JPH09167296A - Method for measuring traffic flow parameter on road - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure traffic flow parameter on road at a low cost by processing an acoustic signal collected by means of microphones, comparing it with a previously stored database specifying a vehicle, measuring the traffic flow parameter and also enabling the judgement of a traffic state. SOLUTION: A road 1 is divided into plural areas 1-n and the microphones 3 are properly arranged along the lane of the respective areas 1-n. The acoustic signal from the respective microphones 3 are inputted to a processor 5 with an input means 4 and compared with the database 51. Moreover, relation and a phase are inspected so as to specify vehicle and the respective vehicles are tracked, etc., so that the various kinds of parameters are calculated. Time sequence characteristic and frequency characteristic, etc., are stored for every vehicle kind and every noise generating place (engine noise, wheel noise and whizing noise, etc.), for example, in the database 51. Then, the traffic flow parameter adding the number of the vehicles, speed and inter-vehicle distance is measured and also the judgement of the traffic state is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring traffic flow parameters on a road, which enables determination of traffic conditions by measuring traffic flow parameters including the number of vehicles traveling on a road, speed, and the like.

[0002]

2. Description of the Related Art Conventionally, there are the following methods for measuring a moving object. (1) By image processing. (2) Detection of aircraft by microphone. (3) Detection of railway vehicles by microphone.

[0003]

However, the method (1) described above has a problem that it is relatively expensive. Also,
Although the methods (2) and (3) are inexpensive, there is a problem in that they cannot be applied as they are to vehicles moving on a road. Therefore, an object of the present invention is to make it possible to measure traffic flow parameters on a road at low cost.

[0004]

In order to solve such a problem, the present invention divides a road into a plurality of areas, installs a plurality of microphones in each area, and processes acoustic signals collected by each microphone. Then, the vehicle is identified by comparing it with a database stored in advance, the traffic flow parameters including the number of vehicles, the speed, and the inter-vehicle distance are measured, and the traffic condition can be determined. By doing so, the traffic flow parameter can be measured easily and inexpensively.

[0005]

1 is a system configuration diagram showing an embodiment of the present invention. In the figure, 1 is a road, 2
Is a vehicle, 3 is a microphone as an acoustic signal collecting (sound collecting) means, 4 is input means including an A / D converter, and 5 is a processing device (traffic flow measuring device). That is, the road 1 is divided into a plurality of areas 1 to n, and the microphone 3 is appropriately installed along the lane of each area. The acoustic signal from each microphone 3 is input to the processing device 5 via the input means 4, and after comparing with the database 51, the vehicle is specified by further checking the correlation and the phase to track each vehicle. By doing so, various parameters are calculated. As the database 51, for example, time series characteristics, frequency characteristics, etc. are stored for each vehicle type and noise generation location (engine noise, tire noise, wind noise, etc.).

Next, various amounts (hereinafter, also referred to as traffic flow parameters) calculated based on the collected sounds from the microphones in the same area will be specifically described below.
FIG. 2 is an explanatory view therefor, in which a certain area is indicated by a one-dot diagonal line, and microphones are indicated by circles 3A to 3D. (I-1) Judgment of traveling lane (upper and lower lines) of passing vehicle: Collected sound data (sound volume) of two microphones on both sides, for example, 3A and 3C are compared with each other, and the lane with a larger sound is used as a vehicle. Determine that is running. (I-2) Discrimination of vehicle type (large vehicle, small vehicle) This is determined from the collected sound data (sound volume) of one microphone 3A or 3B in the lane on one side. For example,
If the loudness exceeds a certain level, it is a large vehicle, otherwise it is a small vehicle.

(I-3) Calculation of Traffic Volume Here, focusing on a certain microphone, the number of vehicles passing through one microphone per unit time (for example, one minute) is defined as the traffic volume. (I-4) Calculation of Congestion Degree Here, from the traffic volume calculated in (I-3) and the maximum value of the allowable number of vehicles in the area, the congestion degree = the traffic volume / the maximum value of the allowable number of vehicles in the area. Calculate as.

Tracking the same vehicle in the (I-5) area Correlation of acoustic data of two microphones in one lane, for example, 3A and 3B, and those having a high degree of correlation are determined to be the same vehicle. From this, it is possible to calculate the time taken for a vehicle to pass within the area. (I-6) Calculation of vehicle speed Here, two microphones in one lane, for example, 3
The distance between A and 3B is divided by the time required for the vehicle to pass through the area, and is calculated as the distance between the two microphones in one lane / the time required for the vehicle to pass through the area. (I-7) Calculation of Average Distance Between Vehicles Here, the average distance between vehicles is calculated according to the following equation. Average inter-vehicle distance = distance between two microphones in one lane / number of vehicles that passed a point B from the time when a vehicle passed the point A to the time when the vehicle passed a point B

As shown in FIG. 3, the microphones 3 are provided in a plurality of areas.
By installing A to 3L, the following traffic flow parameters can be collected. (II-1) Tracking a vehicle over a plurality of areas For example, the collected sound data in area 1 and area 2 in FIG. 3 are correlated, and if the value is a certain value or more, the correlation is high and the same across two areas. Judge as a vehicle. Less than,
By correlating the collected sound data in the areas 2 and 3, the areas 3 and 4, and the like, it becomes possible to track the vehicle over a plurality of areas, and as a result, the vehicle speed calculation and the vehicle trend in a wide section can be known. It becomes possible. (II-2) Section vehicle speed For example, the section vehicle speed can be calculated as follows: Section vehicle speed = Tracked section / Time required for section passage.

[0010]

According to the present invention, the following effects can be expected. (1) The installation cost can be reduced as compared with that for image processing. (2) By installing a plurality of microphones, the sound generation position can be known and the traffic flow can be measured. (3) By installing a microphone over a wide area, it becomes possible to grasp road conditions over a wide area. (4) By comparing the acoustic signal collected by the microphone with the data of the traveling vehicle sound stored in the database, the accuracy of the vehicle type determination is improved.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method of calculating traffic flow parameters.

FIG. 3 is an explanatory diagram of another method of calculating traffic flow parameters.

[Explanation of symbols]

1 ... Road, 2 ... Vehicle, 3, 3A-3L ... Microphone,
4 ... Input means, 5 ... Processing device (traffic flow measuring device), 51
… Database.

Front page continuation (72) Inventor Kenji Mochizuki 1st Fujimachi, Hino-shi, Tokyo Inside Fujifacom Control Co., Ltd. (72) Toshiharu Sasamoto 1st Tanabe Shinden, Kawasaki-ku, Kanagawa Prefecture Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. A road is divided into a plurality of areas, a plurality of microphones are installed in each of the areas, acoustic signals collected by the microphones are processed, and a vehicle is identified by comparing with a database stored in advance. A method for measuring traffic flow parameters on a road, which is capable of measuring traffic flow parameters including the number of vehicles, speed, and vehicle-to-vehicle distance and determining the traffic condition.