JP4067543B2 - Road surface condition determination method and system - Google Patents

Description

  The present invention relates to a road surface condition determination technique.

  In snowy and cold regions such as northern countries and highlands, the road surface becomes pressed due to snowfall or frozen due to cold. Due to such a road surface condition, a traveling vehicle causes a slip accident, or a traffic jam occurs due to falling into a snow pool and being unable to travel (stack). In addition, the road surface becomes uneven due to the snow pressure, which causes adverse effects such as an increase in travel time due to poor ride comfort and reduced travel speed.

  In winter, road managers can prevent such deterioration of road surface conditions by removing snow and spraying anti-freezing agents (drugs), while maintaining good road surface conditions for the convenience of road users. , Doing business to increase safety. In this winter road surface management work, it is important to spray a freezing inhibitor to keep the road surface in good condition, but the effect of the drug spraying does not last for a long time, It is known that the effect disappears in a few hours and is re-frozen by being splashed or thinned by the thawing water from a new snowfall. This refreezing is a very dangerous state in terms of road management, and it is necessary to spray the medicine again. However, it is impossible to accurately predict refreezing with the conventional road surface management method, and it is necessary to directly check the road surface by performing patrols at regular intervals.

For example, Japanese Patent Application Laid-Open No. 11-21834 discloses a road surface freezing determination method for accurately determining a road surface freezing state even when an antifreezing agent is sprayed. Specifically, a temperature sensor that detects the road surface temperature and a wetness sensor that detects the wet state of the road surface are installed, and the time transition of these measured values is measured to determine whether the road surface is frozen or not. It is. More specifically, when sprayed cryoprotectant, the temperature was lowered in accordance with the spray volume from 0 ℃ is maintained for a predetermined time to detect this condition, to check for freezing by further wetting sensor.

  Japanese Patent Laid-Open No. 2003-35686 discloses the following technique. When snowfall is detected, it is judged that snow melting agent or anti-freezing agent has been sprayed when the temperature of the road surface thermometer suddenly drops, and the road surface temperature from the road surface thermometer is time-series due to geothermal or salt dilution. It is determined whether or not there is a possibility of road surface freezing depending on whether or not the increased temperature is a preset temperature.

Furthermore, Japanese Patent Laid-Open No. 2003-287577 discloses the following technique. That is, the road surface freezing determination is performed with high accuracy from the absolute value of the road surface temperature measured by the road surface sensor, the road surface temperature gradient, and whether the absolute value of the road surface temperature has continued for a predetermined time or more. In the frozen state, moisture changes phase from liquid to solid, so latent heat such as heat of solidification (heat of fusion when changing to the non-frozen state) is required. From this, it is possible to detect the phase change by measuring the road surface temperature change in time series and improve the detection accuracy, and the state below the road surface temperature that can be assumed that the effect of the inhibitor disappears from the regulation of the spray amount of the antifreeze agent. If it lasts for a long time, it is determined to be frozen.
JP-A-11-21834 JP 2003-35686 A JP 2003-287777 A

In JP-A 11-21834 discloses mentioned above, the temperature dropped in accordance with the spray volume from 0 ℃ is determined that there is the possibility of freezing is maintained for a predetermined time when sprayed with antifreeze However, according to the technique in this publication, the determination of whether or not the antifreezing agent has been sprayed and the determination of the possibility of freezing are made simultaneously, which is not sufficient for grasping the road surface condition.

  Japanese Patent Application Laid-Open No. 2003-35686 determines that a snow melting agent or an antifreezing agent has been sprayed when the temperature is drastically decreased by a road surface thermometer. However, even if the road surface temperature drops due to a sudden drop in ambient temperature, the same change is often shown.Therefore, the road temperature drop caused by the actual spraying of the drug and the road temperature drop caused by the sudden drop in ambient temperature Difficult to identify.

  Further, in Japanese Patent Application Laid-Open No. 2003-287577, although determination is made using temperature and a temperature gradient, it is not particularly specified to spray the antifreezing agent.

  Accordingly, an object of the present invention is to provide a technique for accurately detecting the spread of a medicine such as an antifreezing agent.

  Another object of the present invention is to provide a technique for accurately detecting refreezing after the application of a medicine such as an antifreezing agent.

  The road surface condition determination method according to the present invention uses the data stored in the measurement result data storage unit in which the time series data of the road surface temperature measured on the monitored road is accumulated, within the first predetermined time, A first determination step for determining whether a decrease in road surface temperature that is equal to or greater than a predetermined decrease determination threshold has occurred, and if the determination result in the first determination step is affirmative, a predetermined condition is satisfied after the decrease in road surface temperature A second determination step for determining whether a rise in road surface temperature has occurred, and a first determination step for outputting a signal representing detection of drug spraying on the monitored road if the determination result in the second determination step is affirmative Including.

  In this way, a phenomenon that appears after the medicine is sprayed can be definitely detected. In particular, many other phenomena are not erroneously detected by the second determination step.

  Moreover, you may make it further include the 3rd judgment step which judges whether the road surface of a monitoring object road is a wet state from the observation result of the road surface state of a monitoring object road. At this time, in the first determination step, if the determination result in the third determination step is affirmative, a signal indicating detection of drug distribution on the monitored road may be output. By confirming that the road surface is in a wet state with another means, the accuracy of drug spray detection can be increased.

  Furthermore, after the signal indicating the detection of the drug spraying on the monitoring target road is output in the first determination step, the data stored in the measurement result data storage unit is used to determine whether the increase in the road surface temperature has stopped. If the determination result of the determination step and the third determination step is affirmative, it may further include a second determination step of outputting a signal indicating detection of refreezing of the monitored road. In this way, it becomes possible to know the next timing of drug distribution.

  A program for causing a computer to execute the method according to the present invention can be created, and the program is stored in a storage medium or storage device such as a flexible disk, a CD-ROM, a magneto-optical disk, a semiconductor memory, or a hard disk. Is done. In some cases, digital signals are distributed over a network. Note that data being processed is temporarily stored in a storage device such as a computer memory.

  According to the present invention, it is possible to accurately detect the spread of a medicine such as an antifreezing agent.

  Moreover, according to the other aspect of this invention, the refreezing after spraying chemical | medical agents, such as a cryoprotectant, can be detected correctly.

  FIG. 1 shows an example of a computer system according to an embodiment of the present invention. Connected to the network 1 are a plurality of sensors (only the sensors A, B, and C are shown in the figure) and a road surface condition determination device 5 that performs main processing in the present embodiment. The sensor is installed at a predetermined position on the road that needs to be monitored. Then, the road surface state observation unit 31, the road surface temperature measurement unit 32 that is, for example, a radiation thermometer, and the observation data and measurement data, for example, are transmitted to the road surface state determination device 5 via the network 1 periodically or at an arbitrary timing. Function (not shown). If necessary, the sensor is also provided with a storage device for storing observation data and measurement data. In FIG. 1, only the sensor A is representatively shown as the road surface state observation unit 31 and the road surface temperature measurement unit 32, but other sensors have the same configuration.

  The road surface condition determination device 5 includes a data receiving unit 51 that receives data from a sensor via the network 1, a road surface data storage unit 52 that stores observation data of a road surface state received from the sensor, and a road surface received from the sensor. A road surface temperature data storage unit 53 that stores temperature data, a road surface state determination unit 54 that determines a road surface state using data stored in the road surface state data storage unit 52, and a road surface temperature data storage unit 53 Based on the temperature change detection unit 55 that detects a predetermined road surface temperature change using the data, and the detection result of the temperature change detection unit 55 and the determination result of the road surface state determination unit 54, whether or not a medicine such as an antifreeze agent is sprayed is determined. The medicine spraying detection unit 56 to be determined and the data stored in the road surface temperature data storage unit 53 when the medicine spraying detection unit 56 determines that the medicine spraying is present. Having a refreezing determination unit 57 determines the presence or absence of re-freezing of the road surface, the detection result of the chemical spray detector 56, and an output unit 58 for output to the output device a determination result of the re-freeze determining section 57 using.

  Next, the operation of the computer system shown in FIG. 1 will be described with reference to FIGS. First, the road surface temperature measurement unit 32 of each sensor measures the road surface temperature of the road in charge, and each sensor transmits road surface temperature data as a measurement result to the road surface condition determination device 5 through the network 1 along with time data. To do. On the other hand, the data receiving unit 51 of the road surface condition determining apparatus 5 receives time data and road surface temperature data from the sensor, and stores them in the road surface temperature data storage unit 53 (step S1). In the road surface temperature data storage unit 53, road surface temperature data and time data are stored in pairs for each sensor. In the present embodiment, it is assumed that road surface temperature data and time data are transmitted from the sensor at any time and accumulated in the road surface temperature data storage unit 53. Although the road surface state observation unit 31 also performs observation processing to generate observation data and transmits the data to the road surface state determination device 5, the observation processing is not necessarily performed in synchronization with the road surface temperature measurement unit 32. Absent. In addition, the observation result is transmitted to the road surface condition determination device 5 through the network 1 and stored in the road surface state data storage unit 52 by the data reception unit 51. However, in the present embodiment, the observation result is not immediately used.

  The temperature change detection unit 55 is road surface temperature data stored in the road surface temperature data storage unit 53 in order to detect a rapid decrease in the road surface temperature that occurs first when a medicine such as an antifreezing agent is sprayed. Then, from the time data, it is determined whether a temperature decrease equal to or greater than a predetermined decrease determination threshold has occurred within a predetermined first predetermined time (step S3).

  When a medicine such as an antifreezing agent is sprayed on a frozen road surface, the road surface temperature rapidly decreases. This is because the drug melts the ice using the energy of ice. FIG. 3A shows an example of a change in road surface temperature. The Δ (black) mark indicates the measurement result. In the graph of FIG. 3A, the vertical axis represents road surface temperature and the horizontal axis represents time. When the medicine is sprayed at time a, the road surface temperature rapidly decreases by time b. It is known that the road surface temperature rapidly decreases due to chemical spraying when the road surface state is a sherbet or a frozen state, and the road surface temperature does not decrease during wet or fresh snow. Therefore, it is difficult to detect drug spraying (pre-spraying) performed when the road surface is not frozen, but drug spraying (post-spraying) performed when the road surface is frozen or in a sherbet state is this abrupt. It can be detected by capturing the road surface temperature drop. Accordingly, in step S3, such a rapid decrease in road surface temperature is detected.

  However, as can be seen from FIG. 3A, after spraying the drug, the road surface temperature tends to decrease rapidly and then gradually increase. This is because the action of trying to balance the difference between the road surface temperature and the temperature, which has been rapidly reduced, works. When the road surface temperature is actually measured, a rapid temperature drop occurs in situations other than the drug spraying, and it is impossible to detect the drug spraying even if only the sharp drop is detected. In the present embodiment, drug distribution is detected by capturing such characteristics. Therefore, even if a sudden decrease in road surface temperature is detected in step S3, a detection signal for “medicine spraying” is not output.

  In step S3, the most recently measured road surface may be determined by determining whether the value obtained by subtracting the most recently measured road surface temperature from the road surface temperature before the first predetermined time is equal to or greater than the decrease determination threshold value. It may be determined whether the value obtained by subtracting the temperature from the maximum road surface temperature before the first predetermined time is equal to or higher than the decrease determination threshold. Further, it is determined whether the maximum road surface temperature before the first predetermined time is equal to or lower than a specific temperature, and a value obtained by subtracting the most recently measured road surface temperature from the maximum road surface temperature is equal to or greater than a decrease determination threshold value. May be.

  If it is determined in step S3 that no temperature decrease equal to or greater than the decrease determination threshold has occurred within the first predetermined time, the process returns to step S1. On the other hand, if it is determined in step S3 that a temperature decrease that is equal to or greater than the decrease determination threshold has occurred within the first predetermined time, a transition is made to the first state in which an abrupt road surface temperature decrease is detected, Move on to the next process. In addition, the road surface temperature measurement part 32 of each sensor measures the road surface temperature of the road in charge, and each sensor transmits the road surface temperature data as a measurement result to the road surface state determination device 5 through the network 1 together with time data. To do. The data receiving unit 51 of the road surface condition determination device 5 receives time data and road surface temperature data from the sensors, and stores the data in the road surface temperature data storage unit 53 for each sensor (step S5).

  And the temperature change detection part 55 judges whether the lower limit of road surface temperature was detected using the road surface temperature data stored in the road surface temperature data storage part 53 (step S7). That is, it is determined whether the road surface temperature has started to rise. If the road surface temperature is still decreasing, the process returns to step S5. However, for example, when the road surface temperature does not start rising within a certain time after the transition to the first state, the first state may not be maintained and the process may return to step S1.

  On the other hand, when an increase in road surface temperature is detected, the lower limit value of the road surface temperature and the time when the lower limit value is measured are specified. Further, when the increase rate of the road surface temperature is used in the following processing and is defined as the increase rate = the road surface temperature increase width / the road surface temperature decrease width, for example, from the time when the temperature decrease equal to or higher than the decrease determination threshold occurs. The difference between the maximum road surface temperature up to a predetermined time before 1 and the lower limit value of the road surface temperature is calculated as the road surface temperature decrease width. When the lower limit value of the road surface temperature is detected in step S7, the process proceeds to the next process. In addition, the road surface temperature measurement part 32 of each sensor measures the road surface temperature of the road in charge, and each sensor transmits the road surface temperature data as a measurement result to the road surface state determination device 5 through the network 1 together with time data. To do. The data receiving unit 51 of the road surface condition determination device 5 receives time data and road surface temperature data from the sensors, and stores the data in the road surface temperature data storage unit 53 for each sensor (step S9).

  Thereafter, the temperature change detection unit 55 uses the road surface temperature data stored in the road surface temperature data storage unit 53 to perform a second predetermined operation from the time when the lower limit value is detected (time b in the example of FIG. 3A). After the time, it is determined whether the temperature rise satisfies a predetermined condition (step S11). As described above with reference to FIG. 3 (a), after the spraying of the medicine, the road surface temperature rapidly decreases and then gradually increases. In the present embodiment, a “slow increase” in the road surface temperature is detected. Specifically, it is determined whether the rate of increase in road surface temperature (= road surface temperature increase width / road surface temperature decrease width) is within a predetermined range (from a lower limit value to an upper limit value). The road surface temperature rise width is the difference between the road surface temperature and the lower limit value after a second predetermined time from the time when the lower limit value is detected. In the example of FIG. 3A, it is determined that the rate of increase in road surface temperature is within a predetermined range at time c. Note that the predetermined condition is not limited to the above-described condition for the rate of increase, but may be determined using, for example, the range of increase.

  If it is determined in step S11 that the temperature rise does not satisfy the predetermined condition, the first state is not maintained and the process returns to step S1. On the other hand, if it is determined in step S11 that the temperature rise satisfies the predetermined condition, the state transitions to the second state, and the temperature change detection unit 55 sends the drug spray detection signal based on the road surface temperature to the drug spray detection unit. To 56. Furthermore, the medicine spraying detection unit 56 instructs the road surface state determination unit 54 to perform processing.

  The road surface state observation unit 31 of the sensor observes the road surface state at a predetermined cycle or in response to an instruction from the road surface state determination device 5 or the like, and transmits the observation data to the road surface state determination device 5 via the network 1. Send. The data receiving unit 51 of the road surface condition determining apparatus 5 receives the observation data and stores it in the road surface state data storage unit 52 (step S13). Here, in response to the transition to the second state, the medicine scatter detection unit 56, the road surface state determination unit 54, etc. cause the road surface state observation unit 31 of the sensor to observe the current road surface state, or already the road surface The latest observation data stored in the state data storage unit 52 is used.

  Then, the road surface state determination unit 54 determines whether the road surface is wet using the data stored in the road surface state data storage unit 52 (step S15). In this embodiment, various methods for determining the road surface state can be employed. For example, a determination method using an image (for example, a method disclosed in Japanese Patent Laid-Open No. 2002-140789) is used. In this determination method, the road surface state observation unit 31 is a camera, and image data captured by the camera is transmitted as observation data to the road surface state determination device 5 via the network 1. The road surface state determination unit 54 converts the image data into a hue image, a saturation image, and a brightness image. Then, an average value and a variance value of each of hue, saturation, and brightness are calculated from the road surface detection range of the hue image, saturation image, and brightness image. Furthermore, road surface dryness, wetness, water film state, and the like are determined based on the calculated average value and dispersion value.

  For example, FIG. 4A shows an example of an image photographed by the road surface state observation unit 31. This image is an image representing the road surface state immediately before the medicine is sprayed. If the road surface state determination part 54 performs the process which concerns on the technique of the gazette description described above, an image like FIG.4 (b) will be produced | generated. In the image of FIG. 4B, in the road surface detection range X, the white portion and the black portion are separately painted. The black part is the part where the snow is melting as the vehicle travels. The area of this black portion is relatively narrow and is not determined to be wet. On the other hand, when the image as shown in FIG. 4C is obtained, if the road surface state determination unit 54 performs the process according to the technique described in the above publication, the image as shown in FIG. Generate. In the image of FIG. 4D, the road surface detection range Y is divided into a white portion and a black portion, but the black portion is increased compared to FIG. 4B. Thus, when it is determined that the area of the black portion has increased sufficiently, it is determined that the road surface has become wet.

  In addition to the method described above, a visible image sensor provided with a deflection filter may be used to detect four events of drying, wetting, snow accumulation, and freezing based on the difference in reflected light on the road surface. . Furthermore, it is possible to determine snow accumulation by emitting near-infrared rays with a light wave sensor and measuring the road surface height, or to determine whether it is dry or wet from the amount of received light of the reflected light.

  Further, the road surface state observation unit 31 in the sensor may determine the road surface state and transmit the determination result to the road surface state determination device 5. In that case, since the road surface state determination result is stored in the road surface state data storage unit 52, the road surface state determination unit 54 only checks the data.

  In step S15, whichever method is adopted, it is determined whether the road surface is “wet”. If it is determined that the road surface is not wet, the second state is not maintained and step S1 is performed. Return to. In the present embodiment, even if the medicine spray is detected from the temperature change of the road surface as described above, the effect of the medicine spraying does not appear unless it is actually in a wet state. However, for example, when it can be determined that the temperature change on the road surface indicates the spraying of the drug based on other data related to the current weather condition, it may be handled as the detection of the spraying of the drug.

  On the other hand, when it is determined in step S15 that the road surface is wet, the road surface state determination unit 54 outputs a signal indicating that the road surface state is wet to the medicine spraying detection unit 56. When the medicine distribution detection unit 56 receives a drug distribution detection signal based on the road surface temperature from the temperature change detection unit 55 and receives a signal indicating that the road surface state is wet from the road surface state determination unit 54, an output unit The medicine detection is output to 58, for example, to an output device such as a display device (step S17). Further, the medicine spraying detection unit 56 instructs the refreezing determination unit 57 to start processing for refreezing determination.

  As a result, the user can grasp that the medicine has been automatically sprayed without directly looking at the road surface. Note that the output content is not only a message indicating the detection of drug distribution, but also, for example, image data at the time of drug distribution detection stored in the road surface state data storage unit 52 (an image after processing generated by the road surface state determination unit 54 is also included). And a graph representing a change in road surface temperature generated from road surface temperature data within a predetermined time stored in the road surface temperature data storage unit 53.

  The processing shifts to the processing in FIG. Note that the state transitions from the second state to the third state. The road surface temperature measuring unit 32 of each sensor measures the road surface temperature of the road in charge, and each sensor transmits road surface temperature data as a measurement result together with time data to the road surface condition determination device 5 via the network 1. To do. The data receiving unit 51 of the road surface condition determination device 5 receives time data and road surface temperature data from the sensors, and stores the data in the road surface temperature data storage unit 53 for each sensor (step S19).

  Then, the refreezing determination unit 57 uses the data stored in the road surface temperature data storage unit 53, and the second predetermined time before the road surface temperature related to the latest measurement result and the time related to the latest measurement result. It is determined whether the temperature increase has been completed by comparison with the road surface temperature at the time (step S21). The end of the temperature rise means that the road surface temperature related to the latest measurement result and the road surface temperature at the time two second predetermined time before the time related to the latest measurement result have not changed, and the former is the latter The lower case. Note that a fourth predetermined time may be newly defined and used instead of the second predetermined time. Further, when the road surface temperature related to the newest measurement result is lower than or equal to the maximum road surface temperature between the time related to the newest measurement result and the second predetermined time before, it is determined that the temperature increase has ended. You may do it.

  If it is determined that the temperature rise has not ended, the third state is maintained and the process returns to step S19. On the other hand, when it is determined that the temperature increase has ended, the refreezing determination unit 57 uses the road surface temperature data stored in the road surface temperature data storage unit 53 to further stop the temperature increase to the third predetermined value. It is determined whether or not it has continued for more than the time (step S23). For example, if the road surface temperature is lowered only in the latter half of the second predetermined time, it may not be said that the temperature rise has stopped, so here the temperature rise stop is longer than the third predetermined time. It is additionally determined whether or not it continues.

  If it is not determined that the temperature increase has stopped for a third predetermined time or longer, the third state is maintained and the process returns to step S19. It is still considered that the road surface temperature has risen. On the other hand, if it is determined that the temperature increase has stopped for a third predetermined time or longer, the refreezing determination unit 57 determines that refreezing has started and displays refreezing detection on the output unit 58. The output is made to an output device such as a device (step S25).

  When a drug is sprayed on a frozen road surface, the drug is not evenly dispersed, so the concentration of the drug is partially very high. Thereby, the road surface temperature is lowered to a temperature lower than the freezing point calculated from the concentration of the medicine. The road surface is partially wetted and becomes wet as the vehicle passes. When the road surface becomes wet, the concentration of the drug becomes thinner with moisture. In addition, the road surface temperature gradually rises due to the action of balancing the temperature difference between the road surface and the atmosphere. When a drug is sprayed in the daytime, the concentration of the drug gradually diminishes due to the effects of the melting of snow, the passing of a vehicle, and the like due to an increase in temperature. However, when the medicine is sprayed at night, the road surface temperature that has risen slowly after the sudden drop due to the spraying of the medicine gradually keeps constant or begins to fall, and the road surface refreezes in the process. Since re-freezing starts from the water portion of the aqueous solution in which the drug is dissolved, the concentration of the aqueous solution gradually increases. This means that the road surface after spraying the medicine is not in a slippery state like when water is frozen, but in a frozen state like a sherbet in which ice and a solution are mixed. In the present embodiment, refreezing after spraying the drug is detected by capturing such characteristics.

  The output content in step S25 may be a refreezing detection message output, and further, for example, image data at the time of refreezing detection stored in the road surface state data storage unit 52 (generated by the road surface state determination unit 54). And a graph representing a road surface temperature change generated from road surface temperature data within a predetermined time stored in the road surface temperature data storage unit 53, and the like.

  In the case of FIG. 3A, refreezing is detected at time d. The temperature rise has stopped from time e, which is a second predetermined time before time d. How long the third predetermined time is set depends on the road to be monitored. For example, one observation period (a period between two adjacent Δ (black) marks) in FIG. If it is, since it has not changed at all, it can be determined that the increase in the road surface temperature has stopped.

  The above judgment results are summarized as shown in FIG. In FIG. 3B, the vertical axis represents road conditions such as “freezing”, “snow accumulation”, “wet”, and “dry”, and the horizontal axis represents time. In FIG. 3B, a cross indicates a determination result (output) by the road surface state determination device 5 and a circle indicates an actual situation (true value). In FIG. 3B, the medicine is actually sprayed at time a, and the true value at that time is in the “snow cover” state. The true value then transitions to a “frozen” state at time b, a “snow cover” state at time c, a “wet” state after time c, and a “frozen” state again at time d. On the other hand, the determination result transitions to the “snow cover” state at time a and the “frozen” state at time b. The determination results so far represent the results determined by a mechanism different from the present embodiment. On the other hand, at the time c, as described above, it is detected that the “wet” state, that is, the medicine spraying has been performed. It is determined that the state is “wet” until time d after time c, and is determined to be “frozen” again at time d as described above. Although the true value and the determination result at time c are different from each other, since the true value and the determination result coincide after time c, it can be said that an appropriate determination is made by the processing in the present embodiment.

  As described above, according to the present embodiment, it is possible to automatically determine from the spraying to refreezing from the road surface temperature and the road surface state observation mechanism. By installing such a system in a place where there is a risk of freezing, the road manager will not be able to go to the site and the effect of "spraying the medicine" will be lost in the freezing places that are scattered. It is possible to grasp the state that “the risk of refreezing has increased” and to perform road surface management work such as appropriate re-spraying of medicines.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this. For example, the functional block diagram shown in FIG. 1 does not necessarily correspond to an actual program module. In addition, the threshold value and the predetermined value used in the processing flow should be appropriately adjusted according to the area, environment, and the like of the location to be monitored.

(Appendix 1)
Using the data stored in the measurement result data storage unit in which the time-series data of the road surface temperature measured on the monitored road is accumulated, the road surface that is equal to or higher than the predetermined drop determination threshold value within the first predetermined time. A first determination step for determining whether a temperature drop has occurred;
A second determination step for determining whether an increase in road surface temperature that satisfies a predetermined condition has occurred after a decrease in road surface temperature when the determination result in the first determination step is affirmative;
If the determination result in the second determination step is affirmative, a first determination step for outputting a signal representing detection of drug distribution on the monitored road;
A road surface condition determination method executed by a computer.

(Appendix 2)
A third determination step of determining whether the road surface of the monitored road is wet from the observation result of the road surface condition of the monitored road;
The road surface according to claim 1, wherein in the first determination step, if the determination result in the third determination step is further affirmative, a signal indicating detection of drug distribution on the monitored road is output. Situation judgment method.

(Appendix 3)
In the first determination step, after a signal indicating the detection of drug dispersion on the monitoring target road is output, it is determined whether or not the increase in the road surface temperature has been stopped using data stored in the measurement result data storage unit. A third determination step;
A second determination step of outputting a signal representing refreezing detection of the monitored road if the determination result of the third determination step is affirmative;
The road surface condition determination method according to supplementary note 1 or 2, further including:

(Appendix 4)
The road surface condition determination method according to claim 1, wherein the increase in the road surface temperature satisfying the predetermined condition is an increase having a rate of increase in the road surface temperature falling within a predetermined range.

(Appendix 5)
A program for causing a computer to execute the road surface condition determination method according to any one of appendices 1 to 4.

(Appendix 6)
A sensor device for measuring the road surface temperature of the monitored road;
A road surface condition determination device connected to the sensor device via a network;
Have
The road surface condition judging device is
A measurement result data storage unit in which time-series data of road surface temperature measured by the sensor device in the monitored road is accumulated;
First determination means for determining whether or not a decrease in road surface temperature equal to or greater than a predetermined decrease determination threshold has occurred within a first predetermined time using the data stored in the measurement result data storage unit;
Second determination means for determining whether an increase in road surface temperature that satisfies a predetermined condition has occurred after a decrease in road surface temperature if the determination result in the first determination step is affirmative;
If the determination result in the second determination step is affirmative, a first determination means for outputting a signal representing detection of drug dispersion on the monitored road;
A road surface condition determination system.

(Appendix 7)
The sensor device has means for observing a road surface state of the monitored road,
The road surface condition judging device is
Further comprising third determination means for determining whether the road surface of the monitored road is wet from the observation result of the road surface condition of the monitored road;
The road surface according to appendix 6, wherein the first determination means outputs a signal indicating detection of drug distribution on the monitored road when the determination result in the third determination step is affirmative. Situation judgment system.

(Appendix 8)
After the first determination means outputs a signal indicating the detection of the drug distribution on the monitored road, it is determined whether the increase in the road surface temperature has stopped using the data stored in the measurement result data storage unit. A third determination means;
A second determination means for outputting a signal indicating re-freezing detection of the monitored road if the determination result of the third determination step is affirmative;
The road surface condition determination system according to appendix 6 or 7, further comprising:

It is a functional block diagram of an embodiment of the invention. It is a figure which shows the processing flow (1st part) which concerns on embodiment of this invention. (A) And (b) is a figure which shows the graph showing a temperature measurement result and a determination result. (A) is an image before drug distribution, (b) is a processed image before drug distribution, (c) is an image after drug distribution, and (d) is an example of a processed image after drug distribution. . It is a figure which shows the processing flow (2nd part) which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Network 31 Road surface state observation part 32 Road surface temperature measurement part 5 Road surface state determination apparatus 51 Data receiving part 52 Road surface state data storage part 53 Road surface temperature data storage part 54 Road surface state determination part 55 Temperature change detection part 56 Drug distribution detection part 57 Freezing judgment part 58 Output part

Claims (5)

Using the data stored in the measurement result data storage unit in which the time-series data of the road surface temperature measured on the monitored road is accumulated, the road surface that is equal to or higher than the predetermined drop determination threshold value within the first predetermined time. A first determination step for determining whether a temperature drop has occurred;
If the determination result in the first determination step is affirmative, the road surface temperature has an increase rate or increase width of the road surface temperature that falls within a predetermined range after the second predetermined time after the decrease in the road surface temperature has stopped. A second determination step for determining whether or not an increase in
If the determination result in the second determination step is affirmative, a first determination step for outputting a signal representing detection of drug distribution on the monitored road;
A road surface condition determination method executed by a computer. A third determination step of determining whether the road surface of the monitored road is wet from the observation result of the road surface condition of the monitored road;
The signal representing detection of drug distribution on the monitored road is output when the determination result in the third determination step is affirmative in the first determination step. Road surface condition judgment method. In the first determination step, after a signal indicating the detection of drug dispersion on the monitoring target road is output, it is determined whether or not the increase in the road surface temperature has been stopped using data stored in the measurement result data storage unit. and rising stop determination step,
A second determination step of outputting a signal representing re-freezing detection of the monitored road if the determination result of the ascending / stopping determination step is affirmative;
The road surface condition determination method according to claim 1 or 2, further comprising: The program for making a computer perform the road surface condition determination method of any one of Claims 1 thru | or 3 . A sensor device for measuring the road surface temperature of the monitored road;
A road surface condition determination device connected to the sensor device via a network;
Have
The road surface condition judging device is
A measurement result data storage unit in which time-series data of road surface temperature measured by the sensor device in the monitored road is accumulated;
First determination means for determining whether or not a decrease in road surface temperature equal to or greater than a predetermined decrease determination threshold has occurred within a first predetermined time using the data stored in the measurement result data storage unit;
If the determination result in the first determination means is affirmative, the road surface temperature has an increase rate or increase width of the road surface temperature that falls within a predetermined range after the second predetermined time after the decrease in the road surface temperature has stopped. Second judging means for judging whether or not an increase in
If the determination result in the second determination means is affirmative, a first determination means for outputting a signal representing detection of drug dispersion on the monitored road;
A road surface condition determination system.