Traffic index calculation device, traffic index calculation method, and traffic index calculation program

Abstract

A traffic index calculation device according to the present invention is provided with: an acquisition unit that acquires traffic information of vehicles entering an intersection from inflow routes, said information being related to traffic conditions at the intersection; and an index calculation unit that calculates, on the basis of the traffic information acquired by the acquisition unit, a direction-specific traffic index which is the traffic index for at least one direction of travel at the intersection.

Description

Traffic index calculation device, traffic index calculation method, and traffic index calculation program

[0001] This application claims priority based on Japanese Patent Application No. 2023-97394, filed on June 14, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0002] Patent Document 1 (WO 2020 / 071040) describes the following calculation device: That is, the calculation device calculates a traffic index required for calculating a signal control parameter, and includes a first calculation unit that calculates normalized data in which a traffic variable of an incoming road at a target intersection is expressed as a ratio to a saturation traffic flow rate, and a second calculation unit that uses the normalized data to calculate the traffic index defined by an equation in which the traffic variable of the incoming road is included in the numerator and the saturation traffic flow rate is included in the denominator.

[0003] International Publication No. 2020 / 071040

[0004] The traffic index calculation device of the present disclosure includes an acquisition unit that acquires traffic information regarding traffic conditions at an intersection for vehicles entering the intersection from an incoming road, and an index calculation unit that calculates a directional traffic index, which is a traffic index for at least one direction of travel at the intersection, based on the traffic information acquired by the acquisition unit.

[0005] One aspect of the present disclosure can be realized not only as a traffic index calculation device equipped with such a characteristic processing unit, but also as a semiconductor integrated circuit that realizes part or all of the traffic index calculation device, or as a traffic signal control system that includes the traffic index calculation device.

[0006] Fig. 1 is a diagram illustrating a configuration of a traffic signal control system according to an embodiment of the present disclosure. Fig. 2 is a diagram illustrating a configuration of a traffic index calculation device according to an embodiment of the present disclosure. Fig. 3 is a diagram illustrating an example of a method for calculating traffic information by an acquisition unit in the traffic index calculation device according to an embodiment of the present disclosure. Fig. 4 is a diagram illustrating an example of a split calculated by a calculation unit in the traffic index calculation device according to an embodiment of the present disclosure. Fig. 5 is a flowchart defining an example of an operation procedure when the traffic index calculation device according to an embodiment of the present disclosure controls a traffic signal.

[0007] A technology has been developed to calculate signal control parameters used for remote control of traffic signals installed at intersections.

[0008] [Problem to be Solved by the Present Disclosure] There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of more appropriately controlling traffic signals in accordance with the traffic conditions at an intersection.

[0009] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a traffic index calculation device, a traffic index calculation method, and a traffic index calculation program that are capable of more appropriately controlling traffic signals according to traffic conditions at intersections.

[0010] Effect of the Present Disclosure According to the present disclosure, traffic signals can be controlled more appropriately in accordance with the traffic conditions at an intersection.

[0011] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0012] (1) A traffic index calculation device according to an embodiment of the present disclosure includes an acquisition unit that acquires traffic information regarding traffic conditions at an intersection for vehicles entering the intersection from an entrance road, and an index calculation unit that calculates a directional traffic index, which is a traffic index for at least one direction of travel at the intersection, based on the traffic information acquired by the acquisition unit.

[0013] In this way, by calculating directional traffic indices for the direction of travel at an intersection based on traffic information about the traffic conditions at the intersection, it is possible to control traffic signals using signal control parameters calculated based on directional traffic indices, which makes it possible to control traffic signals according to directional traffic demand, compared to a configuration in which traffic signals are controlled using signal control parameters calculated based on traffic indices for an incoming road. Therefore, it is possible to control traffic signals more appropriately according to the traffic conditions at the intersection.

[0014] (2) In (1) above, the acquisition unit may acquire, as the traffic information, a branching rate, which is the ratio of the number of vehicles in each direction of travel to the number of vehicles flowing into the intersection from the entering road, and the index calculation unit may calculate an entering road traffic index, which is a traffic index for the entering road, and calculate the directional traffic index, which is a traffic index for each direction of travel, based on the calculated entering road traffic index and the branching rate.

[0015] With this configuration, for example, the incoming road traffic index can be allocated to each traveling direction according to the branching rate, so that a more accurate traffic index by direction can be calculated.

[0016] (3) In (1) or (2) above, the acquisition unit may acquire, as the traffic information, a green time rate, which is the ratio of the green time for each direction of travel to the green time for the incoming road, and the index calculation unit may calculate an incoming road traffic index, which is a traffic index for the incoming road, and calculate the directional traffic index, which is a traffic index for each direction of travel, based on the calculated incoming road traffic index and the green time rate.

[0017] With this configuration, for example, the incoming road traffic index can be allocated to each direction of travel according to the green time rate, thereby enabling more accurate calculation of direction-specific traffic indexes. Furthermore, when the branching rate cannot be obtained, the green time rate, which is more easily obtainable than the branching rate, can be used to calculate direction-specific traffic indexes.

[0018] (4) In the above (2) or (3), the index calculation unit may calculate the incoming road traffic index based on probe information indicating measurement results related to vehicle travel.

[0019] With this configuration, it is possible to calculate the oncoming road traffic index without using the detection results from vehicle detectors, so that at intersections where vehicle detectors are not installed, traffic signals can be controlled more appropriately according to the traffic conditions at the intersection.

[0020] (5) In the above (4), the index calculation unit may calculate a delay time per vehicle due to waiting at a traffic light based on the probe information, and calculate the incoming road traffic index based on the calculated delay time.

[0021] With this configuration, the load factor of the incoming road can be calculated as an incoming road traffic index using the delay time.

[0022] (6) In any of (1) to (5) above, the acquisition unit may acquire, as the traffic information, a direction-specific travel time, which is the travel time for each direction of travel of a vehicle flowing into the intersection from the entrance road, and the index calculation unit may calculate, based on the direction-specific travel time, the direction-specific traffic index, which is a traffic index for each direction of travel.

[0023] With this configuration, it is possible to calculate more accurate direction-specific traffic indices than when using the branching rate and green time rate.

[0024] (7) In any of (1) to (6) above, the traffic index calculation device may further include a split calculation unit that calculates a split for each direction of travel based on the direction-specific traffic index calculated by the index calculation unit.

[0025] With this configuration, it is possible to calculate a more appropriate split according to traffic demand for each direction.

[0026] (8) In the above (7), the traffic index calculation device may further include a control unit that controls a traffic signal at the intersection based on the split calculated by the split calculation unit.

[0027] With this configuration, traffic signals can be controlled according to traffic demand in each direction.

[0028] (9) A traffic index calculation method according to an embodiment of the present disclosure is a traffic index calculation method in a traffic index calculation device, and includes the steps of: acquiring traffic information regarding traffic conditions at an intersection for a vehicle entering an intersection from an entrance road; and calculating, based on the acquired traffic information, a directional traffic index that is a traffic index for at least one direction of travel at the intersection.

[0029] In this way, the method of calculating directional traffic indicators for the direction of travel at an intersection based on traffic information about the traffic conditions at the intersection makes it possible to control traffic signals using signal control parameters calculated based on directional traffic indicators, which makes it possible to control traffic signals according to directional traffic demand, compared to methods of controlling traffic signals using signal control parameters calculated based on traffic indicators for incoming roads. Therefore, it is possible to control traffic signals more appropriately according to the traffic conditions at the intersection.

[0030] (10) A traffic index calculation program according to an embodiment of the present disclosure is a traffic index calculation program used in a traffic index calculation device, and is a program for causing a computer to function as an acquisition unit that acquires traffic information related to traffic conditions at an intersection for vehicles entering an intersection from an incoming road, and an index calculation unit that calculates, based on the traffic information acquired by the acquisition unit, a directional traffic index, which is a traffic index for at least one direction of travel at the intersection.

[0031] In this way, by calculating directional traffic indices for the direction of travel at an intersection based on traffic information about the traffic conditions at the intersection, it is possible to control traffic signals using signal control parameters calculated based on directional traffic indices, which makes it possible to control traffic signals according to directional traffic demand, compared to a configuration in which traffic signals are controlled using signal control parameters calculated based on traffic indices for an incoming road. Therefore, it is possible to control traffic signals more appropriately according to the traffic conditions at the intersection.

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0033] [Configuration and Basic Operation] Fig. 1 is a diagram showing the configuration of a traffic signal control system according to an embodiment of the present disclosure. Referring to Fig. 1, a traffic signal control system 201 includes a vehicle 1A and a traffic index calculation device 101. Vehicles 1A and 1B travel on a road 41. Vehicle 1A is a vehicle 1 equipped with an on-board device 2. Vehicle 1B is a vehicle 1 not equipped with an on-board device 2. In the example shown in Fig. 1, vehicle 1 must travel on the right side of road 41. That is, road 41 is a road where traffic keeps to the right. Note that road 41 may also be a road where traffic keeps to the left.

[0034] The road 41 includes an intersection 31 and entrance roads 51A, 51B, 51C, and 51D that are entrance roads 51 to the intersection 31. At the intersection 31, a traffic signal 21 is provided for each entrance road 51.

[0035] The on-board device 2 in the vehicle 1A can communicate with the traffic index calculation device 101 via the wireless base station 111 and the network 121. The on-board device 2 generates probe information indicating measurement results regarding the traveling of the vehicle 1A equipped with the on-board device 2, and transmits the generated probe information to the traffic index calculation device 101 via the wireless base station 111 and the network 121.

[0036] More specifically, the in-vehicle device 2 receives GPS signals from multiple GPS (Global Positioning System) satellites and detects the current position and speed of vehicle 1A based on the received GPS signals. The in-vehicle device 2 detects the current position and speed of vehicle 1A at a timing according to a predetermined detection period and stores vehicle data indicating the detection results and the detection times in a storage unit (not shown). The in-vehicle device 2 periodically or irregularly acquires multiple vehicle data from the storage unit, generates probe information including the acquired multiple vehicle data and the ID of the in-vehicle device 2, and transmits the generated probe information to the traffic index calculation device 101 via the wireless base station 111 and the network 121.

[0037] The traffic index calculation device 101 calculates a directional traffic index, which is a traffic index for each traveling direction of the vehicle 1 at the intersection 31. The traffic index calculation device 101 calculates a split for the intersection 31 based on the calculated directional traffic index.

[0038] Here, "split" refers to the proportion of time each aspect occupies in one signal period. In other words, split refers to the ratio of the length of time allocated to each aspect to the cycle length C. Split is generally expressed as a percentage or a ratio.

[0039] The "cycle length C" refers to the time required for one cycle of the traffic signal 21. In other words, the cycle length C of the traffic signal 21 is the time from the start of the green light of the traffic signal 21 to the start of the next green light. Note that the cycle length C of the traffic signal 21 may also be the time from the start of the red light of the traffic signal 21 to the start of the next red light.

[0040] <Traffic Index Calculation Device> Fig. 2 is a diagram illustrating the configuration of a traffic index calculation device according to an embodiment of the present disclosure. Referring to Fig. 2, the traffic index calculation device 101 includes a receiver 11, an acquirer 12, a calculator 13, a controller 14, and a memory 15. The calculator 13 is an example of an index calculator and an example of a split calculator. The receiver 11, the acquirer 12, the calculator 13, and the controller 14 are all or partly realized by, for example, a processing circuit including one or more processors. The memory 15 is, for example, a non-volatile memory included in the processing circuit.

[0041] (Receiving Unit) The receiving unit 11 acquires traffic light information indicating the cycle length C, green time G, and red time R of the traffic light 21. The cycle length C is equal to the sum of the red time R and the green time G.

[0042] Here, "green time" refers to a time period during which vehicle 1 has the right of way at intersection 31. Green time G includes straight-through right-turn green time G1, which is a time period during which vehicle 1 going straight and vehicle 1 turning right have the right of way at intersection 31, and left-turn green time G2, which is a time period during which vehicle 1 turning left has the right of way at intersection 31. In other words, green time G is the green time for the entire oncoming road 51. For example, green time G is made up of left-turn green time G2 and straight-through right-turn green time G1 following left-turn green time G2. The start of left-turn green time G2 is when the green arrow light for left turns is turned on, and the end of left-turn green time G2 is when the green arrow light for left turns is turned off. The start of straight-through right-turn green time G1 is when the green light is turned on, and the end of straight-through right-turn green time G1 is when the green light is turned off. The end point of the straight-ahead right-turn green time G1 may be the time when the yellow light is turned off.

[0043] Furthermore, the "red period" refers to a period of time during which the vehicle 1 does not have the right of way at the intersection 31. The start of the red period R is when the green light is turned off, and the end of the red period R is when the green arrow light for a left turn is turned on. Note that the start of the red period R may also be when the yellow light is turned off.

[0044] For example, the receiving unit 11 receives traffic light information of the traffic light 21 from a control device (not shown) in a traffic control center via the network 121. The receiving unit 11 stores the received traffic light information in the storage unit 15.

[0045] The receiver 11 also acquires probe information indicating measurement results related to the traveling of the vehicle 1A. More specifically, the receiver 11 receives the probe information from the in-vehicle device 2 via the wireless base station 111 and the network 121. The receiver 11 stores the received probe information in the storage unit 15.

[0046] (Acquisition Unit) The acquisition unit 12 acquires traffic information regarding traffic conditions at the intersection 31 for the vehicle 1A entering the intersection 31 from the entrance road 51. For example, the acquisition unit 12 acquires traffic information regarding traffic conditions for each traveling direction at the intersection 31.

[0047] (1) Direction-specific travel time TtN The acquisition unit 12 acquires, as traffic information, direction-specific travel time TtN [seconds], which is the travel time for each traveling direction of the vehicle 1A entering the intersection 31 from the entering road 51.

[0048] For example, the acquisition unit 12 acquires from the storage unit 15, at processing timings according to a predetermined processing cycle Cy, a plurality of pieces of probe information received by the receiving unit 11 during a period from the previous processing timing to the current processing timing. The acquisition unit 12 calculates the direction-specific travel time TtN based on the acquired plurality of pieces of probe information. The processing cycle Cy may be the same length as the cycle length C of the traffic signal 21, or may be a predetermined length different from the cycle length C.

[0049] 3 is a diagram illustrating an example of a method for calculating traffic information by an acquisition unit in a traffic index calculation device according to an embodiment of the present disclosure. Referring to FIG. 3, an entrance road 51 includes a lane CL1 for going straight, a lane CL2 for turning right, and a lane CL3 for turning left.

[0050] The acquisition unit 12 calculates directional travel times Tt1, Tt2, and Tt3, which are directional travel times TtN for a driving section S of a predetermined length L to an intersection 31 on the entrance road 51, based on the detection results of the positions of each of the multiple vehicles 1A indicated by the multiple probe information.

[0051] The direction-specific travel time Tt1 is the average travel time when multiple vehicles 1A traveling straight through the intersection 31 travel through the travel section S. In other words, the direction-specific travel time Tt1 is the average travel time when multiple vehicles 1A travel through the travel section S in the lane CL1.

[0052] The direction-specific travel time Tt2 is the average travel time when multiple vehicles 1A turning right at the intersection 31 travel through the travel section S. In other words, the direction-specific travel time Tt2 is the average travel time when multiple vehicles 1A travel through the travel section S in the lane CL2.

[0053] The direction-specific travel time Tt3 is the average travel time when multiple vehicles 1A turning left at the intersection 31 travel through the travel section S. In other words, the direction-specific travel time Tt3 is the average travel time when multiple vehicles 1A travel through the travel section S in the lane CL3.

[0054] For example, the acquisition unit 12 calculates the direction-specific travel times Tt1, Tt2, and Tt3 for each incoming road 51 and outputs the calculated direction-specific travel times Tt1, Tt2, and Tt3 to the calculation unit 13.

[0055] (2) Branching Rate RtN The acquisition unit 12 acquires, as traffic information, a branching rate RtN, which is the ratio of the number of vehicles 1A in each traveling direction to the number of vehicles 1A entering the intersection 31 from the entering road 51.

[0056] For example, when the number of pieces of probe information acquired from the storage unit 15 is small, the acquisition unit 12 cannot calculate the direction-specific travel time TtN or cannot calculate a sufficiently accurate direction-specific travel time TtN. In this case, the acquisition unit 12 calculates the average travel time Tt [seconds] and the branch rate RtN of the vehicle 1A entering the intersection 31 from the entering road 51 based on the plurality of pieces of probe information acquired from the storage unit 15.

[0057] More specifically, based on the detection results of the positions of the plurality of vehicles 1A indicated by the plurality of pieces of probe information, the acquisition unit 12 calculates an average travel time Tt for the traveling section S on the entire entrance road 51. The average travel time Tt is the average travel time when the plurality of vehicles 1A traveling in each direction at the intersection 31 travels through the traveling section S on the entrance road 51.

[0058] Furthermore, the acquisition unit 12 calculates branching rates Rt1, Rt2, and Rt3, which are the branching rate RtN, based on the detection results of the positions of the multiple vehicles 1A indicated by the multiple pieces of probe information. The branching rate Rt1 is the ratio of the number of vehicles 1A going straight at the intersection 31 to the number of vehicles 1A entering the intersection 31 from the entering road 51. The branching rate Rt2 is the ratio of the number of vehicles 1A turning right at the intersection 31 to the number of vehicles 1A entering the intersection 31 from the entering road 51. The branching rate Rt3 is the ratio of the number of vehicles 1A turning left at the intersection 31 to the number of vehicles 1A entering the intersection 31 from the entering road 51.

[0059] For example, the acquisition unit 12 calculates the branch rates Rt1, Rt2, Rt3 and the average travel time Tt for each inflow road 51, and outputs the calculated branch rates Rt1, Rt2, Rt3 and the average travel time Tt to the calculation unit 13.

[0060] Here, in addition to the vehicle 1A, the intersection 31 also includes a vehicle 1B that does not transmit probe information. However, in recent years, the proportion of vehicles 1A among the total number of vehicles 1 has been increasing, so the branch rate RtN calculated based on the probe information can be considered as the proportion of the number of vehicles 1 in each direction of travel to the total number of vehicles 1 entering the intersection 31 from the entering road 51.

[0061] (3) Green Time Ratio GrN The acquisition unit 12 acquires, as traffic information, a green time ratio GrN, which is the ratio of the green time for each traveling direction to the green time G of the incoming road 51.

[0062] More specifically, the acquisition unit 12 acquires traffic light information from the storage unit 15 and calculates the green time rates GrX and GrY, which are the green time rate GrN, based on the received traffic light information. The green time rate GrX is the ratio of the straight-through right-turn green time G1 to the green time G. The green time rate GrY is the ratio of the left-turn green time G2 to the green time G. The acquisition unit 12 calculates the green time rates GrX and GrY for each incoming road 51 and stores the calculated green time rates GrX and GrY in the storage unit 15.

[0063] For example, when the number of pieces of probe information acquired from the storage unit 15 is small, the acquisition unit 12 cannot calculate the direction-specific travel time TtN and branch rate RtN or cannot calculate sufficiently accurate direction-specific travel time TtN and branch rate RtN. In this case, the acquisition unit 12 calculates the average travel time Tt for each incoming road 51 based on the multiple pieces of probe information acquired from the storage unit 15.

[0064] The acquisition unit 12 also acquires the green time ratio GrN from the storage unit 15 and outputs the acquired green time ratio GrN and the calculated average travel time Tt to the calculation unit 13 .

[0065] (Calculation unit) The calculation unit 13 calculates, as a direction-specific traffic index, a load factor LrN, which is a load factor for at least one traveling direction at the intersection 31, based on the traffic information acquired by the acquisition unit 12. For example, the calculation unit 13 calculates the load factor LrN for each traveling direction. Here, the load factor is the ratio of traffic demand to the maximum traffic volume that can be handled in one cycle. The load factor LrN is an example of a direction-specific traffic index. The calculation unit 13 calculates a split for each traveling direction based on the calculated load factor LrN.

[0066] (1) Calculation of Load Factor LrN The load factor Lr, which is the load factor of the entire incoming road 51, is expressed by the following formula (1) using the traffic volume Vin [vehicles / second], the number of queued vehicles Qin [vehicles / second] converted to traffic volume, the saturation traffic flow rate Sf [vehicles / second], and a predetermined weighting coefficient k. The load factor Lr is an example of an incoming road traffic index. Lr = (Vin + k × Qin) / Sf (1)

[0067] The traffic volume Vin is the number of vehicles passing through within a unit time. In the case of a supersaturated state where there is a backlog of vehicles waiting at the traffic light at the end of the green time G, the traffic volume Vin is expressed by the following formula (2): Vin = (1 - R / C) x Sf (2)

[0068] In the case of an oversaturated state where vehicles are left waiting in line at the end of the green light period G, the number of vehicles waiting in line Qin is expressed by the following equation (3) using the delay time dav [seconds] due to waiting at the traffic light per vehicle 1A: Qin = {(dav - R / 2) / R} × (1 - R / C) × Sf (3)

[0069] The delay time dav is a value obtained by subtracting the travel time (seconds) that vehicle 1A would take to travel through travel section S without waiting at traffic lights from the average travel time Tt that vehicle 1A would take to travel through travel section S. The delay time dav is expressed by the following equation (4) using the speed limit Ve (km / h) for travel section S: dav=Tt-{L / (Ve / 3.6)} (4)

[0070] The saturation flow rate Sf is expressed as the flow rate at which the second or third vehicle or more passes the stop line after the traffic signal 21 turns green when there is a sufficiently long queue at the entrance to the intersection 31. In other words, the saturation flow rate Sf is the maximum number of vehicles that can pass the stop line per lane per unit time at the entrance to the intersection 31 when there is sufficient traffic demand. The value of the saturation flow rate Sf differs depending on the presence or absence of a dedicated right-turn lane, the presence or absence of a dedicated left-turn lane, the lane width, etc.

[0071] As shown in equations (1) to (3), by substituting the traffic volume Vin and the number of queueing vehicles Qin into equation (1), the saturation flow rate Sf is offset by the numerator and denominator on the right-hand side of equation (1). Therefore, the load factor Lr can be calculated using the delay time dav, and the cycle length C and red time R indicated by the traffic light information.

[0072] (1-1) When the direction-specific travel time TtN is used The calculation unit 13 calculates the load factor LrN based on the direction-specific travel time TtN. More specifically, when the calculation unit 13 receives the direction-specific travel times Tt1, Tt2, and Tt3 from the acquisition unit 12, the calculation unit 13 calculates the delay times dav1, dav2, and dav3, which are the direction-specific delay times dav, by substituting the received direction-specific travel times Tt1, Tt2, and Tt3 for the average travel time Tt in the above-mentioned formula (4).

[0073] The delay time dav1 is the delay time dav of the vehicle 1A traveling on the straight lane CL1. The delay time dav2 is the delay time dav of the vehicle 1A traveling on the right-turn lane CL2. The delay time dav3 is the delay time dav of the vehicle 1A traveling on the left-turn lane CL3.

[0074] Then, the calculation unit 13 substitutes the calculated delay times dav1, dav2, dav3, as well as the cycle length C and red time R indicated by the traffic light information in the memory unit 15 into the above-mentioned equation (3), to calculate the number of queued vehicles Qin for each direction, Qin, which is expressed using the unknown saturation traffic flow rate Sf, as Qin1, Qin2, Qin3.

[0075] The number of queueing vehicles Qin1 is the number of queueing vehicles Qin in the straight lane CL1, the number of queueing vehicles Qin2 is the number of queueing vehicles Qin in the right-turn lane CL2, and the number of queueing vehicles Qin3 is the number of queueing vehicles Qin in the left-turn lane CL3.

[0076] Furthermore, the calculation unit 13 calculates the traffic volume Vin expressed using the saturation flow rate Sf, which is an unknown quantity, according to the above-mentioned equation (2) based on the traffic light information in the storage unit 15 .

[0077] The calculation unit 13 calculates the load factors Lr1, Lr2, and Lr3, which are the load factor LrN, by substituting the calculated traffic volume Vin and the calculated numbers of queued vehicles Qin1, Qin2, and Qin3 into the above-mentioned equation (1).

[0078] The load factor Lr1 is the load factor Lr in the straight lane CL1. The load factor Lr2 is the load factor Lr in the right-turn lane CL2. The load factor Lr3 is the load factor Lr in the left-turn lane CL3. The calculation unit 13 calculates the load factors Lr1, Lr2, and Lr3 for each entrance road 51.

[0079] (1-2) When the branch rate RtN is used The calculation unit 13 calculates the load rate Lr, which is a traffic index of the inflow road 51, and calculates the load rate LrN based on the calculated load rate Lr and the branch rate RtN.

[0080] The calculation unit 13 calculates the load factor Lr based on the probe information. For example, the calculation unit 13 calculates a delay time dav based on the probe information, and calculates the load factor Lr based on the calculated delay time dav.

[0081] More specifically, when the calculation unit 13 receives the branch rates Rt1, Rt2, Rt3 and the average travel time Tt from the acquisition unit 12, it calculates the delay time dav by substituting the received average travel time Tt into the above-mentioned equation (4).

[0082] Then, the calculation unit 13 calculates the number of vehicles in the queue Qin, which is expressed using the unknown saturation traffic flow rate Sf, by substituting the calculated delay time dav, as well as the cycle length C and red time R indicated by the traffic light information in the memory unit 15, into the above-mentioned equation (3).

[0083] Furthermore, the calculation unit 13 calculates the traffic volume Vin expressed using the saturation flow rate Sf, which is an unknown quantity, according to the above-mentioned equation (2) based on the traffic light information in the storage unit 15 .

[0084] The calculation unit 13 calculates the load factor Lr by substituting the calculated traffic volume Vin and the calculated number of queued vehicles Qin into the above-mentioned equation (1).

[0085] Then, the calculation unit 13 calculates load factors Lr1, Lr2, and Lr3, which are load factors for each direction, according to the following equations (5) to (7) using the calculated load factor Lr and the branch factors Rt1, Rt2, and Rt3 received from the acquisition unit 12. Lr1=Lr×{Rt1 / (Rt2+Rt3)}×{(Ln2+Ln3) / Ln1} (5) Lr2=Lr×{Rt2 / (Rt1+Rt3)}×{(Ln1+Ln3) / Ln2} (6) Lr3=Lr×{Rt3 / (Rt1+Rt2)}×{(Ln1+Ln2) / Ln3} (7)

[0086] Here, Ln1 is the number of lanes in the straight-through lane CL1, Ln2 is the number of lanes in the right-turn lane CL2, and Ln3 is the number of lanes in the left-turn lane CL3. The calculation unit 13 calculates the load factors Lr1, Lr2, and Lr3 for each entrance road 51.

[0087] (1-3) When using the green time rate GrN The calculation unit 13 calculates the load rate Lr, which is a traffic index for the incoming road 51, and calculates the load rate LrN based on the calculated load rate Lr and the green time rate GrN.

[0088] More specifically, when the calculation unit 13 receives the green time rate GrN and the average travel time Tt from the acquisition unit 12, it calculates the delay time dav by substituting the received average travel time Tt into the above-mentioned equation (4).

[0089] Then, the calculation unit 13 calculates the number of vehicles in the queue Qin, which is expressed using the unknown saturation traffic flow rate Sf, by substituting the calculated delay time dav, as well as the cycle length C and red time R indicated by the traffic light information in the memory unit 15, into the above-mentioned equation (3).

[0090] Furthermore, the calculation unit 13 calculates the traffic volume Vin expressed using the saturation flow rate Sf, which is an unknown quantity, according to the above-mentioned equation (2) based on the traffic light information in the storage unit 15 .

[0091] The calculation unit 13 calculates the load factor Lr by substituting the calculated traffic volume Vin and the calculated number of queued vehicles Qin into the above-mentioned equation (1).

[0092] Then, the calculation unit 13 uses the calculated load factor Lr and the green time rate GrN received from the acquisition unit 12 to calculate the load factors Lr1, Lr2, and Lr3 according to the following equations (8) to (10): Lr1=Lr×(GrY / GrX)×{(Ln2+Ln3) / Ln1} (8) Lr2=Lr×(GrY / GrX)×{(Ln1+Ln3) / Ln2} (9) Lr3=Lr×(GrX / GrY)×{(Ln1+Ln2) / Ln3} (10)

[0093] The calculation unit 13 calculates the load factors Lr1, Lr2, Lr3 for each inflow passage 51. Hereinafter, the load factors Lr1, Lr2, Lr3 of the inflow passage 51A will also be referred to as load factors Lr1A, Lr2A, Lr3A, the load factors Lr1, Lr2, Lr3 of the inflow passage 51B will also be referred to as load factors Lr1B, Lr2B, Lr3B, the load factors Lr1, Lr2, Lr3 of the inflow passage 51C will also be referred to as load factors Lr1C, Lr2C, Lr3C, and the load factors Lr1, Lr2, Lr3 of the inflow passage 51D will also be referred to as load factors Lr1D, Lr2D, Lr3D.

[0094] (2) Split Calculation Fig. 4 is a diagram illustrating an example of a split calculated by a calculation unit in a traffic index calculation device according to an embodiment of the present disclosure. Fig. 4 shows a phase diagram of rings Ra and Rb at a dual-ring intersection 31.

[0095] 4, the ring Ra includes aspects Ra1, Ra2, Ra3, and Ra4, and the ring Rb includes aspects Rb1, Rb2, Rb3, and Rb4.

[0096] Aspect Ra1 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51C and turning left. Aspect Ra2 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51A and going straight or turning right. Aspect Ra3 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51D and turning left. Aspect Ra4 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51B and going straight or turning right.

[0097] Aspect Rb1 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51A and turning left. Aspect Rb2 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51C and going straight or turning right. Aspect Rb3 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51B and turning left. Aspect Rb4 is a time period during which the right-of-way is assigned to a vehicle 1 entering the intersection 31 from the incoming road 51D and going straight or turning right.

[0098] The calculation unit 13 calculates the load factors Lr1, Lr2, and Lr3 for each inflow path 51, and then calculates the load factor LrAC, which is the load factor for the inflow paths 51A and 51C, and the load factor LrBD, which is the load factor for the inflow paths 51B and 51D, based on the calculated load factors Lr1, Lr2, and Lr3.

[0099] More specifically, the calculation unit 13 calculates the load factors LrAC and LrBD using the load factors Lr1, Lr2, and Lr3 for each inflow passage 51 according to the following equations (11) and (12): LrAC=Max{Lr3C+Lr1A+Lr2A, Lr3A+Lr1C+Lr2C} (11) LrBD=Max{Lr3D+Lr1B+Lr2B, Lr3B+Lr1D+Lr2D} (12)

[0100] After calculating the load factors LrAC and LrBD, the calculation unit 13 uses the calculated load factors LrAC and LrBD to calculate the split Sp1 of the inflow channels 51A and 51C and the split Sp2 of the inflow channels 51B and 51D according to the following equations (13) and (14): Sp1 = LrAC / (LrAC + LrBD) (13) Sp2 = LrBD / (LrAC + LrBD) (14)

[0101] Then, the calculation unit 13 uses the split Sp1 to calculate the split Spa1 of the aspect Ra1, the split Spa2 of the aspect Ra2, the split Spb1 of the aspect Rb1, and the split Spb2 of the aspect Rb2 according to the following equations (15) to (18). Spa1=Sp1×Lr3C / (Lr3C+Lr1A+Lr2A)...(15) Spa2=Sp1×(Lr1A+Lr2A) / (Lr3C+Lr1A+Lr2A)...(16) Spb1=Sp1×Lr3A / (Lr3A+Lr1C+Lr2C)...(17) Spb2=Sp1×(Lr1C+Lr2C) / (Lr3A+Lr1C+Lr2C)...(18)

[0102] In addition, the calculation unit 13 uses the split Sp2 to calculate the split Spa3 of the aspect Ra3, the split Spa4 of the aspect Ra4, the split Spb3 of the aspect Rb3, and the split Spb4 of the aspect Rb4 according to the following equations (19) to (22). Spa3=Sp2×Lr3D / (Lr3D+Lr1B+Lr2B)...(19) Spa4=Sp2×(Lr1B+Lr2B) / (Lr3D+Lr1B+Lr2B)...(20) Spb3=Sp2×Lr3B / (Lr3B+Lr1D+Lr2D)...(21) Spb4=Sp2×(Lr1D+Lr2D) / (Lr3B+Lr1D+Lr2D)...(22)

[0103] The calculation unit 13 outputs the calculated splits Spa1, Spa2, Spa3, Spa4, Spb1, Spb2, Spb3, and Spb4 to the control unit 14. Hereinafter, each of the splits Spa1, Spa2, Spa3, Spa4, Spb1, Spb2, Spb3, and Spb4 will also be referred to as a split SpN.

[0104] (Controller) Referring back to FIG. 2 , the controller 14 controls the traffic signal 21 at the intersection 31 based on the split SpN calculated by the calculator 13 .

[0105] More specifically, the control unit 14 receives the split SpN from the calculation unit 13 and transmits a signal control instruction including the received split SpN to a control device (not shown) that controls the traffic signal 21 via the network 121.

[0106] The control device receives the signal control instruction from the traffic index calculation device 101, and controls the traffic signal 21 based on the split SpN included in the received signal control instruction.

[0107] [Operation Flow] FIG. 5 is a flowchart defining an example of an operation procedure when the traffic index calculation device according to the embodiment of the present disclosure controls a traffic signal.

[0108] Referring to FIG. 5, the traffic index calculation device 101 waits for a processing timing according to the processing cycle Cy (NO in step S11), and when the processing timing arrives (YES in step S11), it acquires from the memory unit 15 a plurality of pieces of probe information received from the vehicle 1A during the period from the previous processing timing to the current processing timing (step S12).

[0109] Next, if the traffic index calculation device 101 can calculate the direction-specific travel time TtN based on the probe information (YES in step S13), it calculates the direction-specific travel time TtN (step S14).

[0110] Next, the traffic index calculation device 101 calculates the load factor LrN based on the calculated direction-specific travel time TtN (step S15).

[0111] On the other hand, if the traffic index calculation device 101 is unable to calculate the direction-specific travel time TtN based on the probe information (NO in step S13) and is able to calculate the branch rate RtN based on the probe information (YES in step S17), it calculates the branch rate RtN and the average travel time Tt (step S18).

[0112] Next, the traffic index calculation device 101 calculates the load factor Lr of the inflow road 51 based on the probe information (step S19).

[0113] Next, the traffic index calculation device 101 calculates the load factor LrN based on the load factor Lr, the branch rate RtN, and the average travel time Tt (step S20).

[0114] On the other hand, if the traffic index calculation device 101 is unable to calculate the direction-specific travel time TtN based on the probe information (NO in step S13) and is unable to calculate the branch rate RtN based on the probe information (NO in step S17), it calculates the average travel time Tt (step S21).

[0115] Next, the traffic index calculation device 101 calculates the load factor Lr of the inflow road 51 based on the probe information (step S22).

[0116] Next, the traffic index calculation device 101 calculates the load factor LrN based on the load factor LrN, the green light ratio GrtN, and the average travel time Tt (step S23).

[0117] Next, the traffic index calculation device 101 calculates the split SpN for each traveling direction based on the load factor LrN calculated for each incoming road 51 (step S24).

[0118] Next, the traffic index calculation device 101 controls the traffic signal 21 at the intersection 31 based on the split SpN (step S25).

[0119] Next, the traffic index calculation device 101 waits for a new processing timing according to the processing cycle Cy (NO in step S11).

[0120] In the traffic index calculation device 101 according to the embodiment of the present disclosure, the acquisition unit 12 is configured to acquire traffic information related to traffic conditions for each traveling direction at the intersection 31, but this is not limited thereto. The acquisition unit 12 may be configured to acquire traffic information related to traffic conditions for any one traveling direction at the intersection 31.

[0121] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the calculation unit 13 is configured to calculate the load factor LrN for each traveling direction, but this is not limited to this. The calculation unit 13 may be configured to calculate the load factor LrN for any one traveling direction at the intersection 31.

[0122] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the calculation unit 13 is configured to calculate the load factor LrN as a directional traffic index, but this is not limited to this. The calculation unit 13 may be configured to calculate the current saturation degree DsN, which is the current saturation degree for each traveling direction, instead of or in addition to the load factor LrN. Here, the current saturation degree is the ratio of the arriving traffic volume to the maximum traffic volume that can be processed during the green time G. The arriving traffic volume is the number of vehicles 1 arriving at the stop line of the incoming road 51. The current saturation degree Ds, which is the current saturation degree for the entire incoming road 51, is expressed by the following equation (23). The current saturation degree Ds is an example of an incoming road traffic index. Ds = Vin × C / (Sf × G) (23)

[0123] For example, the calculation unit 13 calculates the current saturation degree DsN for each inflow passage 51, and calculates the split SpN using the current saturation degree DsN instead of the load factor LrN according to the above-mentioned equations (11) to (22).

[0124] In addition, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the acquisition unit 12 is configured to be able to acquire the direction-specific travel time TtN, the branch rate RtN, and the green time rate GrN as traffic information, but this is not limited to this. The acquisition unit 12 may be configured without the function of acquiring any one or two of the direction-specific travel time TtN, the branch rate RtN, and the green time rate GrN.

[0125] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the calculation unit 13 is configured to calculate the load factor Lr based on probe information, but this is not limited to this. The calculation unit 13 may be configured to calculate the traffic volume Vin, the number of queuing vehicles Qin, and the saturation traffic flow rate Sf based on detection results from vehicle detectors installed at intersections instead of the probe information, and to calculate the load factor Lr based on the calculated traffic volume Vin, the number of queuing vehicles Qin, and the saturation traffic flow rate Sf.

[0126] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the calculation unit 13 is configured to calculate the delay time dav based on the probe information and calculate the load factor Lr based on the calculated delay time dav, but this is not limited to this. The calculation unit 13 may be configured to calculate the load factor Lr by some method without using the delay time dav.

[0127] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the calculation unit 13 is configured to calculate the split SpN based on the load factor LrN, but this is not limited to this. The calculation unit 13 may be configured to calculate the load factor LrN but not calculate the split SpN. In this case, the calculation unit 13 transmits the calculated load factor LrN to a device external to the traffic index calculation device 101.

[0128] Furthermore, although the traffic index calculation device 101 according to the embodiment of the present disclosure has been described as including the control unit 14, this is not limiting. The traffic index calculation device 101 may be configured without including the control unit 14. In this case, the calculation unit 13 transmits the calculated split SpN to a device external to the traffic index calculation device 101.

[0129] Furthermore, in the traffic index calculation device 101 according to the embodiment of the present disclosure, the receiver 11 is configured to receive probe information from the in-vehicle device 2, but this is not limiting. The receiver 11 may be configured to receive probe information from a communication device such as a smartphone in the vehicle 1 instead of the in-vehicle device 2.

[0130] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[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 as an integrated circuit or the like 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 may execute each of the processes according to a logic circuit designed in advance to execute each of the processes. The processor may be any of various processors suitable for computer control, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). Note that 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 LAN (Local Area Network), a WAN (Wide Area Network), or the Internet to execute the processes. The program may be installed into the memory from an external server device or the like via the network, or may be distributed in a state stored on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a semiconductor memory, and then installed into the memory from the recording medium.

[0132] The above description includes the following additional features: [Additional Note 1] A traffic index calculation device comprising: an acquisition unit that acquires traffic information related to traffic conditions at an intersection for vehicles entering an intersection from an incoming road; and an index calculation unit that calculates a direction-specific traffic index, which is a traffic index for at least one traveling direction at the intersection, based on the traffic information acquired by the acquisition unit, wherein the index calculation unit calculates a load factor for the traveling direction as the direction-specific traffic index.

[0133] [Supplementary Note 2] A traffic index calculation device comprising a processing circuit, wherein the processing circuit acquires traffic information relating to traffic conditions at an intersection for vehicles entering the intersection from an incoming road, and calculates a directional traffic index, which is a traffic index for at least one traveling direction at the intersection, based on the acquired traffic information.

[0134] 1, 1A, 1B Vehicle 11 Receiving unit 12 Acquisition unit 13 Calculation unit 14 Control unit 15 Memory unit 21 Traffic signal 31 Intersection 41 Road 51, 51A, 51B, 51C, 51D Entering road 101 Traffic index calculation device 111 Radio base station 121 Network 201 Traffic signal control system Rt1, Rt2, Rt3 Branching rate CL1, CL2, CL3 Lanes Ra1, Ra2, Ra3, Ra4, Rb1, Rb2, Rb3, Rb4 Aspect Sp1, Sp2, Spa1, Spa2, Spa3, Spa4, Spb1, Spb2, Spb3, Spb4 Split

Claims

1. An acquisition unit that acquires traffic information regarding the traffic conditions at the intersection for vehicles entering the intersection from an access road, A traffic indicator calculation device comprising: an indicator calculation unit that calculates a direction-specific traffic indicator, which is a traffic indicator for at least one direction of travel at the intersection, based on the traffic information acquired by the acquisition unit.

2. The acquisition unit acquires, as traffic information, the branching ratio, which is the ratio of the number of vehicles in each direction of travel to the number of vehicles entering the intersection from the entrance road. The traffic indicator calculation device according to claim 1, wherein the indicator calculation unit calculates an inflow road traffic indicator, which is a traffic indicator for the inflow road, and calculates the direction-specific traffic indicator, which is a traffic indicator for each direction of travel, based on the calculated inflow road traffic indicator and the branching ratio.

3. The acquisition unit acquires the blue time rate, which is the ratio of the blue time for each direction of travel to the total blue time for the entry road, as traffic information. The traffic indicator calculation device according to claim 1, wherein the indicator calculation unit calculates an on-ramp traffic indicator, which is a traffic indicator for the on-ramp, and calculates the direction-specific traffic indicator, which is a traffic indicator for each direction of travel, based on the calculated on-ramp traffic indicator and the green time rate.

4. The traffic indicator calculation device according to claim 2, wherein the indicator calculation unit calculates the inflow road traffic indicator based on probe information indicating measurement results related to the movement of a vehicle.

5. The traffic indicator calculation device according to claim 4, wherein the indicator calculation unit calculates the delay time per vehicle due to waiting at a traffic light based on the probe information, and calculates the on-ramp traffic indicator based on the calculated delay time.

6. The acquisition unit acquires, as traffic information, the travel time by direction, which is the travel time for each direction of travel of vehicles entering the intersection from the entrance road. The traffic indicator calculation device according to claim 1, wherein the indicator calculation unit calculates the direction-specific traffic indicator, which is a traffic indicator for each direction of travel, based on the direction-specific travel time.

7. The traffic indicator calculation device further, The traffic indicator calculation device according to any one of claims 1 to 6, further comprising a split calculation unit that calculates the split for each direction of travel based on the direction-specific traffic indicator calculated by the indicator calculation unit.

8. The traffic indicator calculation device further, The traffic indicator calculation device according to claim 7, further comprising a control unit that controls a traffic signal at the intersection based on the split calculated by the split calculation unit.

9. A method for calculating traffic indicators in a traffic indicator calculation device, A step of acquiring traffic information regarding the traffic conditions at the intersection for vehicles entering the intersection from an access road, A method for calculating traffic indicators, comprising the step of calculating a direction-specific traffic indicator, which is a traffic indicator for at least one direction of travel at the intersection, based on the acquired traffic information.

10. A traffic indicator calculation program used in a traffic indicator calculation device, Computers, An acquisition unit that acquires traffic information regarding the traffic conditions at the intersection for vehicles entering the intersection from an access road, An indicator calculation unit calculates a directional traffic indicator, which is a traffic indicator for at least one direction of travel at the intersection, based on the traffic information acquired by the acquisition unit. A traffic indicator calculation program designed to function as such.