JPH0628595A - Traffic flow measurement method - Google Patents

Abstract

PURPOSE:To make a facility cost for installing a detection means, etc. cheaper by measuring a traffic flow by detecting a vibration propagated on the surface of a road through the traveling of a vehicle by means of a vibration sensor buried in the roadside band of the road. CONSTITUTION:Each traffic flow sensor 2 buried in the roadside band 1c is provided a pair of the vibration sensors 5 and 6 which are arranged at the prescribed intervals along traveling roads 1a and 1b and detect vibration propagated on the surface of the road 1, an amplitude/frequency measurement part 7 which observes the output signals of the respective vibration sensors 5 and 6 and determines useful vibration data, frequency data, etc., from vibration detected by the vibration sensors 5 and 6, and a data transmission part transmitting vibration data, frequency data, etc., obtained by the vibration/frequency measurement part 7 to CPU. Then, the traffic flow is measured by detecting vibration propagated through the surface of the road by the traveling of the vehicle by the respective vibration sensors 5 and 6. Consequently, inconvenience that vibration can not be measured unless the vehicle exist just on/under X the detection means is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traffic flow measuring method for measuring the number of vehicles and the traveling speed of vehicles traveling on a road.

[0002]

2. Description of the Related Art Up to now, a loop coil type or an ultrasonic reflection time type has been widely used as a traffic flow measuring method for measuring the number of vehicles traveling on a road and the traveling speed. ing.

Here, the loop coil type means that a loop coil is buried under the road surface on which a vehicle runs, and a change in an electric constant (inductance) when a vehicle passes over the loop coil is detected. , It is a method of detecting the vehicle that is running. In addition, the ultrasonic reflection time type means that an ultrasonic transmitter / receiver equipped with a transmitter that emits ultrasonic waves and a receiver that detects reflected ultrasonic waves is installed in the space above the roadway. The ultrasonic wave is emitted from the wave transmitter intermittently toward the road surface at a cycle of 20 to 50 ms, and the reflected wave is detected by the wave receiver. Is a method of detecting.

[0004]

However, in the case of the above-mentioned loop coil type, the inductance of the loop coil drifts due to weather conditions such as temperature and affects the sensing accuracy. Therefore, it is necessary to correct the variation of the inductance. Therefore, there is a problem that the processing of the detection result of the loop coil becomes complicated. Further, since the detecting means such as a loop coil is buried right under the traveling path of the vehicle, there is a problem that the impact during traveling of the vehicle is easily transmitted to the detecting means and the life of the detecting means depends on the strength of the road. .

On the other hand, in the case of the ultrasonic reflection time type, it is necessary to increase the directivity of the transmitter and the receiver in order to increase the detection sensitivity of the wave receiver. A motorcycle or the like having a narrow vehicle body may not be detected unless it passes under the ultrasonic transceiver.

Further, in any of the methods, there is a problem that the equipment becomes expensive because the detecting means must be equipped for each traveling lane. Further, in any of the methods, when the detecting means is installed, there is a problem. There is also a problem that it is not possible to install easily because it requires installation work that interrupts temporary traffic.

The present invention has been made in view of the above circumstances, the equipment is relatively inexpensive, the sensing accuracy of the detection means for sensing the vehicle is not affected by weather conditions such as temperature, and An object of the present invention is to provide a traffic flow measuring method that can easily install a detecting means without blocking traffic.

[0008]

A traffic flow measuring method according to the present invention detects a vibration propagating on a road surface by a vehicle traveling by a vibration sensor embedded in a roadside zone of the road,
The detection signal of this vibration sensor is analyzed, and the number of vehicles traveling on the road and the traveling speed are measured from the information such as the amplitude and frequency of the vibration propagating on the road surface.

[0009]

In the traffic flow measuring method according to the present invention, since the vibration propagating on the road surface due to the running of the vehicle is detected by the vibration sensor embedded in the road side zone of the road, the traffic flow is measured. Unlike the conventional loop coil type or ultrasonic wave reflection time type, there is no inconvenience that measurement cannot be performed unless there is a vehicle directly above or below the detection means. Therefore, even when measuring the traffic flow on a road with a plurality of lanes, there is no inconvenience that a detecting means is required for each lane, and the facility cost due to the installation of the detecting means can be reduced.

Further, there is no inconvenience that sensitivity correction is required according to weather conditions such as temperature as in the loop coil system, and management is easy. Furthermore, since the vibration sensor, which is the detection means, is buried in the roadside belt instead of the traveling road, there is an advantage that the detection means can be easily installed and repaired without blocking the traffic.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a traffic flow measurement for measuring the traveling speed, traveling direction, number of vehicles per unit time, etc. of a vehicle traveling on a road by an embodiment of a traffic flow measuring method according to the present invention. 1 shows a schematic configuration of an apparatus.

In FIG. 1, reference numeral 1 is a road for which traffic flow is to be measured, 2 is a traffic flow detector embedded in one of the roadside zones of the road 1, and A to D are vehicles running on the road 1. Is.

The road 1 has one lane each for up and down lanes, reference numeral 1a is a traveling road as an up lane, 1b is a traveling lane as a down lane, and 1c is a roadside band on the down lane side, The arrows (a) and (b) shown in each traveling route indicate the traveling direction of the vehicle.

A traffic flow measuring apparatus for measuring the traveling speed, traveling direction, number of vehicles traveling per unit time, etc. by the traffic flow measuring method of one embodiment of the present invention is a roadside belt at predetermined intervals along a traveling road. The traffic flow detection units 2 embedded in 1c, and the information obtained by each traffic flow detection unit 2 is processed to travel speed, traveling direction, number of vehicles per unit time, type of vehicle (large vehicle or small vehicle). Central processing unit (not shown)
The central processing unit is installed in a remote management facility.

As shown in the figure, each traffic flow detecting section 2 is provided with a pair of vibration sensors 5 and 6 which are arranged at a predetermined interval along the traveling road and detect vibration propagating on the road surface of the road 1. Amplitude / frequency measuring unit 7 that obtains useful amplitude data and frequency data from the vibration detected by vibration sensors 5 and 6 by observing the output signals of vibration sensors 5 and 6, and the amplitude / frequency measuring unit 7 obtained A data transmission section 8 for transmitting amplitude data, frequency data and the like to the central processing unit.

Here, the pair of vibration sensors 5 and 6 are
All of them are vibration sensors made of PTZ piezoelectric material, and when a vibration (that is, mechanical displacement) is received, a voltage waveform corresponding to the magnitude and frequency of the vibration is output, and conversely, when a voltage is applied, the voltage waveform is outputted. The mechanical displacement (vibration) is generated. In the case of this embodiment, the vibration sensors 5 and 6 are embedded in the ground of the roadside belt 1c at intervals of 1 m along the lengthwise direction of the traveling road (the traveling direction of the vehicle).

FIG. 2A shows an example of the voltage waveform output from the vibration sensor 5, and FIG. 2B shows an example of the voltage waveform output from the vibration sensor 6. In the voltage waveforms shown in FIGS. 2A and 2B, the vertical axis represents voltage V and the horizontal axis represents time t. Further, in FIGS. 2A and 2B, reference numeral I1 indicates a voltage waveform for traveling of a small vehicle such as a passenger vehicle, and reference numeral I2 indicates a voltage waveform for traveling of a large vehicle such as a truck. Generally, the voltage waveform of a small vehicle having a small weight has a high frequency, a small amplitude, and a short duration. In addition, the voltage waveform of a large heavy vehicle has a low frequency, a large amplitude, and a long duration.

Next, how to determine the traveling speed of the vehicle, the traveling direction, the number of vehicles traveling per unit time, the type of large and small vehicles, etc. from the voltage waveform shown in FIG. 2 will be described.

Consider a case where the vehicle A shown in FIG. 1 passes in front of a pair of vibration sensors 5 and 6 embedded in a roadside belt at an interval of 1 m. The vibration generated by the traveling of the vehicle A is first detected by the vibration sensor 5 located in front of the vehicle, then sent for a time required for propagation of 1 m which is the distance between the sensors, and the position is rearward. The vibration sensor 6 detects it. Therefore, by comparing the timings at which the respective vibration sensors 5 and 6 detect the same waveform, it is judged which one is detected first, and whether the strength of the detection signal is increasing or decreasing with the passage of time. By determining, it is possible to determine whether the vehicle A is currently approaching or moving away from the traveling direction.
For example, when the waveform I1 in FIG. 2A and the waveform I1 in FIG. 2B are for the same vehicle, a voltage value equal to or higher than a predetermined threshold value (voltage value v) on each waveform is According to the context of the observed time points t1 and t2,
It can be determined that the vehicle is running from the vibration sensor 5 side to the vibration sensor 6 side.

Further, when the observation of the output signal of one of the vibration sensors 5 is continued at the time when it is determined that the vehicle A is approaching from the vibration sensor 5 side, before and after the vehicle A passes in front of the vibration sensor 5, Then, as shown in FIG. 2A, the frequency changes from f1 to f2. This is due to the Doppler effect, where the frequency f1 before passing is high and the frequency f2 after passing is low. By measuring the frequencies f1 and f2 before and after passing in front of the vibration sensor, the speed S of the vehicle can be calculated by the following equation (1).

S = a (f1−f2) / (f1 + f2) (1) where a: sound velocity of medium (underground here) f1: observation frequency when approaching f2: observation frequency when moving away It should be noted that the vibration sensors 5 and 6 are connected to the traveling path 1a on the opposite side.
Vibrations from a vehicle traveling on the road also propagate. For example, the vibrations of the vehicle C shown in FIG.
Is detected by the vehicle C, as in the case of the vehicle A described above.
It is possible to determine that the vehicle C is approaching from the vibration sensor 6 side by determining which vibration sensor first detects the voltage waveform corresponding to the vibration. In this case, the speed of the vehicle C can be obtained by continuing to observe the output signal of the vibration sensor 6 and measuring the frequencies before and after the vehicle C passes in front of the vibration sensor 6. Become. That is, it is possible to measure the traffic flow on a plurality of lanes having different traveling directions by using only the pair of vibration sensors 5 and 6 provided in one traffic flow detection unit 2. The waveform I2 in FIG. 2 is for a vehicle C traveling on the traveling path 1a.

Further, the number of running vehicles per unit time can be obtained by counting the number of times the above-mentioned Doppler effect occurs, and the type of vehicle (discrimination between large vehicle and small vehicle) is determined by the vibration sensor 5, It is possible to make a determination by measuring the maximum value of the amplitude on the voltage waveform output by 6 (that is, the peak voltage Vmax).

Next, a traffic flow measuring method according to an embodiment of the present invention will be described. When a vehicle travels on the road 1, vibrations according to the weight and traveling speed of the vehicle propagate on the road surface of the road 1.
Vibration propagating on the road surface (under the surface) of the road 1 is detected by the vibration sensors 5 and 6, and the amplitude / frequency measuring unit 7 is detected.
Send to.

The amplitude / frequency measuring section 7 outputs a clock signal to monitor the output signals (voltage waveforms) of the vibration sensors 5 and 6, and the threshold value (voltage value v) or more is determined. Amplitude data in a range in which the amplitude (voltage value) is equal to or higher than the threshold value v, when the signal is observed (for example, t1 in FIG. 2A, t2 in FIG. 2B) is a measurement start point of useful data. And frequency data are detected as useful data. Naturally, this useful various data includes the peak voltage value (Vmax) necessary for distinguishing the size of the vehicle and the frequencies (f1, f before and after passing through the sensor).
2) etc. are included.

Then, the data transmission unit 8 transmits the amplitude and frequency data obtained as useful data by the amplitude / frequency measurement unit 7 to a central processing unit (not shown).

In a central processing unit (not shown), useful amplitude data and frequency data sent from the data transmission unit 8 are analyzed, and frequencies (f1, f2) before and after passing through the sensor are analyzed.
From the above, the traveling speed S of the vehicle is calculated based on the above equation (1), and the traveling direction is calculated from the sensing timing of useful data in the vibration sensors 5 and 6, and the traveling time per unit time is calculated from the number of occurrences of Doppler effect The number of vehicles is calculated, and the size of the traveling vehicle is calculated from the peak voltage value.

In the traffic flow measuring method of one embodiment described in detail above, the vibrations propagated on the road surface by the traveling of the vehicle are detected by the vibration sensors 5 and 6 embedded in the roadside zone of the road to detect the traffic flow. Therefore, there is no inconvenience that the measurement cannot be performed unless there is a vehicle directly above or below the detecting means unlike the conventional loop coil type and ultrasonic reflection time type. Therefore, even when measuring the traffic flow on a road with a plurality of lanes, there is no inconvenience that a detecting means is required for each lane, and the facility cost due to the installation of the detecting means can be reduced.

Further, there is no inconvenience that sensitivity correction is required according to weather conditions such as temperature as in the loop coil type, and management is easy. Further, since the vibration sensor as the detection means is buried in the roadside zone, there is an advantage that the detection means can be easily installed and repaired without blocking the traffic.

In the above-described embodiment, the traffic flow detectors 2 are provided along the road at appropriate intervals, but this is to accurately measure the traffic flow over a long section. It is obvious that the number of traffic flow sensing units 2 may be one as long as it only measures the traffic flow in a short section.

In addition, in the above-described embodiment, a pair of vibration sensors is provided for one traffic flow detection unit 2, but this can detect traffic flow on a plurality of roads having different traveling directions. Considering the measurement with one traffic flow sensing unit 2, if the traffic flow is measured on a one-way road, etc.,
It is also possible that one vibration sensor is enough.

Further, in the above-described embodiment, the interval between the pair of vibration sensors 5 and 6 is set to 1 m, but it is not necessary to limit to the value of the embodiment as long as the difference in arrival time of vibration can be measured.

[0032]

As is clear from the above description, in the traffic flow measuring method according to the present invention, the vibration propagating on the road surface due to the traveling of the vehicle is detected by the vibration sensor embedded in the roadside zone of the road. Since the traffic flow is measured by the method, there is no inconvenience that the measurement cannot be performed unless there is a vehicle directly above or below the detection means as in the conventional loop coil type and ultrasonic reflection time type. Therefore, even when measuring the traffic flow on a road with a plurality of lanes, there is no inconvenience that a detecting means is required for each lane, and the facility cost due to the installation of the detecting means can be reduced.

Further, there is no inconvenience that sensitivity correction is required according to weather conditions such as temperature as in the loop coil system, and management is easy. Furthermore, since the vibration sensor, which is the detection means, is buried in the roadside belt instead of the traveling road, there is an advantage that the detection means can be easily installed and repaired without blocking the traffic.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a traffic flow measuring method of the present invention.

FIG. 2 is an explanatory diagram of a measurement principle in one embodiment of the present invention.

[Explanation of symbols]

 1 Road 1a, 1b Traveling road 2 Traffic flow detection unit A, B, C, D Vehicle 5,6 Vibration sensor 7 Amplitude / frequency measurement unit 8 Data transmission unit

Claims (1)

[Claims] 1. A traffic flow measuring method for measuring the number of vehicles and the traveling speed of a vehicle traveling on a road, wherein vibration propagating on a road surface due to traveling of the vehicle is buried in a roadside zone of the road. It is characterized by detecting with a vibration sensor, analyzing the detection signal of this vibration sensor, and obtaining the number of vehicles traveling on the road and the traveling speed from information such as the amplitude and frequency of the vibration propagating on the road surface. Traffic flow measurement method.