JP2000241563A - Road surface freeze determination method and device, and road surface freeze prediction method and device. - Google Patents

Abstract

(57) [Summary] [Problem] The range of the road surface to be judged / predicted is wide,
Provided is a road surface freezing determination method and device, and a road surface freezing prediction method and device thereof, which can accurately determine / predict even if a deicing agent is sprayed. SOLUTION: The temperature under the road is measured by an optical fiber 3 buried in the road 1, and the amount of weather such as solar radiation, rain and snow, and temperature is measured on the road, and the temperature under the road and the weather on the road are measured. The road surface temperature is determined from the amount, the salt condition of the road surface is detected, the moisture condition of the road surface is further detected, and the freezing of the road surface 2 is determined from the detection result of the road surface temperature, the salt condition, and the detection result of the moisture condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for determining the current state of freezing of a road surface and for predicting the subsequent state, and in particular, the range of a road surface to be determined / predicted is wide, and even if a deicing agent is sprayed. The present invention relates to a road surface freezing determination method and device capable of accurately determining / predicting, and a road surface freezing prediction method and device therefor.

[0002]

2. Description of the Related Art Maintenance of expressways and general roads is progressing, and a road network is spreading all over the country. On these roads, cars are more likely to slip when it rains, snows, or freezes. For this reason, it is considered important to develop a system for promptly detecting and reporting the road surface condition such as the degree of wetness of the running road surface and the presence or absence of freezing to the driver while traveling, thereby alerting the driver. Conventionally, as a sensor developed to meet this need, there is a non-contact type road surface state detection sensor.

As shown in FIG. 6, a non-contact type road surface condition detecting sensor is provided on a support column 61 installed on the shoulder of the road 1.
And a temperature measuring device (typically an infrared radiation thermometer) 62 attached to the horizontal portion of the support column 61 and measuring the surface temperature of the road surface 2, an infrared projector 63 and an infrared receiver 64, and a reflection ratio of infrared rays Surface reflection ratio meter 6 for measuring
5, the temperature measuring device 62 and the road surface reflection ratio meter 65
And a wet / freeze determination output device 66 that determines the road surface condition based on the information from the vehicle. This road surface condition detection sensor uses an infrared method for temperature measurement, and also uses an infrared method for wetness measurement.

[0004] Such a road surface condition detection sensor is a road surface 2
Of the reflected wave from the road surface 2 and a ratio of a component (specularly reflected wave) 68 that does not return to the incident direction and a component (diffusely reflected wave) 69 that returns to the incident direction (due to the magnitude of this ratio, the road surface). The degree of wetting can be ascertained), the wetness / freezing determination output device 66 calculates the degree of wetness from this ratio, and the surface temperature of the road surface 2 is measured by the temperature measuring device 63 based on the amount of infrared radiation from the road surface 2. The road surface condition is detected from the measured temperature value and the degree of wetness obtained.

For example, when the surface temperature of a road surface is below freezing,
When the road surface is wet, the wet / freeze determination output device 66 determines that the road is "freeze".

[0006]

However, the conventional road surface condition detecting sensor has the following problems.

(1) The irradiation range of infrared rays is narrow, and the detection range is limited.

(2) It is not always possible to accurately detect the road surface condition such as freezing only by measuring the road surface temperature. For example, when a deicing agent (sodium chloride) is sprayed on a road, the temperature leading to freezing changes depending on the situation. Incorrect judgment will cause a large error. The actual temperature at which the road surface freezes depends on the type of deicing agent, the amount of the antifreezing agent applied, and the moisture condition of the road surface. It is difficult. Furthermore, a method for accurately measuring the type of antifreeze, the amount of sprayed antifreeze, and the wetness of the road surface (moisture state) has not yet been established.

(3) Even if the present state of freezing can be determined, subsequent prediction cannot be performed.

Therefore, an object of the present invention is to solve the above-mentioned problems, to provide a road surface determination method for determining / predicting a road surface which can be accurately determined / predicted even when a deicing agent is sprayed by widening a range of a road surface to be determined / predicted. It is an object of the present invention to provide an apparatus, a road surface freezing prediction method, and an apparatus therefor.

[0011]

In order to achieve the above object, a road surface freezing judging method of the present invention measures a temperature under a road by using an optical fiber buried in the road, and measures a solar radiation amount, a rainfall and snowfall amount on the road. , Measuring meteorological quantities such as air temperature, obtaining the road surface temperature from the temperature under these roads and the weather quantity on the roads, detecting the salt state of this road surface, and further detecting the moisture state of the road surface,
The determination of freezing of the road surface is made based on the detection result of the road surface temperature, the salinity state, and the detection result of the moisture state.

The road surface freezing judging device according to the present invention measures an optical fiber temperature measuring device for measuring a temperature under a road by using an optical fiber embedded in a road, and a meteorological amount such as a solar radiation amount, a rain / snow amount, and a temperature on the road. A meteorological measuring device for measuring, a salinity state detecting means for detecting a salinity state of the road surface, and a moisture state detecting means for detecting a moisture state of the road surface, the temperature under the road, the weather amount on the road, the salinity state of the road surface Is determined based on the detection result of the road surface and the detection result of the moisture condition of the road surface.

According to the road surface freezing prediction method of the present invention, the temperature under the road is measured using an optical fiber buried in the road, the subsequent temperature is predicted from the temporal change of the temperature, and the amount of solar radiation on the road is calculated from the weather forecast. Predict weather conditions such as rainfall and snowfall, temperature, etc., predict road surface temperature from these predicted under-road temperatures and predicted road weather conditions, and detect the salinity of this road surface and the detection results To predict the subsequent salinity condition, further predict the road surface moisture condition from the weather forecast, and predict the road surface freezing from the predicted road surface temperature, the predicted salinity condition and the predicted moisture condition.

An apparatus for predicting freezing of a road surface according to the present invention comprises an optical fiber temperature measuring device for measuring the temperature under a road using an optical fiber buried in a road, and a temperature estimating means for estimating a subsequent temperature from a temporal change of the temperature. Weather forecasting means for forecasting the amount of solar radiation, rainfall, snowfall, temperature, etc. on the road from the weather forecast, salinity state detecting means for detecting the salinity state of the road surface, and the subsequent salinity state from the detection result It is provided with a salinity state predicting means for predicting, and a moisture state predicting means for predicting the moisture state of the road surface from the weather forecast, a predicted temperature under the road, a predicted weather amount on the road, a predicted salinity state,
This is to predict the freezing of the road surface based on the predicted moisture state.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

As shown in FIG. 1, a road surface freezing determination / prediction system according to the present invention is embedded in a road 1 and a road surface 2
An optical fiber 3 continuously laid along the road, an optical fiber temperature measuring device 4 for measuring the temperature distribution along the optical fiber 3 under the road, and an optical fiber 3 dispersed at appropriate intervals in the longitudinal direction of the road 1. A plurality of meteorological measuring devices 5 (5a, 5b, 5c,...) Arranged to measure the amount of solar radiation, rainfall and snowfall (rainfall or snowfall), temperature, etc. on the road, and in the longitudinal direction of the road 1 A plurality of salinity measuring devices 6 (6a, 6a,
6b, 6c,...) And a plurality of wetness measuring devices (or water film thickness measuring devices for measuring the water film thickness) which are arranged at appropriate intervals in the longitudinal direction of the road 1 and measure the wetness of the road surface. )
7 (7a, 7b, 7c,...), A transmission device 9 for collecting information of the distributed measurement devices 5, 6, 7 via a transmission line 8, and a Meteorological Agency or a private weather company 10. An antenna 11 for receiving the transmitted weather forecast, and a transmission device 9
From the road surface determination / prediction device 12 that determines / predicts road surface freezing using the information of each measurement device collected by the optical fiber temperature measurement device 4, the temperature distribution information measured by the optical fiber temperature measurement device 4, and the weather forecast received by the antenna 10. It is configured.

The optical fiber 8 can be laid, for example, in the longitudinal direction of the road 1, or in the transverse direction, or in both directions. In the case of the system of FIG.
In the vertical direction, laying in the longitudinal direction and reciprocating laying in the transverse direction are repeated at appropriate intervals in the longitudinal direction of the road 1. The salinity measuring device 6 constitutes a salinity state detecting means for detecting the salinity state of the road surface 2, and measures the concentration and type of salinity. Note that the salt state detecting means may measure the amount of salt. The wetness measuring device 7
It constitutes a moisture condition detecting means for detecting the moisture condition of the road surface 2, and the detection result of the moisture condition is the degree of wetness. It should be noted that the water condition measuring means may be constituted by a water film thickness measuring device. In this case, the detection result of the water condition is the water film thickness.

Next, the freeze determination algorithm will be described in detail.

First, the outside air and the road surface are obtained from the temperature under the road measured by the optical fiber temperature measuring device 4 and the weather amount such as the amount of solar radiation, the amount of rain and snow, and the temperature on the road measured by the weather measuring device 5. The road surface temperature is determined by heat calculation in consideration of heat transfer with the road and heat conduction inside the road. Next, the road surface temperature, the detection result of the salt state (the amount of salt or the concentration of the salt and the type of salt) by the salt state detection means, and the detection result of the water state (wetness or water film thickness) by the water state detection means. From the road surface is determined.

FIGS. 2 and 3 show the time-dependent characteristics of the road surface temperature during freezing measured on an actual road. In each figure, the time change of the road surface state (whether frozen or not) is also shown below the graph of the road surface temperature.

FIG. 2 shows the characteristics when the deicing agent is not sprayed on the road surface. The road surface temperature decreases with the passage of time, becomes constant at about 0 ° C. for a certain period of time, and then returns again. Is declining. In this case, freezing can be determined based on 0 ° C.

FIG. 3 shows the characteristics when 100 g of sodium chloride was sprayed on a predetermined area as a deicing agent. The change in the road surface temperature is similar to that when the deicing agent is not sprayed. The constant temperature value is usually below the freezing point of water (about -10 ° C in this case). in this case,
Freezing can be determined based on -10 ° C.

This indicates that when the antifreezing agent is sprayed, the reference temperature for judging freezing may be changed. The temperature at which the road surface actually freezes depends on the type of the antifreeze, the amount of the antifreeze applied, and the water condition of the road. Therefore, the relationship between the type of antifreeze (the type of salt), the amount of the antifreeze applied (the amount of salt or the concentration of salt), the moisture condition of the road surface and the temperature at which the road surface freezes is determined in advance and measured. It is preferable that the reference temperature is determined based on the type and amount of salt or the salt concentration obtained, and that the freezing is comprehensively determined by taking into account the information of the moisture state such as the degree of wetness obtained by measurement.

FIG. 4 shows the relationship between the amount of the antifreezing agent (salt) applied and the road surface freezing temperature. As shown in the figure, the road surface freezing temperature decreases substantially in proportion to the amount of the salt dispersion cloth, and the slope thereof differs depending on the type of salt. Therefore, if the type and amount of salt are known, the road surface freezing temperature can be known.

The road surface freezing judging / predicting device 12 determines a reference temperature based on the concentration and type of the salt obtained by the salt measuring device 6, and determines the reference temperature and the wetness obtained by the wetness measuring device. , And determine freezing.

Next, the freeze prediction algorithm will be described in detail.

First, the road surface temperature is predicted. The weather measurement device 5 can only obtain the current weather quantity. Therefore, in the case of the freezing prediction, the weather forecast is received by the antenna 11, and the weather forecast such as the amount of solar radiation, the amount of rain and snow, and the temperature after a desired time is predicted from the weather forecast. On the other hand, the optical fiber temperature measuring device 4
By storing the temperature measured in the above, the temporal change of the temperature under the road is obtained. A predicted temperature curve is created based on the temporal change, and a temperature after a desired time is predicted from the predicted temperature curve. From the temperature under the road predicted in this way and the predicted weather amount on the road, the road surface temperature after a desired time is calculated by heat calculation considering heat transfer between the outside air and the road surface and heat conduction inside the road. Predict.

Next, the state of salt, particularly the amount (or concentration) of salt
Cannot be predicted by the salinity measuring device 6. Therefore, the salinity is assumed to be constant, and the current salinity is predicted to be maintained after a desired time, or the salinity changes over time due to the influence of wind and rain, so the amount of salinity is adjusted according to the weather amount. A predicted salt amount curve is created, and a predicted salt amount after a desired time is predicted from the predicted salt amount curve.

As for the state of moisture, for example, the wetness cannot be predicted by the wetness measuring device 7. Therefore, the water condition is predicted from the information on the rainfall included in the weather forecast as follows.

FIG. 5 shows the relationship between the rainfall intensity (rainfall) and the road surface water film thickness during rainfall on an asphalt road surface in an experiment. The road surface on which this experiment was performed has substantially the same inclination angle as a normal road surface. As shown in the figure, when the rainfall time has sufficiently passed, the road surface water film thickness does not depend on the rainfall intensity (rainfall) and becomes a substantially constant value (at this time, the road surface wetness is saturated). In addition, even before the road surface wetness is saturated, the road surface water film thickness can be shown as a function of the precipitation intensity and the elapsed time. Therefore, it is possible to predict the water film thickness after a desired time by applying the rainfall amount of the weather forecast to the water film thickness change characteristic in FIG.

In an actual road, there are differences in the material of the road surface, the degree of unevenness of the road surface, and the like. In addition, there are deformations and special shapes due to ruts on the road surface. However, if data is collected in advance and the water film thickness change characteristics for each rainfall are grasped, the water film thickness after a desired time can be predicted from the rainfall in the weather forecast.

As described above, the road surface temperature, the salt content, and the water film thickness after a desired time are predicted. Using these prediction results, the freezing of the road surface after a desired time can be predicted by an algorithm similar to the above-described freezing determination algorithm.

The road surface freezing determination / prediction system shown in FIG. 1 comprises an optical fiber 3 laid continuously under the road along the road surface 2.
In addition to measuring the temperature distribution over a wide range by the optical fiber temperature measuring device 4, the plural meteorological measuring devices 5, the salinity measuring devices 6, and the wetness measuring devices 7 arranged in a distributed manner are used to measure the meteorological amount and the salt concentration at a plurality of places. In addition, since the type and the degree of wetness are measured, it is possible to perform road surface freezing determination over a wide range. In addition, since road surface freezing is determined according to the concentration and type of salt content, accurate determination can be made even when the antifreeze is sprayed. Furthermore, since a prediction method of various quantities required for road surface freezing determination has been established, freezing prediction based on the predicted various quantities becomes possible. Therefore, the road surface condition such as the degree of wetness of the road surface and the presence / absence of freezing can be determined / predicted and reported to the traveling driver as soon as possible, and the driver can be alerted, thereby contributing to the reduction of accidents.

[0034]

The present invention exhibits the following excellent effects.

(1) The range of the road surface to be determined is widened.

(2) Accurate determination can be made even when the antifreezing agent is sprayed.

(3) Freezing can be predicted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a road surface freeze determination / prediction system showing an embodiment of the present invention.

FIG. 2 is a time change characteristic diagram of a road surface temperature and a road surface state when an antifreeze is not sprayed.

FIG. 3 is a time change characteristic diagram of a road surface temperature and a road surface state when a deicing agent is sprayed.

FIG. 4 is a characteristic diagram showing a relationship between a salt dispersion cloth amount and a road surface freezing temperature.

FIG. 5 is a characteristic diagram showing a relationship between a precipitation intensity on a road surface and a water film thickness.

FIG. 6 is a configuration diagram of a conventional road surface state detection sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Road 2 Road surface 3 Optical fiber 4 Optical fiber temperature measuring device 5 Weather measuring device 6 Salt content measuring device 7 Wetness measuring device 12 Road surface freezing judgment / prediction device

Claims (4)

[Claims] 1. An under-road temperature is measured using an optical fiber buried in a road, and a solar radiation amount, a rain-snow amount, a temperature and other weather amounts are measured on the road, and the under-road temperature and the on-road weather amount are measured. From this, the road surface temperature is obtained, and the salt state of this road surface is detected,
A road surface freeze determination method, further comprising detecting a road surface moisture state, and determining whether the road surface is frozen based on a detection result of the road surface temperature, a salt content state, and a moisture state detection result. 2. An optical fiber temperature measuring device for measuring a temperature under a road by an optical fiber buried in a road, a weather measuring device for measuring a weather amount such as a solar radiation amount, a rainfall and snowfall amount, and an air temperature on the road; It is provided with a salt condition detecting means for detecting a salt condition of the road surface, and a moisture condition detecting device for detecting a moisture condition of the road surface, the temperature under the road, the weather amount on the road, the detection result of the salt condition of the road surface, the moisture of the road surface. A road surface freezing determination device that determines whether the road surface is freezing based on a detection result of a state. 3. A method of measuring a temperature under a road by using an optical fiber buried in the road, predicting a subsequent temperature from a temporal change of the temperature, and calculating a solar radiation amount, a rainfall amount, a temperature, etc. on the road from a weather forecast. Predict the weather amount, predict the road surface temperature from the predicted temperature under the road and the predicted weather amount on the road, detect the salinity condition of this road surface, and predict the subsequent salinity condition from the detection result A road surface freezing prediction method, further comprising: predicting a road surface moisture state from a weather forecast; and predicting road surface freezing from a predicted road surface temperature, a predicted salinity state, and a predicted moisture state. 4. An optical fiber temperature measuring device for measuring a temperature under a road by using an optical fiber buried in the road, a temperature predicting means for predicting a subsequent temperature from a temporal change of the temperature, and an on-road based on a weather forecast. Meteorological forecasting means for predicting the amount of solar radiation, rainfall, snowfall, temperature, etc., salinity detecting means for detecting the salinity of the road surface, and salinity predicting means for predicting the subsequent salinity from the detection result And a moisture condition predicting means for predicting the moisture condition of the road surface from the weather forecast, based on the predicted temperature under the road, the predicted weather amount on the road, the predicted salt condition, and the predicted moisture condition. A road surface freezing prediction device, which predicts freezing of a road surface by using the method.