematic illustration of a speed monitoring device operating with Doppler radar.
• Figure 4 is a block diagram of the speed monitor of Figure 3.

Preferred embodiment of the invention

1 is a schematic perspective illustration of an intersection 10, which is regulated by a traffic light 12. The remaining traffic lights of the intersection are not shown to simplify the illustration. A sensor 16 in the form of an induction loop is embedded in the road surface of a road 14 leading into the intersection just before the intersection with the intersection 10. The sensor 16 responds when a vehicle 18 drives over it.

A device 18 for photographically monitoring the intersection 10 is arranged in a housing 20 which is arranged on a column 22 at a short distance from the intersection 10. The device 18 includes a signal processing unit 24, a photographic camera 26 controlled by the signal processing unit and a flash unit 28. The signal processing unit 24 receives a sensor signal from the sensor 16 via a line 30 and a blocking phase signal from the traffic light 12 via a line 32 when the traffic light switches to blocking phase.

As can be seen from the block diagram in FIG. 2, the traffic light 12 contains a transmitter 34 which supplies the blocking phase signal. The signal processing unit 24 supplies a trigger signal to a camera trigger 36 if a sensor signal appears during the blocking phase. The camera trigger 36 then triggers the camera 26. The camera then takes a picture of the intersection 10 with the traffic light 12 on the blocking phase and the vehicle 40 (FIG. 1) which has triggered the sensor signal. Furthermore, a clock 42 and a date generator 44 provided. These form means 46 for generating time information. The displays of clock 42 and date generator 44 are reflected in the recording or otherwise recorded on the film.

When the sensor 16 responds, at least two recordings are usually triggered during the blocking phase. Precautions have been taken to prevent additional triggering between these shots and during the film transport by another vehicle. Provisions have also been made to detect such a vehicle, which also enters the intersection between these two images. These measures are known and are therefore not shown in detail.

In such a device for monitoring a traffic light-controlled intersection, a memory 48 is now provided. The processes recorded by the device can be stored in this memory for later evaluation for statistical purposes.

The sensor signals from the sensor 16 can be applied via a line 50. These provide the total number of all vehicles that entered the intersection, regardless of whether they entered the intersection during the blocking phase and were photographed or not. This information is lost in conventional devices of this type. The memory 48 also receives the signals from the signal processing unit 24 via a line 52, through which the camera trigger 36 is controlled. These signals provide the number of violations detected. Finally, the memory 48 also receives time information from the clock 42 via a data line 54 and from the date generator 44 via a data line 56.

The memory can be part of a microprocessor, in which the information is classified, so that the number of events received in predetermined time intervals (pulses on lines 50 and 52, respectively) is stored together with the associated time information (time and date).

The information thus obtained during the operation of the device can later be statistically evaluated. For example, the traffic density in the street 14 can be determined as a function of time. It can be determined what the ratio of the number of violations to the total number of vehicles driven is and whether this ratio changes with time or with the vehicle density. It can also be determined what influence traffic light settings, for example an extension of the "yellow phase", has on the absolute or relative number of registered violations. The stored data of various devices of the present type arranged at traffic hotspots of a city provide a continuous overview of the traffic events in the city and thus documents for traffic planning. All of this is achieved using existing components with a relatively small additional effort.

3 shows schematically a speed monitoring device working with Doppler radar. The device 58 is arranged laterally from a street 60. 62 denotes a vehicle to be monitored. The device 58 contains a radar antenna 64 which emits a "radar lobe" 66, which is shown in broken lines. The "radar lobe" represents the emitted radiation energy per solid angle as a function of the angle. The device 58 also contains one photographic camera 68 that captures a field of view 70. The signals of the radar antenna 64 are connected to a measuring and evaluation circuit 72. The measurement and evaluation circuit provides speed measurements when the vehicle 62 passes through the radar lobe. The camera 68 is triggered when a permissible maximum speed is exceeded. It is triggered at a point in time at which the vehicle 62 is essentially in the middle of the field of view 70 of the camera 68.

Information provided by the measurement and evaluation circuit, including the number of vehicles passing through (regardless of whether it is too fast or not), is stored in a memory 74 for later statistical processing.

4, the device 58 is shown schematically as a block diagram. A Doppler radar 76, which comprises the radar antenna and the associated transmitting and receiving device and an evaluation circuit, provides measured speed values. The speed measurement values are processed into a histogram, that is to say a distribution of the frequencies of speed measurement values over different speed classes. Overtaking processes or the like can be made from this histogram. can be recognized, which could lead to incorrect measured values, so that measured values obtained in this way are suppressed and do not lead to the camera being triggered. It can also be recognized whether the detected vehicle is a car or a truck. And the histogram results in a measured value for the speed of the monitored vehicle 62. In FIG. 4, the evaluation "car / truck" is symbolized by a block 80. The determination of the speed from the histogram is represented by a block 82. The evaluation "car / truck" controls a comparator 84 or 86. On the Comparator is the measured value of the speed of vehicle 62 from block 82 and is compared in each of the comparators with a permissible maximum speed predetermined for the type of vehicle in question, for example of 120 or 80 km / h. Depending on the type of vehicle, a trigger signal is given to a camera trigger 88 at a measured value of more than 120 km / h or a measured value of more than 80 km / h. The camera trigger 88 then triggers the camera 68. The time then taken from a clock 90 and the date from a date generator are simultaneously reflected in the recording that is then made.

This technique is known per se and is therefore not described in detail here.

The various information accumulating in this device are transferred to the memory 74. In particular, the memory 74 receives the time from the clock 90 via a data line 94 and the date from the date generator 92 via a data line 96. Furthermore, the memory 74 receives the measured value of the speed from block 82 via a data line 98. The memory 74 also receives Pulses from the evaluation "car / truck" 80 depending on whether a car or a truck is detected via line 100 or 102. Finally, the memory 74 receives pulses from the comparators 84 and 86 via line 104 or line 106, if a vehicle has exceeded the permissible maximum speed specified for his vehicle type and a triggering pulse is given to the camera trigger.

In the memory 74, the events can also be summed and classified according to speed and / or time. In this device too, the information about non-photographed vehicles is also a "waste product" and can be relative little effort can be recorded and statistically evaluated. Of course, it is not necessary to save all the information given here if not all of this information is to be evaluated.

The statistical evaluation can also be important for the assessment of a single, recorded violation. For example, exceeding the speed limit can be more or less serious depending on whether there was heavy traffic at the time or the road was almost empty.

Finally, the electronic storage of the data associated with a recorded violation of the traffic rules can be used to relieve the police when dealing with the violations found. This is because the data stored in the electronic memory can be used to fill out or create forms for a notification or a fine notice by means of a computer. These forms then contain the date, time, place and type of violation from the memory. The police need only enter the vehicle registration number in such a form from the photograph.

This routine work when evaluating the recordings is very time-consuming and often represents the limiting factor when using automatically operating traffic monitoring devices: There is no point in detecting more violations and taking recordings than can be subsequently worked up with the available personnel .

Claims (8)

1. Device for traffic monitoring, containing (a) a sensor responsive to passing vehicles (40; 62), (b) means (24; 84,86) for detecting a violation of traffic rules by the passing vehicle and (c) a receiving device (26; 68) for receiving such a vehicle by said means (24; 84,86) for determining an over
traffic control is controlled,
marked by
(d) an electronic memory (48; 74) in which processes recorded by the device can be stored for later evaluation. 2. Device according to claim 1, characterized in that (a) means (46; 90, 92) are provided for generating time information and (b) events in the memory (48; 74) can be stored together with associated time information. 3. Apparatus according to claim 1 or 2, characterized in that the stored operations include the passage of vehicles. 4. Device according to one of claims 1 to 3, characterized in that the stored processes include the detected violations of traffic rules. 5. Device according to one of claims 1 to 4, characterized in that (a) the means for determining the violation of a traffic rule comprise a speed measuring device <82> for measuring the speeds of the monitored vehicles and (b) the measured speeds can be stored in the memory (74). 6. Device according to one of claims 1 to 4, characterized in that (a) the means for determining the violation of a traffic rule include a facility <80> for determining the type of vehicle (car, truck) and (b) the types of vehicles passing through can be stored numerically in the memory (74). 7. The device according to claim 1, characterized in that it is a photographic traffic light monitoring system. 8. The device according to claim 1, characterized in that it is a photographic speed monitoring system working with Doppler radar <76>.

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