JP2001042053A - Method and system for estimating road surface condition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly estimate the road surface conditions even when there exist uneven parts such as wheel tracks, hollows or the like, shadow parts and the traffic of vehicles on a road by a method wherein the balance of heat flowing in the horizontal direction of the road surface is found based on the distribution of the temperature along the road surface and the balance of the heat in the horizontal direction is added so as to estimate the road surface state. SOLUTION: Since an optical-fiber temperature sensor 13 can measure a temperature at a distance resolution of 1 m or lower, a road surface temperature in a point whose road surface state is to be measured and a road surface temperature around the point can be detected. Since a horizontal-direction heat transfer amount is found on the basis of a heat transfer decided by the material of a road surface and on the basis of a temperature difference in the horizontal direction of the road surface, the horizontal-direction heat transfer amount in the point can be found when a temperature difference in the horizontal direction in an arbitrary point is calculated. A heat balance calculation is classified largely into a heat balance in the vertical direction of the road surface and a heat balance in the horizontal direction. A road surface condition decision apparatus 10 individually calculates heat in respective points based on weather data which is read out from an information acquisition apparatus 9, and the sum of the heat is found. Thereby, the heat balance in an arbitrary point is calculated. When this heat balance model is used, the balance of the heat which comes in and out from the road surface as an object can be calculated with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a system for estimating a road surface condition on the basis of weather information, and more particularly to a road having irregularities such as ruts and depressions, shaded areas, and traffic of vehicles. The present invention relates to a road surface condition estimation method and a system for correctly estimating a road surface condition even in such a case.

[0002]

2. Description of the Related Art As a system for estimating a road surface condition of a road, a system using weather information is known. As shown in FIG. 3, a conventional road surface condition estimating system includes a thermometer 2, a rain gauge 3, a pyranometer 4, an anemometer 5, a hygrometer 6, a road surface thermometer installed near a target road 1. A meteorological sensor such as 15; a meteorological information receiving device 7 for receiving meteorological data such as the amount of cloud from the Meteorological Agency and transmitting it to a signal line 12; and a signal transmitting device 8 for transmitting the meteorological data of the meteorological sensor via the signal line. An information collection device 9 for receiving weather data from the weather information receiving device 7 and the signal transmission device 8 and a road surface condition determination for determining (estimating) a road surface condition (also referred to as a road surface condition) based on the received weather data. Device (also referred to as a road surface condition estimation device) 10 and a display 11 for displaying a determination result
It is composed of

[0003] The road surface condition judging device 10 calculates the vertical position of a road entering and exiting a road surface based on a heat balance model of the road surface as shown in FIG. 4 from weather data of temperature, rainfall, solar radiation, wind speed, humidity, road surface temperature and cloudiness. Direction heat (heat 25 due to solar radiation from the sun 22, heat due to surface blackbody radiation on the road surface 21, air 2
In addition to calculating the balance of heat 27 due to sensible heat, latent heat, and rainfall from 3 and heat transfer 28) from the ground 24, the relational expression between precipitation and water film thickness, the relational expression between snowfall and snowfall thickness, A road surface condition such as dryness / wetness / water film / snowfall / freezing is determined on the road surface by using a relational expression between a heat balance, a water evaporation amount, and a snowmelt amount.

[0004]

When there is an uneven portion such as a rut or a depression on a road, water easily accumulates in the concave portion. Therefore, even if the concave portion is in a wet state or a water film state under the same weather condition, the convex portion is not. Even when the vehicle is only a distance of about 1 m from each other, such as in a dry state, the road surface conditions may be different. Even on the same road surface, road surface physical quantities such as the reflection coefficient of solar radiation are different in a dry state, a wet state, and a snowy state, so that a large difference in road surface temperature occurs depending on road surface conditions.

[0005] Further, since the amount of solar radiation differs between the shaded part and the sunlit part, a large difference occurs in the road surface temperature.

[0006] When a vehicle is running on the target road surface, the vehicle is in a wet state in the traffic area, but is in a snowy state in other areas due to the friction of tires and the crushing of snow due to the weight of the vehicle. The road surface condition is different, for example, and a large temperature difference occurs on the road surface due to a difference in the road surface physical quantity such as the reflection coefficient.

As described above, there are many cases where a large temperature difference occurs in the horizontal direction of the road surface, and the amount of heat transfer in the horizontal direction of the road surface caused by the temperature difference cannot be ignored.

However, the prior art does not detect such uneven temperature in the horizontal direction of the road surface, and does not perform heat balance calculation in consideration of heat transfer in the horizontal direction of the road surface. there were.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a road surface condition estimation method and a road surface condition estimation system capable of correctly estimating a road surface condition even when a road has an uneven portion such as a rut or a depression, a shaded portion, and a vehicle. Is to provide.

[0010]

According to the present invention, there is provided a method of estimating a state of a road surface by calculating a balance of heat flowing into and out of the road surface from weather information. The balance of the heat flowing in the horizontal direction of the road surface is obtained from the temperature distribution thus obtained, and the road surface condition is estimated by adding the balance of the heat in the horizontal direction.

The temperature distribution along the road surface may be obtained by measuring the temperature distribution in a direction transverse to the road surface.

Further, the system of the present invention provides a sensor group that obtains weather information by actually measuring various weather quantities, a receiving device that obtains weather information by communication, and a balance of heat flowing into and out of a road surface from the weather information. In a road surface condition estimation system including a road surface condition estimation device that calculates and estimates the road surface condition, an optical fiber temperature sensor that measures a temperature distribution along the road surface is provided, and the road surface condition estimation device is provided on the road surface. The balance of the heat flowing in the horizontal direction of the road is obtained from the temperature distribution along the road, and the state of the road surface is estimated by adding the balance of the heat in the horizontal direction.

[0013]

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 condition estimating system according to the present invention includes a thermometer 2, a rain gauge 3, a pyranometer 4, an anemometer 5, and a hygrometer 6 installed near a target road 1. A meteorological sensor such as a meteorological information receiving device 7 that receives meteorological data such as cloud cover from the Meteorological Agency and transmits the data to the signal line 12;
An optical fiber temperature sensor 1 laid alternately and obliquely across the road 1 to measure the temperature distribution in the cross direction of the road 1
3, a signal processor 14 for transmitting the temperature distribution to the signal line 12, and weather data from a weather sensor or the like to the signal line 12.
Signal transmission device 8 for transmitting signals via
4. An information collecting device 9 for receiving weather data from the weather information receiving device 7 and the signal transmitting device 8, and a road surface determining device 10 for determining a road surface condition based on the received weather data.
And a display 11 for displaying the determination result. The road surface condition determination device 10 can determine the road surface condition by executing the road surface condition determination program according to the present invention.

The operation of the road surface condition estimation system shown in FIG. 1 will be described.

The road surface condition judging device reads the weather data collected by the information collecting device 9, calculates the heat balance in the vertical direction and the horizontal direction of the road on the target road surface, and calculates the relation between the precipitation and the water film thickness. Using the relational expression between the amount of snowfall and snow thickness, the relational expression between the heat balance and the amount of water evaporation, the amount of snowmelt, and the like, the road surface condition such as dryness / wetness / water film / snowfall / freezing on the road surface is determined.

First, the operation of estimating the horizontal heat transfer amount will be described.

Since the optical fiber temperature sensor 13 can measure the temperature with a distance resolution of 1 m or less, the optical fiber temperature sensor 13 can detect the road surface temperature at the target point for determining the road surface condition and the surrounding road surface temperature. Since the horizontal heat transfer amount is obtained from the heat transfer determined by the material of the road surface and the temperature difference in the road surface horizontal direction, the horizontal heat transfer amount at that point is calculated by calculating the road surface temperature difference at an arbitrary point. be able to.

Next, the operation of the heat balance calculation will be described.

FIG. 2 shows a model of a heat balance of heat entering and exiting a road surface used in the present invention. The heat balance on the road surface for which the road surface condition is to be determined is roughly classified into a heat balance in the vertical direction of the road surface and a heat balance in the horizontal direction of the road surface.

The heat balance in the vertical direction of the road surface includes heat 25 due to solar radiation from the sun 22, heat due to surface blackbody radiation on the road surface 21, sensible heat from the atmosphere 23, latent heat, heat due to rainfall 27, and heat from the underground 24. Heat such as transfer heat 28 is involved.

On the other hand, in the heat balance in the horizontal direction of the road surface, there is a heat transfer 29 in the horizontal direction of the road surface 21 caused by the road surface temperature difference.

The road surface condition judging device 10 includes the information collecting device 9
Based on the weather data read from, each of the above-mentioned heats is individually calculated, and the heat balance of any point is calculated by calculating the sum of the heats.

By using this heat balance model, the balance of heat entering and exiting the target road surface can be calculated more accurately than in the prior art using only the heat balance in the vertical direction of the road surface. In this way, by estimating the road surface condition by adding the horizontal heat balance obtained from the temperature distribution along the road surface to the conventional method, the unevenness of the road such as a rut or a depression, the shaded portion, and the vehicle Even when there is traffic, the road surface condition can be estimated correctly.

The road surface condition estimating system of the present invention may use a non-contact type temperature sensor as a means for measuring the temperature distribution along the road surface. As a non-contact type temperature sensor,
There is an infrared thermometer. Although a continuous temperature distribution cannot be obtained unlike the optical fiber temperature sensor, a plurality of temperature sensors may be installed along the road surface. For example, a representative point of a road uneven part, a shade part, and a vehicle traffic part is selected, and a temperature sensor is installed only at the representative point, and the temperature of this representative point is changed to the temperature of another road uneven part, a shade part, and a vehicle traffic part. May be considered.

Further, the road surface condition estimation system of the present invention
The present invention is not limited to roads such as expressways and general roads, and can be applied to objects similar to roads such as airfield runways.

[0027]

The present invention exhibits the following excellent effects.

(1) Since the heat balance in the horizontal direction is taken into consideration, the road surface condition can be correctly estimated even when the road has irregularities such as ruts and depressions, shaded areas, and vehicles.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a road surface condition estimation system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a model of a heat balance used in the present invention.

FIG. 3 is a configuration diagram of a conventional road surface condition estimation system.

FIG. 4 is a diagram showing a conventional heat balance model.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Road 2 Thermometer 3 Rain gauge 4 Pyranometer 5 Anemometer 6 Hygrometer 7 Weather information receiving device 9 Information collecting device 10 Road surface condition judging device 13 Optical fiber temperature sensor

Claims (3)

[Claims] 1. A method for estimating the state of a road surface by calculating a balance of heat entering and exiting a road surface from weather information, obtaining a balance of heat flowing in a horizontal direction of the road surface from a temperature distribution along the road surface, A road surface condition estimating method, wherein the road surface condition is estimated by adding the heat balance in the horizontal direction. 2. The road surface condition estimating method according to claim 1, wherein the temperature distribution along the road surface is obtained by measuring the temperature distribution in a direction transverse to the road surface. 3. A sensor group that obtains weather information by actually measuring various weather quantities, a receiving device that obtains weather information by communication, and calculating a balance of heat flowing into and out of the road surface from the weather information to calculate the balance of the road surface. In a road condition estimation system including a road condition estimation device that estimates a condition, an optical fiber temperature sensor that measures a temperature distribution along the road is provided.
The road surface condition estimating device obtains the balance of heat flowing in the horizontal direction of the road surface from the temperature distribution along the road surface, and estimates the road surface condition by adding the heat balance of the horizontal direction. Road surface condition estimation system.