Delay time calculation device, calculation method, and computer program

Abstract

A device according to one aspect of the present disclosure comprises an acquisition unit that acquires probe information for a probe vehicle traveling on an inflow path to an intersection, and an information processing unit that uses the probe information as original data to execute calculation processing of a delay time per vehicle due to waiting for a traffic light to change on the inflow path. The calculation processing includes: first processing of calculating, on the basis of the probe information, a plurality of section speeds that are average speeds of vehicles for each of a plurality of sections obtained by dividing the inflow path; and second processing of calculating, on the basis of the plurality of section speeds, the delay time in a traffic light waiting section on the inflow path. The second processing includes: addition processing of adding the delay time for each section arranged in order from a downstream side of the inflow path, the section speed satisfying a speed condition of being equal to or less than a speed threshold; and output processing of setting, as an output target, the delay time of a most upstream section where the length obtained by adding respective section lengths of one or more sections that do not satisfy the speed condition is equal to or greater than a distance threshold.

Description

Delay time calculation device, calculation method, and computer program

[0001] This disclosure relates to a delay time calculation device, a calculation method, and a computer program. This application claims priority to Japanese Application No. 2024-129684, filed on August 6, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Document 1 describes a traffic index calculation device that includes a first calculation unit that calculates normalized data that expresses the traffic variables of the incoming road of a target intersection as a ratio to a saturation traffic flow rate, and a second calculation unit that uses the calculated normalized data to calculate a traffic index defined by an equation in which the traffic variables of the incoming road are included in the numerator and the saturation traffic flow rate is included in the denominator.

[0003] In the calculation device of Patent Document 1, the delay time per vehicle due to waiting at traffic lights on the approach road is calculated from the average travel time of the probe vehicles, and the above-mentioned normalized data is calculated based on the calculated delay time.

[0004] International Publication No. 2020 / 071040

[0005] According to one aspect of the present disclosure, an apparatus includes an acquisition unit that acquires probe information of a probe vehicle traveling on an entrance road to an intersection, and an information processing unit that executes a calculation process for a delay time per vehicle due to waiting at a traffic light on the entrance road using the probe information as source data. The calculation process includes a first process that calculates, based on the probe information, a plurality of section speeds that are average vehicle speeds for each of a plurality of sections that divide the entrance road, and a second process that calculates the delay time in a section where the vehicle is waiting at a traffic light on the entrance road based on the plurality of section speeds.

[0006] The second process also includes an addition process that adds up the delay time for each section lined up in order from the downstream side of the inflow channel, satisfying the speed condition that the section speed is below the speed threshold, and an output process that outputs the delay time for the most upstream section, where the sum of the section lengths of one or more sections that do not satisfy the speed condition is above the distance threshold.

[0007] FIG. 1 is an overall configuration diagram of a traffic signal control system. FIG. 2 is a block diagram of an information processing device, an on-board device of a probe vehicle, and a central device included in the traffic signal control system. FIG. 3 is a flowchart showing an overview of remote control according to a comparative example. FIG. 4 is a flowchart showing an overview of remote control according to this embodiment. FIG. 5 is an explanatory diagram showing an example of a method for calculating normalized data when the target intersection of remote control is a single intersection. FIG. 6 is an explanatory diagram showing the traffic situation at an intersection when not saturated and the relational expression required to derive the traffic volume Vin normalized by Sf. FIG. 7 is an explanatory diagram showing an example of the traffic situation at an intersection when oversaturated. FIG. 8 is an explanatory diagram showing an example of a stop event that affects the accuracy of the delay time per vehicle due to waiting at a traffic light. FIG. 9 is an explanatory diagram showing an example of the definition of variables used to calculate the delay time in a traffic light waiting section. FIG. 10 is a flowchart showing an example of a process for calculating the delay time per vehicle due to waiting at a traffic light. FIG. 11 is a flowchart showing an example of a process for calculating the delay time in a traffic light waiting section (second process). FIG. 12 is an explanatory diagram showing an example of determining a traffic light waiting section. 13 and 14 are explanatory diagrams showing an example of a method for calculating a delay time when a link between intersections has multiple lanes.

[0008] <Problem to be Solved by the Present Disclosure> Conventional calculation devices use the link travel time from an upstream intersection to a target intersection as the average travel time of a probe vehicle. Therefore, if a probe vehicle experiences a stopping event other than waiting at a traffic light, the delay time may be greater than the actual delay time. In view of the above conventional problems, the present disclosure aims to improve the accuracy of calculating the delay time per vehicle due to waiting at a traffic light.

[0009] Effect of the Present Disclosure According to the present disclosure, it is possible to improve the accuracy of calculating the delay time per vehicle due to waiting at a traffic light.

[0010] <Outline of Embodiments of the Present Invention> The following is a description of outlines of embodiments of the present invention. (1) A calculation device of this embodiment includes an acquisition unit that acquires probe information of a probe vehicle traveling on an entrance road to an intersection, and an information processing unit that executes a calculation process for a delay time per vehicle due to waiting at a traffic light on the entrance road using the probe information as source data. The calculation process includes a first process that calculates, based on the probe information, a plurality of section speeds that are average vehicle speeds for each of a plurality of sections formed by dividing the entrance road, and a second process that calculates the delay time in a section on the entrance road where the vehicle is waiting at a traffic light, based on the plurality of section speeds.

[0011] The second process also includes an addition process that adds up the delay time for each section lined up in order from the downstream side of the inflow channel, satisfying the speed condition that the section speed is below the speed threshold, and an output process that outputs the delay time for the most upstream section, where the sum of the section lengths of one or more sections that do not satisfy the speed condition is above the distance threshold.

[0012] According to the calculation device of this embodiment, the information processing unit executes the second process to calculate the delay time in the traffic light waiting section on the incoming road, thereby obtaining an accurate delay time that is not affected by the presence or absence of stop events other than waiting at the traffic light. Furthermore, since the second process includes the above-mentioned addition process and output process, the delay time can be calculated directly without using intermediate variables such as the "total number of traffic light waiting sections" (WO 2022 / 085429 A1). This has the advantage of reducing the processing load on the information processing unit.

[0013] (2) In the calculation device of (1) described above, the second process may include a process of continuing the addition process when the sum of the lengths of one or more sections that do not satisfy the speed condition is less than the distance threshold. The reason for this is that if the length of the section that does not satisfy the speed condition is short, it is considered to be the result of the probe vehicle repeatedly stopping and moving within the red light waiting section, and it cannot necessarily be said that the section being searched has reached the upstream side of the red light waiting section.

[0014] (3) In the calculation device described in (1) or (2) above, if the oncoming road is an oncoming road for which multiple lanes have the right of way defined by the same traffic aspect, the information processing unit may execute the calculation process for each of the multiple lanes, and use the delay time with the largest calculated time value as the source data for the traffic indicator required for traffic signal control of the oncoming road. In this case, the delay time of the lane with the greatest degree of backlog among the multiple lanes processed by the same traffic aspect is applied. This allows for accurate calculation of traffic indicators for the intersection based on actual traffic conditions, thereby improving the calculation accuracy of signal control parameters.

[0015] (4) The calculation method of this embodiment is a calculation method executed by the calculation device described above in (1) to (3), and therefore has the same effects as the calculation device described above in (1) to (3).

[0016] (5) The computer program of this embodiment is a computer program for causing a computer to function as the calculation device described above in (1) to (3). Therefore, the computer program of this embodiment has the same effects as the calculation device described above in (1) to (3).

[0017] <Details of the Embodiments of the Present Invention> Hereinafter, the details of the embodiments of the present invention will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0018] [Definition of Terms] Before describing the details of this embodiment, we will first define the terms used in this specification. "Vehicle": refers to any vehicle traveling on a road. Therefore, in addition to automobiles, light vehicles, and trolleybuses, motorcycles also fall under the category of vehicles. In this embodiment, when simply referring to a "vehicle," it includes both a probe vehicle that has an on-board device capable of transmitting probe information and a normal vehicle that does not have such an on-board device.

[0019] "Probe information" refers to various types of information about a vehicle sensed by a probe vehicle traveling on a road. Probe information is also called probe data or floating car data. Probe information can include various types of vehicle data, such as the identification information of the probe vehicle, vehicle position, vehicle speed, vehicle direction, and the time of occurrence of these. Probe information may also use information such as position and acceleration acquired by a smartphone or tablet inside the vehicle.

[0020] "Probe vehicle": A vehicle that senses probe information and transmits it to the outside. Vehicles traveling on roads include both probe vehicles and other vehicles. However, even if a vehicle does not have an on-board device capable of transmitting probe information, it is still considered a probe vehicle if it has a smartphone, tablet PC, or the like as mentioned above that can transmit probe information such as vehicle location information to the outside.

[0021] "Signal control parameters": The cycle length, split, and offset, which are the time elements of signal display, are collectively called signal control parameters or signal control constants. "Cycle length": The time of one cycle from the start of the green (or red) signal on a traffic signal to the start of the next green (or red) signal. In Japan, it is stipulated by law that a green signal light color must be called green.

[0022] "Aspect": A traffic signal aspect that shows the relationship between the display status of each light included in a traffic signal. Aspects indicate the right of way given to vehicles, pedestrians, etc. at an intersection for each approach road, and the time period during which that right of way is given. "Split": The ratio of the length of time allocated to each aspect to the cycle length. Generally expressed as a percentage or ratio. Strictly speaking, it is the value obtained by dividing the effective green time by the cycle length. "Offset": In coordinated or local control, this refers to the deviation of a certain point in a signal display, such as the start of the main road green light, from a reference point common to the group of signals, or the deviation of the start point of the same display between adjacent intersections. The former is called absolute offset, and the latter is called relative offset, and is expressed as time (seconds) or a percentage of the cycle.

[0023] "Green time": This refers to the time period during which vehicles have the right of way at an intersection. The end of the green time can be set at the earliest when the green light goes out, and at the latest when the yellow light goes out. In the case of intersections with arrow lights, it can also be set at the end of the right-turn arrow. "Red time": This refers to the time period during which vehicles do not have the right of way at an intersection. The start of the red time can be set at the earliest when the green light goes out, and at the latest when the yellow light goes out. In the case of intersections with arrow lights, it can also be set at the end of the right-turn arrow.

[0024] As described above, in this embodiment, the time periods included in one cycle are roughly divided into green periods when a right of way is given and red periods when a right of way is not given. Therefore, if the green period is G, the red period is R, and the cycle length is C, then there is a relationship of C = G + R. Therefore, in calculation formulas that include R (such as equations (10) and (11) described below), (C - G) may be used instead of R. In other words, the red period R in this embodiment may be a value calculated indirectly from the cycle length C and the green period G.

[0025] "Queue": A line of vehicles stopped in front of an intersection, for example, waiting for a red light. "Link": A road section that connects nodes such as intersections and has an uphill or downhill direction. When viewed from an intersection, a link that flows into the intersection is called an inflow link, and when viewed from an intersection, a link that flows out of the intersection is called an outflow link.

[0026] "Travel time": The time required for a vehicle to travel a certain section. Travel time may include stop times and delays along the way. "Link travel time": The travel time when the road section used as the unit for calculating travel time is a "link," that is, the travel time required for a vehicle to travel from the start point to the end point of a link.

[0027] "Traffic capacity": The traffic capacity of a road refers to the maximum number of vehicles that can comfortably travel in one direction on a road or a specified section of one lane within a certain period of time, given road conditions such as road shape, width, gradient, etc., and traffic conditions such as vehicle type composition and speed limit. However, for two-lane or three-lane roads, both traffic volumes are taken into account.

[0028] "Traffic volume" refers to the number of vehicles passing through within a unit of time. Unless otherwise specified, it is expressed as the number of vehicles passing through in one hour, but for control and evaluation purposes, traffic volume over a short period of time, such as seconds, 5 minutes, or 15 minutes, may be used. Generally, traffic volume increases in response to traffic demand, but decreases when traffic demand exceeds traffic capacity.

[0029] "Load rate": In an oversaturated state, it is necessary to consider the "load traffic volume", which is the volume of traffic passing the stop line plus the number of vehicles waiting in line to be released, as a variable to be controlled. The ratio of the load traffic volume (traffic flow rate) per unit time to the saturation traffic flow rate is called the load rate. When the number of vehicles remaining to be released due to an oversaturated state is small, the load rate is equivalent to the demand rate. "Traffic demand": For a given intersection or entrance route, or for each traffic route, the traffic volume or traffic flow rate that arrives at the stop line of the entrance route within a certain time is called traffic demand.

[0030] "Traffic flow rate": The number of vehicles passing through a certain cross section of a lane or roadway in a certain time (usually less than an hour) converted into a value per unit time (usually an hour). For example, if the traffic volume for 15 minutes is 90 vehicles, the traffic flow rate for this 15 minute period is 360 (vehicles / hour) or 6 (vehicles / minute). The traffic flow rate is the reciprocal of the average headway of vehicles passing through during a certain period of time.

[0031] "Oversaturated, non-saturated, near-saturated": When there is a backlog of people waiting in line at the light when the green light ends, traffic demand exceeds traffic capacity. This state is called "oversaturated." Conversely, when traffic demand is below traffic capacity and the traffic queue clears when the green light ends, this state is called "non-saturated." A state where the demand rate is high (for example, 0.85 or higher) but not oversaturated is called near-saturated. Note that the demand rate is less than 1.

[0032] "Saturation flow rate": When there is sufficient traffic demand, the saturation flow rate is the maximum number of vehicles that can pass the stop line per lane in a unit time (for example, one second) at the entrance to an intersection. The value of the saturation flow rate will differ depending on the traffic flow line, such as when there are dedicated right-turn or left-turn lanes in addition to the straight-through lane. The value of the saturation flow rate also differs depending on road or traffic conditions, such as lane width and the proportion of large vehicles.

[0033] "Point control": Traffic signal control can be classified into three types based on the number of intersections and spatial configuration: point control, coordinated control, and area control. Of these, point control is a method of controlling signalized intersections individually.

[0034] "System control": A method of controlling a series of adjacent intersections in a linked manner. The feature of this method is that a common cycle length (common cycle length of the system) and offset are set for multiple signals that are controlled in a system. "Area control": A method of collectively controlling a large number of traffic lights installed on a road network that spreads over an area. It is an area-wide expansion of route system control.

[0035] "Fixed-cycle control": Traffic signal control can be classified into three types based on the method of setting signal control parameters: fixed-cycle control, traffic-responsive control, and traffic-adaptive control. Of these, fixed-cycle control is a method in which signal control parameters are set in advance according to the time of day. One of the combinations of signal control parameters (called a program) that are set in advance according to the time of day and day of the week (weekdays, Saturdays, Sundays, and holidays) is selected and implemented.

[0036] "Traffic-responsive control": A traffic signal control method that uses vehicle detectors and is implemented at each signal controller. It is also called terminal-responsive control. Traffic-responsive control determines the start and end points of green indication in response to short-term changes in traffic demand, and as a result, changes the green time duration and cycle length.

[0037] "Traffic adaptive control": A control method in which a central device at a traffic control center changes signal control parameters for traffic signal controllers at important intersections or traffic signal controllers at multiple intersections that are controlled by coordinated or area control. In this embodiment, this is also referred to as "remote control" because the central device remotely controls one or multiple traffic signal controllers. Because traffic adaptive control enables advanced coordinated control that responds to fluctuations in traffic flow, it is applied to roads where traffic volume and its time fluctuations are large and high traffic processing efficiency is required.

[0038] Traffic adaptive control is classified into two types: "program selection control" and "program formation control." Program selection control is a method of selecting from multiple pre-prepared combinations (programs) the one that is most suitable for the current traffic situation based on information from vehicle detectors, etc. Program formation control is a method of determining the timing of switching signal control parameters or signal light colors instantly based on information from vehicle detectors, etc., without preparing a finite number of combinations of signal control parameters.

[0039] "MODERATO" (Management by Origin-Destination Related Adaptation for Traffic Optimization): This is the name of programmatic control in Japan's Universal Traffic Management System (UTMS). MODERATO is a system that automatically generates signal control parameters based on the load factor (= (incoming traffic volume + number of queuing vehicles) / saturation traffic flow rate) for each incoming road at an intersection.

[0040] "SCOOT" (Split Cycle Offset Optimisation Technique): A program formation control method developed in the UK. It is widely adopted, particularly in European countries. SCOOT is a system that uses data from vehicle detectors installed on roads to automatically adjust the colour of traffic lights to adapt to current traffic conditions in near real time.

[0041] "SCATS" (Sydney Coordinated Adaptive Traffic System): A program selection control method developed in Australia. It is used at approximately 42,000 intersections in over 1,800 cities in roughly 40 countries. SCATS is a system that finds the best signal control parameters (cycle length, split, and offset) for the current traffic by selecting an automatic plan from a library in response to data obtained from loop detectors installed on the road.

[0042] [Overall System Configuration] Fig. 1 is a diagram showing the overall configuration of a traffic signal control system 1 according to this embodiment. Fig. 2 is a block diagram of an information processing device 2, an on-board device 4 of a probe vehicle 3, and a central unit 5 included in the traffic signal control system 1. As shown in Figs. 1 and 2, the traffic signal control system 1 includes the information processing device 2 installed in a data center or the like, the on-board device 4 mounted on the probe vehicle 3, the central unit 5 installed in a traffic control center, and traffic signal controllers 6 installed at each intersection.

[0043] The traffic signal control system 1 of this embodiment is a system in which an information processing device 2 collects probe information including vehicle positions and the times at which they pass from probe vehicles 3, obtains intersection signal information from a central device 5, and uses the probe information and signal information to calculate traffic indicators such as load factors required to generate intersection signal control parameters.

[0044] In this way, the information processing device 2 of this embodiment functions as a "traffic index calculation device" necessary for generating signal control parameters. The information processing device 2 of this embodiment also functions as a "delay time calculation device" for each vehicle due to waiting at a traffic light on an incoming road, which serves as source data for traffic indexes such as load factors.

[0045] There is no particular limitation on the operator of the information processing device 2. For example, the operator of the information processing device 2 may be the manufacturer of the vehicle 3, an IT company that provides various types of information, or a public business operator in charge of traffic control that operates the central device 5. The server of the information processing device 2 may be operated as either an on-premise server or a cloud server.

[0046] The on-board device 4 of the probe vehicle 3 is capable of wireless communication with wireless base stations 7 (e.g., mobile base stations) in various locations. The wireless base stations 7 are capable of communicating with the information processing device 2 via a public communication network 8 such as the Internet. Therefore, the on-board device 4 can wirelessly transmit uplink information S1 addressed to the information processing device 2 to the wireless base station 7. In addition, the information processing device 2 can transmit downlink information S2 addressed to a specific on-board device 4 to the public communication network 8.

[0047] 2, the information processing device 2 includes a server computer 10 consisting of a workstation, and various databases 21 to 24 connected to the server computer 10. The server computer 10 includes an information processing unit 11, a storage unit 12, and a communication unit 13. The storage unit 12 is a storage device that includes at least one nonvolatile memory (recording medium) of a hard disk drive (HDD) or a solid state drive (SSD), and a volatile memory (recording medium) consisting of a random access memory or the like. The nonvolatile memory may be removable.

[0048] The information processing unit (hereinafter also referred to as the "processing unit") 11 is an arithmetic processing device including a CPU (Central Processing Unit) that reads a computer program 14 stored in the nonvolatile memory of the storage unit 12 and performs information processing in accordance with the program 14. The computer program 14 of the information processing unit 2 includes a program that causes the CPU of the processing unit 11 to execute calculation processing of predetermined traffic indices, such as calculation of a delay time due to waiting at a traffic light for the probe vehicle 3 and calculation of a load factor based on the delay time.

[0049] The communication unit 13 is composed of a communication interface that communicates with the central device 5 and the wireless base station 7 via the public communication network 8. The communication unit 13 can receive uplink information S1 transmitted by the wireless base station 7 to the device itself, and can transmit downlink information S2 generated by the device itself to the wireless base station 7. The uplink information S1 includes probe information transmitted from the in-vehicle device 4. The downlink information S2 includes the link travel time calculated by the processing unit 11, etc.

[0050] The communication unit 13 can receive traffic light information of intersections included in the traffic control area that is transmitted to the device by the central device 5. The traffic light information of the intersection includes at least the cycle length and red time length of the intersection. The communication unit 13 may be connected to the central device 5 of the traffic control center via a dedicated communication line 9 instead of the public communication network 8.

[0051] The various databases 21 to 24 are made up of large-capacity storage devices such as HDDs or SSDs. These databases 21 to 24 are each connected to the server computer 10 so that data can be transferred. The databases 21 to 24 include a map database 21, a probe database 22, a member database 23, and a traffic light information database 24.

[0052] The map database 21 stores road map data 25 covering the entire country. The road map data 25 includes "intersection data" and "link data." The "intersection data" is data that associates intersection IDs assigned to domestic intersections with location information of the intersections. The "link data" is data that associates the following information 1) to 4) with link IDs of specific links assigned to domestic roads.

[0053] Information 1) Location information of the start point, end point, and interpolation point of a specific link. Information 2) Link ID connecting to the start point of a specific link. Information 3) Link ID connecting to the end point of a specific link. Information 4) Link cost of a specific link.

[0054] The road map data 25 forms a network corresponding to the actual road alignment and driving direction of the road. For this reason, the road map data 25 is a network in which road sections between nodes n representing intersections are connected by directed links l (lowercase L). Specifically, the road map data 25 is configured as a directed graph in which a node n is set for each intersection and each node n is connected by a pair of directed links l in opposite directions. Therefore, in the case of a one-way road, nodes n are connected only by one-way directed links l.

[0055] The road map data 25 also includes road type information indicating whether a specific directional link l corresponding to each road on the map is a general road or a toll road, and facility information indicating the type of facility, such as a toll booth or parking area, included in the directional link l.

[0056] The probe database 22 stores probe information received from probe vehicles 3 pre-registered in the information processing device 2 for each identification information of the vehicle 3. The stored probe information includes at least the vehicle position and the time of passing. The probe information may also include vehicle data such as vehicle speed, vehicle direction, and vehicle status information (stop / running events). The sensing cycle of the probe information is at a granularity that allows accurate identification of the running history of the probe vehicle 3, and is, for example, 0.5 to 1.0 seconds.

[0057] The member database 23 stores personal information such as the address and name of the owner (registered member) of the probe vehicle 3, the vehicle identification number (VIN), and identification information (e.g., at least one of MAC address, email address, and telephone number) of the in-vehicle device 4. The traffic light information database 24 stores traffic light information including the cycle length and red time length of the on-ramp road at each intersection for each intersection ID and link ID.

[0058] The traffic signal controllers 6 installed at each intersection in the traffic control area include two types of traffic signal controllers: a first controller 6A and a second controller 6B. First controller 6A: A traffic signal controller that is not subject to remote control (system control, area control, etc.) by the central unit 5, but performs point control (fixed cycle control, etc.) that independently determines the signal light color. Second controller 6B: A traffic signal controller that is subject to remote control (system control, area control, etc.) by the central unit 5.

[0059] The central unit 5 transmits the signal information of the first controller 6A to the information processing device 2 only when there is a change in operation. The processing unit 11 updates the signal information of the first controller 6A contained in the signal information database 24 to the received signal information. The central unit 5 transmits the signal information of the second controller 6B to the information processing device 2 at predetermined control intervals (for example, 1.0 to 2.5 minutes). The processing unit 11 updates the signal information of the second controller 6B contained in the signal information database 24 to the received signal information.

[0060] 2, the in-vehicle device 4 is a computer device including a processing unit 31, a storage unit 32, and a communication unit 33. The processing unit 31 is an arithmetic processing device including a CPU that reads a computer program 34 stored in the non-volatile memory of the storage unit 32 and performs various information processing in accordance with the program 34.

[0061] The storage unit 32 is a storage device including at least one nonvolatile memory (recording medium) of an HDD and an SSD, and a volatile memory (recording medium) made of a random access memory, etc. The computer program 34 of the in-vehicle device 4 includes programs that cause the CPU of the processing unit 31 to sense and generate probe information, search for a route for the probe vehicle 3, and perform image processing for displaying search results on the display of the navigation device.

[0062] The communication unit 33 is composed of a wireless communication device permanently mounted on the probe vehicle 3 or a data communication terminal (e.g., a smartphone, a tablet computer, or a node-type personal computer) temporarily mounted on the probe vehicle 3. The communication unit 33 has, for example, a GPS (Global Positioning System) receiver. The processing unit 31 monitors the current position of the vehicle in almost real time based on the GPS position information received by the communication unit 33. For positioning, it is preferable to use a global navigation satellite system such as GPS, but other methods may also be used.

[0063] The processing unit 31 measures vehicle data such as the vehicle position, vehicle speed, vehicle direction, and CAN information of the host vehicle at predetermined sensing intervals (e.g., 0.5 to 1.0 seconds) and records the measured data together with the measurement time in the storage unit 32. When the vehicle data has been accumulated for a predetermined recording time (e.g., 1 minute) in the storage unit 32, the communication unit 33 generates probe information including the accumulated vehicle data and the identification information of the host vehicle, and transmits the generated probe information via uplink to the information processing device 2.

[0064] The in-vehicle device 4 includes an input interface (not shown) that accepts operational inputs from the driver. The input interface may be, for example, an input device associated with the navigation device or an input device of a data communication terminal mounted on the probe vehicle 3.

[0065] 2, the central unit 5 is a server computer that controls the traffic signal controllers 6 at multiple intersections included in the traffic control area. The central unit 5 includes a processing unit 51, a storage unit 52, a communication unit 53, and the like.

[0066] The traffic signal controllers 6 within the traffic control area include a first controller 6A of a point control type that operates independently (standalone), and a second controller 6B that is the object of remote control (traffic adaptive control) by the central device 5. The processing unit 51 is made up of an arithmetic processing device including a CPU that reads out a computer program 54 stored in the nonvolatile memory of the storage unit 52 and performs various information processing in accordance with the program 54.

[0067] The storage unit 52 is a storage device including at least one non-volatile memory (recording medium) of an HDD or an SSD, and a volatile memory (recording medium) such as a random access memory. The computer program 54 of the central device 5 includes a program for remote control (traffic adaptive control) of at least one of MODERATO, SCOOT, and SCATS.

[0068] When the processing unit 51 generates the signal control parameters by remote control, it generates a signal control command to be executed by the second controller 6B, which is the control target of the remote control. The signal control command is information related to the timing of switching the light color of the signal lamp corresponding to the newly generated signal control parameters, and is generated every control period of the remote control (for example, 1.0 to 2.5 minutes).

[0069] The communication unit 53 is composed of a communication interface that communicates with the information processing device 2 via the public communication network 8 and with the second controller 6B via a dedicated communication line 9. The communication unit 53 may be connected to the information processing device 2 via the dedicated communication line 9.

[0070] The communication unit 53 transmits the signal control command generated by the processing unit 51 for each control period of the signal control parameters to the second controller 6B, which is the target of remote control. The communication unit 53 transmits signal information including the cycle length and red time length currently being used by the first and second controllers 6A, 6B to the information processing device 2. The signal information of the second controller 6B is transmitted to the information processing device 2 for each control period of the remote control (for example, 1.0 to 2.5 minutes).

[0071] [Outline and Problems of Remote Control According to Comparative Example] Fig. 3 is a flowchart showing an outline of remote control (traffic adaptive control) according to a comparative example. As shown in Fig. 3, the remote control according to the comparative example includes "measuring traffic flow" (step S1), "calculating traffic indexes" (step S2), "calculating signal control parameters" (step S3), and "reflecting the signal control parameters" (step S4).

[0072] The processing unit 51 of the central unit 5 repeatedly executes each of steps S1 to S4 at a predetermined control period (for example, 1.0 to 2.5 minutes). Traffic flow measurement (step S1) is a process of measuring the traffic flow for each approach road at a target intersection. Conventional traffic flow measurement is a process of calculating actual measurement data based on detection signals (such as pulse signals) from vehicle detectors. The actual measurement data includes actual measurements of traffic volume Vin, number of queuing vehicles Qin, and saturation traffic flow rate Sf. Note that Sf may be a set value based on the road structure.

[0073] Calculating the traffic index (step S2) is a process of using the measurement results of step S1 to calculate the traffic index for each incoming road required to calculate the signal control parameters. The traffic index used in MODERATO is the load factor Lr. The load factor Lr is the ratio of traffic demand to the maximum traffic volume that can be handled in one cycle. The traffic index used in SCOOT and SCATS is the actual saturation degree Ds. The actual saturation degree Ds is the ratio of arriving traffic volume to the maximum traffic volume that can be handled during green time.

[0074] The calculation formula for the load factor Lr is as follows: (1) The calculation formula for the phase saturation degree Ds is as follows: Lr = (Vin + k x Qin) / Sf ... (1) Ds = Vin x C / (Sf x G) ... (2) Where, Vin: inflow traffic volume to the intersection (vehicles / second) k: weighting coefficient (for example, 1.0) Qin: traffic volume equivalent of the number of queuing vehicles (vehicles / second) Sf: saturation traffic flow rate (vehicles / second) G: effective green time (seconds) C: cycle length (seconds)

[0075] As shown in equation (1), the calculation formula for load factor Lr includes the inflow traffic volume Vin and the number of queued vehicles Qin as traffic variables for the inflow route. As shown in equation (2), the calculation formula for current saturation level Ds includes the inflow traffic volume Vin as a traffic variable for the inflow route. The processing unit 51 of the central unit 5 substitutes the actual measured values ​​of Vin, Qin, and Sf obtained in step S1 into equation (1) or (2) to calculate at least one traffic index of the load factor Lr and the current saturation level Ds.

[0076] Calculating signal control parameters (step S3) is a process of calculating signal control parameters such as the split and cycle length of the intersection to be controlled using the traffic indicators calculated in step S2. Here, we assume that the central unit 5 employs MODERATO and calculates the split and cycle length of a crossroads intersection that includes only two aspects. Furthermore, the number of the aspect is represented by "i" (i = 1, 2), and the direction of the incoming lane for each aspect i is represented by "j" (j = 1, 2).

[0077] If the load factor of each inflow route j of aspect i is "Lij", the traffic volume on inflow route j is "Vij", the number of queueing vehicles on inflow route j is "Qij", and the saturation traffic flow rate on inflow route j is "Sij", the load factor Lij is as shown in the following formula (3): Lij = (Vij + Qij) / Sij (3)

[0078] The processing unit 51 of the central device 5 calculates the load factor Lri of the aspect i using the following formula (4), and calculates the load factor Lrt of the entire intersection using the following formula (5). In formula (4), "maxj" means the maximum value among the j load factors Lij included in the aspect i. Lri = maxj(Lij) (4) Lrt = Lr1 + Lr2 (5)

[0079] Then, the processing unit 51 of the central device 5 calculates the split λi and cycle length C of aspect i using the following equations (6) and (7). In equation (6), K represents the lost time, and a1 to a3 are coefficients. λi = Lri / Lrt (6) C = (a1 x K + a2) / (1 - a3 x Lrt) (7)

[0080] Reflecting the signal control parameters (step S4) is a process of having the second controller 6B of the target intersection execute the signal control parameters calculated in step S3. Specifically, the processing unit 51 of the central device 5 calculates a signal control command including the light color change timing from the new signal control parameters, and transmits the calculated signal control command to the second controller 6B. Note that, in the case where the second controller 6B is capable of calculating the light color change timing from the signal control parameters, the signal control parameters may be transmitted directly to the second controller 6B.

[0081] As described above, in the remote control according to the comparative example, the traffic indicators Lr and Ds are calculated by substituting the actual measured values ​​of Vin, Qin, and Sf obtained from the detection signals of the vehicle detectors into the definition formulas for the traffic indicators Lr and Ds (formula (1) or (2)). Therefore, the remote control according to the comparative example has a problem in that the control target is limited to the traffic signal controller 6 at the intersection where the vehicle detector is installed. Also, as long as the load factor of MODERATO and the phase saturation degree of SCOOT and SCATS are used, there has been a fixed idea that vehicle detectors are necessary for remote control.

[0082] As shown in equations (1) and (2), the definitions of the load factor Lr and the current saturation level Ds include Vin and Qin in the numerator and the saturation flow rate Sf in the denominator. Therefore, if the traffic volume Vin and the number of queueing vehicles Qin input into equations (1) and (2) are defined as variables representing the ratio to the saturation flow rate Sf, it becomes possible to calculate the load factor Lr and the current saturation level Ds even if the true values ​​of Vin, Qin, and Sf are unknown.

[0083] That is, if the traffic volume on the inlet road is defined as Vin = α × Sf and the number of queued vehicles is defined as Qin = β × Sf, and these are substituted into equations (1) and (2), Sf is canceled out by the numerator / denominator on the right-hand side, as shown in the following calculation equations (8) and (9). This means that as long as α and β can be determined, the load factor Lr and the current saturation degree Ds can be calculated even if any value is used for the saturation flow rate Sf in the calculation process. By using the traffic volume Vin (= α × Sf) normalized by Sf and the number of queued vehicles Qin (= β × Sf) normalized by Sf, the load factor Lr and the current saturation degree Ds can be calculated without determining the values ​​of Vin, Qin, and Sf themselves.

[0084] Lr = (Vin + k × Qin) / Sf = (α × Sf + k × β × Sf) / Sf = α + k × β ... (8) Ds = Vin × C / (Sf × G) = α × Sf × C / (Sf × G) = α × C / G ... (9)

[0085] Hereinafter, the traffic volume Vin (= α × Sf) and the number of queueing vehicles Qin (= β × Sf), expressed as a ratio to Sf, are referred to as the "normalized traffic volume" and the "normalized number of queueing vehicles," respectively. Furthermore, the "normalized traffic volume" and the "normalized number of queueing vehicles" are collectively referred to as the "normalized data." As mentioned above, the saturation flow rate Sf here can take any value. Meanwhile, as will be described later, the above-mentioned α and β can be determined by using the results of calculations using probe information, and therefore, signal control parameters can be calculated from the load factor Lr and the current saturation level Ds even without vehicle detectors.

[0086] Therefore, in this embodiment, the normalized traffic volume Vin (= α × Sf) and the normalized queue number Qin (= β × Sf), which can be calculated from probe information, are used as traffic variables for the incoming road used to calculate the traffic index (see FIG. 5). In this way, by calculating the traffic index used to calculate the signal control parameters using normalized data obtained from probe information, etc., remote control can be performed even if vehicle detectors are not installed. Below, an overview of the remote control of this embodiment will be explained with reference to FIG. 4.

[0087] [Outline of Remote Control of This Embodiment] Fig. 4 is a flowchart showing an outline of the remote control (traffic adaptive control) of this embodiment. As shown in Fig. 4, the remote control of this embodiment includes "measuring traffic flow" (step S11), "calculating traffic indexes" (step S12), "calculating signal control parameters" (step S13), and "reflecting the signal control parameters" (step S14).

[0088] The processing unit 11 of the information processing device 2 repeatedly executes the processes of steps S11 to S12 at predetermined control intervals (e.g., 1.0 to 2.5 minutes). The processing unit 51 of the central device 5 repeatedly executes the processes of steps S13 to S14 at the same control intervals (e.g., 1.0 to 2.5 minutes).

[0089] Traffic flow measurement (step S11) is a process of measuring the traffic flow for each incoming road at a target intersection. In this embodiment, traffic flow measurement is a process of calculating normalized data using probe information as the original data. The normalized data includes a normalized traffic volume Vin (= α × Sf) that represents the ratio to Sf, and a normalized queue number Qin (= β × Sf) that represents the ratio to Sf.

[0090] Calculation of traffic indices (step S12) is a process of calculating traffic indices for each approach road required for calculating signal control parameters using the measurement results of step S11. The calculation formula for the load factor Lr is as shown in equation (1) above. The calculation formula for the actual saturation degree Ds is as shown in equation (2) above.

[0091] The processing unit 11 of the information processing device 2 substitutes the normalized data Vin (= α × Sf) and Qin (= β × Sf) obtained in step 11 into equation (1) or (2) to calculate at least one traffic index of the load factor Lr and the current saturation degree Ds. In this case, as is clear from the above-mentioned equations (8) and (9), Sf is canceled out by the numerator / denominator on the right-hand side, so it is possible to calculate the load factor Lr and the current saturation degree Ds even if the values ​​of Vin, Qin, and Sf themselves are unknown.

[0092] The processing unit 11 of the information processing device 2 transmits the calculation result of the load factor Lr or the current saturation degree Ds obtained in step S13 to the central device 5. When the processing unit 51 of the central device 5 receives the calculation result of the load factor Lr or the current saturation degree Ds from the information processing device 2, it executes the calculation process of steps S13 and S14 using the received calculation result.

[0093] Calculation of signal control parameters (step S13) is a process of calculating signal control parameters such as the split and cycle length of the controlled intersection using traffic indicators received from the information processing device 2. The processing content of step S13 is the same as step S3 in FIG. 3. Reflection of signal control parameters (step S14) is a process of causing the second controller 6B of the target intersection to execute the signal control parameters calculated in step S13. The processing content of step S14 is the same as step S4 in FIG. 3.

[0094] [Method of calculating normalized data for an isolated intersection] Figure 5 is an explanatory diagram showing an example of a method of calculating normalized data when the intersection to be remotely controlled is an isolated intersection. The meanings of the variables included in Figure 5 are as follows. Note that an "isolated intersection" is an intersection that is the target of remote control and is an intersection that is controlled independently of other intersections.

[0095] dav: delay time per vehicle due to waiting at traffic lights (average value) (seconds) L: link length between intersections (m) Tt: average travel time of probe vehicles (= link travel time between J1 and J2) (seconds) Ve: expected speed (e.g., speed limit) (km / hour) J1: intersection upstream of target intersection J2: target intersection for remote control (single intersection)

[0096] As shown in Fig. 5, in the case of remote control of a single intersection, the processing unit 11 of the information processing device 2 calculates the normalized traffic volume Vin and the normalized number of queued vehicles Qin according to the saturation state (non-saturated / over-saturated) of the intersection using the following formula (10) or formula (11). In formulas (10) and (11), "R" represents the red time (seconds).

[0097] If dav≦R / 2 (in the case of non-saturation) Vin={1−R ２ / (2×dav×C)}×Sf (10) If R / 2<dav (in the case of supersaturation) Vin=(1−R / C)×Sf Qin={(dav−R / 2) / R}×(1−R / C)×Sf (11) Hereinafter, the basis for the validity of equations (10) and (11) will be described with reference to FIGS. 5 to 7.

[0098] (Relationship between link travel time and delay time) The graph in the lower part of Fig. 5 shows the travel trajectories of multiple vehicles traveling along the link between intersections J1 and J2. The horizontal axis of the graph represents the distance from intersection J1, and the vertical axis of the graph represents the travel time.

[0099] When multiple vehicles pass through the link between intersections J1 and J2, the delay time dav per vehicle due to waiting at a traffic light is the total delay time (area of ​​the triangle) of all vehicles passing through intersection J2 after waiting at a traffic light divided by the number of vehicles. The average travel time Tt of multiple probe vehicles 3 can be considered to include the delay time dav per vehicle.

[0100] Therefore, the delay time dav per vehicle due to waiting at a traffic light is the average travel time Tt of the multiple probe vehicles 3 minus the travel time (= L / (Ve / 3.6)) when traveling along the link at the assumed speed Ve without waiting at a traffic light. That is, the delay time dav can be defined by the following equation (12): dav = Tt - {L / (Ve / 3.6)} ... (12)

[0101] The processing unit 11 of the information processing device 2 extracts probe information of a plurality of probe vehicles 3 that have passed through the link between intersections J1 and J2 during the current control period (for example, 1.0 to 2.5 minutes) from the positions and times of the probe information contained in the probe database 22. Then, the processing unit 11 calculates the average travel time Tt of the probe vehicles 3 along the link based on the positions and times (or speed) of the extracted plurality of pieces of probe information, and obtains the delay time dav by substituting the calculated Tt into equation (12).

[0102] (When the Single Intersection is Unsaturated) Figure 6 is an explanatory diagram showing the traffic situation at intersection J2 when it is unsaturated, and the relational equation required to derive the traffic volume Vin normalized by Sf. In the example of Figure 6, it is assumed that vehicles stopped just before intersection J2 stop overlapping at the same position just before the stop line (imagine a vertical line of vehicles). Also, in Figure 6, "D" is the total delay time (seconds) during one cycle, and "Gc" is the time (seconds) relative to the start of the green light, which represents the time when the last vehicle passes the stop line at intersection J2.

[0103] If the approach road at intersection J2 is not saturated (dav≦R / 2), the number of vehicles that enter after the red light starts (=(R+Gc)×Vin) is equal to the number of vehicles that enter by time Gc (=Gc×Sf). Therefore, the time Gc at which the rearmost vehicle crosses the stop line is given by the following equation (13): Gc=Vin×R / (Sf−Vin) (13)

[0104] The formulas for calculating the total delay time D of the train of vehicles in one cycle and the delay time dav per vehicle are the following formulas (14) and (15), respectively: D = 0.5 × {(R + Gc) × R × Vin} (14) dav = D / (C × Vin) = 0.5 × {(R + Gc) × R} / C (15) By substituting Gc from formula (13) into formula (15) and solving for Vin, the formula for calculating the normalized traffic volume Vin when intersection J2 is unsaturated becomes the above-mentioned formula (10).

[0105] (When a Single Intersection is Oversaturated) Figure 7 is an explanatory diagram showing an example of traffic conditions at intersection J2 when the intersection is oversaturated. As shown in Figure 7, a simple model of only moving and stopping is assumed as a model representing an oversaturated state in which vehicles wait at two or more traffic lights. In this case, the stopping time per stop at the second or subsequent traffic lights is equal to the red light time R.

[0106] Pattern 1 in Fig. 7 shows the traffic situation when the queue is cleared in the current cycle (waiting 0 cycles), i.e., when intersection J2 is just saturated. Pattern 2 in Fig. 7 shows the traffic situation when the queue is cleared in the next cycle (waiting 1 cycle), and pattern 3 in Fig. 7 shows the traffic situation when the queue is cleared in the cycle after that (waiting 2 cycles).

[0107] In pattern 1, dav = 0.5R, and Qin = 0. In pattern 2, dav = 1.5R, and Qin = (1 - R / C) x Sf. In pattern 3, dav = 2.5R, and Qin = 2 x (1 - R / C) x Sf. Therefore, when intersection J2 is oversaturated, the calculation formulas for normalized traffic volume Vin and normalized queue size Qin are the above-mentioned formula (11).

[0108] [Problems with Using Average Link Travel Time] Figure 8 is an explanatory diagram showing an example of a stop event that affects the accuracy of the delay time dav per vehicle due to waiting at a traffic light. As shown in Figure 8, possible stop events that may occur when the probe vehicle 3 travels the link from intersection J1 to intersection J2 include waiting at a traffic light at intersection J2, as well as the following events E1 and E2. Event E1: Stop due to being the following vehicle of bus 3X that has stopped at a bus stop Event E2: Stop due to being the following vehicle of another vehicle 3Y entering or leaving a parking lot

[0109] However, in the above-mentioned formula (12), the link travel time between the intersections J1 and J2 is used as the average travel time Tt calculated from the probe information. Therefore, if the events E1 and E2 occur to the probe vehicle 3, the stopping times of the events E1 and E2 will be included in the average travel time Tt, and the delay time dav based on formula (12) will be larger than the actual delay time.

[0110] In this case, the normalized traffic volume Vin and normalized queue Qin, which are based on the delay time dav, become inaccurate, and the load factor Lr and current saturation degree Ds, which are based on the normalized traffic volume Vin and normalized queue Qin, also become inaccurate. Therefore, there is a possibility that the accuracy of the signal control parameters calculated from the load factor Lr and current saturation degree Ds will decrease.

[0111] [Solution Method Using Average Travel Time in Traffic Light Waiting Sections] In this embodiment, in order to solve the above-mentioned problem, a "traffic light waiting section" estimated to have occurred on the approach road to intersection J2 is determined, rather than the "entire link" which may include stop times for events E1 and E2 other than traffic light waiting, and the delay time dav per vehicle in the determined traffic light waiting section is calculated (see Figures 10 and 11).

[0112] In the traffic light waiting section just before intersection J2, the stop times for events E1 and E2 other than waiting at a traffic light are not included, or are very unlikely to be included. Therefore, by adopting the above calculation method, it is possible to accurately calculate the delay time dav per vehicle due to waiting at a traffic light on the approach road leading to intersection J2, regardless of whether there are stop events other than waiting at a traffic light, such as events E1 and E2.

[0113] 9 is an explanatory diagram showing an example of the definition of variables used to calculate the delay time dav in the traffic light waiting section. The variables include section i (i = 1, 2 ... N), the length Li (m) of section i, and the average speed Vi (km / h) of the probe vehicle 3 passing through section i. Section i is made up of multiple small sections when the link between intersections J1 and J2 is divided by a predetermined number N of divisions. The length Li of section i (hereinafter also referred to as "section length") is a calculated value or a set value that is determined to be sufficiently shorter than the link length L between intersections J1 and J2.

[0114] The processing unit 11 of the information processing device 2 executes the following processes a1 and a2 as preprocessing for the calculation process of the delay time dav (see FIG. 10). Process a1: The value (= L / N) obtained by dividing the link length L by the division number N is set as the section length Li. Process a2: An identification number (i = 1, 2 ... N) is assigned to section i in order from the downstream side to the upstream side of the link. Specifically, the identification number on the most downstream side is set to "1", and the identification number is incremented toward the upstream side, with the final identification number being "N".

[0115] The processing unit 11 of the information processing device 2 may execute the following processes b1 and b2 as preprocessing for the process of calculating the delay time dav (see FIG. 10). Process b1: The quotient M obtained by dividing the link length L by a predetermined distance Lo is added to the quotient M (=M+1), and the resulting value is set as the number of divisions N of the link, and the remaining distance value is set as the section length LN of the last section N. Process b2: An identification number (i=1, 2...N) is assigned to each section i in order from the downstream side of the link to the upstream side. Specifically, process b2 is the same as process a2.

[0116] In the above preprocessing, if the link between intersections J1 and J2 has a branch node such as an unsignalized intersection, section i may be divided at the branch node. Furthermore, the section lengths Li of each section i (i = 1, 2 ... N) included in the link do not all have to be a constant distance, and the section lengths Li included in one link may be varied, for example, by shortening the downstream portion of the link and lengthening the upstream portion.

[0117] In the above preprocessing, the length (section length) Li of each of the multiple sections i may be set to a value smaller than the installation interval (e.g., 200 m) of vehicle detectors actually installed on roads to measure vehicle speed. In this way, the measurement granularity of the average vehicle speed can be finer than when the average vehicle speed is measured using a vehicle detector. Therefore, the traffic light waiting section determined based on the total number of sections I can be calculated more precisely, improving the calculation accuracy of the delay time dav.

[0118] The average speed Vi of the probe vehicle 3 in the section i (hereinafter also referred to as the "section speed") is the average speed of the probe vehicle 3 calculated from the positions and times of multiple pieces of probe information. A method for calculating the average speed Vi for each section i will be described later.

[0119] 10 is a flowchart showing an example of a process for calculating a delay time dav per vehicle due to waiting at a traffic light, which is executed by the processing unit 11 of the information processing device 2. As shown in Fig. 10, the processing unit 11 of the information processing device 2 first extracts probe information of a plurality of probe vehicles 3 that have passed through the link between intersections J1 and J2 during the current control period (for example, 1.0 to 2.5 minutes) from the positions and times of the probe information contained in the probe database 22 as a process for collecting data required for calculating the delay time dav (step ST10).

[0120] Next, as a first step in the process of calculating the delay time dav, the processing unit 11 calculates the average speed Vi of each section i (i = 1, 2 ... N) included in the link (step ST11). Specifically, the processing unit 11 calculates the traveling speed of each probe vehicle 3 that has passed through the link in the section i based on the position and time (or speed) included in the probe information. Next, the processing unit 11 determines the average speed Vi of the section i by dividing the sum of the traveling speeds of each probe vehicle 3 in the section i by the number of probe vehicles 3.

[0121] Next, as a second process of the process for calculating the delay time dav, the processing unit 11 repeatedly adds the average travel time Ttt and the delay time dav per vehicle each time the end of the traffic light waiting section is searched for based on the average speed Vi (step ST12). Hereinafter, a specific example of the second process executed in conjunction with the search for the end of the traffic light waiting section will be described with reference to FIG.

[0122] 11 is a flowchart showing an example of a calculation process (second process) of a delay time dav in a traffic light waiting section executed by the processing unit 11 of the information processing device 2. In Fig. 11, "Li" is the length of the section (m), "Vi" is the average travel time (km / hour) in the section i, "Ti" is the average travel time (seconds) in the section i, and "dav_i" is the average delay time (seconds) in the section i.

[0123] "T" is the average travel time (seconds) in the traffic light waiting section, and "dav" is the average delay time (seconds) per vehicle in the traffic light waiting section. "ML" is a variable that represents the section length (m) at which the section speed Vi exceeds the speed threshold TS. "TS" is the speed threshold (km / h), and "TL" is the distance threshold (m).

[0124] The speed threshold TS is an estimated value of the average speed of the vehicle when the vehicle stops to wait for a traffic light before intersection J2. The speed threshold TS is a set value determined depending on factors such as the length of the section length Li, and here it is assumed that TS = 25 km / h. The distance threshold TL is an estimated value of the cruising distance of a vehicle traveling at an average speed exceeding the speed threshold TS when the vehicle continues traveling without intending to stop. The distance threshold TS is a set value determined depending on factors such as the length of the speed threshold TS, and here it is assumed that TL = 100 m.

[0125] 11, the processing unit 11 of the information processing device 2 first initializes variables (step ST20). Specifically, the processing unit 11 sets the initial values ​​of the section i, the section length ML (the sum of the section lengths Li), the average travel time T, and the average delay time dav to i=1, ML=0, T=0, and dav=0, respectively.

[0126] Next, the processing unit 11 determines whether Vi≦TS is satisfied (step ST21). If the determination result of step ST21 is affirmative (if the section speed Vi of the section i being determined is equal to or less than the speed threshold TS), the processing unit 11 performs addition processing of the following equations (16) and (17) (step ST22), and then increments the section i (step ST23). T=T+Ti (16) dav=dav+dav_i (17)

[0127] Here, the average speed Ti and average delay time dav_i in equations (16) and (17) are calculated by the following equations, respectively: Ti=Li / (Vi / 3.6) (18) dav_i=Ti-Li / (Ve / 3.6) (19) As shown in equation (19), the average delay time dav_i for section i is the travel time T for section i minus the travel time (Li / (Ve / 3.6)) when traveling through section i at an assumed speed Ve without waiting at traffic lights.

[0128] Next, the processing unit 11 determines whether i≧N is true (step ST24). If the determination result of step ST24 is positive, the processing unit 11 ends the processing. If the determination result of step ST24 is negative, the processing unit 11 returns the processing to before step ST21. By a loop including steps ST21 to ST24, a section i that satisfies the speed condition in which the section speed Vi is equal to or less than the speed threshold value TS is searched for sequentially from the downstream side of the inflow channel, and an addition process is performed in which the average speed Ti and the delay time dav are repeatedly added for each section that satisfies the speed condition.

[0129] If the judgment result of step ST21 is negative (if the section speed Vi of the section i being judged exceeds the speed threshold TS), the processing unit 11 adds the section length Li of the section i being judged to the variable ML (step ST25), and then judges whether ML≧TL is true (step ST26).

[0130] If the determination result in step ST26 is negative (if the variable ML is less than the distance threshold TL), the processing unit 11 resets the variable ML to 0 (step ST27) on the condition that Vi+1≦TS is established, and returns the process to before step ST23. Therefore, if Vi+1>TS, the value of the variable ML is maintained without being reset, and the process returns to before step ST23.

[0131] The reason why the variable ML is reset to 0 when Vi+1≦TS is established is that if the section speed Vi+1 of the next section i+1 is equal to or less than the speed threshold TS, it is clear that the variable ML will not increase in the next section i+1. If the determination result of step ST26 is positive (if the variable ML is equal to or greater than the distance threshold TL), the processing unit 11 determines the last average travel time T and average delay time dav that satisfy Vi≦TS to be output (step ST28), and ends the processing.

[0132] [Example of determining a traffic light waiting section] Figure 12 is an explanatory diagram showing an example of determining a traffic light waiting section. In Figure 12, the numerical values ​​"u1" to "u5" are actual measured values ​​of the section speed Vi obtained from the probe information of multiple probe vehicles 3, and are assumed to be the following numerical values. Also, it is assumed that the number of divisions N of the link is 15, the section length Li of each section i is 50 m, TS is 25 km / h, and TL is 100 m.

[0133] u1 = Value below 10 km / h u2 = Value below 15 km / h u3 = Value below 20 km / h u4 = Value below 25 km / h u5 = Value above 25 km / h

[0134] As shown in Figure 12, section speeds V1 and V2 (=u1) are equal to or less than the speed threshold value TS, and section speeds V3 and V4 (=u3) are also equal to or less than the speed threshold value TS. Therefore, section i is counted up to "4" by the loop of steps ST21 to ST24 in Figure 11. Because section speed V5 (=u5) exceeds the speed threshold value TS (No in step ST21 in Figure 11), the loop of steps ST21 to ST24 in Figure 11 is exited, and variable ML becomes L5 (step ST25 in Figure 11).

[0135] Since the value of variable ML (L5 = 50 m) is less than distance threshold TL (= 100 m) and the section speed V6 (= u4) of the next section 6 is less than speed threshold TS (No in step ST26 in FIG. 11), ML is reset to 0 and the search for the end of the traffic light waiting section continues (step ST27 in FIG. 11). That is, the process of adding delay time dav continues. Therefore, section i is counted up to "5".

[0136] The section speeds V6 and V7 (= u4) are equal to or less than the speed threshold value TS. Therefore, the section i is counted up to "7" by the loop of steps ST21 to ST24 in Fig. 11. Because the section speed V8 (= u5) exceeds the speed threshold value TS (No in step ST21 in Fig. 11), the loop of steps ST21 to ST24 in Fig. 11 is exited, and the variable ML becomes L8 (step ST25 in Fig. 11).

[0137] Since the value of variable ML (L8 = 50 m) is less than distance threshold TL (= 100 m) and the section speed V9 (= u5) of the next section 9 is equal to or greater than speed threshold TS (No in step ST26 in FIG. 11), the search for the end of the traffic light waiting section continues while maintaining ML = L8 (step ST27 in FIG. 11). That is, the process of adding delay time dav continues. Therefore, section i is counted up to "8".

[0138] Since the section speed V9 (=u5) exceeds the speed threshold TS (No in step ST21 in FIG. 11), the loop of steps ST21 to ST24 in FIG. 11 is exited, and the variable ML becomes L8+L9 (step ST25 in FIG. 11).

[0139] Since the value of variable ML (L8 + L9 = 100 m) is equal to or greater than the distance threshold TL (= 100 m) (Yes in step ST26 in FIG. 11), the last section i (= 7) that satisfies Vi ≦ TS is determined as the value of the total number of sections I (step ST28 in FIG. 11), and the process ends. In this case, the most upstream end of the last section i (= 7) is considered to be the end of the traffic light waiting section. As a result, the speed Vi and section length Li of sections 8 to 15 upstream of section 7 are excluded from the data used to calculate the average travel time Ttt and the average delay time dav.

[0140] 13 and 14 are explanatory diagrams showing an example of a method for calculating the delay time dav when the link between intersections J1 and J2 has multiple lanes. As shown in Figures 13 and 14, the approach road from intersection J1 to intersection J2 includes multiple lanes R1 to R3, where lane R1 is a lane for turning left and going straight, lane R2 is a lane for going straight, and lane R3 is a lane exclusively for turning right.

[0141] Also, at the approach road to intersection J2, the right-of-way for lanes R1 and R2 for going straight and turning left is defined by a phase φ1, and lane R3 for turning right is defined by another phase φ2. In this case, as shown in Figure 13, if there are multiple lanes R1 and R2 that are processed by the same phase φ1, the processing unit 11 of the information processing device 2 executes the calculation process of the delay time dav (Figures 10 and 11) for each of the multiple lanes R1 and R2.

[0142] Specifically, the processing unit 11 calculates the delay time dav for lane R1 and the delay time dav for lane R2 in parallel, calculates the normalized traffic volume Vin and the normalized number of vehicles in queue Qin using the larger delay time dav as the original data, and calculates the load factor Lr or the current saturation degree Ds based on these traffic indices.

[0143] In the example of Figure 13, of the multiple lanes R1 and R2 processed by the same aspect φ1, the delay time dav of lane R2, which has a large degree of backlog, is adopted as the original data. Therefore, the traffic indices (Vin and Qin) for intersection J2 can be accurately calculated based on the actual traffic situation, and the calculation accuracy of the signal control parameters can be improved.

[0144] As shown in Figure 14, when there is only one lane R3 processed with the same current aspect φ2, the processing unit 11 of the information processing device 2 executes the calculation process of the delay time dav (Figures 10 and 11) only for that lane R3, and adopts the delay time dav of that lane R3 as the original data for calculating the signal control parameters.

[0145] 14, for example, since section i (=3) of lane R3 is the end of the traffic light waiting section, the processing unit 11 calculates the delay time dav of lane R3 in section i (=3). The processing unit 11 also applies the calculated delay time dav of lane R3 to equation (10) or equation (11) to calculate the normalized traffic volume Vin and the normalized number of queued vehicles Qin, and calculates the load factor Lr or the current saturation degree Ds based on these traffic indices.

[0146] In addition, if there are multiple lanes R3, R4 dedicated to right turns at intersection J2 in Figure 14, the calculation process for the delay time dav (Figures 10 and 11) is performed for each of the multiple lanes R3, R4, and the delay time dav of the lane R3 (or R4) with the larger time value is used.

[0147] [Other Modifications] The above-described embodiment (including modifications) is illustrative in all respects and is not restrictive. The scope of the present invention includes all modifications within the scope of the claims and equivalents thereof.

[0148] For example, in the above-described embodiment, the information processing device 2 may perform up to traffic flow measurement (step S11 in FIG. 4), and the central device 5 may perform the processes from calculation of traffic indexes onward (steps S12 to S14 in FIG. 4). Furthermore, if the central device 5 is capable of collecting and analyzing probe information, the central device 5 may perform all processes from traffic flow measurement to reflection of signal control parameters (steps S11 to S14 in FIG. 4). Each unit in the above-described embodiment and the processes performed by each unit can be realized using one or more circuits. The circuits may be general-purpose arithmetic circuits or dedicated circuits for specific processes.

[0149] REFERENCE SIGNS LIST 1 Traffic signal control system 2 Information processing device (delay time calculation device) 3 Probe vehicle 3X Bus 3Y Other vehicle 4 On-board device 5 Central device (delay time calculation device) 6 Traffic signal controller 6A First controller 6B Second controller 7 Wireless base station 8 Public communication network 9 Communication line 10 Server computer 11 Information processing unit 12 Memory unit 13 Communication unit (acquisition unit) 14 Computer program 21 Map database 22 Probe database 23 Membership database 24 Signal information database 25 Road map data 31 Processing unit 32 Memory unit 33 Communication unit 34 Computer program 51 Processing unit 52 Memory unit 53 Communication unit 54 Computer program

Claims

1. A delay time calculation device comprising: an acquisition unit that acquires probe information of probe vehicles traveling on an entrance road to an intersection; and an information processing unit that uses the probe information as source data to execute a calculation process for a delay time per vehicle due to waiting at a traffic light on the entrance road, wherein the calculation process includes: a first process that calculates multiple section speeds, which are the average speeds of vehicles for each of multiple sections formed by dividing the entrance road, based on the probe information; and a second process that calculates the delay time in a section of the entrance road where the vehicle is waiting at a traffic light, based on the multiple section speeds, wherein the second process includes: an addition process that adds up the delay time for each section lined up in order from the downstream side of the entrance road, which satisfies a speed condition that the section speed is equal to or less than a speed threshold; and an output process that outputs the delay time for the most upstream section, where the length obtained by adding up the section lengths of one or more sections that do not satisfy the speed condition is equal to or greater than a distance threshold.

2. The delay time calculation device of claim 1, wherein the second process includes a process of continuing the addition process when the sum of the section lengths of one or more sections that do not satisfy the speed condition is less than a distance threshold.

3. The oncoming road is an oncoming road for which right-of-way for multiple lanes is defined at the same phase, and the information processing unit executes the calculation process for each of the multiple lanes, and the delay time calculated as the largest time value is used as the source data for the traffic indicators required for traffic signal control of the oncoming road. A delay time calculation device as described in claim 1 or claim 2.

4. A delay calculation method comprising the steps of: acquiring probe information of a probe vehicle traveling on an entrance road to an intersection; and using the probe information as source data, executing a calculation process for a delay time per vehicle due to waiting at a traffic light on the entrance road, wherein the calculation process comprises: a first process for calculating, based on the probe information, a plurality of section speeds which are the average speeds of vehicles for each of a plurality of sections formed by dividing the entrance road; and a second process for calculating, based on the plurality of section speeds, the delay time in a section of the entrance road where the vehicle is waiting at a traffic light, wherein the second process comprises: an addition process for adding up the delay time for each section arranged in order from the downstream side of the entrance road which satisfies a speed condition that the section speed is equal to or less than a speed threshold; and an output process for outputting the delay time for the most upstream section where the length obtained by adding up the section lengths of one or more sections which do not satisfy the speed condition is equal to or greater than a distance threshold.

5. A computer program for causing a computer to function as: an acquisition unit that acquires probe information of probe vehicles traveling on an entrance road to an intersection; and an information processing unit that uses the probe information as source data to execute a calculation process for the delay time per vehicle due to waiting at a traffic light on the entrance road, wherein the calculation process includes: a first process that calculates, based on the probe information, multiple section speeds that are the average speed of vehicles for each of multiple sections formed by dividing the entrance road; and a second process that calculates the delay time in a section of the entrance road where the vehicle is waiting at a traffic light, based on the multiple section speeds; and the second process includes: an addition process that adds up the delay time for each section lined up in order from the downstream side of the entrance road that satisfies a speed condition that the section speed is equal to or less than a speed threshold; and an output process that outputs the delay time for the most upstream section, where the length obtained by adding up the section lengths of one or more sections that do not satisfy the speed condition is equal to or greater than a distance threshold.

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