JP2004252520A - Road monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road monitoring system for detecting the number of passing vehicles, travel speed and vehicle weight, which are required for road management, by using one type of sensor. <P>SOLUTION: Oscillation sensors S1 and S4 are installed in a roadbed of a road by leaving a space in a travel direction of the vehicle. The number of oscillation detection times by the sensor S1 or S4 is counted and the number of the passing vehicles is obtained. Travel speed of the vehicle is obtained from a detection time difference by the sensors S1 and S4. Weight of the vehicle is estimated and obtained from a size of amplitude of detected oscillation and from travel speed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a road monitoring system used for road maintenance, management, operation, and the like.
[0002]
[Prior art]
It is important for the road manager to grasp the traffic volume on the road, the weight of the passing vehicles, the approximate vehicle type group, and the presence or absence of overloading. This is because the information is necessary for road management operations such as changing the signal form according to the traffic volume and examining the timing of road surface repair.
[0003]
Even with the same traffic volume, the pain on the road is large if there are many heavy vehicles, and the pain on the road surface also changes depending on the weight of the vehicle and the traveling speed. Therefore, a system that can obtain five pieces of information such as traffic volume on a road, traveling speed of a vehicle, vehicle weight, approximate vehicle type group, and overloading would be very useful for a road manager.
[0004]
Techniques for individually collecting these five pieces of information already exist. For example, for detection of the number of vehicles, there is a system in which an arm extends above a road surface, and an ultrasonic sensor is installed on the arm in a downward direction, and the number of passing vehicles is counted based on a change in an ultrasonic reflection distance.
[0005]
There is also a system in which a coil sensor for detecting a magnetic field change called a vehicle detector is embedded in a roadbed to detect the presence or absence of a vehicle at an intersection or the like.
[0006]
Further, an image monitoring system and a speed detection system are used for traffic control and the like.
[0007]
In addition, truck scales are used to prevent overloading.
[0008]
[Problems to be solved by the invention]
A system that counts the number of vehicles using an ultrasonic sensor cannot measure vehicle weight. Since the difference in vehicle height can be determined, it seems possible to estimate the vehicle weight and the vehicle type group from the difference in vehicle height, but this has a problem in reliability. In this system, the vehicle speed can be detected technically by installing a plurality of sensors, but it is difficult to accurately calculate the speed depending on the shape of the vehicle.
[0009]
Although a dedicated ultrasonic sensor is used for speed detection, it is not used for measuring the number of vehicles.
[0010]
The coil sensor can also detect the traffic amount and the speed with this, but cannot obtain information on weight.
[0011]
Also, a truck scale cannot be used for measuring the weight of a running car.
[0012]
As described above, according to the related art, it is not possible to reliably measure the weight of a running vehicle. Further, the measurement of the number of vehicles and the speed detection need to be performed by different sensors, which complicates the system.
[0013]
Accordingly, an object of the present invention is to make it possible to detect the number of vehicles passing, speed, weight, vehicle type group, and presence / absence of overloading using one type of sensor.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the road monitoring system of the present invention, a vibration sensor is installed in a roadbed of a road, the sensor detects vibration caused by vehicle traffic, and counts the number of times of detection to count the number of vehicles traveling. Was asked.
[0015]
In addition, a plurality of vibration sensors are installed at required intervals in the traveling direction in the roadbed in the same lane of the road, and each sensor detects vibration due to vehicle traffic, and the speed of the passing vehicle is determined based on the detection time difference of the sensors at intervals. Was asked.
[0016]
In addition, a plurality of vibration sensors are installed at required intervals in the traveling direction in the roadbed in the same lane of the road, and each sensor detects vibration due to vehicle traffic, and the passing time of passing vehicles is determined based on the detection time difference of the spaced sensors. The speed is obtained, and the weight of the passing vehicle is estimated from the magnitude of the amplitude of the detected vibration and the passing speed.
[0017]
Further, the axle interval of the traveling vehicle is determined from the traveling speed obtained from a plurality of sensors installed at required intervals in the traveling direction and the time difference between the front wheel and the rear wheel obtained from any one of the plurality of sensors. The vehicle type group is estimated by comparing a group of vehicle types with close axle intervals in advance with data stored as a database.
[0018]
Further, the measured weight of the vehicle is compared with the allowable total weight including the estimated allowable load weight of each estimated vehicle type group as a database to estimate whether or not the vehicle is overloaded.
[0019]
In any system, the vibration sensor used is preferably an optical vibration sensor using an optical fiber as a detector.
[0020]
In the case of an asphalt paved road, it is preferable to embed the vibration sensor in a coarse-grained asphalt layer below the dense-grained asphalt on the surface.
[0021]
The vibration sensor is configured by connecting metal rods to both sides of the detector, and this vibration sensor is set to a length that is almost the lane width and is arranged in the direction crossing the lane, or it passes through the road surface near the vibration sensor installation point, Forming a step that vibrates the vehicle, providing a vibration transmitting member anchored to the roadbed between the vibration sensor in the roadbed and the road surface, bringing the vibration transmitting member into contact with the vibration sensor, and an upper end of the vibration transmitting member. It is also preferable to dispose in the same plane as the road surface and cover the exposed portion of the upper end of the vibration transmitting member to the road surface with a protective tape stuck on the road surface.
[0022]
[Action]
When the vibration sensor detects the vibration caused by vehicle traffic and determines the number of vehicles passing, the vibration sensors are installed at intervals in the direction of travel in the subgrade on the same lane of the road to detect the vibration of the spaced sensors. The speed of the passing vehicle can be obtained from the time difference between the vehicle and the traveling speed obtained from the plurality of sensors and the time difference between the front wheel and the rear wheel obtained from any one of the plurality of sensors. The interval is calculated, and the vehicle group is estimated by comparing the group of the vehicle types with close axle intervals with the data stored in the database in advance, and comparing the allowable load weight stored in the database of the estimated vehicle type group. It is also possible to estimate the weight of the passing vehicle from the amplitude of the detected vibration and the vehicle speed to some extent accurately. Sensors can detect five pieces of information necessary for road management, that is, the number of passing vehicles, vehicle speed, vehicle weight, vehicle type, and whether or not the vehicle is overloaded, thereby simplifying the system and improving the installation efficiency. Become like
[0023]
The number of vehicles passing can be accurately detected because a clear signal is obtained even with a vibration sensor.
[0024]
In addition, the vehicle speed can be accurately determined from the distance between the sensors installed at an interval, which is known in advance, and the time difference between the distance and the time detected by the front and rear sensors.
[0025]
Furthermore, the weight of the vehicle can be estimated only from the amplitude of the detected vibration (magnitude of the vibration). However, in the present invention, the passing speed is also used as a material for the determination, so that the influence of the force due to the acceleration is corrected. Therefore, the vehicle weight can be estimated with some accuracy. When an optical vibration sensor using an optical fiber as a detector is used, malfunction due to electromagnetic induction is eliminated, and the reliability of the system is improved. In addition, since a long distance section can be constructed by one system, the number of signal transmission terminals can be reduced, and signal transmission can be simplified.
[0026]
In addition, if the vibration sensor is buried in the fine-grained asphalt layer on the surface of asphalt-paved roads, the sensor will be damaged when the surface is leveled with a grader during road renovation work, etc. Therefore, on asphalt-paved roads, it is preferable to bury the sensor in a coarse-grained asphalt layer underneath dense-grained asphalt. It is also possible to bury it in the lower layer, but if it is too deep, it will be difficult to construct, and vibration will be difficult to transmit, and the sensitivity of the sensor will decrease, so it is not preferable to make the burying point deeper than necessary .
[0027]
When the vibration sensor is arranged in the direction crossing the lane with a length substantially equal to the lane width, the vibration is detected even if the running position of the vehicle is slightly shifted left and right, and the reliability of monitoring is further improved. If the sensor itself is divided into a limited length, handling properties are good and carrying-in work is easy.
[0028]
In addition, if the vibration sensor is embedded in the roadbed, the vibration transmitted from the road surface will be attenuated and reduced, so if necessary, auxiliary measures such as amplifying the vibration generated by providing a step on the road surface near the sensor will be necessary. Apply. Instead of providing a step, a vibration transmitting member may be provided between the vibration sensor in the roadbed and the road surface. In this case, if the vibration transmitting member comes off and rises on the road surface, the traveling of the vehicle may be hindered. Therefore, it is preferable that the vibration transmitting member is fixed to the roadbed so as to be prevented from coming off. Also, when the vibration transmitting member is exposed on the road surface, rainwater or the like enters the interface with the asphalt, and the asphalt is easily peeled, and the possibility of hastening the road surface is increased. Therefore, the exposed portion of the vibration transmitting member to the road surface is attached to the road surface. It is better to cover it with protective tape. Depending on the material and thickness of the protective tape, this sheet can be expected to play a role of amplifying vibration. Further, the protection tape can prevent the vibration transmitting member from jumping out onto the road surface.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 schematically illustrates a situation in which a vibration sensor embedded in a road detects vibration (amplitude) when passing a vehicle and measures a time difference. In FIG. 1, vibrations caused by the front and rear wheels of the vehicle are separately detected.
[0030]
When the vehicle passes near the vibration sensor, if the vehicle is a normal two-wheeled or four-wheeled vehicle, the sensor first detects the vibration due to the influence from the front wheels, and then detects the vibration from the rear wheels. By combining this with information from another sensor (one whose characteristics are similarly adjusted) installed at a certain distance, the traveling speed V of the vehicle is calculated from the distance L between the sensors and the transit time difference (t2−t1). Can be calculated and found accurately.
[0031]
Further, since the vibration at the time of passing the front wheel and the rear wheel corresponds to one vehicle, the number of vehicles passing can be known by counting the vibration. Further, from the time difference between the front wheel and the rear wheel, the axle interval of the traveling vehicle is obtained, and the vehicle type group is estimated by comparing the group of the vehicle type having the close axle interval with the data stored in the database in advance, and It is also possible to estimate whether or not the vehicle is overloaded by comparing the allowable loading weight stored as a database of the vehicle type groups.
[0032]
Further, the amplitude W of the vibration varies depending on the weight of the vehicle. The amplitude when passing heavy vehicles is large, and the amplitude when passing light vehicles is small. The weight of the vehicle can be estimated from the magnitude of the amplitude. This estimated weight may deviate from the actual weight because the increase in force due to acceleration increases as the vehicle speed increases and its effect appears in the amplitude of the detected vibration, but if the vehicle speed is known, the speed can be determined. Since the error component of the estimated weight due to the acceleration can be corrected by using this, the reliability required in road management can be secured without any problem.
[0033]
FIG. 2 shows an example of the installation state of the vibration sensor. FIG. 2A shows a road having two lanes on each side. S in the figure is a vibration sensor embedded in the roadbed. The main body of the sensor S is housed and protected in a housing. In addition, in order to reliably detect vibrations when the vehicle is passing, metal rods are connected to both sides of the main body, and the entire length is substantially the same as the width of the lane, and is disposed so as to cross the lane. Here, two sensors are provided in each lane, that is, a total of four sensors, and numerals 1 to 4 are added to the reference numerals to distinguish the sensors. R is a signal transmission lead connected to each sensor, and CZ is a median strip on the road.
[0034]
As shown in FIG. 2B, the vibration sensors S1 to S4 are embedded not in the surface of the pavement road (dense-grain asphalt layer 1) but in the coarse-grain asphalt layer 2 thereunder. The reason is that the asphalt pavement surface is easily damaged by running of the vehicle, and is frequently repaired or repaired. At that time, there is a high possibility that the sensor is also dug up. In order to avoid this excavation, the vibration sensor S is embedded in the coarse-grained asphalt layer 2. Thereby, in the case of the repair in which the dense grain asphalt layer 1 is replaced, the sensor is not dug. In addition, in the case of renovation, it is impossible to say unconditionally because the extent to which the roadbed is damaged determines how much depth area to repair, but in this case the possibility of excavating the sensor is low, Even if there is excavation, the frequency decreases.
[0035]
Asphalt-paved roads include those with a fine-grained asphalt layer or dense-grained asphalt layer on a roadbed crusher run or slag, and those with a coarse-grained asphalt layer and a fine-grained asphalt layer stacked on a roadbed crusher run or slag. is there. The former has a thickness of the fine-grained asphalt layer or the dense-grained asphalt layer of 4 to 5 cm, and the latter has a thickness of the fine-grained asphalt layer of 5 cm. Therefore, the vibration sensor is arranged at a depth of 4 to 5 cm or more. Will be. In this case, in a sense, the buffer layer exists between the road surface and the sensor, and it becomes difficult for the vibration to be transmitted to the sensor. Even with this, a certain degree of sensitivity can be expected for heavy vehicles, but it becomes difficult to detect vibrations for light passenger vehicles and the like.
[0036]
The problem is that a sensor protection plate (vibration transmission plate) 3 is provided in the dense-grained asphalt layer 1 as shown in FIG. 2 (c). As shown in FIG. The problem can be solved by, for example, providing a step for use, or providing a vibration transmitting member 5 in the roadbed as shown in FIG.
[0037]
The purpose of the sensor protection plate (vibration transmission plate) 3 in FIG. 2 (c) is to suppress the attenuation of the vibration in the fine-grained asphalt and transmit a larger vibration to the sensor. This is expected to be effective. In this case, it is necessary to increase the strength of the asphalt in the thinned portion.
[0038]
The step in FIG. 3 is set to a height that does not hinder the running of the car, for example, 1 cm or less. In terms of image, it may be the same as the alerting unevenness provided at the sharp curve point of the road. The number of asperities for alerting is large, but the system of the present invention only needs to generate an impact once, so that only one step is required.
[0039]
The vibration transmitting member 5 in FIG. 4 is inevitably removed during repair, but when this is brought into contact with the sensor, the vibration is reliably transmitted to the sensor. If the vibration transmitting member 5 peels off from the asphalt and protrudes largely on the road surface, it hinders the running of the vehicle. Therefore, it is necessary to prevent the vehicle from falling out of the roadbed, and in order to meet the demand, a T-shaped metal plate capable of obtaining the anchoring effect is inverted and embedded in the roadbed.
[0040]
The vibration transmitting member 5 is configured to transmit vibration to the sensor without being restricted by the protective housing of the main body of the sensor. When integrated with a housing or the like, vibration is absorbed in the middle and becomes difficult to be transmitted, which is not preferable.
[0041]
The material of the vibration transmitting member 5 is not limited to metal, and may be formed of ceramics, resin, or the like. The shape only needs to be anchored to the roadbed so as not to protrude on the road surface. For example, it is possible to use an upright simple plate material as a vibration transmission member, attach a chain to the lower side of the plate material and embed it in the roadbed together with the plate material, but this is necessary when repairing and repairing the road surface Is likely to be removed, and the time and effort required for recovery will be greater than when a T-shaped member is used.
[0042]
Reference numeral 6 in FIG. 4 denotes a protective tape stuck on the road surface. The protective tape 6 also presses the vibration transmitting member 5 to prevent the vibration transmitting member 5 from jumping out onto the road surface. The protrusion of the vibration transmitting member 5 can be prevented by using only this tape, but it may be used in combination with the above-mentioned retaining measure in consideration of safety. As the protective tape 6, it is preferable to use a tape which has been used in a connection portion of a viaduct on a highway.
[0043]
The protective tape 6 has another utility. The flow of rainwater or the like to the interface between the vibration transmitting member 5 and the asphalt is suppressed, and the separation of the two and the damage to the road surface due to the separation are suppressed. In addition, a step is generated on a flat road to generate an impact for amplifying vibration when the vehicle passes.
[0044]
The vibration sensor S may be a conventional one, for example, a sensor using a strain gauge, a sensor that detects vibration using a change in resistance, a sensor that detects vibration using a change in capacitance, or the like. However, an optical vibration sensor that uses an optical fiber as a detector and detects vibration from transmission loss of light due to distortion, wavelength change of a reflected wave, or the like is particularly preferable. If this optical vibration sensor is used, detection can be performed even in a place where there is no power supply, and it is possible to avoid a situation in which measurement cannot be performed due to an obstacle to equipment due to a lightning strike or the like. Further, by connecting a vibration sensor in series to one optical fiber for signal transmission (the lead wire R in FIG. 2A corresponds thereto), a long distance section can be constructed by one system, and the system is simplified. In addition, cost reduction and reliability improvement can be achieved.
[0045]
【The invention's effect】
As described above, the road monitoring system according to the present invention can detect the number of vehicles passing, the traveling speed, and the vehicle weight with one kind of few sensors, which brings great benefits to the road manager.
[0046]
In particular, those using an optical sensor have a simple system, low construction cost, high reliability, and higher effects can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a detection situation by the system of the present invention; FIG. 2 (a) is a plan view showing a simplified installation situation of a vibration sensor; FIG. 1 (b) is a line AA in FIG. 2 (a); FIG. 3C is a cross-sectional view showing an example of installation of a sensor protection plate. FIG. 3 is a cross-sectional view showing an installation state of a step for amplifying vibration. FIG. 4 is a cross-sectional view showing an installation state of a vibration transmission member for improving sensitivity. Explanation of code]
S Vibration sensor R Lead wire 1 Fine-grained asphalt layer 2 Coarse-grained asphalt layer 3 Sensor protection plate 4 Convex portion 5 Vibration transmission member 6 Protective tape

Claims (11)

A road monitoring system that installs a vibration sensor in the roadbed, detects vibrations caused by vehicle traffic with the sensor, counts the number of detections, and obtains the number of vehicles passing. A plurality of vibration sensors are installed in the same lane on the road at a required interval in the traveling direction, and each sensor detects the vibration caused by the traffic of the vehicle, and calculates the speed of the passing vehicle from the detection time difference of the sensors at the intervals. Road monitoring system. A plurality of vibration sensors are installed at required intervals in the traveling direction in the roadbed in the same lane of the road, and each sensor detects vibration due to vehicle traffic, and determines the passing speed of the passing vehicle based on the detection time difference of the spaced sensors. A road monitoring system that estimates the weight of a passing vehicle based on the magnitude of the amplitude of the vibration detected and detected, and the passing speed. Based on the traveling speed obtained from a plurality of sensors laid in the roadbed in the same lane of the road and the time difference between the front wheel and the rear wheel detected by one sensor, the axle interval of the traveling vehicle is obtained, and a database of the interaxle distance of each vehicle group is obtained. Road surveillance system for estimating the vehicle type group from vehicle. As a database of the traveling speed obtained from a plurality of sensors laid in the roadbed in the same lane of the road, the vehicle weight estimated from the magnitude of the vibration amplitude detected by one of the sensors, and the vehicle group estimated from the inter-axle distance. A road monitoring system that estimates overload by comparing stored allowable load weights. The road monitoring system according to any one of claims 1 to 5, wherein an optical vibration sensor using an optical fiber as a detector is used as the vibration sensor. The road monitoring system according to any one of claims 1 to 6, wherein the vibration sensor is embedded in a coarse-grained asphalt layer under the dense-grained asphalt on the surface of the asphalt-paved road. The road monitoring device according to any one of claims 1 to 7, wherein the vibration sensor is configured by connecting metal rods to both sides of the detector, and the vibration sensor is arranged to have a length substantially equal to the lane width and to cross the lane. system. The road monitoring system according to any one of claims 1 to 8, wherein a step for vibrating a passing vehicle is formed on a road surface immediately near the vibration sensor installation point. The road monitoring system according to any one of claims 1 to 9, wherein a vibration transmitting member fixed to the roadbed is provided between the vibration sensor in the roadbed and the road surface, and the vibration transmitting member is brought into contact with the vibration sensor. The road surveillance according to any one of claims 1 to 10, wherein an upper end of the vibration transmitting member is arranged in the same plane as a road surface, and an exposed portion of the upper end of the vibration transmitting member with respect to the road surface is covered with a protective tape stuck on the road surface. system.

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