JP3677542B2 - Road surface condition estimation method - Google Patents

Road surface condition estimation method Download PDF

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JP3677542B2
JP3677542B2 JP2002043880A JP2002043880A JP3677542B2 JP 3677542 B2 JP3677542 B2 JP 3677542B2 JP 2002043880 A JP2002043880 A JP 2002043880A JP 2002043880 A JP2002043880 A JP 2002043880A JP 3677542 B2 JP3677542 B2 JP 3677542B2
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road
amount
temperature
calculated
radiation
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JP2003240867A (en
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博朗 北川
晃之 中村
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National Institute for Land and Infrastructure Management
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National Institute for Land and Infrastructure Management
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【0001】
【発明の属する技術分野】
この発明は、長距離にわたって道路の路面状態を推定する方法に関するものである。
【0002】
【従来の技術】
道路交通において、湿潤、積雪、凍結などの路面状態が生じるとスリップ事故が発生しやすい。このため、路面湿潤や路面凍結などの危険な路面状態を速やかに検知して、自動車の運転手に注意を促す必要がある。しかし、長距離に及ぶ道路を常に巡回監視するのは、人手及びコストの面で困難であるため、このような路面の状態を把握する手段として路面状態検出センサが用いられる。
【0003】
従来の路面状態検出センサは、主に2つに分けられる。第1のグループは、道路表面に赤外線又は電磁波を照射し、路面からの反射率を測定するものである。本センサの代表的な構成を図3に示す。道路22の近傍に超音波式の距離計23、赤外線照射装置24と赤外線受光装置25からなる赤外線装置26および信号処理装置27を設置し、道路への入射光28と反射光29および反射光30の強度比が、路面状態によって異なることを用いて路面状態を推定する。21は支持ポール、21aはセンサ取り付け部である。
【0004】
第2のグループとしては、道路近傍の気象量及び路面温度を測定するセンサが挙げられる。路面温度計測には、熱電対、赤外放射温度計等の単点計測用のセンサに加えて、多点計測が可能で長距離の温度を計測するのに適した光ファイバー温度レーダを用いる方法が提案されている。また、気象量計測値は、計測地点を含むある程度の領域に対して代表値として適用する方法のほかに、道路近傍の複数の気象量を推定する方法が提案されている(特願2000−359288号:道路気象検出方法及び検出システム)。これらのセンサ情報は、道路管理担当者が過去の知見に基づいて路面状態を推定する材料として用いられるほかに、道路近傍の気象量観測値と組み合わせて路面状態を推定する方法も提案されている。
【0005】
ところで、赤外線又は電磁波を照射する方式のセンサを用いて、路面状態を道路の長手方向に沿って連続的に把握するためには、多数のセンサを設置する必要があり、コストがかかる。
一方、路面温度と気象量を計測する場合は、光ファイバ温度レーダが長距離に敷設可能であることと、気象量が広範囲の代表値として使用可能であることから低コストである。しかし、これらの情報から道路管理者が路面状態を判断するには、経験が求められること、及び危険と判断する地域を限定することが難しいという問題がある。
また、過去に提案されている気象量及び路面温度から路面状態を推定する方法においては、気象量計測値から道路表面への流入熱量を計算する過程で必要となる物理量以外のファクター(熱伝達係数hr、雲量係数ζ、及び日陰の影響)が計測困難であるという問題があった。
【0006】
【発明が解決しようとする課題】
そこでこの発明は、前記のような諸問題に鑑み、過去に提案されている路面温度計測値、及び地上気象量計測値に基づいて路面状態を推定する方法を改良し、気象量計測地点以外における路面状態推定精度を向上させることができる路面状態推定方法を提供することを目的とする。
【0007】
【課題を解決するための手段】
前記目的を達成するため、の発明は、路面温度計測値並びに地上気象量計測値を用いて、長距離にわたって道路の路面状態を推定する方法において、道路内部に埋設した光ファイバにより路面温度を計測すると共に、地上気象量計測装置により気温、及び放射エネルギーの収支量を計測し、この計測値に基づいて路面状態推定計算を行う路面状態推定装置は、前記路面温度に基づいて路面への流入熱量を算出し、前記放射エネルギーの収支量から輻射率を算出し、式 ( ) に基づいて雲量係数を算出し、式 ( ) に基づいて日射量遮蔽率を算出し、式 ( ) に基づいて算出した熱伝達係数を前記日射量遮蔽率と共に適時更新し、前記雲量係数、前記日射量遮蔽率、及び前記熱伝達係数を用いて気象量計測地点以外の路面流入熱量を算出し、該気象量計測地点以外の路面流入熱量及び前記路面への流入熱量を用いて、路面状態を推定することを特徴とする。
ζ=W0/[E0・σ・{Te −f(Tair)・Tair }]・・・ ( )
ただし、ζ:雲量係数、W0:放射収支計で計測した長波放射エネルギーの収支量、E0:放射収支計の計測値から算出できる輻射率、σ:ステファンポルツマン定数、Te:路面温度(光ファイバー温度データから算出した値)、Tair:気温、f( ):気温Tairの関数
η=Ws/ { (1−A)・Ws0 } ・・・ ( 2)
ただし、η:日射量遮蔽率、Ws:短波放射エネルギーの収支量、A:路面アルベド定数、Ws0:日向の日射量
hr=(We−W0)/ { (Tair−Te)・S } ・・・ ( 3)
ただし、hr:熱伝達係数、We:路面への流入熱量、W0:放射収支計で計測した長波放射エネルギーの収支量、Tair:気温、Te:路面温度、S:熱が伝わる面積
【0009】
【発明の実施の形態】
この発明の一実施の形態を、添付図面を参照して説明する。図1は全体構成図であり、対象となる道路4の近傍に設置される気温計、風向風速計、雨雪量計などの各種気象センサ1、道路に埋設される光ファイバ2、気象センサ1により計測されたデータを、信号線6を介して伝送する信号伝送装置3と、光ファイバ2により計測されたデータを、信号線6を介して伝送する信号伝送装置5、計測データを受信する情報収集装置7と、受信したデータに基づいて路面状態推定計算を行う路面状態推定装置8と、その結果を出力する表示部9により構成されている。
【0010】
気象センサ1は、電気的な出力が得られるものであれば特に限定されない。情報収集装置7は、気象センサ1及び光ファイバ2からの情報をリアルタイムで受信し、データの種類や遅延時間等を考慮して必要なデータを路面状態推定装置8に与える。路面状態推定装置8では、これらの入力データに基づき路面状態推定計算を行い、その結果である路面状態を表示部9に出力する。
【0011】
気象計測値から路面流入熱量Waを推定する方法において、計算ファクターである熱伝達係数hr、雲量係数ζ、及び日陰の影響を評価し、精度よく求める方法である。計算手順とそれを含む路面状態判定計算の流れを図2に示す。図2の個々の内容についての概要は以下の通りである。
(1)路面流入熱量Weの算出
光ファイバ温度データに基づいて、路面への流入熱量Weを算出する。
(2)雲量係数ζの算出
放射収支計で計測した長波エネルギーから、放射収支計の計測場所以外で計算に使用する雲量係数ζを算出する。
(3)日陰の影響度の算出
路面乾燥時において、熱量WaとWeの比較から日陰による日射量遮蔽率を算出し、データベースとして蓄える。
(4)熱伝達係数hrの算出
路面乾燥時において、熱量WaとWeの比較から熱伝達係数hrを算出し、次回以降の計算に使用する。
(5)気象量計測地点以外の場所における路面流入熱量Waの算出
項目(2),(3),(4)で求めた各計算ファクターを用いて、路面流入熱量Waを算出する。雲量係数ζは逐次求めた値を使用し、日陰の影響度は過去の乾燥時に求めた係数の中から日付が最も近いものを使用する。また、熱伝達係数hrは過去に最新の計算値を使用する。
(6)路面状態の推定
2つの方式で求めた路面流入熱量WaとWeを用いて、路面状態を推定する。
【0012】
次に原理の詳細を説明する。
(a)雲量係数ζの算出
長波放射エネルギー収支量Wr1を算出する式が提案されている(武市 靖「路面凍結の予測に関する研究」土木学会論文集No.470、P175〜P184、1993年7月)。これによると、Wrlは次の数式1で近似することができる。
【0013】
【数式1】
Wrl=ζ・E・σ・{Te4−f(Tair)・Tair4
ここで
ζ:雲量係数
E:輻射率
σ:ステファンポルツマン定数
Te:路面温度(光ファイバー温度データから算出した値)
Tair:気温
f( ):気温Tairの関数
輻射率Eは、路面状態(乾燥、湿潤、積雪、凍結)に対応した値を事前に実験で求めておき、最新の路面状態推定結果に基づいた値を使用する。数式1では雲量係数ζが未知数となるので、これらの算出方法を以下に述べる。雲量係数ζの求め方としては、雲量が数kmのオーダーでほぼ変化しないことを前提として、気象量計測場所で求めた値を代表値として使用する。すなわち、
【0014】
【数式2】
ζ=W0/[E0・σ・{Te 4 f (Tair)・Tair 4 }]
ここで、
W0:放射収支計で計測した長波放射エネルギー収支量
E0:放射収支計の計測値から算出できる輻射率E
数式2の右辺は既知につき、ζを求めることができる。
【0015】
(b)日陰の影響度の算出
面状態推定の対象となる場所は、それぞれ固有の遮蔽物(建造物、土手など)が存在し、場所毎に路面に対する日射量が異なる。実際には、太陽の方角と高度角に対する遮蔽物と路面の位置関係によって、日射量の遮蔽率は定まる。ここで、太陽の方角と高度角は、季節と時刻によって決まっているので、路面状態推定計算時に対象となる場所毎に日射量遮蔽率ηを求めて日時のデータベースとして蓄積することにより、次年度以降の近い日時の計算において、より正確な日射量遮蔽率ηを使用することができるようになる。ただし、計算上Wa=Weの関係を必要とするため、この関係が成立する路面状態が乾燥している場合にのみ日射量遮蔽率ηを算出する。
短波の放射エネルギー収支量Ws(日射量の収支量)は、次の数式3で表現できる。
【0016】
【数式3】
Ws=η・(1−A)・Ws0
ここで
η:日射量遮蔽率
A:路面アルベド定数
Ws0:日向の日射量
数式3から、求める未知数ηは、
【0017】
【数式4】
η=W s /{(1−A)・W s 0}
【0018】
【数式5】
Ws=Wa−Wrl−Wc
ここで、
Wc:大気と路面の対流熱伝達量
乾燥時という前提からWa=Weなので、数式4と数式5からηを算出することができる。
【0019】
(c)熱伝達係数hrの算出
熱伝達係数hrと項目(b)の日射量遮蔽率ηは、同時に求めることはできないため、熱伝達係数hrは日射量がゼロとなる夜間において調整する。また、計算上Wa=Weの関係を必要とするため、路面乾燥時にのみ計算を行う。大気と路面の対流熱伝達率Wcは、次の数式6で表わすことができる。
【0020】
【数式6】
Wc=hr・(Tair−Te)・S
ここで
hr:熱伝達係数
S:熱が伝わる面積
夜間という条件からWsであるので、数式5とWa=Weの関係から、
【0021】
【数式7】
r =(W e −Wrl)/{(T a ir−T e )・S}
【0022】
【発明の効果】
の発明によれば、前記のように気象量計測地点以外における路面状態推定精度を向上させることができるので、実際の道路(長距離、広範囲)に適用した場合に、赤外線又は電磁波を照射する方式よりも低コストで路面状態判定を実現できる。また、従来の気象量及び路面温度から路面状態を推定する方法の精度を向上し、より適切な道路情報を提供することができるという優れた効果がある。
【図面の簡単な説明】
【図1】この発明の一実施の形態を示す、全体構成図である。
【図2】同上における路面状態推定計算フローである。
【図3】従来の電波式路面状態検知センサの構成例を示す図面である。
【符号の説明】
1 気象センサ
2 光ファイバ
3 信号伝送装置
4 道路
5 信号伝送装置
6 信号線
7 情報収集装置
8 路面状態推定装置
9 表示部
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for estimating a road surface condition over a long distance.
[0002]
[Prior art]
In road traffic, slip accidents are likely to occur when road conditions such as wetting, snow accumulation, and freezing occur. For this reason, it is necessary to promptly detect a dangerous road surface condition such as road surface wetness or road surface freezing to alert the driver of the automobile. However, since it is difficult to constantly monitor a road over a long distance in terms of manpower and cost, a road surface state detection sensor is used as means for grasping such a road surface state.
[0003]
Conventional road surface condition detection sensors are mainly divided into two. The first group measures the reflectance from the road surface by irradiating the road surface with infrared rays or electromagnetic waves. A typical configuration of this sensor is shown in FIG. In the vicinity of the road 22, an ultrasonic distance meter 23, an infrared device 26 composed of an infrared irradiation device 24 and an infrared light receiving device 25, and a signal processing device 27 are installed, and incident light 28, reflected light 29 and reflected light 30 on the road are installed. The road surface state is estimated by using the fact that the intensity ratio of the vehicle is different depending on the road surface state. 21 is a support pole and 21a is a sensor mounting part.
[0004]
The second group includes sensors that measure the weather and road surface temperature near the road. In addition to sensors for single-point measurement such as thermocouples and infrared radiation thermometers, road surface temperature measurement includes a method that uses an optical fiber temperature radar that can measure multiple points and is suitable for measuring long-distance temperatures. Proposed. In addition to a method of applying meteorological measurement values as representative values to a certain area including a measurement point, a method of estimating a plurality of meteorological amounts in the vicinity of a road has been proposed (Japanese Patent Application No. 2000-359288). No .: Road weather detection method and detection system). These sensor information is used as a material for road managers to estimate road surface conditions based on past knowledge, and a method for estimating road surface conditions in combination with meteorological observation values in the vicinity of roads has also been proposed. .
[0005]
By the way, in order to continuously grasp the road surface state along the longitudinal direction of the road using a sensor of the type that irradiates infrared rays or electromagnetic waves, it is necessary to install a large number of sensors, which is costly.
On the other hand, when measuring the road surface temperature and the meteorological amount, the optical fiber temperature radar can be installed at a long distance, and the meteorological amount can be used as a representative value in a wide range, so that the cost is low. However, in order for the road manager to determine the road surface condition from these pieces of information, there is a problem that experience is required and it is difficult to limit the area determined to be dangerous.
Moreover, in the method of estimating the road surface condition from the meteorological amount and the road surface temperature proposed in the past, factors other than the physical quantity (heat transfer coefficient) required in the process of calculating the inflow heat amount to the road surface from the meteorological measurement value. hr, influence of cloud amount coefficient ζ, and shade) is difficult to measure.
[0006]
[Problems to be solved by the invention]
Therefore, in view of the above problems, the present invention has improved a method for estimating a road surface state based on a previously measured road surface temperature measurement value and a ground weather amount measurement value, and is used at a place other than a weather amount measurement point. An object of the present invention is to provide a road surface state estimation method capable of improving the road surface state estimation accuracy.
[0007]
[Means for Solving the Problems]
To achieve the above object, this invention uses a surface temperature measurements and surface weather quantity measurement value, a method of estimating a road surface condition of a road over a long distance, the road surface temperature by optical fibers embedded in the road The road surface state estimation device that measures the air temperature and the amount of radiant energy balance with the ground meteorological amount measurement device and performs the road surface state estimation calculation based on the measured value, the inflow to the road surface based on the road surface temperature The amount of heat is calculated, the emissivity is calculated from the amount of radiant energy, the cloudiness coefficient is calculated based on the equation ( 1 ) , the solar radiation shielding rate is calculated based on the equation ( 2 ) , and the equation ( 3 ) The heat transfer coefficient calculated based on the solar radiation shielding rate is updated in a timely manner, and the inflow heat amount on the road surface other than the meteorological point is calculated using the cloudiness coefficient, the solar radiation shielding rate, and the heat transfer coefficient, The mind Using the flow amount of heat to the road surface inflow heat and the road surface other than the amount measurement point, and estimates the road surface condition.
ζ = W0 / [E0 · σ · {Te 4 −f (Tair) · Tair 4 }] ( 1 )
Where ζ: cloud cover coefficient, W0: long-wave radiant energy balance measured with a radiation balance meter, E0: emissivity that can be calculated from the measured value of the radiation balance meter, σ: Stefan Poltzmann constant, Te: road surface temperature (optical fiber temperature) (Value calculated from data), Tair: temperature, f (): temperature Tair function
η = Ws / {(1- A) · Ws0} ··· (2)
Where η: solar radiation shielding rate, Ws: shortwave radiation energy balance, A: road albedo constant, Ws0: solar radiation
hr = (We-W0) / {(Tair-Te) · S} ··· (3)
Where, hr: heat transfer coefficient, We: amount of heat flowing into the road surface, W0: balance amount of long-wave radiant energy measured with a radiation balance meter, Tair: temperature, Te: road surface temperature, S: area where heat is transmitted
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram. Various weather sensors 1 such as a thermometer, an anemometer, and a rain and snow meter installed in the vicinity of a target road 4, an optical fiber 2 embedded in a road, and a weather sensor 1 The signal transmission device 3 for transmitting the data measured by the signal line 6, the signal transmission device 5 for transmitting the data measured by the optical fiber 2 via the signal line 6, the information for receiving the measurement data It comprises a collecting device 7, a road surface state estimation device 8 that performs road surface state estimation calculation based on the received data, and a display unit 9 that outputs the result.
[0010]
The weather sensor 1 is not particularly limited as long as an electrical output can be obtained. The information collecting device 7 receives information from the weather sensor 1 and the optical fiber 2 in real time, and gives necessary data to the road surface state estimating device 8 in consideration of the type of data and delay time. The road surface state estimation device 8 performs road surface state estimation calculation based on these input data, and outputs the road surface state as a result to the display unit 9.
[0011]
In the method of estimating the road surface inflow heat amount Wa from the meteorological measurement value, the heat transfer coefficient hr, the cloud amount coefficient ζ, and the influence of the shade, which are calculation factors, are evaluated and obtained with high accuracy. A calculation procedure and a flow of road surface condition determination calculation including the calculation procedure are shown in FIG. The outline of the individual contents in FIG. 2 is as follows.
(1) Calculation of road surface inflow heat amount We Calculate the inflow heat amount We to the road surface based on the optical fiber temperature data.
(2) Calculation of cloudiness coefficient ζ From the long wave energy measured by the radiation balance meter, the cloudiness coefficient ζ used for the calculation is calculated outside the measurement place of the radiation balance meter.
(3) Calculation of shade influence level When the road surface is dried, the shade amount shielding rate by shade is calculated from the comparison between the heat amounts Wa and We and stored as a database.
(4) Calculation of heat transfer coefficient hr When the road surface is dried, the heat transfer coefficient hr is calculated from a comparison between the heat amounts Wa and We and used for the next and subsequent calculations.
(5) Calculation of road surface inflow heat amount Wa at locations other than the meteorological point measurement point The road surface inflow heat amount Wa is calculated using the respective calculation factors obtained in items (2), (3), and (4) . A value obtained sequentially is used as the cloudiness coefficient ζ, and the influence degree of the shade is the coefficient having the closest date among the coefficients obtained during past drying. The latest calculated value is used for the heat transfer coefficient hr in the past.
(6) Estimation of road surface state The road surface state is estimated using the road surface inflow heat amounts Wa and We obtained by the two methods.
[0012]
Next, the details of the principle will be described.
(A) Calculation of cloudiness coefficient ζ A formula for calculating the long-wave radiant energy balance Wr1 has been proposed (Satoshi Takeichi, “Study on prediction of road surface freezing”, JSCE Proceedings No. 470, P175-P184, July 1993. ). According to this, Wrl can be approximated by the following Equation 1.
[0013]
[Formula 1]
Wrl = ζ · E · σ · {Te 4 −f (Tair) · Tair 4 }
Where ζ: cloud cover coefficient E: emissivity σ: Stefan Poltzmann constant Te: road surface temperature (value calculated from optical fiber temperature data)
Tair: Temperature f (): The function emissivity E of the temperature Tair is a value based on the latest road surface state estimation result obtained in advance by experiment with a value corresponding to the road surface state (dry, wet, snow cover, freezing). Is used. Since the cloud amount coefficient ζ is an unknown number in Equation 1, these calculation methods will be described below. As a method of obtaining the cloud amount coefficient ζ, a value obtained at a weather amount measurement place is used as a representative value on the assumption that the cloud amount does not substantially change in the order of several kilometers. That is,
[0014]
[Formula 2]
ζ = W0 / [E0 · σ · {Te 4 - f (Tair) · Tair 4}]
here,
W0: Long wave radiant energy balance measured with a radiation balance meter E0: Emissivity E that can be calculated from the measured value of the radiation balance meter
Since the right side of Equation 2 is known, ζ can be obtained.
[0015]
(B) Calculation of the degree of influence of the shade As the target of the surface state estimation, there are unique shielding objects (buildings, banks, etc.), and the amount of solar radiation with respect to the road surface varies from place to place. Actually, the shielding rate of the solar radiation amount is determined by the positional relationship between the shielding object and the road surface with respect to the sun direction and altitude angle. Here, since the direction and altitude of the sun are determined by the season and time, the solar radiation shielding rate η is calculated and stored as a date and time database for each target location at the time of road surface condition estimation calculation. In the calculation of the near date and time thereafter, the more accurate solar radiation shielding rate η can be used. However, since the relationship of Wa = We is required for calculation, the solar radiation amount shielding rate η is calculated only when the road surface condition in which this relationship is established is dry.
The shortwave radiant energy balance Ws (the amount of solar radiation) can be expressed by the following Equation 3.
[0016]
[Formula 3]
Ws = η · (1-A) · Ws0
Here, η: solar radiation shielding ratio A: road surface albedo constant Ws0: solar radiation amount in the sun
[0017]
[Formula 4]
η = W s / {(1-A) · W s 0}
[0018]
[Formula 5]
Ws = Wa-Wrl-Wc
here,
Wc: From the premise that the convective heat transfer amount between the atmosphere and the road surface is dry, Wa = We. Therefore, η can be calculated from Equation 4 and Equation 5.
[0019]
(C) Calculation of Heat Transfer Coefficient hr Since the heat transfer coefficient hr and the solar radiation amount shielding rate η of the item (b) cannot be obtained simultaneously, the heat transfer coefficient hr is adjusted at night when the solar radiation amount is zero. Moreover, since the relationship of Wa = We is required for calculation, the calculation is performed only when the road surface is dry. The convective heat transfer coefficient Wc between the atmosphere and the road surface can be expressed by the following formula 6.
[0020]
[Formula 6]
Wc = hr · (Tair−Te) · S
Here, hr: heat transfer coefficient S: area where heat is transmitted is Ws because of the condition of nighttime. From the relationship of Equation 5 and Wa = We,
[0021]
[Formula 7]
h r = (W e −Wrl) / {(T a ir−T e ) · S}
[0022]
【The invention's effect】
According to this invention, it is possible to improve the road surface condition estimation accuracy in the non-meteorological quantity measuring point as, when applied to actual road (long range, broad), irradiation with infrared rays or electromagnetic waves Road surface condition determination can be realized at a lower cost than the method. In addition, there is an excellent effect that the accuracy of the conventional method for estimating the road surface state from the weather amount and the road surface temperature can be improved and more appropriate road information can be provided.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.
FIG. 2 is a road surface state estimation calculation flow as described above.
FIG. 3 is a diagram illustrating a configuration example of a conventional radio wave type road surface state detection sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Weather sensor 2 Optical fiber 3 Signal transmission device 4 Road 5 Signal transmission device 6 Signal line 7 Information collection device 8 Road surface state estimation device 9 Display part

Claims (1)

路面温度計測値並びに地上気象量計測値を用いて、長距離にわたって道路の路面状態を推定する方法において、
道路内部に埋設した光ファイバにより路面温度を計測すると共に、地上気象量計測装置により気温、及び放射エネルギーの収支量を計測し、この計測値に基づいて路面状態推定計算を行う路面状態推定装置は、前記路面温度に基づいて路面への流入熱量を算出し、前記放射エネルギーの収支量から輻射率を算出し、式 ( ) に基づいて雲量係数を算出し、式 ( ) に基づいて日射量遮蔽率を算出し、式 ( ) に基づいて算出した熱伝達係数を前記日射量遮蔽率と共に適時更新し、前記雲量係数、前記日射量遮蔽率、及び前記熱伝達係数を用いて気象量計測地点以外の路面流入熱量を算出し、該気象量計測地点以外の路面流入熱量及び前記路面への流入熱量を用いて、路面状態を推定することを特徴とする路面状態推定方法。
ζ=W0/[E0・σ・{Te −f(Tair)・Tair }]・・・ ( )
ただし、ζ:雲量係数、W0:放射収支計で計測した長波放射エネルギーの収支量、E0:放射収支計の計測値から算出できる輻射率、σ:ステファンポルツマン定数、Te:路面温度(光ファイバー温度データから算出した値)、Tair:気温、f( ):気温Tairの関数
η=Ws/ { (1−A)・Ws0 } ・・・ ( 2)
ただし、η:日射量遮蔽率、Ws:短波放射エネルギーの収支量、A:路面アルベド定数、Ws0:日向の日射量
hr=(We−W0)/ { (Tair−Te)・S } ・・・ ( 3)
ただし、hr:熱伝達係数、We:路面への流入熱量、W0:放射収支計で計測した長波放射エネルギーの収支量、Tair:気温、Te:路面温度、S:熱が伝わる面積
In the method for estimating the road surface condition over a long distance using the road surface temperature measurement value and the ground meteorological measurement value,
A road surface state estimation device that measures road surface temperature with an optical fiber embedded inside the road, measures the amount of air temperature and radiant energy with a ground meteorological measurement device, and performs road surface state estimation calculation based on this measured value The amount of heat flowing into the road surface is calculated based on the road surface temperature, the radiation rate is calculated from the balance of the radiant energy, the cloudiness coefficient is calculated based on the equation ( 1 ) , and the solar radiation is calculated based on the equation ( 2 ). The amount of heat shielding coefficient is calculated, and the heat transfer coefficient calculated based on the equation ( 3 ) is updated with the solar radiation amount shielding time in a timely manner. A road surface state estimation method , wherein a road surface inflow heat amount other than the measurement point is calculated, and a road surface state is estimated using the road surface inflow heat amount other than the meteorological amount measurement point and the inflow heat amount to the road surface.
ζ = W0 / [E0 · σ · {Te 4 −f (Tair) · Tair 4 }] ( 1 )
Where ζ: cloud cover coefficient, W0: long-wave radiant energy balance measured with a radiation balance meter, E0: radiation rate that can be calculated from the measured value of the radiation balance meter, σ: Stefan Poltzmann constant, Te: road surface temperature (optical fiber temperature) (Value calculated from data), Tair: temperature, f (): temperature Tair function
η = Ws / {(1- A) · Ws0} ··· (2)
Where η is the solar radiation shielding rate, Ws is the shortwave radiation energy balance, A is the road albedo constant, and Ws0 is the solar radiation.
hr = (We-W0) / {(Tair-Te) · S} ··· (3)
Where, hr: heat transfer coefficient, We: amount of heat flowing into the road surface, W0: balance of long-wave radiant energy measured with a radiation balance meter, Tair: temperature, Te: road surface temperature, S: area where heat is transmitted
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