JP5159238B2 - Abnormality detection device for vehicle detector and abnormality detection method for vehicle detector - Google Patents

Description

  The present invention, for example, in a toll collection system for a toll road such as an expressway, is a vehicle detection system that detects an abnormality of a transmission type vehicle detector that is installed in a toll collection lane of a toll gate and optically detects a traveling vehicle. The present invention relates to an abnormality detection device for a detector and an abnormality detection method for a vehicle detector.

  Recently, for example, in a toll collection lane of a toll road such as an expressway, an ETC system (non-stop automatic toll collection system) that automatically performs toll collection processing for the toll road for vehicles passing through the toll collection lane A toll collection system called “A” is rapidly spreading (see, for example, Patent Document 1).

  The ETC system is a toll road toll gate between a lane control device installed on the toll collection lane side and an on-board unit equipped with an ETC card (IC card) for fare payment installed on the vehicle side. In this system, the toll collection processing is automatically performed on the vehicle in a non-stop manner by performing wireless communication via a roadside radio device (antenna device) installed on the toll collection lane.

  In such an ETC system, a plurality of transmission type vehicle detectors that optically detect a vehicle traveling in a toll collection lane are installed at predetermined intervals along the toll collection lane in the traveling direction of the vehicle.

  This type of vehicle detector is an apparatus that plays an important role in grasping the behavior of a vehicle in an ETC system. In particular, it is used to generate wireless communication start, guidance display start / end, start control device gate cutoff timing, and the like. In order for the vehicle detector to detect the vehicle, a device using various sensors is used. In particular, a transmission type vehicle detector using a transmission type sensor is generally used.

  The vehicle detector is an important device that grasps the behavior of the vehicle as described above. Therefore, when an abnormality (failure) occurs in the vehicle detector, it must be promptly detected and appropriate measures taken.

  When a transmission type vehicle detector is used, if the optical axis is blocked due to dust or mud splashing mud, the vehicle detector will always be in a light-shielded state, so it will always be in a fake vehicle detection state. Becomes abnormal. On the other hand, even when a traffic jam occurs at the toll gate, the vehicle is in the vehicle detection state because the optical axis is always blocked by the vehicle. In this case, the vehicle is normally detected, so the equipment state is normal. It is.

  If the above two detection events are determined by the vehicle detector alone, the detection state is the same for both states, and it is impossible to determine whether the vehicle detection is normal or abnormal fake vehicle detection.

  A conventional abnormality detection method for a vehicle detector detects time when the vehicle detection state of the vehicle detector exceeds a certain time by monitoring the time with a timer means (for example, see Patent Document 2). .

However, in this abnormality detection method, even when an abnormality actually occurs, the abnormality cannot be detected unless the set time has elapsed, and the vehicle behavior cannot be accurately grasped during that time. If the behavior of the vehicle cannot be accurately grasped, the ETC system cannot be operated normally. Therefore, when an abnormality occurs in the vehicle detector, it is important to quickly detect the abnormality and take appropriate measures.
Japanese Patent No. 3256642 JP 2000-215389 A

  Therefore, the present invention complements the detection states of a plurality of installed vehicle detectors so that the abnormality of the vehicle detector can be detected quickly, for example, with minimal adverse effects on the toll collection system operation. An object of the present invention is to provide a vehicle detector abnormality detection device and a vehicle detector abnormality detection method that can be limited to the limit.

  The abnormality detector for a vehicle detector according to the present invention is installed at predetermined intervals in the traveling direction of a vehicle along a road on which the vehicle travels, and detects an abnormality of at least two vehicle detectors that detect the vehicle traveling on the road. An abnormality detection device for a vehicle detector to detect, when the vehicle detector on the upstream side with respect to the traveling direction of the vehicle in the two vehicle detectors is in a continuous detection state in which the vehicle is continuously detected. First counting means for counting the number of vehicles detected by the downstream vehicle detector with respect to the traveling direction of the vehicle during the continuous detection state, and the count value of the first counting means is the value of the road When the maximum number of vehicles that can exist between two vehicle detectors is exceeded, a first determination unit that determines that the upstream vehicle detector is abnormal, and a traveling direction of the vehicle among the two vehicle detectors Downstream vehicle detection for When the vehicle is in the continuous detection state where the vehicle is continuously detected, the second detection unit counts the number of times the upstream vehicle detector with respect to the traveling direction of the vehicle has detected the vehicle entering the vehicle during the continuous detection state. When the count value of the counting means and the second counting means exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road, the downstream vehicle detector determines that there is an abnormality. 2 determination means.

  The abnormality detection method for a vehicle detector according to the present invention includes at least two vehicle detectors installed at predetermined intervals in the traveling direction of the vehicle along the road on which the vehicle travels, and detecting the vehicle traveling on the road. An abnormality detection method for a vehicle detector for detecting an abnormality when the vehicle detector on the upstream side of the two vehicle detectors with respect to the traveling direction of the vehicle continuously detects the vehicle. A first counting step for counting the number of vehicles detected by the downstream vehicle detector with respect to the traveling direction of the vehicle during the continuation detection state, and the count value of the first counting step is the road A first determination step of determining that the upstream vehicle detector is abnormal when the maximum number of vehicles that can exist between the two vehicle detectors is exceeded, and of the two vehicle detectors, In the direction of travel When the downstream vehicle detector is in a continuous detection state in which the vehicle is continuously detected, the number of vehicles detected by the upstream vehicle detector in the continuous detection state when the vehicle detector enters the vehicle traveling direction. And when the count value of the second counting step exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road, the downstream vehicle detector Includes a second determination step of determining that the error is abnormal.

  According to the present invention, by mutually complementing the detection states of a plurality of installed vehicle detectors, it is possible to quickly detect an abnormality of the vehicle detector, and minimize, for example, adverse effects on the toll collection system operation. It is possible to provide a vehicle detector abnormality detection device and a vehicle detector abnormality detection method that can be limited to the limit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of an ETC system used as, for example, a toll collection system for a toll road according to the present embodiment. In FIG. 1, a booth 12 is provided at a side of a toll collection lane (road) 11 of a toll booth where a toll collector (person in charge) who performs toll collection processing manually or performs lane closure or the like. .

  A transmission-type first vehicle detector 14 for detecting the vehicle 13 entering the lane 11 is installed on the side of the toll collection lane 11 and upstream of the booth 12. The first vehicle detector 14 optically detects, for example, the vehicle 13 traveling in the lane 11 using infrared rays, and is configured by a pair of vehicle detectors 14a and 14b in this example.

  Between the first vehicle detector 14 and the booth 12 at the side of the toll collection lane 11, a transmissive second vehicle detector 15 that detects the vehicle 13 traveling in the lane 11 is installed. . The second vehicle detector 15 optically detects the vehicle 13 traveling on the lane 11 using infrared rays, for example.

  Above the toll collection lane 11, a predetermined portion between the second vehicle detector 15 and the booth 12 has a toll collection onboard device 16 mounted on the vehicle 13 entering the lane 11. A roadside wireless device (antenna device) 17 for performing wireless communication is installed.

  On the side of the toll collection lane 11 and downstream of the booth 12, a roadside indicator 18 for displaying charges, various messages, etc. to users in the vehicle 13 is installed.

  A start control device (opening / closing gate) 19 that controls passage permission and prohibition of the vehicle 13 leaving the lane 11 is installed on the side of the toll collection lane 11 and downstream of the roadside indicator 18.

  In the vicinity of the start control device 19 on the side of the toll collection lane 11, a transmission type third vehicle detector 20 that detects the vehicle 13 leaving the lane 11 is installed. The third vehicle detector 20 optically detects the vehicle 13 exiting from the lane 11 using, for example, infrared rays, and is configured by a pair of vehicle detectors 20a and 20b in this example.

  The first vehicle detector 14, the second vehicle detector 15, the roadside wireless device 17, the roadside indicator 18, the start control device 19, and the third vehicle detector 20 are respectively connected to the lane control device 21. These are controlled by the lane control device 21.

  The lane control device 21 starts wireless communication via the roadside wireless device 17 with the vehicle-mounted device 16 mounted on the vehicle 13 at the timing when the first vehicle detector 14 detects the vehicle 13. Toll collection processing by communication and toll collection processing completed normally (appropriate vehicle, hereinafter referred to as an ETC vehicle) and a vehicle with an ETC card not inserted response from the vehicle-mounted device 16 (inappropriate vehicle) Hereinafter, this is referred to as a vehicle without a card inserted) and a vehicle in which wireless communication is not normally performed due to the absence of a vehicle-mounted device (non-appropriate vehicle, hereinafter referred to as a non-ETC vehicle).

  When the lane control device 21 determines that the vehicle is an ETC vehicle, the lane control device 21 allows the vehicle 13 to pass by transmitting a gate opening command to the start control device 19 installed on the exit side of the toll lane and opening the gate. If it is determined that the vehicle has not been inserted into a card or a non-ETC vehicle, a gate closing command is transmitted to the start control device 19 to hold the gate in a closed state, thereby rejecting passage of the vehicle 13. Stop. For these non-appropriate vehicles, for example, fee collection processing with cash or a credit card or the like is performed by manual operation of a receipt person in the booth 12. The lane control device 21 opens the gate of the start control device 19 and permits the vehicle 13 to pass when the toll collection process of the toll collector is completed.

  Further, the lane control device 21 displays a charge, various messages, and the like on the roadside indicator 18 at the timing when the second vehicle detector 15 detects the vehicle 13, and the third vehicle detector 20 displays the vehicle 13. At the timing when the exit is detected, control such as closing the gate of the start control device 19 is performed.

  Each vehicle detector 14a, 14b, 15, 20a, 20b includes, for example, an infrared projector 31 installed on one side of the lane 11 and a projector 31 on the other side of the lane 11, as shown in FIG. The control unit 33 that controls lighting of the infrared light receiver 32 and the projector 31 that are installed opposite to each other, and also determines vehicle detection from the output of the light receiver 32, and an external device (lane control device 21) and an interface And an interface unit 34 for performing

It is assumed that the first vehicle detector 14 and the third vehicle detector 20 can determine whether the vehicle 13 is moving forward or backward in addition to the presence / absence detection function of the vehicle 13. In addition, the second vehicle detector 15 has only the function of detecting the presence or absence of the vehicle 13, and the forward / reverse determination is not possible.

  Next, the abnormality detection process of the vehicle detector in such a configuration will be described. Note that this abnormality detection processing is performed in the lane control device 21.

  In general, the number of vehicles that can exist in the same lane of a tollgate can be determined roughly by the installation position of the vehicle detector and the vehicle dimensions (vehicle length). In the present embodiment, it is assumed that the vehicles 13 are arranged in a line in the lane 11. Assuming that the distance from the first vehicle detector 14 to the third vehicle detector 20 is about 13 m and the vehicle length of one vehicle 13 is 3.5 m, the first vehicle detector 14 The maximum number of vehicles 13 that can exist between the third vehicle detector 20 is about four.

  In the present embodiment, from the maximum number of vehicles 13 that can exist between the first vehicle detector 14 and the third vehicle detector 20, the number of vehicles 13 that have entered the lane 11 or exit. The abnormality (failure) of the detection function of the vehicle detectors 14, 15, and 20 is detected by associating with the number of vehicles 13 that have been performed, and the details will be described below.

First, the abnormality detection process for the first vehicle detector 14 will be described with reference to the schematic diagram shown in FIG. 3 and the flowchart shown in FIG.
For example, as shown in FIG. 3, the maximum number of vehicles 13 that can exist between the first vehicle detector 14 and the third vehicle detector 20 in the lane 11 is the first vehicle detector 14. Except for the passing vehicle 13, the number is three.

  First, as an initial value in a vehicle number management counter (not shown), the maximum number (3) of vehicles 13 that can exist between the first vehicle detector 14 and the third vehicle detector 20 in the lane 11 is set to “3”. The number “4” obtained by adding “+1” is set (step S1).

  Next, it is checked whether or not the first vehicle detector 14 has detected the entry of the vehicle 13 (step S2). If the first vehicle detector 14 does not detect the entry of the vehicle 13, it is regarded as normal. Then, the process returns to step S1, and the same operation as described above is repeated.

  When the first vehicle detector 14 detects the entry of the vehicle 13 as a result of the check in step S2, it is checked whether the third vehicle detector 20 has detected the exit of the vehicle 13 (step S3). If the third vehicle detector 20 does not detect the exit of the vehicle 13, it is regarded as normal and the process returns to step S1 to repeat the same operation as described above.

  When the third vehicle detector 20 detects the exit of the vehicle 13 as a result of the check in step S3, the vehicle number management counter is counted as “−1” (step S4), and then the value of the vehicle number management counter is counted. Is checked to see if it is “0” (step S5).

  As a result of the check in step S5, if the value of the vehicle number management counter is not “0”, it is checked whether or not the first vehicle detector 14 detects the exit of the vehicle 13 (step S6). If the vehicle detector 14 does not detect the exit of the vehicle 13, the process returns to step S3 and the same operation is repeated.

  As a result of the check in step S6, when the first vehicle detector 14 detects the exit of the vehicle 13, it is regarded as normal and the process returns to step S1 to repeat the same operation as described above.

  As a result of the check in step S5, if the value of the occupancy management counter is “0”, it is determined that the first vehicle detector 14 is abnormal (failure), and this is indicated to the staff by a display or voice. Notification is made (step S7).

  As described above, in the example of FIG. 3, when the first vehicle detector 14 is in the continuous detection state in which the vehicle 13 is continuously detected, the third vehicle detector 20 includes four or more vehicles 13. When the exit is detected, the first vehicle detector 14 is determined to be abnormal (failure).

  In this case, the fact that the first vehicle detector 14 is in the continuous detection state is a state in which the vehicle 13 is passing or stopped, and the vehicle 13 has not been entered. Although the vehicle 13 does not enter from the first vehicle detector 14, four or more vehicles 13 cannot leave.

Next, the abnormality detection process for the second vehicle detector 15 will be described.
In the case of the second vehicle detector 15, two events are conceivable. First, the first event will be described with reference to the schematic diagram shown in FIG. 5 and the flowchart shown in FIG.
For example, as shown in FIG. 5, the maximum number of vehicles 13 that can exist between the second vehicle detector 15 and the first vehicle detector 14 in the lane 11 is one.

  First, as an initial value in a vehicle number management counter (not shown), the maximum number (1) of vehicles 13 that can exist between the second vehicle detector 15 and the first vehicle detector 14 in the lane 11 is set to “ The number “2” obtained by adding “+1” is set (step S11).

  Next, it is checked whether or not the second vehicle detector 15 has detected the entry of the vehicle 13 (step S12). If the second vehicle detector 15 does not detect the entry of the vehicle 13, it is regarded as normal. Returning to step S11, the same operation as described above is repeated.

  As a result of the check in step S12, when the second vehicle detector 15 detects the entry of the vehicle 13, it is checked whether the first vehicle detector 14 has detected the entry of the vehicle 13 (step S13). If the first vehicle detector 14 does not detect the entry of the vehicle 13, it is considered normal and the process returns to step S11 to repeat the same operation as described above.

  If the first vehicle detector 14 detects the entry of the vehicle 13 as a result of the check in step S13, the vehicle number management counter is counted as "-1" (step S14), and then the value of the vehicle number management counter is counted. Is checked to see if it is “0” (step S15).

  As a result of the check in step S15, if the value of the vehicle number management counter is not “0”, it is checked whether or not the second vehicle detector 15 detects the exit of the vehicle 13 (step S16). If the vehicle detector 15 does not detect the exit of the vehicle 13, the process returns to step S13 and the same operation is repeated.

  If the second vehicle detector 15 detects the exit of the vehicle 13 as a result of the check in step S16, it is regarded as normal and the process returns to step S11 to repeat the same operation as described above.

  If the value of the occupancy management counter is “0” as a result of the check in step S15, it is determined that the second vehicle detector 15 is abnormal (failure), and this is indicated to the staff by a display or voice. Notification is made (step S17).

  Thus, in the case of the first event in the example of FIG. 5, when the second vehicle detector 15 is in the continuous detection state in which the vehicle 13 is continuously detected, the first vehicle detector 14 is 2 When the entry of more than 13 vehicles 13 is detected, the second vehicle detector 15 is determined to be abnormal (failure).

  In this case, the second vehicle detector 15 being in the continuous detection state is a state in which the vehicle 13 is passing or stopped. The second vehicle detector 15 is in the continuous detection state, and two or more vehicles 13 cannot enter.

Next, the second event will be described with reference to the schematic diagram shown in FIG. 5 and the flowchart shown in FIG.
For example, as shown in FIG. 5, the maximum number of vehicles 13 that can exist between the second vehicle detector 15 and the third vehicle detector 20 in the lane 11 is two.

  First, as an initial value in a vehicle number management counter (not shown), the maximum number (2) of vehicles 13 that can exist between the second vehicle detector 15 and the third vehicle detector 20 in the lane 11 is set to “2”. The number “3” obtained by adding “+1” is set (step S21).

  Next, it is checked whether or not the second vehicle detector 15 has detected the entry of the vehicle 13 (step S22). If the second vehicle detector 15 does not detect the entry of the vehicle 13, it is regarded as normal. Returning to step S21, the same operation as described above is repeated.

  As a result of the check in step S22, when the second vehicle detector 15 detects the entry of the vehicle 13, it is checked whether the third vehicle detector 20 detects the exit of the vehicle 13 (step S23). If the third vehicle detector 20 does not detect the exit of the vehicle 13, it is considered normal and the process returns to step S21 to repeat the same operation as described above.

  If the third vehicle detector 20 detects the exit of the vehicle 13 as a result of the check in step S23, the vehicle number management counter is counted as "-1" (step S24), and then the value of the vehicle number management counter is counted. It is checked whether or not is “0” (step S25).

  As a result of the check in step S25, if the value of the vehicle number management counter is not “0”, it is checked whether or not the second vehicle detector 15 detects the exit of the vehicle 13 (step S26). If the vehicle detector 15 does not detect the exit of the vehicle 13, the process returns to step S23 and the same operation is repeated.

  If the second vehicle detector 15 detects the exit of the vehicle 13 as a result of the check in step S26, it is considered normal and the process returns to step S21 to repeat the same operation as described above.

  As a result of the check in step S25, if the value of the occupancy management counter is “0”, it is determined that the second vehicle detector 15 is abnormal (failure), and this is indicated to the staff by a display or voice. Notification is made (step S27).

  Thus, in the case of the second event in the example of FIG. 5, when the second vehicle detector 15 is in the continuous detection state in which the vehicle 13 is continuously detected, the third vehicle detector 20 is 3 When the exit of more than 13 vehicles 13 is detected, the second vehicle detector 15 is determined to be abnormal (failure).

  In this case, the second vehicle detector 15 being in the continuous detection state is a state in which the vehicle 13 is passing or stopped. While the second vehicle detector 15 is in the continuous detection state, three or more vehicles 13 cannot enter.

Next, the abnormality detection process for the third vehicle detector 20 will be described with reference to the schematic diagram shown in FIG. 8 and the flowchart shown in FIG.
For example, as shown in FIG. 8, the maximum number of vehicles 13 that can exist between the third vehicle detector 20 and the first vehicle detector 14 in the lane 11 is the third vehicle detector 20. Except for the passing vehicle 13, the number is three.

  First, as an initial value in a vehicle number management counter (not shown), the maximum number (3) of vehicles 13 that can exist between the third vehicle detector 20 and the first vehicle detector 14 in the lane 11 is set to “3”. The number “4” obtained by adding “+1” is set (step S31).

  Next, it is checked whether or not the third vehicle detector 20 has detected the entry of the vehicle 13 (step S32). If the third vehicle detector 20 does not detect the entry of the vehicle 13, it is regarded as normal. Returning to step S31, the same operation as described above is repeated.

  As a result of the check in step S32, when the third vehicle detector 15 detects the entry of the vehicle 13, it is checked whether or not the first vehicle detector 14 has detected the entry of the vehicle 13 (step S33). If the first vehicle detector 14 does not detect the entry of the vehicle 13, it is regarded as normal and the process returns to step S31 to repeat the same operation as described above.

  As a result of the check in step S33, if the first vehicle detector 14 detects the entry of the vehicle 13, the occupancy management counter is counted as "-1" (step S34), and then the value of the occupancy management counter is counted. It is checked whether or not is “0” (step S35).

  As a result of the check in step S35, if the value of the vehicle number management counter is not “0”, it is checked whether or not the third vehicle detector 20 detects the exit of the vehicle 13 (step S36). If the vehicle detector 20 does not detect the exit of the vehicle 13, the process returns to step S33 and the same operation is repeated.

  If the third vehicle detector 20 detects the exit of the vehicle 13 as a result of the check in step S36, it is regarded as normal and the process returns to step S31 to repeat the same operation as described above.

  As a result of the check in step S35, if the value of the occupancy management counter is “0”, it is determined that the third vehicle detector 20 is abnormal (failure), and this is indicated to the staff by a display or voice. Notification is made (step S37).

  As described above, in the example of FIG. 8, when the third vehicle detector 20 is in the continuous detection state in which the vehicle 13 is continuously detected, the first vehicle detector 14 includes four or more vehicles 13. The third vehicle detector 20 is determined to be abnormal (failure) when the entry of is detected.

  In this case, the third vehicle detector 20 being in the continuous detection state is a state in which the vehicle 13 is passing or is stopped and the vehicle 13 has not been completely removed. Although the vehicle 13 has not left the third vehicle detector 20, four or more vehicles 13 cannot enter.

  As described above, according to the above-described embodiment, the vehicle detectors 14, 15, 20 can be complemented with the detection states of the vehicle detectors 14, 15, 20 installed in one lane 11. 20 abnormalities (failures) can be detected quickly and the influence on the operation of the ETC system can be minimized.

  The number of vehicles that can be in the same lane of the toll gate is naturally determined by the installation position of the vehicle detector and the vehicle dimensions. By associating the maximum number of vehicles that can be present with the number of vehicles that have entered the lane or the number of vehicles that have exited, an abnormality (failure) of the vehicle detector is quickly detected.

As described above, the vehicle detector in the ETC system is an apparatus that plays an important role in grasping the behavior of the vehicle. In particular, it is used to generate the start timing of wireless communication by the roadside apparatus, the display start / end timing of roadside display, the gate cutoff timing of the start control apparatus, and the like.
If the abnormality detection of the vehicle detector can be performed promptly, it is possible to take prompt measures in order to avoid the trouble related to the timing generation and the like. This is beneficial not only for toll road operators but also for users (drivers).

  In the above embodiment, the case where the vehicle detector is an optical vehicle detector that detects a vehicle using infrared rays has been described. However, the present invention is not limited to this, and for example, an ultrasonic wave is used. Even if it is an ultrasonic type vehicle detector which detects a vehicle using it, it is applicable similarly.

The schematic diagram which shows schematically the structure of the ETC system used as a toll collection system of the toll road which concerns on embodiment of this invention, for example. The block diagram which shows the structure of a vehicle detector roughly. The schematic diagram for demonstrating the abnormality detection process with respect to a 1st vehicle detector. The flowchart explaining the flow of the abnormality detection process with respect to a 1st vehicle detector. The schematic diagram for demonstrating the abnormality detection process with respect to a 2nd vehicle detector. The flowchart explaining the flow of the abnormality detection process with respect to the 1st event of a 2nd vehicle detector. The flowchart explaining the flow of the abnormality detection process with respect to the 2nd event of a 2nd vehicle detector. The schematic diagram for demonstrating the abnormality detection process with respect to a 3rd vehicle detector. The flowchart explaining the flow of the abnormality detection process with respect to a 3rd vehicle detector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Toll collection lane (road) of a toll gate, 12 ... Booth, 13 ... Vehicle, 14 ... 1st vehicle detector, 15 ... 2nd vehicle detector, 16 ... Onboard equipment, 17 ... Roadside radio | wireless apparatus (antenna) Device), 18 ... roadside indicator, 19 ... start control device, 20 ... third vehicle detector, 21 ... lane control device.

Claims (4)

An abnormality detection device for a vehicle detector that detects an abnormality in at least two vehicle detectors that are installed at predetermined intervals along a road along which the vehicle travels and that detects a vehicle traveling on the road. ,
Of the two vehicle detectors, when the upstream vehicle detector with respect to the traveling direction of the vehicle is in the continuous detection state in which the vehicle is continuously detected, the downstream side of the vehicle traveling direction during the continuous detection state First counting means for counting the number of vehicles detected by the vehicle detector;
First determination means for determining that the upstream vehicle detector is abnormal when the count value of the first counting means exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road When,
Of the two vehicle detectors, when the vehicle detector on the downstream side with respect to the traveling direction of the vehicle is in a continuous detection state in which the vehicle is continuously detected, the upstream side of the traveling direction of the vehicle during the continuous detection state A second counting means for counting the number of detected vehicles entering the vehicle detector;
Second determination means for determining that the downstream vehicle detector is abnormal when the count value of the second counting means exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road When,
An abnormality detection device for a vehicle detector, comprising:   2. The abnormality detector for a vehicle detector according to claim 1, wherein the two vehicle detectors are optical transmission type vehicle detectors for optically detecting a vehicle traveling on the road.   2. The abnormality detector for a vehicle detector according to claim 1, wherein the road is a toll collection lane at a toll gate on a toll road. An abnormality detection method for a vehicle detector that detects an abnormality in at least two vehicle detectors that are installed along a road along which a vehicle travels in a traveling direction of the vehicle and that detects a vehicle traveling on the road. ,
Of the two vehicle detectors, when the upstream vehicle detector with respect to the traveling direction of the vehicle is in the continuous detection state in which the vehicle is continuously detected, the downstream side of the vehicle traveling direction during the continuous detection state A first counting step for counting the number of vehicles detected by the vehicle detector;
A first determination step for determining that the upstream vehicle detector is abnormal when the count value of the first counting step exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road; When,
Of the two vehicle detectors, when the vehicle detector on the downstream side with respect to the traveling direction of the vehicle is in a continuous detection state in which the vehicle is continuously detected, the upstream side of the traveling direction of the vehicle during the continuous detection state A second counting step of counting the number of detected vehicles entering the vehicle detector;
A second determination step for determining that the downstream vehicle detector is abnormal when the count value of the second counting step exceeds the maximum number of vehicles that can exist between the two vehicle detectors on the road; When,
An abnormality detection method for a vehicle detector, comprising:

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