Information processing device, signal control device, accumulation length estimating method, signal control method, and computer program

Abstract

This information processing device includes: a main line congestion estimating unit that estimates the congestion of a predetermined segment of a main line; and an accumulation length estimating unit that estimates, on the basis of the congestion estimated by the main line congestion estimating unit, the accumulation length in a rampway that branches from the main line toward a signal intersection onto another road.

Description

Information processing device, signal control device, residence length estimation method, signal control method, and computer program

[0001] This disclosure relates to an information processing device, a signal control device, a residence length estimation method, a signal control method, and a computer program. This application claims priority to Japanese Application No. 2022-153574 filed on September 27, 2022, and incorporates by reference all of the contents of that Japanese application.

[0002] A proposal for a sensor-responsive traffic signal (hereinafter, the sensor-responsive traffic signal will be referred to as a "sensor-responsive traffic signal") is disclosed in Patent Document 1. The technology disclosed in Patent Document 1 uses information obtained from a probe vehicle (hereinafter, referred to as "probe information"). A probe vehicle is a vehicle equipped with a Global Navigation Satellite System (GNSS) and a gyro sensor, and capable of recording time information, location information, traveling speed, traveling direction, and the like, and transmitting the information to an external device via wireless communication.

[0003] The technology disclosed in Patent Document 1 estimates the end of a traffic jam at an intersection based on the distance from the intersection when a probe vehicle is stopped, the duration of the red light at the intersection, and the elapsed time of the red light when the vehicle is stopped. Similarly, the distance to the end of a traffic jam on another intersecting road is estimated based on information obtained from the probe vehicle. The technology disclosed in Patent Document 1 calculates signal parameters based on the ratio of the end of the traffic jam.

[0004] JP 2009-146138 A

[0005] An information processing device according to one aspect of the present disclosure includes a main line congestion degree estimation unit that estimates the congestion degree of a specified section of a main line, and a stagnant length estimation unit that estimates the stagnant length within a road that branches off from the main line toward a signalized intersection to another road based on the congestion degree estimated by the congestion degree estimation unit.

[0006] This disclosure can be realized not only as an information processing device having such a characteristic processing unit, but also as an information processing method, a residence length estimation method, or a signal control method having such characteristic processing steps, or as a program for causing a computer to execute such steps. Furthermore, it can be realized as a semiconductor integrated circuit that realizes part or all of the information processing device, or as an information processing system or signal control system that includes the information processing device.

[0007] FIG. 1 is a diagram showing a schematic configuration of a signal control system according to a first embodiment of the present disclosure. FIG. 2 is a block diagram showing the functional configuration of a signal control server included in the signal control system according to the first embodiment. FIG. 3 is a flowchart showing the control structure of a program realizing the inflow number calculation unit shown in FIG. 2. FIG. 4 is a schematic diagram showing the configuration of the inflow number storage unit shown in FIG. 2. FIG. 5 is a flowchart showing the control structure of a program realizing the outflow number calculation unit shown in FIG. 2. FIG. 6 is a schematic diagram showing the configuration of the outflow number storage unit shown in FIG. 2. FIG. 7 is a flowchart showing the control structure of a program realizing the signal control unit shown in FIG. 2. FIG. 8 is a diagram showing a schematic configuration of a signal control system according to a second embodiment of the present disclosure. FIG. 9 is a block diagram showing the functional configuration of a signal control server included in the signal control system shown in FIG. 8. FIG. 10 is a flowchart showing the control structure of a program realizing the traffic situation prediction unit shown in FIG. 9. FIG. 11 is a diagram showing the external appearance of the signal control server according to the first embodiment and the second embodiment. FIG. 12 is a block diagram showing the hardware configuration of the signal control server according to the first embodiment and the second embodiment.

[0008] [Problem to be Solved by the Present Disclosure] The technology described in Patent Document 1 has the effect of being able to calculate signal parameters using probe information even if a vehicle detector is not installed at a signalized intersection.

[0009] On the other hand, when exiting a highway's main line onto a local road, a road (called a "rampway") is installed to connect the two. Traffic lights are usually installed at the intersection between the rampway and the local road. If a traffic jam occurs on the rampway, it can sometimes affect the main road as well. Therefore, it is preferable to use sensor-activated traffic lights at the exit of the rampway. However, in the case of rampways, the complex shape often makes it impossible to install vehicle detectors. Therefore, it is difficult to install sensor-activated traffic lights at the intersection of the exit of a rampway.

[0010] The technology of Patent Document 1 can be used if a probe vehicle is present on the ramp. However, a probe vehicle is not always present on the ramp. Therefore, it would be preferable if the traffic light at the ramp exit could be operated as a sensor-activated traffic light even when a probe vehicle is not present.

[0011] Therefore, an object of this disclosure is to provide an information processing device, a signal control device, a method for estimating traffic length, a signal control method, and a computer program that can grasp the traffic conditions on a rampway without installing a vehicle detector on the rampway.

[0012] [Effects of the present disclosure]

[0013] As described above, this disclosure provides an information processing device, a signal control device, a method for estimating traffic length, a signal control method, and a computer program that can grasp the traffic conditions on a ramp way without installing vehicle detectors on the ramp way. [Description of Embodiments of the Present Disclosure] In the following description and drawings, identical components are designated by the same reference numerals. Therefore, detailed description thereof will not be repeated. Note that at least some of the embodiments described below may be combined in any manner.

[0014] (1) An information processing device according to a first aspect of this disclosure includes a main line congestion degree estimation unit that estimates the congestion degree of a specified section of a main line, and a stagnant length estimation unit that estimates the stagnant length within a rampway that branches off from the main line toward a signalized intersection to another road, based on the congestion degree estimated by the main line congestion degree estimation unit.

[0015] The main line congestion degree estimation unit estimates the congestion degree of the main line. The congestion length estimation unit estimates the congestion length, which is an indicator of the congestion degree of the ramp way, based on the estimated congestion degree of the main line. Information can be generated to control the traffic lights at the ramp way exit as sensor-activated traffic lights without the need to install vehicle detectors on the ramp way.

[0016] (2) In the above (1), the main line congestion degree estimation unit may include a unit time congestion degree estimation unit that estimates the congestion degree of a specified section in each unit time based on at least the number of vehicles entering the specified section per unit time.

[0017] It is believed that there is a correlation between the number of vehicles entering a given section per unit time and the number of vehicles on the ramp. Therefore, the degree of congestion on the ramp can be estimated from the number of vehicles entering.

[0018] (3) In (2) above, the unit time congestion degree estimation unit may include an inflow number calculation unit that calculates the number of vehicles flowing into a specified section in each unit time, an outflow number calculation unit that calculates the number of vehicles flowing out of the specified section in each unit time, and a section congestion degree estimation unit that estimates the congestion degree of the specified section based on the difference between the number of inflow vehicles in each unit time calculated by the inflow number calculation unit and the number of outflow vehicles in each unit time calculated by the outflow number calculation unit.

[0019] The number of vehicles entering the ramp from the main line can be estimated with high reliability by calculating the difference between the number of vehicles entering a specified section and the number of vehicles exiting from the specified section, and therefore the degree of congestion within the ramp can be estimated with high reliability based on this estimation result.

[0020] (4) In the above (3), the inflow number calculation unit may calculate the number of vehicles inflowing into the specified section in each unit time based on the output of a vehicle detector installed upstream of the specified section.

[0021] The number of vehicles entering a specific section can be counted with high reliability based on the output of a vehicle detector installed upstream, and as a result, the congestion level on the main line can be estimated with high reliability. Since the congestion level on the rampway is estimated based on the congestion level on the main line, the reliability of the estimation is also high.

[0022] (5) In (3) above, the inflow number calculation unit may calculate the predicted number of vehicles that will inflow into a specified section in each unit time based on the output of an upstream vehicle detector located further upstream than the upstream vehicle detector, in addition to the output of the upstream vehicle detector located on the upstream side.

[0023] The number of vehicles that will enter a specified section in the future can be estimated based on the output of an upstream vehicle detector located further upstream than the upstream vehicle detector. By correcting the output of the upstream vehicle detector using this value, the congestion level on the main line can be predicted not only based on the number of vehicles entering the specified section, but also using the predicted number of vehicles. Since this congestion level is used to estimate the congestion level on the rampway, delays in estimating the congestion level can be reduced.

[0024] (6) In any one of (3) to (5) above, the outflow number calculation unit may calculate the number of vehicles that flow out of the specified section in each unit time based on the output of a vehicle detector installed downstream of the specified section.

[0025] It is believed that there is a correlation between the number of exiting vehicles counted by vehicle detectors installed downstream and the number of vehicles entering the ramp. Therefore, rather than installing vehicle detectors on the ramp, it is possible to estimate the degree of congestion on the ramp by using the output of downstream vehicle detectors installed on the main line.

[0026] (7) In any one of (1) to (6) above, the main line congestion estimation unit may further include a connection area congestion estimation unit that determines that the main line is congested based on the state of a first probe vehicle in a connection area where a rampway branches off from the main line.

[0027] When a first probe vehicle is present in the junction area where the main line branches off to the rampway, the probe information obtained from that probe vehicle can be used to estimate the travel speed and stopping time of vehicles near the junction area. These have a strong correlation with the congestion level of the rampway. Therefore, the probe information can be used to correct the estimate of the congestion level of the rampway, increasing the reliability of the estimate.

[0028] (8) In any one of (1) to (7) above, the information processing device may further include a ramp-way residence length correction unit that corrects the residence length within the ramp-way based on vehicle status information of a second probe vehicle present within the ramp-way.

[0029] If a probe vehicle is present on the ramp, the probe information can be used to estimate the length of time that vehicles are waiting on the ramp. By correcting the length of time that vehicles are waiting on the ramp using this value, the accuracy of estimating the congestion level on the ramp can be improved.

[0030] (9) In any one of (1) to (8) above, the information processing device may further include a signal control unit that controls the signal display period or split based on the dwell length estimated by the dwell length estimation unit.

[0031] Even if vehicle detectors are not installed on the rampway, the traffic lights at the exit of the rampway can be controlled as sensor-activated traffic lights, allowing traffic lights to be controlled appropriately according to the conditions of both the rampway and the general road.

[0032] (10) In (9) above, the signal control unit may control the signal phase period or split based on the dwell length estimated by the dwell length estimation unit and the dwell length of other roads at the signalized intersection.

[0033] The length of traffic within the rampway can be estimated without installing vehicle detectors on the rampway. Signal parameters are generated using the estimation results and the traffic conditions on the general road. As a result, the traffic lights at the exit of the rampway can be controlled as sensor-responsive traffic lights. This makes it possible to control the traffic lights appropriately according to the conditions of both the rampway and the general road.

[0034] (11) In any one of (1) to (10) above, the main line congestion degree estimation unit may include a rampway side lane congestion degree estimation unit that estimates the congestion degree of a lane on the rampway side of a specified section.

[0035] When there are multiple lanes in a given section, vehicles entering a rampway must first move into the lane on the ramp side. Therefore, there is a correlation between the degree of vehicle congestion in the lane on the ramp side and the degree of congestion inside the ramp, and the traffic situation inside the ramp can be estimated using the output of the vehicle detector for the lane on the ramp side of the main line. As a result, the traffic situation inside the ramp can be estimated without installing vehicle detectors on the ramp.

[0036] (12) In any one of (1) to (11) above, the unit time may be a time period equal to or less than two periods and equal to or greater than one period of a signal at a signalized intersection.

[0037] If the unit time is too long, appropriate signal control cannot be performed. Furthermore, if the unit time is shorter than one period, the operation of the traffic light will change before one cycle of the traffic light is completed, which is undesirable. Therefore, the unit time should be set to two or fewer periods of the traffic light cycle and one or more periods, for example, equal to two or one period.

[0038] (13) In (12) above, the unit time may be one period of the signal cycle at a signalized intersection.

[0039] By making the unit time equal to one period of the traffic light cycle, it is possible to respond quickly to changes in traffic volume, and the operation of the signal does not change midway through the cycle.

[0040] (14) A signal control device according to a second aspect of this disclosure includes a main line congestion degree estimation unit that estimates the congestion degree of a predetermined section of a main line, a dwell length estimation unit that estimates the dwell length in a rampway that branches off from the main line toward a signalized intersection to another road based on the congestion degree estimated by the main line congestion degree estimation unit, and a signal control unit that controls the signal phase period or split based on the dwell length estimated by the dwell length estimation unit.

[0041] The main line congestion degree estimation unit estimates the congestion degree on the main line. The congestion length estimation unit estimates the congestion length, which is an indicator of the congestion degree on the rampway, based on the estimated congestion degree on the main line. The signal control unit controls the signal aspect cycle or split based on this congestion length. The traffic light at the exit of the rampway can be controlled as a sensor-activated traffic light, without the need to install a vehicle detector on the rampway.

[0042] (15) A method for estimating a dwell length according to a third aspect of this disclosure includes a step in which a computer estimates the degree of congestion in a predetermined section of a main road, and a step in which the computer estimates the dwell length in a rampway that branches off from the main road toward a signalized intersection to another road, based on the degree of congestion estimated in the step of estimating the degree of congestion.

[0043] In a step of estimating the congestion level of a predetermined section of the main line, the congestion level of the main line is estimated. In a step of estimating the congestion length, the congestion length, which is an index of the congestion level of the ramp way, is estimated based on the estimated congestion level of the main line. Information necessary to control the traffic light at the exit of the ramp way as a sensor-activated traffic light can be generated without the need to install a vehicle detector on the ramp way.

[0044] (16) A signal control method according to a fourth aspect of this disclosure includes the steps of: a computer estimating a degree of congestion in a predetermined section of a main line; a computer estimating a length of traffic congestion in a rampway branching off from the main line toward a signalized intersection to another road based on the degree of congestion estimated in the step of estimating the degree of congestion; and a computer controlling a period or split of a signal displayed at the signalized intersection based on the length of traffic congestion estimated in the step of estimating the length of traffic congestion.

[0045] The computer estimates the congestion level of the main line in a step of estimating the congestion level of a predetermined section of the main line.The computer estimates the congestion length, which is an indicator of the congestion level of the rampway, based on the estimated congestion level of the main line in a step of estimating the congestion length.The computer can generate the information necessary to control the traffic light at the exit of the rampway as a sensor-activated traffic light without the need to install a vehicle detector on the rampway.

[0046] (17) A computer program according to a fifth aspect of this disclosure causes a computer to function as a main line congestion degree estimation unit that estimates the congestion degree of a specified section of a main line, and a congestion length estimation unit that estimates the congestion length within a rampway that branches off from the main line toward a signalized intersection to another road, based on the congestion degree estimated by the main line congestion degree estimation unit.

[0047] By having a computer execute the computer program, the computer functions as a main line congestion degree estimation unit and estimates the congestion degree of the main line.Furthermore, the computer functions as a retention length estimation unit and estimates the retention length, which is an indicator of the congestion degree of the ramp way, based on the estimated congestion degree of the main line.The computer can generate information for controlling the traffic lights at the ramp way exit as sensor-activated traffic lights without the need to install vehicle detectors on the ramp way.

[0048] [Details of Embodiments of the Present Disclosure] Specific examples of an information processing device, a signal control device, a residence length estimation method, a signal control method, and a computer program according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0049] 1. First Embodiment 1.1) Configuration a) Overall Configuration Referring to FIG. 1 , a signal control system 50 according to a first embodiment of this disclosure has a function of detecting traffic conditions on a ramp way 60 that branches off from an expressway 52 and leads to an ordinary road 58. A traffic light 62 is provided at the intersection of the ramp way 60 and the ordinary road 58. The expressway 52 has a first direction road 54 and a second direction road 56. The ramp way 60 connects the first direction road 54 and the ordinary road 58. Another ramp way 64 is provided on the second direction road 56. The ramp way 64 connects the second direction road 56 and the ordinary road 58. A traffic light 66 is also provided at the intersection of the ramp way 64 and the ordinary road 58.

[0050] On the first-direction road 54, a vehicle detector 70 is provided upstream of the ramp way 60. A vehicle detector 74 is provided downstream of the ramp way 60. In this specification, "upstream" of a point on a road refers to the portion of the road before reaching that point if traveling in the direction of travel set for that road. "Downstream" refers to the portion of the road after reaching that point. In other words, these terms are used in the same way as "upstream" and "downstream" in relation to the flow of water in a river.

[0051] Similarly, on the second-direction road 56, a vehicle detector 76 is provided upstream of the ramp way 60. The vehicle detector 76 is provided in the same position as the vehicle detector 74. On the second-direction road 56, a vehicle detector 72 is provided downstream of the ramp way 60. The vehicle detector 72 is provided in the same position as the vehicle detector 70.

[0052] Both the first-direction road 54 and the second-direction road 56 have three lanes. Vehicle detectors 70 and 74 each have the function of independently detecting vehicles traveling on each lane of the first-direction road 54 and outputting a detection signal. Vehicle detectors 72 and 74 each have the function of independently detecting vehicles traveling on each lane of the second-direction road 56 and outputting a detection signal.

[0053] Signal control system 50 estimates the traffic conditions within ramps 60 and 64 using vehicle detectors 70, 72, 74, and 76 and the lane-specific vehicle detection signals obtained therefrom. Signal control system 50 further estimates the traffic conditions within ramps 60 and 64 using probe information obtained from probe vehicles when they are present within ramps 60 and 64. Signal control system 50 controls traffic lights 62 and 66 based on the results of this estimation and the traffic conditions on general roads 58.

[0054] For example, a queue of stranded vehicles 82 forms in the rampway 60 when the traffic light 62 is showing a red light. There is no problem if all of the vehicles in the queue of stranded vehicles 82 exit onto the general road 58 when the traffic light 62 next shows a green light. However, if some of the vehicles in the queue of stranded vehicles 82 are unable to exit the rampway 60 when the traffic light 62 shows a green light, a traffic jam occurs in the rampway 60. If the length of the traffic jam becomes too long, it may have a negative impact on the main road of the first direction road 54. Similarly, it is necessary to avoid traffic jams on the general road 58 as well. Therefore, the purpose of this embodiment is to appropriately operate the traffic light 62 as a sensor-responsive traffic light based on the degree of congestion in the rampway 60 and the degree of congestion on the general road 58.

[0055] In this embodiment, as described above, the signal control system 50 controls not only the signal of the traffic light 62 but also the signal of the traffic light 66. In some cases, it may also control other traffic lights. However, for the sake of brevity, only the control of the traffic light 62 by the signal control system 50 will be described below. The following description will not refer to the parts related to the control of the traffic light 66 and other traffic lights. It will be easily understood that the signal control system 50 can also control the traffic light 66 and other traffic lights in a manner similar to that described below.

[0056] The signal control system 50 includes a signal control server 68 that controls the traffic light 62 based on the vehicle detection signals from the vehicle detectors 70 and 74, and on probe information from probe vehicles (e.g., probe vehicles 84 and 86 shown in the figure) if any are present within the ramp way 60. If the signal control system 50 also controls traffic lights other than the traffic light 62, a configuration similar to the configuration of the signal control server 68 described below may be provided in parallel.

[0057] b) Signal Control Server 68 The signal control server 68 is depicted as a single computer in Fig. 1. However, in reality, the signal control server 68 may be a combination of multiple computers connected in parallel, or may distribute and execute processing across a so-called cloud consisting of multiple remote servers, and receive the results.

[0058] Referring to FIG. 2 , the signal control server 68 includes a receiver 100 that receives vehicle detection signals from the vehicle detectors 70 and 74 shown in FIG. 1 , as well as probe information from the vehicle detectors 70 and 74 if a probe vehicle is present within the ramp way 60. In this embodiment, the receiver 100 receives signals via wired communication; however, wireless communication may be used instead of or in addition to wired communication. Note that, in the area of ​​the first-direction road 54 between the vehicle detectors 70 and 74, vehicles enter from the upstream side by passing through the vehicle detector 70, and vehicles exit by passing through the vehicle detector 74 or via the ramp way 60. In the following description, vehicles entering this area from the upstream side by passing through the vehicle detector 70 are referred to as "entering vehicles," and the number of such vehicles is referred to as the number of entering vehicles or simply the number of entering vehicles. Vehicles exiting this area by passing through the vehicle detector 74 are referred to as "exiting vehicles," and the number of such vehicles is referred to as the number of exiting vehicles or simply the number of exiting vehicles. Vehicles exiting this area via the ramp way 60 are not included in the number of exiting vehicles.

[0059] The signal control server 68 further includes an inflowing number calculation unit 102 that selectively receives vehicle detection signals from the vehicle detectors 70, i.e., detection signals of inflowing vehicles, from the vehicle detection signals received by the receiving unit 100 and executes a process of calculating the number of inflowing vehicles for each predetermined time interval, and an inflowing number memory unit 104 that stores the number of inflowing vehicles calculated by the inflowing number calculation unit 102 for each predetermined time interval. The inflowing number memory unit 104 stores the number of inflowing vehicles for each of the most recent multiple time intervals. The control structure of the program that implements the inflowing number calculation unit 102 and the configuration of the inflowing number memory unit 104 will be described later. Note that in the following description, the predetermined time interval is assumed to be 10 seconds. Of course, this time interval may have any length. In this embodiment, a time consisting of a predetermined number of consecutive time intervals among these time intervals is used as the unit time for calculating the control parameters of the traffic light 62. For example, this unit time is selected to be the same as the cycle period of the traffic light 62. Of course, this is merely an example, and the unit time does not necessarily have to be the same as the cycle period of the traffic light 62. However, as will be described later, in this embodiment, the split or cycle period of the traffic light 62 may be changed. Therefore, in order to avoid changing the split in the middle of one cycle, it is preferable that the unit time be a positive integer multiple of the cycle period of the traffic light 62. When the cycle period is changed, it is desirable to change the unit time accordingly.

[0060] The signal control server 68 further includes an exiting number calculation unit 106 that selectively receives vehicle detection signals from the vehicle detectors 74, i.e., detection signals of exiting vehicles, from the vehicle detection signals received by the receiving unit 100, and executes processing to calculate the number of entering vehicles for each predetermined time interval, and an exiting number storage unit 108 that stores the number of exiting vehicles calculated by the exiting number calculation unit 106 for each predetermined time interval. The exiting number storage unit 108 stores the number of exiting vehicles for each of the most recent multiple time intervals. The control structure of the program that realizes the exiting number calculation unit 106 and the configuration of the exiting number storage unit 108 will be described later.

[0061] The signal control server 68 further includes a signal control unit 110 connected to the inflow number memory unit 104 and the outflow number calculation unit 106 for generating and transmitting a control signal for the traffic light 62 to the traffic light 62 based on the series of inflow vehicle numbers and outflow vehicle numbers stored therein, as well as probe information received by the receiving unit 100, if any.

[0062] The signal control unit 110 includes a traffic condition estimation unit 120 for estimating the congestion status of the main road of the first direction road 54 based on the number of inflows in the most recent unit time recorded in the inflow number memory unit 104, the number of outflows in the most recent unit time stored in the outflow number memory unit 108, and, if any, probe information received via the receiving unit 100, the probe information, and a retention length estimation unit 122 for estimating the retention length in the rampway 60 based on the congestion status of the main road estimated by the traffic condition estimation unit 120. Note that, typically, the "retention length" refers to the length of the queue of vehicles stopped in front of the signal while the signal is red. However, in this specification, the term "retention length" refers to the length of the queue of vehicles stopped by the signal at the time the estimation is performed by the retention length estimation unit 122.

[0063] The signal control unit 110 further includes a residence length correction unit 124 for correcting the residence length estimated by the residence length estimation unit 122, if necessary, in response to receiving probe information from a probe vehicle present on the ramp way 60 via the receiving unit 100, and a control signal generation unit 126 for generating signal parameters for the traffic light 62 based on the residence length estimated by the residence length estimation unit 122 and the output of a vehicle detector provided on the general road 58. The signal control unit 110 further includes a control signal transmission unit 128 for transmitting the signal parameters generated by the control signal generation unit 126 to the traffic light 62.

[0064] b1) Inflow Number Calculation Unit 102 Figure 3 shows, in flowchart form, the control structure of a program for implementing the inflow number calculation unit 102 shown in Figure 2. Referring to Figure 3, this program includes step 150 for initializing to 0 a variable Cin for counting the number of inflowing vehicles within a predetermined time interval and a variable IX, which is an index of the storage area of ​​the inflow number storage unit 104, and step 152 for initializing the storage area of ​​the inflow number storage unit 104. This program further includes step 154 ​​for acquiring the current time, and step 156 for determining whether the current time acquired in step 154 ​​has exceeded the boundary of the above-mentioned predetermined time interval and branching the control flow according to the result of the determination. As will be described later, the inflow number storage unit 104 includes multiple storage areas. The variable IX is an index for accessing a predetermined area within the storage area.

[0065] The processing of step 156 is as follows. In this embodiment, the predetermined time interval is set to 5 seconds as an example. That is, the number of incoming vehicles is counted every 5 seconds. For example, if the previous time interval is from 9:00:00 to 9:00:05, the next time interval is from 9:00:05 to 9:00:10. The boundary is the boundary at which the time interval changes, and in this example, it is 9:00:05. In this embodiment, the boundary belongs to the previous time interval. That is, anything before 9:00:05 is the previous time interval, and anything after 9:00:05 is the next time interval. The same applies below. In step 156, it is determined whether this boundary has been crossed.

[0066] The length of this time interval can be set freely, but it is desirable to select the length of the time interval so that it can be divided evenly into the cycle of the traffic light to be controlled.

[0067] The program further includes step 158, in response to the affirmative determination in step 156, saving the value of variable Cin in area (IX) of inflow number storage unit 104, step 160, adding 1 to the value of variable IX and performing a modulo operation (indicated by the operator "%") with a constant MAX to update the value of variable IX based on the result, and step 162, clearing the value of variable Cin to 0. Note that constant MAX is equal to the number of areas used in inflow number storage unit 104. In other words, constant MAX is the maximum value of the index plus 1, which is 24 in this example.

[0068] This program further includes step 164, which is executed when the determination in step 156 is negative and after the processes of steps 158 to 162 have been executed when the determination in step 156 is positive, for determining whether or not a signal indicating that an oncoming vehicle has been detected has been received from vehicle detector 70 via receiver 100 and branching the flow of control in accordance with the result of the determination, and step 166, which, in response to the determination in step 164 being positive, adds 1 to variable Cin and returns control to step 154. If the determination in step 164 is negative, control returns to step 154.

[0069] b2) Incoming Number Storage Unit 104 Referring to FIG. 4 , the incoming number storage unit 104 in this embodiment is divided into 60 storage areas. Each storage area corresponds to a predetermined time period. However, not all storage areas are necessarily used. In this embodiment, only a portion of these storage areas corresponding to the period of the traffic light cycle is used. For example, if the predetermined time period is 5 seconds as described above and the period of the traffic light cycle is 120 seconds, 24 of the 60 storage areas in the incoming number storage unit 104, corresponding to 120 seconds, are used. Index IX is used to access each storage area. That is, the number of incoming vehicles counted during the first 5 seconds of each traffic light cycle is stored in area (0), the number of incoming vehicles counted during the next 5 seconds is stored in area (1), and so on. Similarly, the number of incoming vehicles counted during the last 5 seconds of the traffic light cycle is stored in area (23). When the next traffic light cycle begins, the number of incoming vehicles counted during the first 5 seconds is again stored in area (0). This process is repeated.

[0070] b3) Outflow number calculation unit 106 Fig. 5 shows the control structure of a program that realizes the outflow number calculation unit 106. The control structure of this program is the same as that shown in Fig. 3.

[0071] 5, this program includes step 200 for initializing to 0 a variable Cout for counting the number of exiting vehicles within a predetermined time interval and a variable IX serving as an index of a storage area in exiting number storage unit 108, and step 202 for initializing the storage area in exiting number storage unit 108. This program further includes step 204 for acquiring the current time, and step 206 for determining whether the current time acquired in step 204 has exceeded the boundary of the above-mentioned predetermined time interval and branching the control flow in accordance with the result of the determination. As will be described later, exiting number storage unit 108 includes multiple storage areas. Variable IX is an index for accessing a predetermined area within the storage area.

[0072] The program further includes step 208, in response to a positive determination in step 206, of saving the value of variable Cout in area (IX) of outflow number memory unit 108, step 210, in which 1 is added to the value of variable IX and a mod operation using MAX is performed to update the value of variable IX, and step 212, in which the value of variable Cout is cleared to 0.

[0073] This program further includes step 214, which is executed when the determination in step 206 is negative and after the processes of steps 208 to 212 have been executed when the determination in step 206 is positive, for determining whether or not a signal indicating that an outflowing vehicle has been detected has been received from vehicle detector 70 via receiver 100 and branching the flow of control in accordance with the result of the determination, and step 216, which, in response to the determination in step 214 being positive, adds 1 to variable Cout and returns control to step 204. If the determination in step 214 is negative, control returns to step 204.

[0074] b4) Outflow number storage unit 108 Fig. 6 shows the configuration of the outflow number storage unit 108. The outflow number storage unit 108 has exactly the same configuration as the inflow number storage unit 104 shown in Fig. 4. In other words, the outflow number storage unit 108 has 60 areas indicated by indexes 0 to 59.

[0075] b5) Signal Control Unit 110 Figure 7 shows in flowchart form the control structure of the program that realizes the signal control unit 110. This program is started at a fixed time interval, for example, at each signal cycle of the controlled object. In this embodiment, this program is started every 120 seconds to calculate signal parameters.

[0076] 7, this program includes step 250 of acquiring the current time, and step 252 of reading the number of incoming vehicles in the most recent unit time from incoming number storage unit 104. In this embodiment, the unit time is 120 seconds, which is the cycle time of traffic light 62. The number of incoming vehicles in the most recent 120 seconds is stored in incoming number storage unit 104. Therefore, by reading out all the incoming numbers stored in incoming number storage unit 104 and calculating the sum thereof, the number of incoming vehicles in the most recent unit time (120 seconds) can be calculated.

[0077] This program further includes step 254 of reading the number of departing vehicles per unit time in the past from departing number calculation unit 106, similar to step 252, step 256 of calculating the difference between the number of entering vehicles obtained in step 252 and the number of departing vehicles obtained in step 254, and step 258 of branching the flow of control depending on whether the difference calculated in step 256 is equal to or greater than a predetermined threshold value. If the determination in step 258 is positive, it is determined that first-direction road 54 is congested.

[0078] In this embodiment, as described above, whether the first-direction road 54 is congested or not is measured using only two levels (congested and not congested). However, this disclosure is not limited to such an embodiment. The degree of congestion may be classified into multiple levels using multiple thresholds.

[0079] The program further includes step 274, in response to the affirmative determination in step 258, attempting to acquire the vehicle status in the connection area 80 (see FIG. 1) between the first direction road 54 and the ramp way 60. Specifically, in step 274, it is determined whether probe information has been received from any probe vehicle, and, if probe information has been received, whether the vehicle is located within the connection area 80.

[0080] This program further includes step 276, which determines whether the vehicle status information has been received as a result of the processing of step 274 and branches the control flow according to the result; and step 278, which determines whether the vehicle status satisfies a congestion condition and branches the control flow according to the result in response to a positive determination in step 276. The congestion condition used in step 278 may be, for example, whether the traveling speed of the probe vehicle is equal to or less than a threshold value (e.g., 15 km / h) or whether the vehicle position remains the same for a certain period of time (e.g., one minute). In the former case, the traveling speed may be an individual vehicle speed or a statistical speed. In the latter case, it is assumed that the traveling trajectory of the probe vehicle can be obtained from the probe information. Even if the determination in step 258 is negative, if the determinations in steps 276 and 278 are both positive, the first-direction road 54 is determined to be congested.

[0081] This program further includes step 260, in response to a positive determination in step 258 or a positive determination in step 278, of determining that the ramp way 60 is congested and estimating the queue length as an index representing congestion on the ramp way 60. In step 260, the queue length is estimated, for example, using the difference calculated in step 256 as the number of vehicles and an average headway of, for example, 7 m. In the calculation of signal parameters, which will be described later, this queue length and the length of the ramp way 60 are important inputs.

[0082] This program further includes step 262 of attempting to acquire probe information from a probe vehicle present on the ramp way 60. This program further includes step 264 of branching the flow of control depending on whether or not probe information has been acquired from a probe vehicle present on the ramp way 60 as a result of the processing of step 262, and step 266 of correcting the residence length estimated in step 260 using the probe information acquired in step 262 in response to the determination in step 264 being affirmative.

[0083] An example of the correction performed in step 266 is as follows. For example, assume that the calculated difference is 10 vehicles. In this case, the estimated waiting length is 70 m. If the probe information reveals that the probe vehicle's stopping position is 90 m from the front of the vehicle line, the estimated waiting length is too short. Therefore, the signal control unit 110 corrects the waiting length to 90 m in step 266. This is because it is known that the actual waiting length is at least 90 m. Conversely, if the probe vehicle's position is closer to the front than the estimated waiting length, the signal control unit 110 maintains the estimated waiting length. This is because the probe vehicle is not necessarily at the end of the vehicle line.

[0084] The program further includes, in response to the completion of step 266 or a negative determination in step 264, step 268 of obtaining the congestion status of the general road 58 on the intersecting side from information from vehicle detectors installed on the general road 58, step 270 of calculating signal parameters using the information obtained by the processing of steps 262 to 268 in a manner similar to that of normal sensory control, and step 272 of transmitting the calculated signal parameters to the traffic light 62 and terminating execution of the program.

[0085] The program further includes step 280, in response to a negative determination in step 276 or step 278, of setting the signal parameters for traffic light 62 to predetermined fixed-cycle parameters and transferring control to step 272.

[0086] 1.2) Operation The signal control system 50 according to the first embodiment described above operates as follows.

[0087] When signal control is started in the signal control server 68 shown in Figure 1, a program for the inflow number calculation unit 102 shown in Figure 3, a program for the inflow number storage unit 104 shown in Figure 5, and a program for the signal control unit 110 shown in Figure 7 are started.

[0088] a) Inflow Number Calculation Unit 102 Referring to FIG. 3, the inflow number calculation unit 102 initializes variables Cin and IX to 0 (step 150). The inflow number calculation unit 102 also initializes the storage area of ​​the inflow number storage unit 104 (step 152). Next, the inflow number calculation unit 102 acquires the current time (step 154). The inflow number calculation unit 102 further determines whether the current time acquired in step 154 ​​exceeds the boundary of the above-mentioned predetermined time interval, and branches the control flow according to the result (step 156). The current time is not set immediately after this program is started. Therefore, the determination in step 156 is affirmative, and control proceeds to step 158.

[0089] The inflow number calculation unit 102 saves the value of the variable Cin (which is 0 at this point) in the area (0) of the inflow number storage unit 104 (step 158). After this, the inflow number calculation unit 102 adds 1 to the value of the variable IX. As a result, the value of the variable IX becomes 1. The inflow number calculation unit 102 further performs a modulo operation on the variable IX using the constant MAX=24, and updates the value of the variable IX based on the result (step 160). As a result, the value of the variable IX becomes 1. The inflow number calculation unit 102 clears the value of the variable Cin to 0 (step 162).

[0090] The inflow number calculation unit 102 further determines whether or not a signal indicating that an inflowing vehicle has been detected has been received from the vehicle detector 70 via the receiving unit 100 (step 164). When a signal indicating that an inflowing vehicle has been detected is received, the inflow number calculation unit 102 adds 1 to the value of the variable Cin (step 166). Thereafter, control returns to step 154. If the determination in step 164 is negative, step 166 is not executed and control immediately returns to step 154.

[0091] The above-described process is then repeated. Note that the determination in step 156 remains negative until a predetermined time period has elapsed during the following repetition. Therefore, if a vehicle detection signal is received, 1 is added to the value of variable Cin in step 166. If no vehicle detection signal is received, the value of variable Cin remains unchanged.

[0092] When the predetermined time period has elapsed, the determination in step 156 becomes affirmative. The value of variable Cin is stored in area (IX) (step 158). One is added to variable IX, and modulo MAX division is performed, updating variable IX with the result. As a result, variable IX increases from 0 to 23 every predetermined time period, and then returns to 0 repeatedly. The number of incoming vehicles counted during the predetermined time period is stored in a storage area indicated by variable IX before updating. In this way, incoming number storage unit 104 operates as a ring buffer, and the number of incoming vehicles for the most recent past one cycle period is always stored in incoming number storage unit 104 in 5-second intervals.

[0093] b) Outflow number calculation unit 106 The operation of the outflow number calculation unit 106 is similar to that of the inflow number storage unit 104. However, the operation of the outflow number calculation unit 106 differs from that of the inflow number storage unit 104 in that the input signal is a detection signal of an outflowing vehicle from the vehicle detector 74, and that the number of outflowing vehicles for the most recent one cycle period every five seconds is stored in the outflow number storage unit 108.

[0094] c) Signal Control Unit 110 When the signal control server 68 is started, a program for the signal control unit 110, whose control structure is shown in Fig. 7, is started every cycle. The signal control unit 110 acquires the current time at the beginning of each cycle (step 250). The signal control unit 110 further reads the number of incoming vehicles in the most recent unit time (120 seconds) from the incoming number storage unit 104 (step 252). The signal control unit 110 reads all the incoming numbers stored in the incoming number storage unit 104 and calculates their sum to calculate the number of incoming vehicles in the most recent unit time (120 seconds).

[0095] Similarly to step 252, signal control unit 110 further reads the number of exiting vehicles per unit time in the past from exiting number calculation unit 106 (step 254). Signal control unit 110 calculates the difference between the number of entering vehicles obtained in step 252 and the number of exiting vehicles obtained in step 254 (step 256). Signal control unit 110 further branches the control flow according to whether the difference calculated in step 256 is equal to or greater than a predetermined threshold value (step 258).

[0096] If the determination in step 258 is affirmative, the signal control unit 110 determines that the first-direction road 54 is congested. As a result, the signal control unit 110 executes the processes from step 260 onward. If the determination is negative, the signal control unit 110 tentatively determines that the first-direction road 54 is not congested. However, just to be sure, the signal control unit 110 operates as follows.

[0097] That is, in this case, the signal control unit 110 attempts to acquire the vehicle status in the connection area 80 (see FIG. 1 ) between the first-direction road 54 and the ramp way 60 (step 274). Specifically, in step 274, the signal control unit 110 determines whether probe information has been received from any probe vehicle, and if probe information has been received, whether the vehicle's location is within the connection area 80. The signal control unit 110 determines whether the vehicle status information has been received as a result of the processing in step 274 and branches the control flow according to the result (step 276). If the determination in step 276 is positive, the signal control unit 110 further determines whether the vehicle status satisfies the congestion condition and branches the control flow according to the result (step 278). If the determination in step 278 is positive, the signal control unit 110 determines that the first-direction road 54 is congested, even though it was determined in step 258 that the first-direction road 54 is not congested. As a result, the signal control unit 110 executes the processing from step 260 onward.

[0098] On the other hand, if the determination in step 276 or the determination in step 278 is negative, the signal control unit 110 determines that the first-direction road 54 is not congested. As a result, control proceeds to step 280. In this case, the signal control unit 110 sets the signal parameters for the traffic light 62 to the fixed-cycle parameters that have been prepared in advance (step 280). Finally, the signal control unit 110 transmits these signal parameters to the traffic light 62 (step 272), and the signal control unit 110 ends the execution of the program for this cycle.

[0099] In contrast, if the determination in step 258 is positive and if the determination in step 278 is positive, the signal control unit 110 estimates the waiting length as an indicator of congestion on the ramp way 60 (step 260). The signal control unit 110 then attempts to acquire probe information from a probe vehicle present on the ramp way 60 (step 262). If, as a result of the processing in step 262, probe information from a probe vehicle present on the ramp way 60 is obtained (the determination in step 264 is positive), the signal control unit 110 corrects the waiting length estimated in step 260 using the probe information acquired in step 262 (step 266). If the determination in step 264 is negative, the signal control unit 110 does not perform the processing in step 266, and uses the waiting length estimated in step 260 as is in the subsequent processing.

[0100] The signal control unit 110 further obtains the congestion status of the general road 58 on the intersecting side from information from a vehicle detector installed on the general road 58 (step 268). Using the information obtained by the processes of steps 262 to 268, the signal control unit 110 calculates signal parameters in the same manner as in normal sensory control (step 270). The signal control unit 110 transmits the calculated signal parameters to the traffic light 62 and ends the execution of the program for this cycle (step 272).

[0101] As described above, according to this embodiment, even if a vehicle detector is not installed on the rampway, the congestion level of the rampway can be determined as long as a vehicle detector is present on the upstream or downstream side or both of the main line. Therefore, even on rampways where vehicle detectors cannot be installed, the exit traffic light can be controlled as a sensor-based traffic light. The congestion length, which is an indicator of the congestion level of the rampway, is estimated based on the congestion level of the main line. Information for controlling the exit traffic light of the rampway as a sensor-based traffic light can be generated without the need to install vehicle detectors on the rampway. It is believed that there is a correlation between the number of vehicles entering a specified section per unit time and the number of vehicles on the rampway. Therefore, the congestion level of the rampway can be estimated from the number of entering vehicles. The number of vehicles entering the rampway from the main line can be reliably estimated based on the difference between the number of vehicles entering the specified section and the number of vehicles exiting the specified section. The congestion level of the rampway can be reliably estimated based on this estimation result. It is also believed that there is a correlation between the number of exiting vehicles counted by a vehicle detector installed downstream and the number of vehicles entering the rampway. Therefore, without installing a vehicle detector on the rampway, the degree of congestion on the rampway can be estimated by using the output of a downstream vehicle detector installed on the main line.

[0102] If a probe vehicle is present in the connection area where the main line branches off to a rampway, the probe information obtained from the probe vehicle can be used to estimate the vehicle's speed, stopping time, and other factors near the connection area. These are strongly correlated with the congestion levels of the main line and the rampway. Therefore, the congestion levels of the main line and the rampway can be estimated using the probe information, increasing the reliability of the estimation. If a probe vehicle is present in the rampway, the probe information can be used to estimate the congestion length within the rampway. By correcting the congestion length using this value, the accuracy of the congestion level estimation for the rampway can be improved. Signal parameters are generated using the estimation results and the traffic conditions on the general road. As a result, traffic lights at the rampway exit can be appropriately controlled based on the conditions of both the rampway and the general road. If a given section has multiple lanes, vehicles entering the rampway should have already moved into the lane on the rampway side before entering. Therefore, there is a correlation between the congestion level of vehicles in the lane on the rampway side and the congestion level within the rampway. The traffic conditions within the rampway can be estimated using the output of vehicle detectors for the lane on the rampway side of the main line. As a result, the traffic conditions within the rampway can be estimated without installing a vehicle detector on the rampway.

[0103] However, if the unit time is too long, appropriate signal control cannot be performed. Furthermore, if the unit time is shorter than one period, the operation of the traffic light will change before one cycle of the traffic light is completed, which is undesirable. Therefore, the unit time should be equal to two or fewer periods of the traffic light cycle and one or more periods, for example, two or one period. The unit time may also be the time of one period of the traffic light cycle at a signalized intersection. By making the unit time equal to one period of the traffic light cycle, it is possible to respond quickly to changes in traffic volume. Furthermore, the operation of the traffic light will not change midway through the cycle.

[0104] In the above embodiment, downstream vehicle detectors are used to estimate the congestion level of the main lane based on the difference between the number of oncoming vehicles detected by upstream vehicle detectors and the number of oncoming vehicles detected by downstream vehicle detectors. Furthermore, the congestion level of the rampway is estimated based on the estimated congestion level of the main lane. However, this disclosure is not limited to such an embodiment. A configuration in which downstream vehicle detectors are not used is also conceivable. Generally, it is believed that a certain relationship (e.g., a proportional relationship) exists between vehicles entering and exiting a certain section of a road that has a rampway formed along the way. Therefore, the difference between the two can be estimated by simply counting the number of vehicles entering that section and multiplying that value by a certain ratio. That is, instead of steps 254 and 256 in FIG. 7 , a step may be introduced in which the number of oncoming vehicles read in step 252 is multiplied by a predetermined coefficient to obtain an estimated value of the difference between the number of oncoming and exiting vehicles. If it is statistically determined that the ratio varies depending on the day type, time of day, etc., the coefficient can be changed depending on the day type, time of day, etc.

[0105] It should be noted that, by using the same logic, it is also possible to use the output of the downstream vehicle detector without using the upstream vehicle detector.

[0106] Furthermore, it is considered normal for vehicles entering the rampway from the main road to travel in the leftmost lane (in Japan) in preparation for this. Given this situation, it is possible to realize the same functionality as in the above embodiment by using both the number of vehicles entering the section including the rampway via the leftmost lane and the number of vehicles exiting the section via the leftmost lane, or by using only one of these. In this case, it is sufficient to limit the vehicle detector used in the above embodiment to the leftmost one. Note that in countries or regions where vehicles are required to drive on the right side, only the rightmost vehicle detector is used.

[0107] Furthermore, in the above embodiment, the congestion level of the main lane is first estimated based on the output of the vehicle detector, and only if it is determined that the main lane is not congested (if the determination in step 258 is negative) is the congestion level determined using a probe vehicle (steps 274 to 278). However, this disclosure is not limited to such an embodiment. The congestion level of the main lane may be determined by processing only steps 274 to 278 without using the output of the vehicle detector. This method is particularly effective when the number of probe vehicles reaches a certain percentage or more. Furthermore, the method of using only upstream or downstream vehicle detectors described above can be combined with the method of using this probe information. The same applies when using only the vehicle detector in the leftmost lane.

[0108] 2. Second Embodiment 2.1) Configuration a) Overall Configuration In the first embodiment described above, both vehicle detectors installed on the upstream side of the ramp and vehicle detectors installed on the downstream side are used. The outputs of these vehicle detectors are used to estimate the congestion level on the main line, and the results are then used to estimate the congestion level on the ramp. In this type of processing, the estimation of the congestion level on the ramp may lag behind the actual congestion level on the ramp. In other words, even when the ramp begins to become congested, this will not become clear until one cycle later, when the number of vehicles entering the section becomes clear. Therefore, there is a possibility that the change in signal parameters may also be delayed by one cycle. The second embodiment takes this possibility into account.

[0109] Figure 8 shows the overall configuration of a signal control system 320 according to the second embodiment. Figure 8 shows the expressway 52 in Figure 1 extended to the right, extending up to the vicinity of an upstream vehicle detector 330 located further upstream than the vehicle detector 70. A vehicle detector 332 is also located on the second direction road 56 at the same position as the upstream vehicle detector 330. However, the vehicle detector 332 has no direct relationship to this embodiment.

[0110] 1 , the signal control system 320 includes a signal control server 334 that has the function of receiving a vehicle detection signal not only from the vehicle detector 70 and the vehicle detector 74 but also from an upstream vehicle detector 330 located further upstream than the vehicle detector 70, and estimating the degree of congestion on the first-direction road 54 in the section between the vehicle detector 70 and the vehicle detector 74. In other respects, the signal control system 320 has the same configuration as the signal control system 50 according to the first embodiment. In the following description, the number of oncoming vehicles detected by the upstream vehicle detector 330 will be referred to as the "upstream oncoming vehicle number" or the "upstream oncoming number."

[0111] b) Signal Control Server 334 Referring to Figure 9, compared to the signal control server 68 according to the first embodiment, the signal control server 334 according to the second embodiment has functions similar to the inflow number calculation unit 102 and the inflow number storage unit 104, and differs from the signal control server 68 in that it includes an upstream inflow number calculation unit 402 for calculating the number of upstream inflow vehicles passing the upstream vehicle detector 330 for each predetermined time interval in response to a vehicle detection signal from the upstream vehicle detector 330, and an upstream inflow number storage unit 404 for storing the number of upstream inflow vehicles calculated by the upstream inflow number calculation unit 402 for each predetermined time interval.

[0112] The signal control server 334 further differs from the signal control server 68 according to the first embodiment in that, instead of the signal control unit 110 of the signal control server 68, it has a signal control unit 400 that is connected to the inflow number storage unit 104, the outflow number calculation unit 106, and the upstream inflow number storage unit 404, and that generates and transmits a control signal for the traffic light 62 to the traffic light 62 based on the series of inflow vehicle numbers, outflow vehicle numbers, and upstream inflow vehicle numbers stored in these units, as well as probe information received by the receiving unit 100, if any. The other functional units (the receiving unit 100, the inflow number calculation unit 102, the inflow number storage unit 104, the outflow number calculation unit 106, and the outflow number storage unit 108) are the same as those in the first embodiment.

[0113] 1 differs from the signal control unit 110 in that it includes, instead of the traffic condition estimation unit 120, a traffic condition prediction unit 410 for predicting the congestion situation on the main line of the first direction road 54 at the next stop, based on the number of inflows in the most recent unit time recorded in the inflow number memory unit 104, the number of outflows in the most recent unit time stored in the outflow number memory unit 108, the number of upstream inflows in the most recent unit time stored in the upstream inflow number memory unit 404, and, if probe information is received via the receiving unit 100, the probe information. The other functional units of the signal control unit 400 are the same as the corresponding functional units in the signal control unit 110.

[0114] b1) Traffic Condition Prediction Unit 410 Figure 10 is a flowchart showing the control structure of a program that realizes traffic condition prediction unit 410. Referring to Figure 10, this program has almost the same configuration as that shown in Figure 7, but differs from that shown in Figure 7 in that it includes step 450 between step 250 and step 252, in which the upstream inflow number for the most recent unit time in the past is read from upstream inflow number storage unit 404, and in that it includes step 452, instead of step 256 in Figure 7, in which the difference between the inflow number and the outflow number in the section between vehicle detector 70 and vehicle detector 74 is predicted based on the information read in step 450, step 252, and step 254, and output as a difference prediction. The contents of the other processing steps are the same as those shown in Figure 7.

[0115] In step 450, the traffic condition prediction unit 410 reads the most recent upstream inflow count stored in the upstream inflow count storage unit 404 as described above. This upstream inflow count is, so to speak, a value that anticipates the number of inflows detected by the vehicle detector 70. Therefore, by using the upstream inflow count, it is possible to predict the difference between the number of inflowing vehicles and the number of outflowing vehicles in the next cycle. Based on the predicted difference, it becomes possible to calculate signal parameters appropriate for the actual number of vehicles exiting the ramp way 60 onto the general road 58 without any time delay.

[0116] The difference is predicted in step 452. Assuming that there are no other rampways between the upstream vehicle detector 330 and the vehicle detector 70, all vehicles detected by the upstream vehicle detector 330 will also be detected by the vehicle detector 70. However, there is a time lag between them, and this time lag varies depending on the vehicle speed. However, assuming that vehicle speeds follow a certain distribution (e.g., a normal distribution), there will not be a significant error even if we assume that all vehicles arrive at the vehicle detector 70 at a speed that is the average of the speeds at which they were detected. As a result, it is sufficient to assume that all vehicles that pass the upstream vehicle detector 330 arrive at the vehicle detector 70 after a certain time. This certain time depends on the distance between the upstream vehicle detector 330 and the vehicle detector 70. However, this time is likely to vary depending on the day, time of day, weather, etc.

[0117] Therefore, in this embodiment, the number of inflowing vehicles used to predict the difference in step 452 is determined as the number of inflowing vehicles into the section, which is the weighted average of the number of vehicles detected by upstream vehicle detector 330 and the number of vehicles detected by vehicle detector 70 in the same unit time. Using the same concept, the number of outflowing vehicles is determined as the weighted average of the number of vehicles detected by vehicle detector 70 and the number of vehicles detected by vehicle detector 74 in the same unit time. The difference between the predicted number of inflowing vehicles and the predicted number of outflowing vehicles is the predicted difference (predicted difference) that will be detected in the next cycle. This predicted difference is used in subsequent processing instead of the difference used in the first embodiment.

[0118] The weight value used in the weighted average of the number of inflowing vehicles on the upstream side and the number of inflowing vehicles varies depending on the distance between the upstream vehicle detector 330 and the vehicle detector 70. For example, when the distance between the upstream vehicle detector 330 and the vehicle detector 70 is large, it is appropriate to weight the number of inflowing vehicles on the upstream side smaller than when the distance is small. The same applies to the weight value used in the weighted average of the number of inflowing vehicles and the number of outflowing vehicles.

[0119] 2.2) Operation The signal control server 334 according to the second embodiment operates as follows: The upstream vehicle detector 330, the vehicle detector 70, and the vehicle detector 74 each detect a passing vehicle and transmit a detection signal to the signal control server 334.

[0120] The upstream inflow number calculation unit 402, the inflow number calculation unit 102, and the outflow number calculation unit 106 of the signal control server 334 respond to these signals and count and store the number of detected vehicles for each predetermined time interval.

[0121] 10 is started, the number of entering vehicles on the upstream side, the number of entering vehicles, and the number of exiting vehicles are read in steps 450, 252, and 254. In step 452, these values ​​are used to calculate a predicted difference between the number of entering vehicles and the number of exiting vehicles for the next cycle. Using the predicted difference, the processing from step 258 onwards is executed, as in the first embodiment. Based on the results, the next signal parameters are calculated and used to control the traffic light 62.

[0122] As described above, according to this embodiment, the vehicle detection signal from the upstream vehicle detector 330 is used to predict the number of oncoming and offcoming vehicles in the next cycle, and signal parameters for the next cycle are calculated based on the prediction. As a result, in the next cycle, signals can be controlled using signal parameters corresponding to the actual congestion level of the main line and the actual congestion level of the rampway 60. As a result, even if it is difficult to install a vehicle detector on the rampway 60, the traffic light at the exit of the rampway 60 can be controlled as a sensor-based traffic light using a vehicle detector on the main line. The number of vehicles entering a specified section in the future can be estimated based on the output of an upstream vehicle detector located further upstream than the upstream vehicle detector. By correcting the output of the upstream vehicle detector using this value, the congestion level of the main line can be predicted using not only the number of vehicles entering the specified section but also the predicted number of vehicles. Using this congestion level to estimate the congestion level of the rampway reduces the delay in estimating the congestion level, and more appropriate signal parameters can be generated.

[0123] In the program shown in FIG. 10, steps 252, 254, and 450 may be performed in any order as long as they are performed between steps 250 and 452.

[0124] 3. Implementation by a Computer The signal control server 68 according to the first embodiment and the signal control server 334 according to the second embodiment are both implemented by computer hardware including a processor, a program executed by the computer hardware, and data stored in the computer hardware. Fig. 11 shows the external appearance of a computer system that implements the signal control server 68, for example, and Fig. 12 shows the internal configuration of the computer system shown in Fig. 11. The same applies to the signal control server 334.

[0125] Referring to FIG. 11, signal control server 68 includes a computer 640 having a DVD (Digital Versatile Disc) drive 650 and an input / output I / F (Interface) 652 , a keyboard 646 , a mouse 648 , and a monitor 642 .

[0126] 12 , computer 640 includes, in addition to DVD drive 650, a CPU (Central Processing Unit) 656, a GPU (Graphics Processing Unit) 658, a bus 666 connected to CPU 656, GPU 658, and DVD drive 650, a ROM (Read-Only Memory) 660 that stores a boot-up program and the like, a RAM (Random Access Memory) 662 connected to bus 666 and that stores program instructions, system programs, working data, and the like during execution, and a SSD (Solid State Drive) 654 that is a non-volatile memory. Computer 640 further includes a network I / F 670 that provides connection to a network 668 that enables communication with other terminals. The network I / F 670 can receive signals from each vehicle detector via the network 668 and transmit signal parameters to the signal control device of the traffic light 62. Although not shown in Fig. 12, instead of the network I / F 670, the computer 640 may be provided with a wireless communication device that connects to the network 668 via a mobile phone network.

[0127] In each of the above embodiments, the variables Cin, Cout, and IX, as well as the constant MAX, are all stored in the RAM 662 shown in Fig. 12. The inflow number storage unit 104, the outflow number storage unit 108, and the upstream inflow number storage unit 404 shown in Fig. 4, Fig. 6, Fig. 9, etc., respectively, are provided as storage areas within the SSD 654.

[0128] A program for operating this computer system as the signal control server 68 and each of its constituent elements is stored on a DVD 664 inserted in a DVD drive 650 and transferred from the DVD drive 650 to the SSD 654. Alternatively, the program may be stored in a portable memory 672 and transferred to the SSD 654 via the input / output I / F 652. Furthermore, the program may be transmitted to the computer 640 via a network 668 and stored in the SSD 654. The program is loaded into the RAM 662 when executed. The program may also be loaded directly into the RAM 662 from the DVD 664 or the portable memory 672, or via the network 668 and the network I / F 670.

[0129] This program includes a plurality of instructions that cause the computer 640 to operate as the signal control server 68 according to the above embodiment. Some of the basic functions required for this operation are provided by an operating system (OS) or third-party programs running on the computer 640, or by modules of various toolkits installed on the computer 640. Therefore, this program does not necessarily include all of the functions required to realize the system and method of this embodiment. The program need only include instructions that execute the operations of the signal control server 68 and its components by calling appropriate functions or "programming toolkits" in a controlled manner to achieve the desired results. The operation of the computer 640 is well known, and therefore will not be repeated here. Note that the GPU 658 is capable of parallel processing and can execute functions for controlling many traffic lights in parallel.

[0130] Furthermore, the signal control server 68 and the signal control server 334 may be realized by multiple computers capable of operating in parallel, rather than by a single computer, and some or all of their functions may be located in a so-called cloud. In this case, even if the hardware that realizes some of the functions of the signal control system 50 described above is located outside the territory of this country, the system is included in the scope of the present disclosure as long as it is provided within this country.

[0131] Each process (each function) in the above-described embodiments is realized by a processing circuit (circuitry) including one or more processors. The processing circuit may be configured with an integrated circuit that combines one or more memories, various analog circuits, and various digital circuits in addition to the one or more processors. The one or more memories store programs (instructions) that cause the one or more processors to execute each of the processes. The one or more processors may execute each of the processes according to the program read from the one or more memories, or according to a logic circuit designed in advance to execute each of the processes. The processor may be a CPU, GPU, DSP (Digital Signal Processor), FPGA (Field-Programmable Gate Array), ASIC (Application Specific Integrated Circuit), or any other processor suitable for computer control. The physically separated processors may cooperate with each other to execute the processes. For example, the processors installed in the physically separated computers may cooperate with each other via a network such as a local area network (LAN), a wide area network (WAN), or the Internet to execute the processes. The program may be installed in the memory from an external server device or the like via the network, or may be distributed in a state stored on a storage medium such as a compact disc read-only memory (CD-ROM), a DVD read-only memory (DVD-ROM), or a semiconductor memory, and installed in the memory from the storage medium.

[0132] 4. Supplementary Note (1) A computer-readable non-transitory storage medium storing a computer program that causes a computer to function as a main line congestion degree estimation unit that estimates the congestion degree of a predetermined section of a main line, and a retention length estimation unit that estimates the retention length in a ramp way that branches off from the main line toward a signalized intersection to another road, based on the congestion degree estimated by the congestion degree estimation unit.

[0133] (2) The method for estimating the length of stay includes a step of estimating the degree of congestion in a specified section of a main line, and a step of estimating the length of stay within a rampway branching off from the main line toward a signalized intersection to another road based on the degree of congestion estimated in the step of estimating the degree of congestion.

[0134] (3) The signal control method includes the steps of: estimating the degree of congestion in a specified section of a main line; estimating a dwell length in a rampway branching off from the main line toward a signalized intersection to another road based on the degree of congestion estimated in the step of estimating the degree of congestion; and controlling the period or split of a signal displayed at the signalized intersection based on the dwell length estimated in the step of estimating the dwell length.

[0135] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is not defined by the detailed description of the disclosure, but by the claims of the appended claims, and is intended to include all modifications within the meaning and scope of the claims.

[0136] 50, 320 Signal control system 52 Motorway 54 First direction road 56 Second direction road 58 General road 60, 64 Rampway 62, 66 Traffic light 68, 334 Signal control server 70, 72, 74, 76, 332 Vehicle detector 80 Connection area 82 Stocked vehicle line 84, 86 Probe vehicle 100 Receiving unit 102 Inflow number calculation unit 104 Inflow number storage unit 106 Outflow number calculation unit 108 Outflow number storage unit 110, 400 Signal control unit 120 Traffic condition estimation unit 122 Stock length estimation unit 124 Stock length correction unit 126 Control signal generation unit 128 Control signal transmission unit 330 Upstream vehicle detector 402 Upstream inflow number calculation unit 404 Upstream inflow number storage unit 410 Traffic condition prediction unit 640 Computer 642 Monitor 646 Keyboard 648 Mouse 650 DVD drive 652 Input / output I / F 654 SSD 656 CPU 658 GPU 660 ROM 662 RAM 664 DVD 666 Bus 668 Network 670 Network I / F 672 Portable memory

Claims

1. A main line congestion estimation unit that estimates the congestion level of a predetermined section of the main line, and a residence time estimation unit that estimates the residence time in a rampway that branches from the main line toward a signal intersection to another road based on the congestion level estimated by the main line congestion estimation unit. An information processing apparatus.

2. The main line congestion estimation unit includes a unit time congestion estimation unit that estimates the congestion level of the predetermined section in each unit time based on at least the number of vehicles flowing into the predetermined section per unit time. The information processing apparatus according to claim 1.

3. The unit time congestion estimation unit includes an inflow number calculation unit that calculates the number of vehicles flowing into the predetermined section in each unit time, an outflow number calculation unit that calculates the number of vehicles flowing out of the predetermined section in each unit time, and a section congestion estimation unit that estimates the congestion level of the predetermined section based on the difference between the number of vehicles flowing in in each unit time calculated by the inflow number calculation unit and the number of vehicles flowing out in each unit time calculated by the outflow number calculation unit. The information processing apparatus according to claim 2.

4. The inflow number calculation unit calculates the number of vehicles flowing into the predetermined section in each unit time based on the output of a vehicle sensor provided on the upstream side of the predetermined section. The information processing apparatus according to claim 3.

5. In addition to the output of the vehicle sensor provided on the upstream side, the inflow number calculation unit calculates the predicted number of vehicles flowing into the predetermined section in each unit time based on the output of an upstream vehicle sensor provided further upstream than the vehicle sensor provided on the upstream side. The information processing apparatus according to claim 4.

6. The outflow number calculation unit calculates the number of vehicles flowing out of the predetermined section in each unit time based on the output of a vehicle sensor provided on the downstream side of the predetermined section. The information processing apparatus according to any one of claims 3 to 5.

7. The main line congestion estimation unit further includes a connection area congestion estimation unit that determines that the main line is congested based on the state of the first probe vehicle in the connection area where the rampway branches off from the main line. The information processing apparatus according to any one of claims 1 to 5.

8. Further, it includes a rampway residence time correction unit that corrects the residence time in the rampway based on the vehicle state information of the second probe vehicle existing in the rampway. The information processing apparatus according to any one of claims 1 to 5.

9. Further, it includes a signal control unit that controls the display cycle or split of the signal based on the residence time estimated by the residence time estimation unit. The information processing apparatus according to any one of claims 1 to 5.

10. The signal control unit controls the display cycle or split of the signal based on the residence time estimated by the residence time estimation unit and the residence time of the other road at the signal intersection. The information processing apparatus according to claim 9.

11. The main line congestion estimation unit includes a rampway side lane congestion estimation unit that estimates the congestion degree of the lane on the rampway side among the predetermined section. The information processing apparatus according to any one of claims 1 to 5.

12. The unit time is a time that is 2 cycles or less and 1 cycle or more of the cycle of the signal at the signal intersection. The information processing apparatus according to any one of claims 2 to 5.

13. The unit time is a time of 1 cycle of the cycle of the signal at the signal intersection. The information processing apparatus according to claim 12.

14. A main line congestion estimation unit that estimates the congestion degree of a predetermined section of the main line; A residence time estimation unit that estimates the residence time in the rampway that branches off from the main line toward the signal intersection to another road based on the congestion degree estimated by the main line congestion estimation unit; A signal control device including a signal control unit that controls the display period or split of the signal based on the residence time estimated by the residence time estimation unit.

15. A step in which a computer estimates the congestion level of a predetermined section of the main line, A residence time estimation method including a step in which a computer estimates the residence time in a rampway branching toward a signal intersection from the main line based on the congestion level estimated in the step of estimating the congestion level.

16. A step in which a computer estimates the congestion level of a predetermined section of the main line, A step in which a computer estimates the residence time in a rampway branching toward a signal intersection from the main line based on the congestion level estimated in the step of estimating the congestion level, A signal control method including a step in which a computer controls the display period or split of a signal provided at the signal intersection based on the residence time estimated in the step of estimating the residence time.

17. A computer, A main line congestion estimation unit that estimates the congestion level of a predetermined section of the main line, A computer program that functions as a residence time estimation unit that estimates the residence time in a rampway branching toward a signal intersection from the main line based on the congestion level estimated by the main line congestion estimation unit.