Patent Publication Number: US-2022223034-A1

Title: Traffic light management system and traffic light management method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-003706 filed on Jan. 13, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a system and a method for managing the display of traffic lights. 
     2. Description of Related Art 
     Japanese Unexamined Patent Application Publication No. 2019-87076 (JP 2019-87076 A) discloses a system that includes a plurality of vehicles traveling in a platoon and a server communicating with these vehicles individually. The server of this conventional system detects an abnormal vehicle among the plurality of vehicles based on the behavior information on each vehicle. An abnormal vehicle is detected based on the statistical processing for the behavior information. When an abnormal vehicle is detected, the server identifies the abnormal part based on the behavior information on the abnormal vehicle received from a normal vehicle traveling in front of or behind the abnormal vehicle. An abnormal part may also be identified using V2V between the abnormal vehicle and the normal vehicle. When the abnormal part is identified, the server provides the information on the abnormal part to the abnormal vehicle or the normal vehicles. 
     SUMMARY 
     However, in the conventional system described above, the information on an abnormal part is provided only to a limited range. Therefore, even when the abnormality is such that it may lead to abnormal traveling, there is no way for the vehicles and pedestrians around the platooning vehicles to know the occurrence of the abnormality. For this reason, when an accident occurs due to abnormal traveling, there is a possibility that surrounding vehicles, pedestrians, etc. may be involved in the accident. 
     In view of the foregoing, the present disclosure provides a technique that minimizes the effect of an accident that may be caused by abnormal traveling even if an abnormality occurs and a vehicle starts traveling abnormally due to the occurrence of the abnormality. 
     A first disclosure is a traffic light management system that manages the display of traffic lights. The first disclosure has the following features. The traffic light management system includes a communication device, a control device, and a map database. The communication device is configured to communicate with the traffic lights and to communicate with a communication vehicle having the communication function. The control device is configured to control the display based on information received from the communication vehicle. The map database is configured to store map information. The control device is configured to perform emergency control of the display when abnormal traveling information indicating information on an abnormally traveling vehicle is included in the information received from the communication vehicle. In the emergency control, the control device is configured to predict a future trajectory of the abnormally traveling vehicle based on the abnormal traveling information, to generate an emergency control signal for temporarily prohibiting passage at an intersection and a crosswalk on a road along the future trajectory based on the map information and the future trajectory, and to send the emergency control signal to controlled traffic lights each indicating a traffic light at the intersection and the crosswalk. 
     A second disclosure according to the first disclosure may further have the following features. The communication vehicle may include an acquisition device, a processing device, and an in-vehicle communication device. The acquisition device may be configured to acquire driving environment information on the communication vehicle. The processing device may be configured to perform abnormal traveling determination of vehicles around the communication vehicle based on the driving environment information. The in-vehicle communication device may be configured to communicate with the communication device. In the abnormal traveling determination, the processing device may be configured to determine whether there is the abnormally traveling vehicle around the communication vehicle, to generate the abnormal traveling information as information indicating the traveling state of the abnormally traveling vehicle when it is determined that there is the abnormally traveling vehicle, and to send the abnormal traveling information to the in-vehicle communication device. 
     A third disclosure according to the second disclosure may further have the following features. In the emergency control, the control device may be configured to repeatedly perform the sending of the emergency control signal and the determination as to whether the reception of the abnormal traveling information from the communication vehicle is ended, to determine whether the communication vehicle has arrived before the controlled traffic light based on the information from the communication vehicle when it is determined that the reception of the abnormal traveling information is ended, and to stop the sending of the emergency control signal to the controlled traffic light when it is determined that the communication vehicle has arrived before the controlled traffic light. 
     A fourth disclosure according to the first disclosure may further have the following features. The communication vehicle may include an acquisition device, a processing device, and an in-vehicle communication device. The acquisition device may be configured to acquire driving environment information on the communication vehicle. The processing device may be configured to perform the abnormal traveling determination of the communication vehicle itself based on the driving environment information. The in-vehicle communication device may be configured to communicate with the communication device. In the abnormal traveling determination, the processing device may be configured to determine whether the communication vehicle is the abnormally traveling vehicle, to generate the abnormal traveling information as information indicating the traveling state of the communication vehicle when it is determined that the communication vehicle is the abnormally traveling vehicle, and to send the abnormal traveling information to the in-vehicle communication device. 
     A fifth disclosure according to the fourth disclosure may further have the following features. In the emergency control, the control device may be configured to repeatedly perform the sending of the emergency control signal and the determination as to whether the communication vehicle has passed the controlled traffic light and to stop the sending of the emergency control signal to the controlled traffic light when it is determined that the communication vehicle has passed the controlled traffic light. 
     A sixth disclosure is a traffic light management method for managing the display of traffic lights. The sixth disclosure has the following features. The traffic light management method includes, by a control device that controls the display, communicating with a communication vehicle having a communication function, predicting a future trajectory of an abnormally traveling vehicle based on abnormal traveling information when the abnormal traveling information indicating information on the abnormally traveling vehicle is included in information received from the communication vehicle, generating an emergency control signal for temporarily prohibiting passage at an intersection and a crosswalk on a road along the future trajectory based on map information and the future trajectory, and sending the emergency control signal to a traffic light at the intersection and the crosswalk. 
     According to the first or sixth disclosure, even if a vehicle is traveling abnormally for some reason, emergency control is performed and the emergency control signal is sent to the controlled traffic lights. This makes it possible to alert the vehicles and pedestrians around the future trajectory of the abnormally traveling vehicle to this abnormal traveling. Therefore, it is possible to minimize the effect of an accident caused by the abnormal traveling. 
     According to the second disclosure, the communication vehicle performs the abnormal traveling determination. Therefore, it is possible to detect that there is an abnormally traveling vehicle around the communication vehicle. 
     According to the third disclosure, when there is an abnormally traveling vehicle around the communication vehicle, the sending of the emergency control signal to the controlled traffic lights can be stopped. Therefore, it is possible to avoid traffic paralysis caused by the continuous sending of the emergency control signal. 
     According to the fourth disclosure, the communication vehicle performs the abnormal traveling determination for itself. Therefore, it is possible to detect that the communication vehicle itself is an abnormally traveling vehicle. 
     According to the fifth disclosure, when the communication vehicle itself is an abnormally traveling vehicle, the sending of the emergency control signal to the controlled traffic signals can be stopped. Therefore, it is possible to avoid traffic paralysis caused by the continuous sending of the emergency control signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a schematic diagram of a traffic light management system according to an embodiment; 
         FIG. 2  is a diagram showing an example of a traffic situation before emergency control is performed; 
         FIG. 3  is a diagram showing an example of a traffic situation when emergency control is performed; 
         FIG. 4  is a diagram showing another example of a traffic situation when emergency control is performed; 
         FIG. 5  is a diagram showing a still another example of a traffic situation when emergency control is performed; 
         FIG. 6  is a block diagram showing a configuration example of the traffic light management system according to the embodiment; 
         FIG. 7  is a flowchart showing a flow of emergency control processing performed by a control device (processor) of a management server; 
         FIG. 8  is a flowchart showing a flow of emergency control processing after sending an emergency control signal; and 
         FIG. 9  is a flowchart showing a flow of emergency control processing after sending an emergency control signal. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A traffic light management system and a traffic light management method according to an embodiment of the present disclosure will be described below with reference to the drawings. The traffic light management method according to the embodiment is implemented by computer processing performed in the traffic light management system according to the embodiment. Note that, in the figures, the same reference numerals will be given to the same or similar components and the description thereof will be simplified or omitted. 
     1. OUTLINE OF PRESENT DISCLOSURE 
     1-1. Communication Information 
       FIG. 1  is a schematic diagram of the traffic light management system according to the embodiment. A traffic light management system  100 , shown in  FIG. 1 , includes a management server  10 . The management server  10  communicates with a communication vehicle  30 , and with traffic lights  40  and  50 , via a network  20  and a base station  60 . The communication vehicle  30  is a moving object, such as a vehicle, having the communication function. The traffic lights  40  and  50  are traffic lights installed on a road. The traffic light  40  is used mainly to control the traffic of moving objects. The traffic light  50  is used mainly to control the traffic of pedestrians. Typically, the traffic light  50  is provided adjacent to a pedestrian crossing. Although the traffic light  40  is a three-position system and the traffic light  50  is a two-position system in  FIG. 1 , the lighting system used for these traffic lights is not particularly limited. 
     The management server  10  communicates with the communication vehicle  30  to acquire various types of information on the communication vehicle  30 . Examples of various types of information include the ID information on the communication vehicle  30  and the traveling state information on the communication vehicle  30 . Examples of the traveling state information include the speed information and the position information on the communication vehicle  30 . The position information is, for example, the latitude/longitude information. As will be described later, the management server  10  has map information. The management server  10  combines the map information and the position information to detect the current position of the communication vehicle  30 . In addition, the management server  10  uses the history of the position information to detect the current traveling direction of the communication vehicle  30 . The various types of information on the communication vehicle  30  may include the external recognition information around the communication vehicle  30  acquired by the communication vehicle  30 . 
     The management server  10  also communicates with the traffic lights  40  and  50  to acquire the display information on these traffic lights. Examples of types of the traffic light  40  include the following two types: one is a program type that controls the light according to a preset control pattern and the other is a traffic-sensitive type that changes the light from “red” to “green” when a moving object is detected in front of the traffic light  40 . Examples of types of the traffic light  50  include the above-mentioned two types and, in addition, a push-button type that changes the light from “red” to “green” when a button is pressed by a pedestrian. The management server  10  uses the display information to detect the current lighting state of the lights (e.g., green, yellow, and red) of the traffic lights  40  and  50 . 
     1-2. Emergency Control of Display 
     The management server  10  also performs emergency control of the display of the traffic lights  40  and  50 . When emergency control is performed, the emergency control signal ECS is sent from the management server  10  to specific traffic lights  40  and  50  to force the current light states of the traffic lights  40  and  50  to change. The emergency control will be described with reference to  FIG. 2  and  FIG. 3 .  FIG. 2  shows an example of a traffic situation before the emergency control is performed, and  FIG. 3  shows an example of a traffic situation when emergency control is performed. 
       FIG. 2  illustrates the communication vehicle  30  traveling in lane L 1  and a vehicle  70  traveling in lane L 2 . The vehicle  70  is an oncoming vehicle traveling in the direction opposite to the traveling direction of the communication vehicle  30 . The vehicle  70  may or may not have the communication function for use in communication with the management server  10 . In  FIG. 2 , traffic lights  41 ,  42 ,  51 , and  52  are also illustrated. In the figure, the light of the traffic lights  41  and  42  is “red.” Therefore, the communication vehicle  30  is decelerating to stop before pedestrian crossing C 1 . The vehicle  70  is stopped before pedestrian crossing C 2 . On the other hand, the light of the traffic lights  51  and  52  is “green.” Therefore, pedestrians P 1  and P 2  are going to cross the pedestrian crossings C 1  and C 2 , respectively. 
       FIG. 3  differs from  FIG. 2  in that a vehicle  80  is traveling abnormally in lane L 2 . It is assumed that the vehicle  80  in  FIG. 3  does not have the communication function for use in communication with the management server  10  or that the vehicle  80  has the communication function but the communication function is abnormal. The vehicle  80  has departed from lane L 1 , in which the vehicle  80  should travel, and continues traveling at accelerated speeds without following the instruction of the light of the traffic light  41 . This abnormal traveling is detected by the abnormal traveling determination performed by the communication vehicle  30 . In the abnormal traveling determination, it is determined whether the traveling state of the vehicle  80  is abnormal based on the external recognition information around the communication vehicle  30  and based on the traveling state information on the communication vehicle  30 . 
     Examples of the “abnormal traveling state” include the traveling state in which the vehicle  80  ignores the instruction of the traffic light  40 , the traveling state in which the vehicle  80  greatly exceeds the legal speed, and the traveling state in which the vehicle  80  meanders across a plurality of lanes. When it is determined in the abnormal traveling determination that the traveling state of the vehicle  80  is abnormal, the communication vehicle  30  sends the abnormal traveling information ABN to the management server  10 . Examples of the abnormal traveling information ABN include the traveling state information (speed information and position information) on the abnormally traveling vehicle (that is, vehicle  80 ). The speed information on the vehicle  80  is calculated based on the traveling speed information on the communication vehicle  30  and the relative speed information on the vehicle  80  included in the external recognition information around the communication vehicle  30 . As will be described later, the communication vehicle  30  has the map information. The position information on the vehicle  80  is calculated based on this map information and on the relative position information on the vehicle  80  included in the external recognition information around the communication vehicle  30 . 
     When the abnormal traveling information ABN is received, the management server  10  predicts the future trajectory TR of the abnormally traveling vehicle based on the received abnormal traveling information. As described above, the management server  10  has the map information. Therefore, the management server  10  combines this map information with the position information on the vehicle  80 , included in the abnormal traveling information ABN, to detect the current position of the vehicle  80 . In addition, the management server  10  refers to the history of the position information on the vehicle  80  to detect the current traveling direction of the vehicle  80 . Then, based on the current position, the current traveling direction, and the history of the speed information on the vehicle  80  included in the abnormal traveling information ABN, the management server  10  predicts the future trajectory TR. The range of time for which the future trajectory TR is predicted is, for example, a period of time from the current time to the time several seconds later. 
     Once the future trajectory TR is predicted, the management server  10  combines the future trajectory TR with the map information to identify the traffic lights  40  and  50  on the road along the future trajectory TR. The traffic lights to which the emergency control signal ECS is to be sent are the traffic lights  40  and  50  identified in this way. In the description below, the traffic lights  40  and  50  on the road along the future trajectory TR are collectively referred to as “controlled traffic lights.” In the example shown in  FIG. 3 , the traffic lights  51  and  52  are controlled traffic lights. The emergency control signal ECS includes the signal for forcing the light of the controlled traffic lights to change from “green” to “red.” 
     Changing the light of the controlled traffic lights from “green” to “red” makes it possible to alert the vehicles and pedestrians around the future trajectory TR (for example, pedestrians P 1  and P 2 ) to the abnormal traveling. When the traffic lights  40  and  50  are equipped with an alarm device that issues an alarm of a predetermined frequency, the emergency control signal ECS may include the signal for activating the alarm device of the controlled traffic lights. 
       FIG. 4  is a diagram showing another example of a traffic situation when emergency control is performed.  FIG. 4  differs from  FIG. 3  in that there is an intersection PI. When there is the intersection PI shown in  FIG. 4 , the total number of the traffic lights  40  and  50  increases. In  FIG. 4 , traffic lights  43 ,  44 ,  53 , and  54  are illustrated as the traffic lights added to the example shown in  FIG. 3 . The traffic light  53  is provided adjacent to the pedestrian crossing C 3 . The traffic light  54  is provided adjacent to the pedestrian crossing C 4 . The light of traffic lights  53  and  54  is “red.” 
     Around the intersection PI, there are vehicles  71  and  72  in addition to the vehicle  70 . In the example shown in  FIG. 4 , the light of the traffic lights  43 ,  44 ,  51 , and  52  was “green” before the emergency control was performed. Therefore, the vehicle  71  passed through the intersection PI, and the vehicle  72  was going to enter the intersection PI. The vehicles  71  and  72  may or may not have the communication function for communication with the management server  10 . 
     As in the example shown in  FIG. 3 , the communication vehicle  30  sends the abnormal traveling information ABN to the management server  10  based on the result of the abnormal traveling determination. Similarly, as in the example shown in  FIG. 3 , the management server  10  predicts the future trajectory TR and sends the emergency control signal ECS to the controlled traffic lights in response to the abnormal traveling information ABN. 
     In the example shown in  FIG. 4 , the traffic lights  43 ,  44 ,  51  and  52  are controlled traffic lights. Changing the light of the controlled traffic lights from “green” to “red” makes it possible to alert the vehicles and pedestrians (for example, pedestrians P 1 , P 2  and vehicle  72 ) around the future trajectory TR to the abnormal traveling. 
       FIG. 5  is a diagram showing a still another example of a traffic situation when emergency control is performed.  FIG. 5  differs from  FIG. 3  in the vehicle that is traveling abnormally. That is, in the example shown in  FIG. 5 , the communication vehicle  30  performs abnormal traveling determination for itself and determines that the communication vehicle  30  is abnormal. The abnormal traveling information ABN is sent from the communication vehicle  30  to the management server  10 . It should be noted that, as in the example shown in  FIG. 3 , the abnormal traveling determination is performed based on the external recognition information around the communication vehicle  30  and on the traveling state information on the communication vehicle  30 . 
     When the abnormal traveling information ABN is received, the management server  10  predicts the future trajectory TR of the abnormally traveling vehicle (that is, the communication vehicle  30 ) based on the received abnormal raveling information ABN. In the example shown in  FIG. 5 , the current position, the current traveling direction, and the history of the speed information on the communication vehicle  30  have been stored in the management server  10  before the abnormal traveling information ABN is received. Therefore, the future trajectory TR is predicted relatively simpler in the example shown in  FIG. 5  than in the example shown in  FIG. 3 . 
     In the example shown in  FIG. 5 , the controlled traffic lights are the traffic lights  51  and  52 , and the light of the controlled traffic lights is changed from “green” to “red”. The effect achieved in this example is the same as that in the example shown in  FIG. 3 . 
     As described above, the communication vehicle  30  performs abnormal traveling determination in this embodiment. When abnormal traveling is detected by the abnormal traveling determination and, as a result, the abnormal traveling information ABN is sent from the communication vehicle  30  to the management server  10 , the management server  10  performs emergency control. The emergency control, performed in this way, makes it possible to alert the vehicles and pedestrians around the future trajectory TR to this abnormal traveling. Therefore, the effect of an accident caused by the abnormal traveling can be minimized. 
     The traffic light management system and the traffic light management method according to the embodiment will be described below more in detail. 
     2. TRAFFIC LIGHT MANAGEMENT SYSTEM 
     2-1. Example of Overall Configuration 
       FIG. 6  is a block diagram showing an example of the configuration of the traffic light management system according to the embodiment. As shown in  FIG. 6 , the traffic light management system  100  includes the management server  10 , the communication vehicle  30 , and the traffic lights  40  and  50 . Communication between the management server  10  and the communication vehicle  30  is carried out via the network  20  and the base station  60  as described in  FIG. 1 . Communication between the management server  10  and the traffic light  40  and between the management server  10  and the traffic light  50  is also carried out as described in  FIG. 1 . 
     As shown in  FIG. 6 , the management server  10  includes a control device  11 , a communication device  12 , and a map database (map DB)  13 . 
     The control device  11  is configured by a computer having at least one processor  11   a  and at least one memory  11   b . At least one program is stored in the memory  11   b . A program is read from the memory  11   b  for execution by the processor  11   a  to implement various functions of the control device  11 . One of these various functions is the emergency control function described above. Various types of information acquired via communication with the communication vehicle  30  is also stored in the memory  11   b . The display information acquired via communication with the traffic lights  40  and  50  is also stored in the memory  11   b.    
     The communication device  12  acquires various types of information from the communication vehicle  30  and from the traffic lights  40  and  50  via the network  20  and the base station  60 . The communication device  12  also sends the emergency control signal ECS to the controlled traffic lights via the network  20  and the base station  60 . 
     The map database  13  is a database that stores map information. Examples of the map information include the road position information, road shape information (for example, whether the road is curved or straight), and position information on intersections and structures. The map information also includes the traffic regulation information. The map database  13  is formed in a predetermined storage device (for example, a hard disk, a flash memory). 
     The communication vehicle  30  is, for example, an automobile powered by an internal combustion engine such as a diesel engine or a gasoline engine, an electric vehicle powered by an electric motor, or a hybrid vehicle equipped with an internal combustion engine and an electric motor. The electric motor is driven by a battery such as a secondary battery, a hydrogen fuel cell, a metal fuel cell, or an alcohol fuel cell. The communication vehicle  30  includes an external sensor  31 , an internal sensor  32 , a Global Navigation Satellite System (GNSS) receiver  33 , and a map database  34 . The communication vehicle  30  also includes a processing device  35  and a communication device (in-vehicle communication device)  36 . 
     The external sensor  31  is a device that detects the surroundings of the communication vehicle  30 . Examples of the external sensor  31  include a radar sensor and a camera. The radar sensor uses radio waves (e.g., millimeter waves) or light to detect targets around the communication vehicle  30 . Targets include static targets and dynamic targets. Examples of static targets include guardrails and buildings. Dynamic targets include pedestrians, bicycles, motorcycles, and vehicles other than the communication vehicle  30 . The camera captures the surroundings of the communication vehicle  30 . The external sensor  31  sends the surroundings information to the processing device  35 . 
     The internal sensor  32  is a device that detects the traveling state of the communication vehicle  30 . Examples of the internal sensor  32  include a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor. The vehicle speed sensor detects the traveling speed of the communication vehicle  30 . The acceleration sensor detects the acceleration of the communication vehicle  30 . The yaw rate sensor detects the yaw rate around the vertical axis of the center of gravity of the communication vehicle  30 . The internal sensor  32  sends the traveling state information to the processing device  35 . 
     The GNSS receiver  33  is a device that receives signals from three or more artificial satellites. The GNSS receiver  33  is also a device that acquires the position information on the communication vehicle  30 . The GNSS receiver  33  calculates the position and attitude (orientation) of the communication vehicle  30  based on the received signals. The GNSS receiver  33  sends the GNSS information to the processing device  35 . 
     The map database  34  is a database that stores map information. Examples of the map information include the same information that is stored in the map database  13 . The map database  34  is formed in an in-vehicle storage device (for example, a hard disk or a flash memory). The map database  34  may be formed in a computer installed in a facility capable of communicating with the communication vehicle  30 . This computer may be the computer of the management server  10 . That is, the map database may be shared between the management server  10  and the communication vehicle  30 . 
     The surroundings information received from the external sensor  31 , the traveling state information received from the internal sensor  32 , the GNSS information received from the GNSS receiver  33 , and the map information stored in the map database  34  are included in the “driving environment information” on the communication vehicle  30 . Therefore, in the present application, the external sensor  31 , the internal sensor  32 , the GNSS receiver  33 , and the map database  34  are collectively referred to as “acquisition devices” for acquiring the driving environment information. 
     The processing device  35  is configured by a microcomputer having at least one processor  35   a  and at least one memory  35   b . At least one program is stored in the memory  35   b . A program is read from the memory  35   b  for execution by the processor  35   a  to implement various functions of the processing device  35 . Examples of these functions include the function to process the surroundings information received from the external sensor  31  and the function to process the traveling state information received from the internal sensor  32 . 
     The various functions of the processing device  35  also include the function to process the abnormal traveling determination. In the abnormal traveling determination, the external recognition information around the communication vehicle  30  is acquired based on the surroundings information received from the external sensor  31 . Then, based on this external recognition information and the traveling state information on the communication vehicle  30 , it is determined whether the traveling state of any one of the vehicles around the communication vehicle  30  is abnormal. Alternatively, based on this external recognition information and the traveling state information on the communication vehicle  30 , it is determined whether the traveling state of the communication vehicle  30  itself is abnormal. When it is determined that there is a vehicle in the abnormal traveling state, the abnormal traveling information ABN is generated. Examples of the abnormal traveling information ABN include the traveling state information on the abnormally traveling vehicle (that is, vehicle  80  or communication vehicle  30 ). 
     The communication device  36  wirelessly communicates with the nearest base station  60 . Examples of communication standards used for this wireless communication include mobile communication standards such as the 4G, LTE, or 5G communication standard. The communication device  36  is connected to the communication device  12  of the management server  10  over the network  20 . For example, the ID information and the traveling state information on the communication vehicle  30  are sent from the communication device  36  to the communication device  12 . The surroundings information, received from the external sensor  31 , may also be sent from the communication device  36  to the communication device  12 . When the abnormal traveling determination is performed, the abnormal traveling information ABN is sent from the communication device  36  to the communication device  12  depending upon the result. 
     The traffic light  40  includes a processing device  45  and a communication device  46 . The traffic light  50  includes a processing device  55  and a communication device  56 . The basic configuration of the traffic light  40  and that of the traffic light  50  are the same. Therefore, in the description below, the configuration of only the traffic light  40  will be described. 
     The processing device  45  is configured by a microcomputer having at least one processor and at least one memory. At least one program is stored in the memory. A program is read from the memory for execution by the processor to implement various functions of the processing device  45 . Examples of the various functions include the processing of the lighting function that controls the lights according to a preset control pattern and the processing of changing the lights when a moving object is detected in front of the traffic light  40 . 
     The communication device  46  wirelessly communicates with the nearest base station  60 . Examples of communication standards for this wireless communication include mobile communication standards such as the 4G, LTE, or 5G communication standard. The communication device  46  is connected the communication device  12  of the management server  10  over the network  20 . For example, the display information on the traffic light  40  is sent from the communication device  46  to the communication device  12 . 
     The traffic lights  40  and  50  may be equipped with an alarm device that issues an alarm of a predetermined frequency. 
     2-2. Example of Emergency Control Processing 
       FIG. 7  is a flowchart showing the flow of emergency control processing performed by the control device  11  (processor  11   a ). The routine shown in  FIG. 7  is repeatedly performed in a predetermined control cycle. 
     In the routine shown in  FIG. 7 , it is first determined whether the abnormal traveling information ABN is received (step S 11 ). As described above, the abnormal traveling information ABN includes the traveling state information on the abnormally traveling vehicle (that is, vehicle  80  or communication vehicle  30 ). When the determination result in step S 11  is negative, the current processing ends. 
     When the determination result in step S 11  is affirmative, the future trajectory TR is predicted (step S 12 ). The future trajectory TR is predicted based on the traveling state information on the abnormally traveling vehicle. First, based on the map information and on the position information included in the traveling state information, the current position of the abnormally traveling vehicle is detected. In addition, the current traveling direction of the abnormally traveling vehicle is detected from the history of the position information on the abnormally traveling vehicle. Then, based on the current position, the current traveling direction, and the speed information included in the traveling state information, the future trajectory TR is predicted. The range of time for which the future trajectory TR is predicted is, for example, a period of time from the current time to the time several seconds later. 
     Following step S 12 , the controlled traffic lights are identified (step S 13 ). As described above, the controlled traffic lights are the traffic lights  40  and  50  on the road along the future trajectory TR. The specified traffic lights are identified based on the future trajectory TR predicted in step S 12  and the map information. 
     Following step S 13 , the emergency control signal ECS is sent (step S 14 ). The emergency control signal ECS is sent to the controlled traffic lights identified in step S 13 . 
     2-3. Example of Emergency Control Processing after Sending Emergency Control Signal 
       FIG. 8  and  FIG. 9  are flowcharts showing the flow of emergency control processing after sending the emergency control signal ECS. The routines shown in  FIG. 8  and  FIG. 9  are performed by the control device  11  (the processor  11   a ) following step S 14  in  FIG. 7 . The routines shown in  FIG. 8  and  FIG. 9  are performed interchangeably according to whether or not the abnormally traveling vehicle is the communication vehicle  30 . 
     The routine shown in  FIG. 8  is an example of processing performed when the abnormally traveling vehicle is not the communication vehicle  30 . In this routine, it is first determined whether the reception of the abnormal traveling information ABN is ended (step S 21 ). For example, when the distance between the communication vehicle  30  and the abnormally traveling vehicle becomes so large that the abnormally traveling vehicle is not recognized any more, the sending of the abnormal traveling information ABN from the communication vehicle  30  to the management server  10  is ended. This sending is also ended when the abnormal traveling is ended. When this sending is ended, the reception of the abnormal traveling information ABN by the management server  10  is also ended. 
     When the determination result in step S 21  is affirmative, it is determined whether the communication vehicle  30  has arrived before a controlled traffic light (step S 22 ). The processing in step S 22  is performed for each of the controlled traffic lights. The processing in step S 22  is performed by detecting the current position of the communication vehicle  30 . As described above, the current position is detected by combining the map information and the position information on the communication vehicle  30 . 
     When the determination result in step S 22  is affirmative, the sending of the emergency control signal ECS is stopped (step S 23 ). As described above, the processing in step S 22  is performed for each of the controlled traffic lights. Therefore, the processing in step S 23  is also performed for each of the controlled traffic lights. 
     The routine shown in  FIG. 9  is an example of processing performed when the abnormally traveling vehicle is the communication vehicle  30 . In this routine, it is first determined whether the reception of the abnormal traveling information ABN is ended (step S 31 ). For example, when the abnormal traveling of the communication vehicle  30  is ended, the sending of the abnormal traveling information ABN from the communication vehicle  30  to the management server  10  is ended. When this sending is ended, the reception of the abnormal traveling information ABN by the management server  10  is also ended. 
     When the determination result in step S 31  is affirmative, the sending of the emergency control signal ECS is stopped all at once (step S 32 ). When the reception of the abnormal traveling information ABN is ended, it is estimated that the abnormal traveling of the communication vehicle  30  is ended. Therefore, the sending of the emergency control signal ECS to all controlled traffic lights is stopped all at once. 
     When the determination result in step S 31  is negative, it is determined whether the communication vehicle  30  has passed a controlled traffic light (step S 33 ). The processing in step S 33  is performed for each of the controlled traffic lights. The processing in step S 33  is performed by detecting the current position of the communication vehicle  30 . As described above, the current position is detected by combining the map information and the position information on the communication vehicle  30 . 
     When the determination result in step S 33  is affirmative, the sending of the emergency control signal ECS is stopped (step S 34 ). As described above, the processing in step S 33  is performed for each of the controlled traffic lights. Therefore, the processing in step S 34  is also performed for each of the controlled traffic lights. 
     3. EFFECTS 
     In this embodiment, even if a vehicle is traveling abnormally for some reason, emergency control is performed and the emergency control signal ECS is sent to the controlled traffic lights as described above. This makes it possible to alert the vehicles and pedestrians around the future trajectory TR of the abnormally traveling vehicle to this abnormal traveling. Therefore, the effect of an accident caused by the abnormal traveling can be minimized. 
     In this embodiment, the processing after sending the emergency control signal ECS is performed. This processing releases the control that has been set up by the emergency control signal ECS sent to the controlled traffic lights. Therefore, it is possible to prevent traffic paralysis that may be caused by the continuous sending of the emergency control signal ECS.