Traffic signal control device

Abstract

To provide a traffic signal control device capable of appropriately setting a display time of a right turn arrow or a left turn arrow in response to a traffic state of a right turn destination or a left turn destination.SOLUTION: In a signal control machine 1A, a communication section 2A acquires a traffic state of a right turn destination of an intersection 10, and a control section 3A changes a display period of right turn arrows 11a, 13a corresponding to the right turn destination of traffic lights 11, 13 installed at the intersection 10 based on the acquired traffic state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a traffic signal control device that controls traffic signals installed at intersections. [Background technology]

[0002] In the past, traffic lights installed at intersections in road networks only displayed a fixed time for the right-turn arrow, which meant that if a large number of vehicles waited to turn right, traffic congestion could occur at the intersection. To prevent this, some traffic lights controlled the time the right-turn arrow was displayed based on the volume of traffic entering the intersection.

[0003] For example, Patent Document 1 describes a method in which a camera sets an area within an intersection where vehicles waiting to turn right are stopped as a right-turn vehicle detection area, photographs each area with the camera, and detects the number of vehicles waiting to turn right with a right-turn vehicle detection device.Then, the signal control device temporarily changes signal control parameters according to the number of vehicles waiting to turn right, thereby extending or shortening the display time of the right-turn arrow and the yellow and red signal lights. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-251910 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the invention described in Patent Document 1 determines the display time of the right-turn arrow depending on the situation at the current intersection, so even if the road where the vehicle is turning right is congested, the display time of the right-turn arrow may be extended if there are many vehicles in the right-turn lane. This may actually worsen the congestion not only at the current intersection but also on the road where the vehicle is turning right.

[0006] Therefore, an object of the present invention is to provide a traffic signal control device that can appropriately set the display time of a right turn arrow or a left turn arrow depending on the traffic conditions at the destination of the right turn or left turn. [Means for solving the problem]

[0007] The invention described in claim 1, which was made to solve the above problem, is Turning in the first direction (right or left) Occasionally a vehicle detector that detects a vehicle waiting for a vehicle; and a signal generator that generates a signal based on the detection result of the vehicle detector. Unit No. 1st direction Corresponding to Arrow The period for which the mark is displayed Has a sensory control function that shortens or extends the reference time a control unit; a traffic signal control device for detecting a traffic condition at a turn destination, the traffic signal control device comprising: an acquisition unit for acquiring a traffic condition at a turn destination; and a determination unit for determining the degree of congestion at the turn destination as none, light, or heavy based on the traffic condition and a predetermined criterion, wherein the control unit performs the sensitive control when there is no congestion, performs only a shortening control of the sensitive control when the congestion is light, and does not perform the sensitive control when the congestion is heavy, and forcibly shortens the display period to the shortest time. The traffic signal control device is characterized by the above. [Effects of the Invention]

[0008] According to the present invention, the display period of the right turn arrow corresponding to the right turn destination or the left turn arrow corresponding to the left turn destination on a traffic light installed at an intersection is changed based on the traffic conditions at the right turn destination or the left turn destination at the intersection, so that the display period of the right turn arrow or the left turn arrow can be appropriately set according to the traffic conditions at the right turn destination or the left turn destination. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a traffic signal control system having a traffic signal control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a functional block diagram of the signal control device shown in FIG. [Figure 3] 2 is a flowchart of the operation of one of the signal control devices shown in FIG. 1. [Figure 4] 2 is a flowchart of the operation of the other signal control device shown in FIG. 1. [Figure 5] FIG. [Figure 6] 10 is a table showing display control of a right turn arrow. [Figure 7] FIG. 2 is a schematic configuration diagram of a traffic signal control system according to a modified example of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to Figures 1 to 6. Figure 1 is a schematic diagram of a traffic signal control system having a traffic signal control device according to an embodiment of the present invention.

[0011] The traffic signal control system includes traffic lights (vehicle traffic lights) 11, 12, 13, and 14 installed at intersection 10, traffic lights 21, 22, 23, and 24 installed at intersection 20, a traffic light controller 1A that controls the traffic lights installed at intersection 10, a traffic light controller 1B that controls the traffic lights installed at intersection 20, a vehicle detector 5A that detects vehicles traveling in the right-turn lane of road 30 at intersection 10, and a vehicle detector 5B that detects vehicles traveling on road 40 from intersection 10 and entering intersection 20.

[0012] The road network shown in FIG. 1 includes intersections 10 and 20. At intersection 10, roads 30 and 40 intersect. At intersection 20, roads 40 and 50 intersect. At intersection 10, road 30 has a right-turn lane, and corresponding traffic lights 11 and 13 have right-turn arrows (blue arrow lights) 11a and 13a. In FIG. 1, when a vehicle traveling on road 30 from the direction of arrow A turns right at intersection 10 according to right-turn arrow 11a, it enters road 40 and passes through intersection 20 (adjacent intersection) where it will turn right.

[0013] 2 shows a functional block diagram of the signal controllers 1A and 1B. The signal controller 1A includes a communication unit 2A, a control unit 3A, and a sensor connection unit 4A.

[0014] The communication unit 2A communicates with external devices. In this embodiment, it communicates with the signal controller 1B to receive traffic conditions at the intersection 20 where a right turn is to be made. In this embodiment, the traffic conditions received are information about the degree of congestion based on vehicles detected by the vehicle detector 5B. The communication method with the signal controller 1B may be either wired communication or wireless communication. In other words, the communication unit 2A functions as an acquisition unit that acquires traffic conditions at the intersection where a right turn or a left turn is to be made.

[0015] The control unit 3A controls the traffic lights installed at the intersection 10. The control unit 3A changes the display times of the green, red, yellow, and other signal lights of the traffic lights 11, 12, 13, and 14 at the intersection 10 based on information about the degree of congestion received by the communication unit 2A and the results of detection by the vehicle detector 5A obtained by the detector connection unit 4A. In this embodiment, the control unit 3A changes the display times of the right-turn arrows 11a and 13a, particularly through control that will be described later. Details of the operation control of the right-turn arrows 11a and 13a by the control unit 3A will be described later.

[0016] The detector connection unit 4A is an interface circuit or the like to which the vehicle detector 5A is connected, and outputs the result of the vehicle detector 5A detecting a vehicle (presence or absence of a vehicle) to the control unit 3A.

[0017] As described above, the vehicle detector 5A is installed near the right-turn lane of the road 30 and detects vehicles traveling in the right-turn lane. The vehicle detector 5A (5B) may be of any type, such as an image type that detects vehicles by processing images taken by a CCD (Charge Coupled Device) camera, an ultrasonic type that detects vehicles using an ultrasonic sensor, or an optical type that detects vehicles using an optical sensor.

[0018] The signal controller 1B includes a communication unit 2B, a control unit 3B, and a sensor connection unit 4B.

[0019] The communication unit 2B transmits the above-mentioned information relating to the degree of congestion to the signal controller 1A.

[0020] The control unit 3B controls the traffic lights installed at the intersection 20. The control unit 3B generates information regarding the degree of congestion based on the results of detection by the vehicle detector 5B acquired by the detector connection unit 4B, and causes the communication unit 2B to transmit the information.

[0021] The detector connection unit 4B is an interface circuit or the like to which the vehicle detector 5B is connected, and outputs the result of the vehicle detector 5B detecting a vehicle (presence or absence of a vehicle) to the control unit 3B.

[0022] Next, the operation of the signal controllers 1A and 1B configured as described above will be described with reference to the flowcharts of Figures 3 and 4. Figure 3 is a flowchart of the operation of the signal controller 1B. The flowchart shown in Figure 3 is executed by the control unit 3B.

[0023] First, the control unit 3B calculates the occupancy rate (step S11). The occupancy rate (vehicle occupancy rate) is a value that indicates the proportion of time that vehicles pass through an intersection while the light is green. In FIG. 1, the occupancy rate at intersection 20, which is the intersection to turn right from, is calculated based on the number of vehicles detected by vehicle detector 5B while traffic lights 22 and 24 are green. Note that calculation of the occupancy rate generally requires the length and passing speed of passing vehicles, but the length may be the average vehicle length, and the passing speed may be the speed limit of the road.

[0024] FIG. 5 shows an example of a graph of changes in occupancy rate. In FIG. 5, the vertical axis represents occupancy rate, and the horizontal axis represents time. As shown in FIG. 5, in this embodiment, two thresholds are set for occupancy rate: heavy congestion and light congestion. In other words, when the occupancy rate is equal to or greater than the threshold for heavy congestion, it is considered to be heavy congestion, and when the occupancy rate is equal to or greater than the threshold for light congestion but less than the threshold for heavy congestion, it is considered to be light congestion. In this embodiment, as long as the relationship between heavy congestion and light congestion is satisfied, the numerical values ​​of the occupancy rates that serve as the respective thresholds are set appropriately according to the characteristics of each intersection.

[0025] Furthermore, even if the occupancy rate has not actually reached the threshold, if it is predicted that the threshold will be exceeded based on changes in the occupancy rate, information regarding the degree of congestion, such as congestion (severe) or congestion (light), may be transmitted.

[0026] Returning to the explanation of Figure 3, the control unit 3B next determines whether the occupancy rate calculated in step S11 is equal to or greater than the congestion (light) level (step S12). That is, it determines whether the occupancy rate calculated in step S11 is equal to or greater than the threshold value for congestion (light) shown in Figure 5. If the occupancy rate is not equal to or greater than the congestion (light) level (step S12; NO), the control unit 3B does not notify the traffic situation to the signal controller 1A (step S13). In other words, since no congestion has occurred at the intersection 20, information regarding the level of congestion is not transmitted to the signal controller 1A.

[0027] If the occupancy rate is equal to or greater than the congestion (light) level (step S12; YES), the control unit 3B determines whether the occupancy rate calculated in step S11 is equal to or greater than the congestion (heavy) level (step S14). That is, it determines whether the occupancy rate calculated in step S11 is equal to or greater than the congestion (heavy) threshold level shown in FIG. 5. If the occupancy rate is not equal to or greater than the congestion (heavy) level (step S14; NO), the control unit 3B notifies the traffic signal controller 1A that the traffic situation is congestion (light) (step S15). That is, since a light congestion is occurring at the intersection 20, information regarding the level of congestion is transmitted to the signal controller 1A.

[0028] If the occupancy rate is equal to or greater than the congestion (severe) level (step S14; YES), the control unit 3B notifies the traffic signal controller 1A that the traffic situation is congestion (severe) (step S16). In other words, since a severe congestion is occurring at the intersection 20, information regarding the degree of congestion is transmitted to the signal controller 1A.

[0029] From the above explanation, it is clear that the information regarding the degree of congestion is information based on the traffic volume at the adjacent intersection where the vehicle is to turn right.

[0030] Fig. 4 is a flowchart of the operation of the signal controller 1A. The flowchart shown in Fig. 4 is executed by the control unit 3A.

[0031] First, the control unit 3A determines whether or not it has received traffic conditions from the right-turn intersection 20 (step S21). In this embodiment, as described above, it determines whether or not it has received information on the degree of congestion, either light congestion or heavy congestion.

[0032] Next, as a result of the determination in step S21, if the traffic situation has been received from the intersection 20 to turn right (step S21; YES), the control unit 3A determines the received traffic situation of the intersection 20 to turn right (step S22).

[0033] If the result of determination in step S22 is that the traffic situation at the intersection 20 where the right turn is made is heavy congestion, the control unit 3A forcibly shortens the display period of the right turn arrows 11a and 13a (step S23). The forcible shortening operation is to shorten the display period of the right turn arrows 11a and 13a to the shortest period (time) within the range set as the display period of the right turn arrows 11a and 13a, regardless of the detection result of the vehicle detector 5A.

[0034] Furthermore, if the result of determination in step S22 is that the traffic situation at the intersection 20 where the right turn is made is congestion (light), the control unit 3A performs right-turn sensitive control for only shortening the time (step S24). Right-turn sensitive control for only shortening the time means that the display period of the right-turn arrows 11a, 13a is only allowed to be shortened. In step S24, unlike step S23, the display period of the right-turn arrows 11a, 13a is not forcibly shortened regardless of the detection result of the vehicle detector 5A, but rather the shortening operation is allowed based on the detection result of the vehicle detector 5A.

[0035] For example, if there are few (or no) vehicles traveling in the right-turn lane detected by the vehicle detector 5A, the display period of the right-turn arrows 11a and 13a may be shortened, but otherwise the initially set period (default period) is used. However, even if there are many vehicles traveling in the right-turn lane, the display period of the right-turn arrows 11a and 13a cannot be extended.

[0036] On the other hand, if the result of the determination in step S21 is that no traffic conditions are received from the intersection 20 at the right turn destination (step S21; NO), the control unit 3A performs right-turn sensitive control, assuming that there is no congestion at the right turn destination (step S25). The right-turn sensitive control in step S25 is a known control method that shortens or extends the display period of the right-turn arrows 11a, 13a based on the vehicle traveling in the right-turn lane detected by the vehicle detector 5A.

[0037] Figure 6 summarizes the display control of the right-turn arrows 11a and 13a in the traffic light controller 1A. As shown in Figure 6, when there is no traffic congestion, the right-turn arrow display can be extended or shortened. When there is light traffic congestion, only shortening operation is performed for right-turn movement. In other words, extension operation is not possible, and only shortening operation is possible. When there is heavy traffic congestion, forced shortening operation is performed. In other words, the arrow advances in the shortest number of seconds.

[0038] In the case of heavy congestion, the right turn arrows 11a and 13a may not be displayed (display period = 0 seconds) without being limited to the shortest number of seconds. Alternatively, two thresholds for heavy congestion may be set, one for the shortest number of seconds and one for no display, and judgment may be made based on each of them.

[0039] In addition, multiple thresholds may be set for the congestion (light). In other words, the thresholds are not limited to two, congestion (heavy) and congestion (light). Thresholds may be set by further subdividing each congestion level. For example, congestion (medium) may be set between congestion (heavy) and congestion (light). If this congestion (medium) is set as a threshold that allows the display period to be shortened based on the detection results of the vehicle detector, it becomes a variation of light congestion, and if it is set as a threshold that forcibly shortens the display period, it becomes a variation of heavy congestion.

[0040] According to this embodiment, the traffic light controller 1A has a communication unit 2A that acquires the traffic conditions at the right turn destination at the intersection 10, and a control unit 3A that changes the display period of the right turn arrows 11a, 13a corresponding to the right turn destination at the traffic lights 11, 13 installed at the intersection 10 based on the acquired traffic conditions.

[0041] By configuring the traffic signal controller 1A as described above, it is possible to prevent unnecessary display of the right-turn arrows 11a and 13a when there is congestion at the right-turn destination. Therefore, the display time of the right-turn arrows 11a and 13a can be appropriately set according to the traffic conditions at the right-turn destination.

[0042] In addition, the traffic conditions are information about the degree of congestion based on the traffic volume at the adjacent intersection 20 where the vehicle turns right, so the traffic conditions at the intersection 10 where the vehicle turns right can be determined from the traffic volume at the adjacent intersection 20 where the vehicle turns right from the intersection 10 that is the target of control.

[0043] The intersection is also equipped with a vehicle detector 5A that detects vehicles traveling in the right-turn lane, and the communication unit 2A acquires information about the degree of congestion. If the information about the degree of congestion indicates a light congestion, the control unit 3A can shorten the display period of the right-turn arrows 11a, 13a based on the detection results of the vehicle detector 5A. By doing so, if there is a slight congestion at the right-turn destination, the number of vehicles that turn right can be reduced. Furthermore, even if there are many vehicles traveling in the right-turn lane, the right-turn arrows 11a, 13a are not extended, so the congestion at the right-turn destination can be prevented from worsening.

[0044] Furthermore, the communication unit 2A acquires information regarding the degree of congestion, and if the information regarding the degree of congestion indicates severe congestion, the control unit 3A forcibly shortens the display period of the right-turn arrows 11a, 13a. By doing so, if the destination is heavily congested, the number of vehicles making a right turn can be reduced. Furthermore, since the display period is forcibly shortened regardless of the number of vehicles traveling in the right-turn lane, it is possible to further prevent the congestion at the destination from worsening.

[0045] Furthermore, since the information regarding the degree of congestion is generated based on the occupancy rate of the adjacent intersection 20, it can be easily calculated and determined if a device for detecting vehicle movement, such as a vehicle detector 5B, is installed at the adjacent intersection 20. Furthermore, since the information regarding the degree of congestion is generated based on a threshold set for the occupancy rate of the adjacent intersection 20, it is possible to easily generate information regarding the degree of congestion by setting a threshold according to the degree of congestion, such as heavy congestion or light congestion.

[0046] In the above-described traffic signal control system, the signal controller 1A and the signal controller 1B communicate directly with each other, but this is not limiting. For example, as shown in Fig. 7, a central unit 100 may be provided, and the signal controllers 1A and 1B may transmit and receive traffic information via the central unit 100. The central unit 100 is installed in, for example, a traffic control center, and acquires the number and occupancy rate of vehicles detected by vehicle detectors 5A, 5B, etc. at each intersection within a control area, accumulates and statistically processes this information, and performs tasks such as monitoring traffic conditions within the target area and adjusting traffic light cycles at each intersection.

[0047] Although the signal controller 1A receives information about the degree of congestion as the traffic condition, it may also acquire an occupancy rate. Then, information about the degree of congestion may be generated and determined within the signal controller 1A based on the occupancy rate. Furthermore, in the configuration of FIG. 7, the occupancy rate may be calculated by the central unit 100, and the central unit 100 may transmit the calculated occupancy rate directly or may generate information about the degree of congestion and transmit it to the signal controller 1A.

[0048] Furthermore, in the above-described embodiment, information regarding the degree of congestion from the adjacent intersection 20 where the vehicle is to make a right turn is acquired as the traffic conditions at the intersection where the vehicle is to make a right turn. However, this is not limiting. For example, the number of vehicles exiting onto the road 40 in the direction of the intersection 20 may be estimated based on the detection results of the vehicle detector 5A installed at the current intersection 10 and vehicle detectors installed on other lanes and intersecting roads 40. The traffic conditions at the intersection where the vehicle is to make a right turn may then be estimated based on the estimated number of vehicles. In this case, the traffic conditions may be estimated based on statistical information such as the relationship between the past number of vehicles exiting onto the road 40 and congestion. In other words, the traffic conditions may be estimated based on the traffic volume heading from the intersection in the direction where the vehicle is to make a right turn.

[0049] Furthermore, although the above-described embodiment has been described with respect to right-turn arrows, similar control can be performed for left-turn arrows as well, thereby making it possible to prevent unnecessary left-turn arrow displays when there is congestion at the left-turn destination. Therefore, the display time of the left-turn arrow can be appropriately set according to the traffic conditions at the left-turn destination.

[0050] Furthermore, probe information may be used to estimate the traffic conditions at the destination of a right or left turn. For example, it may be possible to estimate whether the traffic conditions at the destination of a right or left turn are congested based on information obtained through road-to-vehicle communication or vehicle-to-vehicle communication.

[0051] The present invention is not limited to the above-described embodiment. In other words, a person skilled in the art can implement various modifications in accordance with conventional knowledge without departing from the gist of the present invention. As long as such modifications still comprise the configuration of the traffic signal control device of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0052] 1A Signal controller (traffic signal control device) 2A Communication Department (Acquisition Department) 3A Control Unit 5A Vehicle detector 11a Right turn arrow 13a Right turn arrow

Claims

1. A traffic signal control device comprising: a vehicle detector that detects a vehicle waiting to turn in a first direction (right or left) at an intersection; and a control unit having a response control function that shortens or extends a display period of an arrow corresponding to the first direction of a traffic signal from a reference time based on a detection result of the vehicle detector, an acquisition unit that acquires traffic conditions at the turn destination; a determination unit that determines the degree of congestion at the turn destination as none, light, or heavy based on the traffic conditions and a predetermined standard; The control unit When the degree of congestion is not present, the adaptive control is performed. When the degree of the traffic congestion is light, only the shortening control of the sensitive control is performed, A traffic signal control device characterized in that, when the degree of congestion is severe, the sensitive control is not performed and the display period is forcibly shortened to the shortest time.

2. The traffic signal control device according to claim 1, characterized in that the traffic conditions are information based on the traffic volume at an adjacent intersection to which the vehicle turns right when the arrow corresponding to the first direction is a right-turn arrow, and information based on the traffic volume at an adjacent intersection to which the vehicle turns left when the arrow corresponding to the first direction is a left-turn arrow.

3. The traffic signal control device described in claim 1, characterized in that the traffic conditions are estimated based on the traffic volume heading in the direction of a right turn from the intersection when the arrow corresponding to the first direction is a right turn arrow, and are estimated based on the traffic volume heading in the direction of a left turn from the intersection when the arrow corresponding to the first direction is a left turn arrow.

4. The traffic signal control device according to claim 1, characterized in that the traffic conditions are the vehicle occupancy rate at an adjacent intersection to which a right turn is made when the arrow corresponding to the first direction is a right turn arrow, and the vehicle occupancy rate at an adjacent intersection to which a left turn is made when the arrow corresponding to the first direction is a left turn arrow.

5. The traffic signal control device according to claim 4, wherein the predetermined standard is a threshold value set for the vehicle occupancy rate.

Images