Information generation system, information generation method, and computer program

Abstract

This information generation system is equipped with a generation unit for generating a travel time for a link comprising an entrance from a first intersection and an exit at a second intersection adjacent to the first intersection, wherein, when the absolute value of a difference between a first cycle length of a traffic signal provided at the first intersection and a second cycle length of a traffic signal provided at the second intersection is less than or equal to a prescribed value, the generation unit generates a plurality of types of travel times for the link, for each road leading to the link, for each road leading from the link, or for each combination of a road leading to the link and a road leading from the link, and when the absolute value of a difference between the first cycle length and the second cycle length is greater than the prescribed value, the generation unit generates one type of travel time for the link, regardless of the roads leading to the link and the roads leading from the link.

Description

Technical Field

[0001] The present disclosure relates to an information generation system, an information generation method, and a computer program. This application claims priority based on Japanese Patent Application No. 2021-192837 filed on November 29, 2021, and incorporates all the descriptions described in the above Japanese application.

Background Art

[0002] Conventionally, a technique for performing route search from a departure point to a destination based on the travel time of a link corresponding to a road is known. The travel time is calculated based on a statistical value (for example, an average value) of the time required for each of a plurality of vehicles to pass through the link. In order to improve the accuracy of route search, it is required to generate a more accurate travel time.

[0003] Patent Document 1 discloses a technique for calculating the average value and standard deviation of the travel time of a link for each entry link entering a node at one end of the link or for each exit link exiting from a node at the other end of the link in order to generate a more accurate travel time.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The information generation system disclosed herein includes a generation unit that generates travel times for a link entering from a first intersection and exiting to a second intersection adjacent to the first intersection. The generation unit generates multiple types of travel times for the link for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link, when the absolute value of the difference between the first cycle length of a traffic signal installed at the first intersection and the second cycle length of a traffic signal installed at the second intersection is less than or equal to a predetermined value. When the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, the generation unit generates one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link.

[0006] The information generation method disclosed herein includes a generation step of generating travel time for a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, wherein the generation step includes a first step of generating multiple types of travel time for the link for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link, when the absolute value of the difference between the first cycle length of a traffic signal installed at the first intersection and the second cycle length of a traffic signal installed at the second intersection is less than or equal to a predetermined value, and a second step of generating one type of travel time for the link regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value.

[0007] The computer program of this disclosure is a computer program that causes a computer to execute a generation step to generate travel times for a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, the generation step comprising: a first step of generating multiple types of travel times for the link for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link, when the absolute value of the difference between the first cycle length of a traffic signal installed at the first intersection and the second cycle length of a traffic signal installed at the second intersection is less than or equal to a predetermined value; and a second step of generating one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram illustrating an information generation system according to an embodiment. [Figure 2] Figure 2 is a block diagram illustrating the functional configuration of the processing unit according to the embodiment. [Figure 3] Figure 3 is a flowchart illustrating the sequence of the information generation method according to the embodiment. [Figure 4] Figure 4 is a schematic diagram illustrating a link and its surroundings according to an embodiment. [Figure 5] Figure 5 is a table illustrating the travel time according to the embodiment. [Figure 6] Figure 6 is a table illustrating travel times according to the embodiment. [Figure 7] Figure 7 shows a subroutine illustrating the details of the pathfinding step according to the embodiment. [Figure 8] Figure 8 is a flowchart illustrating the sequence of steps for the information generation method related to the modified example. [Figure 9] Figure 9 is a schematic diagram illustrating a modified example of a link and its surroundings. [Figure 10]Figure 10 is a table illustrating travel times for modified examples. [Figure 11] Figure 11 is a table illustrating travel times for modified examples. [Figure 12] Figure 12 is a schematic diagram illustrating an information generation system related to a modified example. [Modes for carrying out the invention]

[0009] [Problems the invention aims to solve] As described in Patent Document 1, when calculating the average and standard deviation of the link travel time for each combination of access routes to and from the link, it is necessary to calculate multiple types of travel times for a single link, which increases the processing load. Furthermore, because multiple types of travel times need to be stored, the required memory capacity increases. As a result, generating more accurate travel times requires a processing unit with higher performance and a storage unit with a larger memory capacity, leading to increased operating costs.

[0010] In light of these challenges, this disclosure aims to suppress the increase in operating costs when generating highly accurate travel times.

[0011] [Effects of the invention] According to this disclosure, it is possible to suppress increases in operating costs when generating highly accurate travel times.

[0012] [Description of Embodiments in this Disclosure] Embodiments of this disclosure include, in essence, at least the following:

[0013] (1) The information generation system of the present disclosure includes a generation unit that generates the travel time of a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection. When the absolute value of the difference between the first cycle length of the traffic signal provided at the first intersection and the second cycle length of the traffic signal provided at the second intersection is less than or equal to a predetermined value, for each inflow road to the link, for each outflow road from the link, or for each combination of the inflow road to the link and the outflow road from the link, a plurality of types of travel times of the link are generated. When the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, regardless of the inflow road to the link and the outflow road from the link, one type of travel time of the link is generated. This is the information generation system.

[0014] When the absolute value of the difference between the first cycle length and the second cycle length is less than or equal to a predetermined value (that is, when the first cycle length and the second cycle length are substantially equal), a tendency occurs in the travel time depending on the inflow road and the outflow road. In this case, by generating a plurality of types of travel times that reflect this tendency, the accuracy of the travel time can be made higher. On the other hand, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, almost no tendency occurs in the travel time depending on the inflow road and the outflow road. Therefore, in this case, by generating one type of travel time, an increase in the processing load can be suppressed, and an increase in the storage capacity can be suppressed. As a result, an increase in the operation cost can be suppressed when generating a more accurate travel time.

[0015] (2) The information generation system of the present disclosure may further include an acquisition unit that acquires the first cycle length and the second cycle length. The generation unit may generate a plurality of types or one type of travel time of the link based on the first cycle length and the second cycle length acquired by the acquisition unit.

[0016] By configuring it in this way, it is possible to determine whether to generate a plurality of types or one type of travel time of the link based on the first cycle length and the second cycle length.

[0017] (3) The acquisition unit may acquire vehicle information including the position of the vehicle traveling on the link and information on the time when the vehicle passes through the position, and may acquire the first cycle length and the second cycle length as an estimation result based on the vehicle information.

[0018] With such a configuration, even when the information generation system cannot directly acquire the signal control parameters for actually controlling the traffic signal, the first cycle length and the second cycle length can be acquired by estimation.

[0019] (4) The information generation system of the present disclosure may further include an acquisition unit that acquires sub - area information associating a plurality of intersections including the first intersection and the second intersection with sub - areas to which the plurality of intersections respectively belong. Based on the sub - area information acquired by the acquisition unit, when the first intersection and the second intersection belong to the same sub - area, for each inflow road to the link, for each outflow road from the link, or for each combination of the inflow road to the link and the outflow road from the link, a plurality of types of travel times of the link may be generated.

[0020] When a plurality of intersections belong to the same sub - area, it can be indirectly determined that the cycle lengths of the traffic signal devices provided at these plurality of intersections are equal. Therefore, when the first intersection and the second intersection belong to the same sub - area, since a tendency occurs in the travel time of the link depending on the inflow road and the outflow road, by generating a plurality of types of travel times reflecting this tendency, the accuracy of the travel time can be made higher. On the other hand, when the first intersection and the second intersection belong to different sub - areas, since almost no tendency occurs in the travel time depending on the inflow road and the outflow road, one type of travel time is generated. As a result, when generating a more accurate travel time, an increase in operation cost can be suppressed.

[0021] (5) Based on the sub-area information acquired by the acquisition unit, the generation unit may generate multiple types of travel times for the composite link, for each inflow path to the composite link, for each outflow path from the composite link, or for each combination of an inflow path to the composite link and an outflow path from the composite link, by treating the multiple links connecting the multiple intersections belonging to the same sub-area as a single composite link.

[0022] By generating travel times for complex links, it becomes possible to take into account the effects of systematic control of traffic signals within the same sub-area, thereby generating more accurate travel times.

[0023] (6) The information generation system of the present disclosure may further include a communication unit that receives a search request including a starting point and a destination point from a user terminal and transmits a route from the starting point to the destination point to the user terminal, and a route search unit that searches for the route based on the travel time of the link generated by the generation unit.

[0024] The generation unit generates a more accurate travel time if the cycle lengths of traffic signals at adjacent intersections are equal. The route search unit searches for a route based on such an accurate travel time, thereby improving the accuracy of the search results.

[0025] (7) The information generation method of the present disclosure includes a generation step of generating travel time for a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, the generation step of which includes a first step of generating multiple types of travel time for the link for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link, when the absolute value of the difference between the first cycle length of a traffic signal installed at the first intersection and the second cycle length of a traffic signal installed at the second intersection is less than or equal to a predetermined value, and a second step of generating one type of travel time for the link regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value.

[0026] When the absolute value of the difference between the first cycle length and the second cycle length is less than or equal to a predetermined value (i.e., when the first cycle length and the second cycle length are substantially equal), a trend in travel time emerges depending on the inflow and outflow paths. In this case, the accuracy of travel time can be improved by generating multiple types of travel times that reflect this trend. On the other hand, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, there is almost no trend in travel time depending on the inflow and outflow paths. Therefore, in this case, generating only one type of travel time can suppress increases in processing load and memory capacity. As a result, it is possible to suppress increases in operating costs when generating more accurate travel times.

[0027] (8) The computer program of the present disclosure is a computer program that causes a computer to execute a generation step to generate travel times for a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, the generation step comprising: a first step of generating multiple types of travel times for the link for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link, when the absolute value of the difference between the first cycle length of a traffic signal installed at the first intersection and the second cycle length of a traffic signal installed at the second intersection is less than or equal to a predetermined value; and a second step of generating one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value.

[0028] When the absolute value of the difference between the first cycle length and the second cycle length is less than or equal to a predetermined value (i.e., when the first cycle length and the second cycle length are substantially equal), a trend in travel time emerges depending on the inflow and outflow paths. In this case, the accuracy of travel time can be improved by generating multiple types of travel times that reflect this trend. On the other hand, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, there is almost no trend in travel time depending on the inflow and outflow paths. Therefore, in this case, generating only one type of travel time can suppress increases in processing load and memory capacity. As a result, it is possible to suppress increases in operating costs when generating more accurate travel times.

[0029] [Details of the embodiments of this disclosure] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0030] <Information Generation System 1> Figure 1 is a schematic diagram illustrating an information generation system 1 according to an embodiment. Figure 1 also illustrates the peripheral configuration of the information generation system 1. The information generation system 1 is composed of, for example, one or more information processing devices 10. The information processing devices 10 are installed, for example, in a privately owned management center for providing traffic information to vehicles.

[0031] The information processing device 10 comprises a computer device 11, a communication unit 12, a map database 13, a probe information database 14, and a signal information database 15. Each of these units 11 to 15 may be implemented by a single information processing device 10, or by multiple information processing devices 10.

[0032] The computer device 11 comprises a processing unit 21 and a storage unit 22. The computer device 11 is, for example, a workstation. The processing unit 21 is, for example, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit).

[0033] Figure 2 is a block diagram illustrating the functional configuration of the processing unit 21 according to the embodiment. The processing unit 21 comprises an acquisition unit 25, a determination unit 26, a generation unit 27, and a path search unit 28. The functions of each of these units 25 to 28 will be described later.

[0034] Refer to Figure 1. The storage unit 22 has volatile memory and non-volatile memory, and stores various types of data. The volatile memory is, for example, RAM (Random Access Memory). The non-volatile memory includes, for example, flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), or ROM (Read Only Memory).

[0035] The computer device 11 further includes a reading unit (not shown). The reading unit reads information from the recording medium 24. The recording medium 24 is a recording medium that the computer device 11 can read, such as an optical disc like a CD or DVD, or a USB flash memory. A computer program 23 is recorded on the recording medium 24, and the computer program 23 read by the reading unit is stored in the non-volatile memory of the storage unit 22.

[0036] The communication unit 12 is a communication interface. The communication unit 12 communicates with the radio base station 41 and the traffic control center 42 via the network N1 (for example, the Internet). The radio base station 41 communicates with multiple vehicles 50 and collects probe information (an example of "vehicle information" in this disclosure) as information about the vehicles 50 and transmits it to the communication unit 12.

[0037] The traffic control center 42 is a center operated by the road administrator. The traffic control center 42 communicates with multiple traffic signals 30 installed at intersections via a router 43. The traffic control center 42 collects signal information from the traffic signals 30 and transmits it to the communication unit 12.

[0038] The traffic signal 30 comprises a light unit 31 and a controller 32. The light unit 31 has, for example, three illuminated sections of red, yellow, and blue, and by sequentially illuminating and extinguishing these three colors, it indicates permission to proceed or prohibition to proceed to vehicles entering the intersection.

[0039] The controller 32 communicates with the traffic control center 42 via the router 43. The controller 32 controls the lighting unit 31 based on signal control parameters received from the traffic control center 42. The signal control parameters include, for example, cycle length, split, and offset. The controller 32 generates the on and off timings (step seconds) for each color of the lighting unit 31 according to the signal control parameters and outputs a control signal to the lighting unit 31 that includes these on and off timings.

[0040] Here, cycle length refers to the time it takes for the light color of the light unit 31 to complete one cycle, for example, the time from the start time of the blue light of the light unit 31 to the start time of the next blue light. Split refers to the time (or the proportion of time allocated to each road) within the cycle length that is assigned to each road constituting the intersection, for example, the time during which the blue light state of the light unit 31 continues. Offset refers to the time difference (or proportion of difference) that should be allowed between adjacent intersections in the start time of the blue light of the light unit 31.

[0041] The map database 13 is a database in which map information 16 relating to roads is recorded. The map information 16 includes a "directed graph" having nodes ND and links LK, "intersection data," and "link data." Node ND is set for each intersection. Note that nodes ND may also be set at points other than intersections (for example, points along the road). Links LK are set to connect adjacent nodes ND and represent the actual road alignment and direction of travel. Links LK have directionality to represent the direction of travel. In the case of a one-way road, only one-way link LK is set, and in the case of a road that can be traveled in both directions, a pair of link LK with opposite directions are set. Examples of road types for link LK include general roads and toll roads.

[0042] Intersection data is data that associates intersection IDs assigned to intersections (nodes ND) nationwide with the location of those intersections. Link data is data that associates link IDs of links LK assigned to roads nationwide with the following information 1) to 5).

[0043] 1) The positions of the start, end, and interpolation points of the Link LK. 2) Link ID to connect to the starting point of link LK 3) Link ID to connect to the endpoint of Link LK 4) Road type of Link LK 5) Link cost LC of link LK

[0044] A link cost LC is provided for each link LK. The components of the link cost LC stored in the map information 16 include the "travel time X" of the link LK, which is the time required from entering the starting point of the link LK, exiting the ending point of the link LK, and entering the starting point of the next connecting link LK. Travel time X includes the link traverse time and the intersection traverse time. The link traverse time is the time required to travel from the starting point to the ending point of the link LK. The intersection traverse time is the time required to travel from the ending point of the link LK to the starting point of the next link LK, that is, the time required to pass through the intersection connecting the link LK and the next link LK.

[0045] The map database 13 stores travel time X for each day of the week, such as weekdays, Saturdays, Sundays, and public holidays, and also for predetermined time intervals (e.g., every 5 minutes) from the current time to one day in advance. Travel time X is generated, for example, based on probe information recorded in the probe information database 14 described later.

[0046] The probe information database 14 is a database in which probe information is recorded. The probe information is information about the travel trajectory of the vehicle 50, and includes, for example, information about the position of the vehicle 50 and the time it passes through that position. The probe information database 14 is updated sequentially as probe information is collected periodically (for example, every few seconds) from multiple vehicles 50.

[0047] The signal information database 15 is a database in which signal information is recorded. The signal information is information about multiple traffic signals 30, and includes, for example, signal control parameters including cycle length, and sub-area information.

[0048] Sub-area information is information that associates multiple intersections with the sub-areas to which each of those intersections belongs. A sub-area is a group of intersections with similar traffic patterns. Traffic signals 30 at intersections belonging to the same sub-area are systematically controlled with the same or similar cycle lengths.

[0049] The signal information database 15 is updated sequentially as signal information is provided from the traffic control center 42. However, the signal information may be provided from sources other than the traffic control center 42. For example, the information generation system 1 may collect image information of the traffic signals 30 taken by on-board cameras from multiple vehicles 50, obtain the green light start time and green light end time of the traffic signals 30 based on this image information, and store the estimated cycle length and sub-area information from these times as signal information in the signal information database 15.

[0050] <Regarding information generation methods> Figure 3 is a flowchart illustrating the sequence of the information generation method according to the embodiment. The flowchart in Figure 3 shows the operation procedure of the processing unit 21. This operation procedure is achieved by the processing unit 21 reading the computer program 23 from the storage unit 22 and executing various calculations and processes.

[0051] Figure 4 is a schematic diagram illustrating link LK1 and its surroundings according to the embodiment. Link LK1 corresponds to a road that can be traveled eastward and is a link that enters from the first intersection A1 and exits at the second intersection A2. The first intersection A1 is connected to the starting point of link LK1 and also to the ending points of the entrance lanes R11 and R12. Entrance lanes R11 and R12 are links that correspond to roads that enter link LK1 via the first intersection A1. Entrance lanes R11 correspond to, for example, a road that can be traveled eastward and is a link that enters link LK1 by going straight through the first intersection A1. Entrance lanes R12 correspond to, for example, a road that can be traveled southward and is a link that enters link LK1 by turning left at the first intersection A1.

[0052] Intersection 2A2 is adjacent to Intersection 1A1. Intersection 2A2 connects to the end point of Link LK1 and also to the starting points of Exit Roads R21, R22, and R23. Exit Roads R21, R22, and R23 are links corresponding to roads exiting Link LK1 via Intersection 2A2. Exit Road R21 corresponds to a road that can be traveled eastward and is the link taken after exiting Link LK1 and going straight through Intersection 2A2. Exit Road R22 corresponds to a road that can be traveled northward and is the link taken after exiting Link LK1 and turning left at Intersection 2A2. Exit Road R23 corresponds to a road that can be traveled southward and is the link taken after exiting Link LK1 and turning right at Intersection 2A2.

[0053] Traffic signals 30 are provided at both the first intersection A1 and the second intersection A2. For example, in order to suppress congestion at link LK1, a predetermined offset may be provided between the traffic signals 30 at the first intersection A1 and the traffic signals 30 at the second intersection A2, and the cycle lengths of the traffic signals 30 at the first intersection A1 and the second intersection A2 may be made equal. This makes it easier for vehicles that proceed straight from the entrance road R11 through the first intersection A1 on a green light to pass through link LK1 and then through the second intersection A2 on a green light, thereby suppressing congestion at link LK1.

[0054] In this case, vehicles entering Link LK1 from entrance road R11 and exiting via exit road R21 will pass through Link LK1 in a relatively short time. On the other hand, vehicles entering Link LK1 from entrance road R12 will enter Link LK1 while the east-west traffic signal 30 at the first intersection A1 is red, making them more likely to stop at the red light at the second intersection A2, and thus tend to take a relatively long time to pass through Link LK1.

[0055] Furthermore, vehicles exiting from Link LK1 onto Exit R23 tend to take longer to pass through Intersection A2 compared to vehicles exiting from Link LK1 onto Exit R21, because they need to wait for oncoming straight-ahead vehicles to pass before making a right turn. In particular, immediately after traffic light 30 at Intersection A2 turns green, more oncoming straight-ahead vehicles pass through, which tends to increase the waiting time for right turns.

[0056] Vehicles entering from entrance ramp R11 onto link LK1 and exiting via exit ramp R23 pass through intersection A2 at various times, not just immediately after the traffic light 30 at intersection A2 turns green. In some cases, they can pass through intersection A2 with almost no waiting time for a right turn. On the other hand, vehicles entering from entrance ramp R12 onto link LK1 and exiting via exit ramp R23 are more likely to wait at the traffic light at intersection A2 and then wait to turn right immediately after the east-west traffic light 30 at intersection A2 turns green. Therefore, they tend to take longer to pass through intersection A2.

[0057] Thus, when the traffic signals 30 at the first intersection A1 and the second intersection A2 are controlled with the same cycle length, the trend of the travel time X1 of link LK1 differs for each combination of the inflow routes R11, R12 to link LK1 and the outflow routes R21, R22, R23 from link LK1. For this reason, the information generation system 1 generates multiple types of travel time X1 for each combination of the inflow routes R11, R12 to link LK1 and the outflow routes R21, R22, R23 from link LK1, in order to generate more accurate travel times.

[0058] On the other hand, if the traffic signals 30 at the first intersection A1 and the second intersection A2 are controlled with different cycle lengths, the above tendency does not occur. For example, if a vehicle proceeds straight from the entry road R11 to the first intersection A1 on a green light, after traveling along link LK1, whether the traffic signal 30 at the second intersection A2 is green or not will be random when it reaches the second intersection A2. For this reason, if the traffic signals 30 at the first intersection A1 and the second intersection A2 are controlled with different cycle lengths, it is almost pointless to generate a travel time X1 for each combination of entry roads R11, R12 to link LK1 and exit roads R21, R22, R23 from link LK1.

[0059] Therefore, the information generation system 1 generates multiple types of travel times X1 for each combination of inflow routes R11, R12 to link LK1 and outflow routes R21, R22, R23 from link LK1, "only" when the traffic signals 30 at the first intersection A1 and the second intersection A2 are controlled with the same cycle length, thereby achieving the generation of more accurate travel times.

[0060] On the other hand, if the traffic signals 30 at the first intersection A1 and the second intersection A2 are controlled with different cycle lengths, the information generation system 1 generates only one type of travel time X1 for link LK1, regardless of the inflow routes R11, R12 to link LK1 and the outflow routes R21, R22, R23 from link LK1.

[0061] This makes it possible to suppress the processing load in the processing unit 21 and suppress the increase in the memory capacity of the storage unit 22 required for storing the travel time X1, thereby suppressing an increase in the operating costs of the computer device 11, for example. As a result, the information generation system 1 can suppress an increase in operating costs when generating travel time with higher accuracy.

[0062] The following describes a specific method by which the information generation system 1 generates the travel time X1 of link LK1 shown in Figure 4, with reference to Figures 1 to 6 as appropriate.

[0063] Refer to Figure 3. First, the acquisition unit 25 of the processing unit 21 acquires the first cycle length T1, which is the cycle length of the traffic signal 30 installed at the first intersection A1, and the second cycle length T2, which is the cycle length of the traffic signal 30 installed at the second intersection A2 (Step ST11: Acquisition step).

[0064] For example, the acquisition unit 25 acquires the first cycle length T1 and the second cycle length T2 based on the signal information stored in the signal information database 15. Alternatively, the acquisition unit 25 may estimate the first cycle length T1 and the second cycle length T2 based on the probe information stored in the probe information database 14. With this configuration, even if the information generation system 1 cannot directly acquire the signal control parameters that actually control the traffic signal 30, for example, the first cycle length T1 and the second cycle length T2 can be acquired by estimation. In this case, for example, the acquisition unit 25 acquires multiple times from the time a vehicle stops near the end of the inflow road R11 to the time the vehicle starts moving, based on the probe information. The acquisition unit 25 then acquires the average value of these times as the first cycle length T1. With this, step ST11 is completed.

[0065] Next, the determination unit 26 of the processing unit 21 determines whether the first cycle length T1 and the second cycle length T2 acquired by the acquisition unit 25 are equal (step ST12: determination step). The determination unit 26 may determine that the first cycle length T1 and the second cycle length T2 are equal not only when the first cycle length T1 and the second cycle length T2 are exactly equal (T1=T2), but also when the first cycle length T1 and the second cycle length T2 are substantially equal (T1≒T2).

[0066] For example, the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are equal if the following equation (1) is true. The right-hand side of equation (1) is the absolute value of the difference between the first cycle length T1 and the second cycle length T2.

[0067] |T1-T2|≦E1 ···(1)

[0068] Here, E1 is a margin value, which is the value obtained by multiplying the average value of the first cycle length T1 and the second cycle length T2 by a predetermined percentage (a value of 10% or less, for example, 5%) (E1 = (T1 + T2) × 1 / 2 × 0.05). In this case, for example, when the first cycle length T1 is 50 seconds and the second cycle length T2 is 52 seconds, E1 will be "2.55". Then, the right side of equation (1) becomes |T1 - T2| = 2, and since equation (1) is true, the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are equal. In this way, the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are equal when the absolute value of the difference between the first cycle length T1 and the second cycle length T2, |T1 - T2|, is less than or equal to the margin value E1 (predetermined value). If the margin value E1 is set to "0", the determination unit 26 determines whether T1 = T2 is true or false. If the margin value E1 is set to a value greater than 0, the determination unit 26 determines whether T1 ≈ T2 is true or false.

[0069] If the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are equal (the YES route in step ST12), the generation unit 27 of the processing unit 21 generates multiple types of travel time X1 for link LK1 (step ST13: the first step of the generation step). More specifically, the generation unit 27 generates six types (=2 × 3) of travel time X1 for each combination of the two inflow paths R11, R12 to link LK1 and the three outflow paths R21, R22, R23 from link LK1.

[0070] Figure 5 is a table illustrating the travel time X1 generated in step ST13. The generation unit 27 calculates the average time required for multiple vehicles to pass through link LK1, for example, based on probe information stored in the probe information database 14, which flows in from inlet path R11 to link LK1 and outlet path R21 from link LK1. The generation unit 27 then temporarily stores this average time in the storage unit 22 as the travel time X1 corresponding to the combination of inlet path R11 and outlet path R21. In the example in Figure 5, the travel time X1 corresponding to the combination of inlet path R11 and outlet path R21 is 15 seconds.

[0071] Similarly, the generation unit 27 generates travel times X1 (e.g., 20 seconds) corresponding to the combination of inlet path R11 and outlet path R22, travel times X1 (e.g., 30 seconds) corresponding to the combination of inlet path R11 and outlet path R23, travel times X1 (e.g., 40 seconds) corresponding to the combination of inlet path R12 and outlet path R21, travel times X1 (e.g., 45 seconds) corresponding to the combination of inlet path R12 and outlet path R22, and travel times X1 (e.g., 55 seconds) corresponding to the combination of inlet path R12 and outlet path R23, based on the probe information. The generation unit 27 then temporarily stores these five types of travel times X1 in the storage unit 22.

[0072] The memory unit 22 temporarily stores six types of travel times X1 in a table format, associating them with combinations of inflow routes R11, R12 and outflow routes R21, R22, R23, as shown in Figure 5. The generation unit 27 generates travel times X1 corresponding to all combinations, and then updates the map database 13 by storing the six types of travel times X1 stored in the memory unit 22 in the map database 13.

[0073] As described above, when the first cycle length T1 and the second cycle length T2 are equal, a trend occurs in the travel time X1 due to the inflow paths R11, R12 and the outflow paths R21, R22, R23. Therefore, the generation unit 27 can increase the accuracy of the travel time X1 by generating multiple types of travel time X1 that reflect this trend. In addition, in this embodiment, it is possible to decide whether to generate multiple types of travel time X1 for link LK1 or one type based on the first cycle length T1 and the second cycle length T2.

[0074] On the other hand, the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are different if the absolute value of the difference between the first cycle length T1 and the second cycle length T2 |T1-T2| is greater than the margin value E1 (a predetermined value). If the determination unit 26 determines that the first cycle length T1 and the second cycle length T2 are different (the NO route in step ST12), the generation unit 27 of the processing unit 21 generates one type of travel time X1 for link LK1 (step ST14: the second step of the generation step). More specifically, the generation unit 27 generates only one type of travel time X1 for link LK1, regardless of the two inflow paths R11 and R12 to link LK1 and the three outflow paths R21, R22, and R23 from link LK1.

[0075] Figure 6 is a table illustrating the travel time X1 generated in step ST14. The generation unit 27 calculates the average time taken for multiple vehicles to pass through link LK1 based on probe information stored in the probe information database 14, for example. In this case, the generation unit 27 calculates the average time taken for multiple vehicles to pass through link LK1, for example, within a predetermined period, without considering the inflow paths R11, R12 and outflow paths R21, R22, R23 that the multiple vehicles passed through. The generation unit 27 then temporarily stores this average time in the storage unit 22 as the travel time X1 for link LK1. In the example in Figure 6, the travel time X1 is 35 seconds.

[0076] After generating the travel time X1, the generation unit 27 updates the map database 13 by storing one type of travel time X1 stored in the storage unit 22 in the map database 13. As a result, when the first cycle length T1 and the second cycle length T2 are different, there is almost no trend in the travel time X1 due to the inflow routes R11, R12 and outflow routes R21, R22, R23. Therefore, by generating only one type of travel time X1, the generation unit 27 can suppress an increase in the processing load of the processing unit 21 and an increase in the storage capacity of the storage unit 22 and the map database 13. As a result, an increase in operating costs can be suppressed when generating the travel time X1.

[0077] Next, when the information generation system 1 receives a search request, it searches for a route based on the travel time X1 of link LK1 generated by the generation unit 27 (step ST15: route search step).

[0078] Figure 7 shows a subroutine illustrating the details of the route search step. The information generation system 1 receives a search request from a user terminal, including the departure point and destination point (step ST16: reception step). The user terminal may be, for example, a navigation device (not shown) installed in the vehicle 50, or a communication terminal such as a smartphone owned by a passenger in the vehicle 50. The search request may also include the departure time or arrival time.

[0079] Search requests transmitted from user terminals are received by the communication unit 12 via the wireless base station 41 and network N1. The communication unit 12 outputs the received search requests to the computer device 11.

[0080] The route search unit 28 of the processing unit 21 executes route search processing based on the search request (step ST17). For example, the route search unit 28 uses the node ND closest to the starting point as the starting node and the node ND closest to the destination point as the ending node, and obtains network data from the link data included in the map information 16 that includes the distance from the starting node to the ending node. Next, the route search unit 28 searches for the route among the routes included in the obtained network data that minimizes the cumulative link cost LC from the starting point to the destination point.

[0081] For example, the path search unit 28 uses Dijkstra's algorithm or the potential method to search for the path that minimizes the cumulative link cost LC. The link cost LC is calculated, for example, by the following equation (2).

[0082] LC = C1·X + C2·LD ···(2)

[0083] In equation (2), LC is the "link cost," X is the "travel time," and LD is the "link distance." C1 and C2 are coefficients that can be set for each user, for example. That is, the link cost LC is calculated based on the travel time X of link LK (for example, the travel time X1 of link LK1).

[0084] For example, when a user makes a search request using their user terminal, they can select a "time-priority route," a "distance-priority route," or a "balanced route." A time-priority route is the route that reaches the destination faster (the route with the shortest travel time), and is the route that results in a smaller travel time X. When a time-priority route is selected in a search request, coefficient C1 becomes larger and coefficient C2 becomes smaller in order to give a greater weight to travel time X in the link cost LC.

[0085] A distance-first route is a route that reaches the destination in the shortest distance, and is a route with a smaller link distance LD. When a distance-first route is selected in the search request, the coefficient C2 becomes larger and the coefficient C1 becomes smaller in order to give a greater weight to the link distance LD in the link cost LC.

[0086] A balanced route is a route that balances the time required and the distance. When a balanced route is selected in the search request, coefficient C1 will be smaller than in the case of a time-first route, and coefficient C2 will be smaller than in the case of a distance-first route.

[0087] The route search unit 28 stores the route that minimizes the cumulative link cost LC as the "optimal route" in the storage unit 22. Only one type of optimal route may be calculated, or multiple types of optimal routes, including the "time-priority route," "distance-priority route," or "balanced route" described above, may be calculated.

[0088] The information generation system 1 transmits the optimal route acquired by the route search unit 28 to the user terminal (step ST18: transmission step). For example, information including the optimal route is output from the computer device 11 to the communication unit 12. The communication unit 12 transmits the information including the optimal route to the user terminal. The information transmitted from the communication unit 12 is received by the user terminal via the wireless base station 41 and the network N1. The user terminal displays the information to the user.

[0089] As explained above, the route search unit 28 searches for a route based on the travel time X of the link LK generated by the generation unit 27. As described above, the generation unit 27 generates a more accurate travel time X when the cycle lengths of the traffic signals 30 at adjacent intersections are equal. Since the route search unit 28 searches for a route based on such an accurate travel time X, the accuracy of the search result can be further improved.

[0090] <Variation> The following describes modified examples of the embodiments. In the modified examples, components identical to those in the embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0091] <Modified Information Generation Method> Figure 8 is a flowchart illustrating the sequence of the information generation method according to the modified example. The flowchart in Figure 8 shows the operation procedure of the processing unit 21. This operation procedure is achieved by the processing unit 21 reading the computer program 23 from the storage unit 22 and executing various calculations and processes.

[0092] In the above embodiment, the acquisition unit 25 acquires the first cycle length T1 and the second cycle length T2 based on signal information or probe information. In contrast, the acquisition unit 25 in this modified example does not acquire the cycle length of the traffic signal 30, but instead acquires sub-area information relating to the sub-area to which the intersection belongs.

[0093] At intersections belonging to the same sub-area, the cycle lengths of the traffic signals 30 are equal. Therefore, based on whether or not multiple intersections belong to the same sub-area, it is possible to indirectly determine whether or not the cycle lengths of the traffic signals 30 installed at multiple intersections are equal. The determination unit 26 of this modified example determines, based on the sub-area information, whether to generate multiple types of link travel time X or generate only one type.

[0094] Figure 9 is a schematic diagram illustrating links LK2, LK3 and their surroundings in a modified example. Both links LK2 and LK3 correspond to roads that can be traveled eastward. Link LK2 is a link that enters from the first intersection B1 and exits at the second intersection B2. Link LK3 is a link that enters from the second intersection B2 and exits at the third intersection B3.

[0095] Intersection 1 B1 is connected to the starting point of link LK2 and also to the ending points of entrance lanes R31 and R32. Entrance lanes R31 and R32 are links corresponding to roads that enter link LK2 via Intersection 1 B1. Entrance lane R31 corresponds to, for example, a road that can be traveled eastward, and is a link that enters link LK2 by going straight through Intersection 1 B1. Entrance lane R32 corresponds to, for example, a road that can be traveled southward, and is a link that enters link LK2 by turning left at Intersection 1 B1.

[0096] Intersection 2 B2 is an intersection adjacent to Intersection 1 B1. Intersection 2 B2 is connected to the end of Link LK2 and to the beginning of Link LK3. Intersection 2 B2 is further connected to the end of Inbound Road R51 and to the beginning of Outbound Road R41. Inbound Road R51 is a link corresponding to a northbound road that flows into Link LK3 or Outbound Road R41 via Intersection 2 B2. Outbound Road R41 is a link corresponding to a northbound road that exits from Link LK2 or Inbound Road R51 via Intersection 2 B2.

[0097] Intersection 3 B3 is adjacent to Intersection 2 B2. Intersection 3 B3 connects to the end point of Link LK3 and also to the starting points of Exit Roads R42, R43, and R44. Exit Roads R42, R43, and R44 are links corresponding to roads exiting Link LK3 via Intersection 3 B3. Exit Road R42 corresponds to roads that can travel east and is the link taken after exiting Link LK3 and going straight through Intersection 3 B3. Exit Road R43 corresponds to roads that can travel north and is the link taken after exiting Link LK3 and turning left at Intersection 3 B3. Exit Road R44 corresponds to roads that can travel south and is the link taken after exiting Link LK3 and turning right at Intersection 3 B3.

[0098] Traffic signals 30 are provided at the first intersection B1, the second intersection B2, and the third intersection B3. For example, in order to suppress congestion at links LK2 and LK3, the cycle lengths of the traffic signals 30 at the first intersection B1, the second intersection B2, and the third intersection B3 may be made equal, with a predetermined offset between them. This makes it easier for vehicles that proceed straight from the entrance road R31 through the first intersection B1 on a green light to pass through both the second intersection B2 and the third intersection B3 on green lights after traveling through link LK2, thereby suppressing congestion at links LK2 and LK3.

[0099] In this manner, when traffic signals 30 installed at multiple adjacent intersections are systematically controlled, a group of intersections controlled by a common cycle length is referred to as a "sub-area." Sub-area information, which associates multiple intersections with the sub-areas to which each intersection belongs, is generated, for example, at a traffic control center 42. After being provided from the traffic control center 42 to the information generation system 1, the sub-area information is stored in the signal information database 15. Signal control parameters are determined, for example, by the traffic control center 42 on a sub-area basis.

[0100] When a vehicle enters link LK2 from entry lane R31, passes through intersections B1-B3 belonging to the same sub-area heading east, and then exits via exit lane R42, as described above, traffic light delays are unlikely, and the vehicle tends to pass through links LK2 and LK3 in a relatively short time. In this case, if the travel time X3 for link LK2 and the travel time X4 for link LK3 are calculated separately, for example, because the travel time X3 for link LK2 includes the traffic light delay at the second intersection B2, there is a high possibility of errors between the actual time required to pass through links LK2 and LK3 and the sum of the travel times X3 and X4 for links LK2 and LK3.

[0101] Therefore, in this modified example, the generation unit 27 treats multiple links LK2, LK3 connecting multiple intersections B1, B2, B3 belonging to the same sub-area as a single composite link LK4, and generates multiple types of travel time X2 for the composite link LK4 for each combination of inflow routes R31, R32 to the composite link LK4 and outflow routes R42, R43, R44 from the composite link LK4. This allows for the generation of more accurate travel times by taking into account the effect of signal waiting time being eliminated by the systematic control of traffic signals 30 at intersections belonging to the same sub-area.

[0102] On the other hand, if at least one of the multiple intersections B1 to B3 belongs to a different sub-area, the tendency to omit traffic light waiting time does not occur. Therefore, in such cases, generating the travel time X2 for the composite link LK4 is almost useless, so the generation unit 27 generates the travel times X3 and X4 for each link LK2 and LK3, similar to the embodiment described above.

[0103] The following describes a specific method by which the information generation system 1 generates the travel time X2 of the composite link LK4 shown in Figure 9, and the travel times X3, X4 (or travel times X5, X6) of links LK2 and LK3, with appropriate reference to Figures 1, 2 and Figures 8 through 11.

[0104] Refer to Figure 8. First, the acquisition unit 25 acquires sub-area information that associates multiple intersections, including the first intersection B1, the second intersection B2, and the third intersection B3, with the sub-areas to which each of the multiple intersections belongs (step ST21: acquisition step). For example, the acquisition unit 25 acquires sub-area information stored in the signal information database 15.

[0105] Next, the determination unit 26 of the processing unit 21 determines whether the first intersection B1 and the second intersection B2 belong to the same sub-area based on the sub-area information acquired by the acquisition unit 25 (step ST22: determination step).

[0106] If the determination unit 26 determines that the first intersection B1 and the second intersection B2 belong to the same sub-area (the YES route in step ST22), the determination unit 26 determines, based on the sub-area information acquired by the acquisition unit 25, whether or not multiple links are included within the sub-area to which the first intersection B1 and the second intersection B2 belong (step ST23).

[0107] For example, the determination unit 26 determines whether another intersection adjacent to the first intersection B1 or the second intersection B2 belongs to the same sub-area as the first intersection B1 and the second intersection B2. If the determination unit 26 determines that the other intersection belongs to the same sub-area as the first intersection B1 and the second intersection B2, it determines that multiple links are included within the sub-area to which the first intersection B1 and the second intersection B2 belong. In the example in Figure 9, since the third intersection B3 belongs to the same sub-area as the first intersection B1 and the second intersection B2, the determination unit 26 determines that multiple links LK2 and LK3 are included within the sub-area.

[0108] If the determination unit 26 determines that multiple links LK2, LK3 are included within the sub-area to which the first intersection B1 and the second intersection B2 belong (the YES route in step ST23), the generation unit 27 of the processing unit 21 combines the multiple links LK2, LK3 into a single composite link LK4 and generates multiple types of travel times X2 for the composite link LK4 (step ST24). More specifically, the generation unit 27 generates six types (=2 × 3) of travel times X2 for each combination of the two inflow paths R31, R32 into the composite link LK4 and the three outflow paths R42, R43, R44 from the composite link LK4.

[0109] Furthermore, in step ST24, the generation unit 27 generates the travel time X3 when the composite link LK4 is flowing out from the middle (i.e., the travel time X3 of link LK2) and the travel time X4 when the composite link LK4 is flowing in from the middle (i.e., the travel time X4 of link LK3).

[0110] Figure 10 is a table illustrating the travel times X2, X3, and X4 generated in step ST24. The generation unit 27 calculates the average time required for multiple vehicles to pass through the composite link LK4, for example, based on probe information stored in the probe information database 14, when multiple vehicles enter the composite link LK4 from the inflow path R31 and exit the composite link LK4 to the outflow path R42. The generation unit 27 then temporarily stores this average time in the storage unit 22 as the travel time X2 corresponding to the combination of the inflow path R31 and the outflow path R42. In the example in Figure 10, the travel time X2 corresponding to the combination of the inflow path R31 and the outflow path R42 is 40 seconds.

[0111] Similarly, the generation unit 27 generates travel times X2 (e.g., 45 seconds) corresponding to the combination of inlet path R31 and outlet path R43, travel times X2 (e.g., 60 seconds) corresponding to the combination of inlet path R31 and outlet path R44, travel times X2 (e.g., 60 seconds) corresponding to the combination of inlet path R32 and outlet path R42, travel times X2 (e.g., 65 seconds) corresponding to the combination of inlet path R32 and outlet path R43, and travel times X2 (e.g., 80 seconds) corresponding to the combination of inlet path R32 and outlet path R44, based on the probe information. The generation unit 27 then temporarily stores these five types of travel times X2 in the storage unit 22.

[0112] The memory unit 22 temporarily stores six types of travel times X2 in a table format, associating them with combinations of inflow paths R31, R32 and outflow paths R42, R43, R44, as shown in Figure 10.

[0113] Furthermore, based on the probe information, the generation unit 27 calculates the average time required for multiple vehicles to pass through link LK2, which flows in from inlet path R31 to link LK2 and outlet path R41 from link LK2. The generation unit 27 then temporarily stores this average time in the storage unit 22 as a travel time X3 corresponding to the combination of inlet path R31 and outlet path R41. In the example in Figure 10, the travel time X3 corresponding to the combination of inlet path R31 and outlet path R41 is 20 seconds. Similarly, the generation unit 27 generates a travel time X3 (for example, 45 seconds) corresponding to the combination of inlet path R32 and outlet path R41 based on the probe information and temporarily stores it in the storage unit 22.

[0114] Furthermore, based on the probe information, the generation unit 27 calculates the average time required for multiple vehicles to pass through link LK3, which flows in from inlet path R51 to link LK3 and outlet path R42 from link LK3. The generation unit 27 then temporarily stores this average time in the storage unit 22 as a travel time X4 corresponding to the combination of inlet path R51 and outlet path R42. In the example in Figure 10, the travel time X4 corresponding to the combination of inlet path R51 and outlet path R42 is 40 seconds. Similarly, based on the probe information, the generation unit 27 generates a travel time X4 corresponding to the combination of inlet path R51 and outlet path R43 (for example, 45 seconds) and a travel time X4 corresponding to the combination of inlet path R51 and outlet path R44 (for example, 55 seconds), and temporarily stores them in the storage unit 22.

[0115] The generation unit 27 generates travel times X2, X3, and X4 corresponding to all combinations, and then updates the map database 13 by storing the multiple types of travel times X2, X3, and X4 stored in the storage unit 22 in the map database 13.

[0116] Based on the above, if it is indirectly determined that intersections B1 to B3 belong to the same sub-area and that the cycle lengths of the traffic signals 30 installed at these intersections B1 to B3 are equal, then by generating travel times X3 and X4 for links LK2 and LK3 for each combination of entry and exit roads, it is possible to generate travel times with less variation and higher accuracy.

[0117] Furthermore, by combining multiple links LK2 and LK3 within the same sub-area into a single composite link LK4 and generating a travel time X2 for the composite link LK4, it is possible to take into account factors such as the omission of signal waiting time, thereby generating a more accurate travel time.

[0118] On the other hand, if the determination unit 26 determines that the first intersection B1 and the second intersection B2 belong to different sub-areas (route NO in step ST22), the generation unit 27 generates one type of travel time X3 for link LK2 (step ST26). More specifically, the generation unit 27 generates only one type of travel time X3 for link LK2, regardless of the two inflow paths R31 and R32 to link LK2 and the outflow path R41 and link LK3 that flow out from link LK2. This makes it possible to suppress an increase in operating costs when generating travel time X3, similar to the embodiment described above.

[0119] Furthermore, if the determination unit 26 determines that there are no multiple links within the sub-area to which the first intersection B1 and the second intersection B2 belong (i.e., if the determination unit 26 determines that the third intersection B3 belongs to a different sub-area from the first intersection B1 and the second intersection B2: the route of NO in step ST23), the generation unit 27 generates travel times X5 and X6 for each of the multiple links LK2 and LK3 without combining the multiple links LK2 and LK3 into a single composite link LK4 (step ST25).

[0120] Figure 11 is a table illustrating the travel times X5 and X6 generated in step ST25. In this example, since step ST22 is taken via the YES route, the first intersection B1 and the second intersection B2 belong to the same sub-area. Therefore, since the cycle lengths of the traffic signals 30 installed at the first intersection B1 and the second intersection B2 are equal, multiple types of travel time X5 for link LK2 are generated for each combination of inflow lanes R31 and R32 and link LK3 (which functions as one of the outflow lanes here) and outflow lane R41, in order to improve accuracy.

[0121] On the other hand, since the third intersection B3 belongs to a different sub-area from the first intersection B1 and the second intersection B2, the cycle length of the traffic signal 30 installed at the third intersection B3 is different from the cycle length of the traffic signal 30 installed at the second intersection B2. For this reason, in order to suppress the increase in operating costs, only one type of travel time X6 for link LK3 is generated, regardless of link LK2 (which functions as one of the exit routes), exit route R51, and exit routes R42, R42, R44.

[0122] For example, the generation unit 27 calculates the average time taken for multiple vehicles to pass through link LK2, based on the probe information stored in the probe information database 14, for vehicles that entered link LK2 from inflow path R31 and exited link LK2 from outflow path R41. The generation unit 27 then temporarily stores this average time in the storage unit 22 as the travel time X5 corresponding to the combination of inflow path R31 and outflow path R41. In the example in Figure 11, the travel time X5 corresponding to the combination of inflow path R31 and outflow path R41 is 20 seconds.

[0123] Similarly, the generation unit 27 generates travel time X5 (e.g., 15 seconds) corresponding to the combination of inflow path R31 and link LK3 (corresponding to the outflow path), travel time X5 (e.g., 45 seconds) corresponding to the combination of inflow path R32 and outflow path R41, and travel time X5 (e.g., 40 seconds) corresponding to the combination of inflow path R32 and link LK3, based on the probe information. The generation unit 27 then temporarily stores these three types of travel time X5 in the storage unit 22.

[0124] Furthermore, the generation unit 27 calculates the average time required for multiple vehicles to pass through link LK3 based on the probe information. In this process, the generation unit 27 calculates the average time required for multiple vehicles to pass through link LK3, for example, within a predetermined period, without considering link LK2 (corresponding to the inflow path), inflow path R51, and outflow paths R42, R43, R44 that multiple vehicles have passed through. The generation unit 27 then temporarily stores this average time in the storage unit 22 as the travel time X6 for link LK3. In the example in Figure 11, the travel time X6 is 45 seconds.

[0125] The generation unit 27 generates travel times X5 and X6, and then updates the map database 13 by storing the travel times X5 and X6 stored in the storage unit 22 in the map database 13. As a result, it is possible to generate multiple types of travel times X5 with higher accuracy for link LK2, while generating only one type of travel time X6 for link LK3, thereby suppressing an increase in operating costs.

[0126] Next, the information generation system 1 searches for a route in response to a search request, similar to the embodiment described above (step ST15: route search step). The route search unit searches for a route based on travel times X2, X3, X4, or based on travel times X5, X6. This makes it possible to further improve the accuracy of the search results.

[0127] <Modification of the generating part> In step ST13, the generation unit 27 of the embodiment generates six types of travel times X1 for each combination of inflow paths R11, R12 to link LK1 and outflow paths R21, R22, R23 from link LK1.

[0128] However, in step ST13, the generation unit 26 may generate two types of travel time X1 for each inflow path R11, R12 to link LK1, regardless of the outflow paths R21, R22, R23 from link LK1. Alternatively, in step ST13, the generation unit 26 may generate three types of travel time X1 for each outflow path R21, R22, R23 from link LK1, regardless of the inflow paths R11, R12 to link LK1. Even with this configuration, it is possible to generate travel time with higher accuracy compared to the case where only one type of travel time is generated regardless of the inflow paths R11, R12 and the outflow paths R21, R22, R23.

[0129] In other words, the generation unit 26 only needs to generate multiple types of travel time X1 for link LK1 for each inflow path R11, R12 to link LK1, each outflow path R21, R22, R23 from link LK1, or for each combination of inflow paths R11, R12 to link LK1 and outflow paths R21, R22, R23 from link LK1, when the first cycle length T1 and the second cycle length T2 are equal.

[0130] Furthermore, in step ST24, the modified model generation unit 26 generates six types of travel times X2 for each combination of inflow passages R31 and R32 to the composite link LK4 and outflow passages R42, R43 and R44 from the composite link LK4.

[0131] However, in step ST24, the generation unit 26 may generate two types of travel time X2 for each inflow path R31, R32 to the composite link LK4, regardless of the outflow paths R42, R43, R44 from the composite link LK4. Alternatively, in step ST24, the generation unit 26 may generate three types of travel time X2 for each outflow path R42, R43, R44 from the composite link LK4, regardless of the inflow paths R31, R32 to the composite link LK4.

[0132] Even with this configuration, it is possible to generate more accurate travel times compared to generating only one type of travel time regardless of the inflow paths R31, R32 and outflow paths R42, R43, R44. Furthermore, by generating travel time X2 as a single composite link LK4 using links LK2 and LK3, it is possible to take into account the omission of signal waiting times, etc., thereby generating even more accurate travel times.

[0133] In other words, when multiple links LK2 and LK3 connect intersections B1 to B3 belonging to the same sub-area, the generation unit 26 can generate multiple types of travel times X2 for the composite link LK4, for each inflow route R31 and R32 into the composite link LK4, for each outflow route R42, R43, and R44 from the composite link LK4, or for each combination of inflow routes R31 and R32 into the composite link LK4 and outflow routes R42, R43, and R44 from the composite link LK4.

[0134] <Modified version of the acquisition part> In the modified example shown in Figure 8, the acquisition unit 25 acquires the sub-area information itself. However, similar to the embodiment shown in Figure 3, the acquisition unit 25 may first acquire the cycle length of the traffic signal 30 and then estimate the sub-areas to which each of the multiple intersections belongs based on the cycle length of the traffic signal 30 installed at each of the multiple intersections.

[0135] For example, the acquisition unit 25 acquires the cycle lengths of the traffic signals 30 installed at the first intersection B1, the second intersection B2, and the third intersection B3, respectively. If these cycle lengths are all the same, the acquisition unit 25 estimates that the first intersection B1, the second intersection B2, and the third intersection B3 belong to the same sub-area and outputs information to that effect to the determination unit 26. Even with this configuration, the processing unit 21 can execute steps ST22 to ST26 in the same way as the modified example described above.

[0136] <Variations of information generation systems> Figure 12 is a schematic diagram illustrating an information generation system 1a according to a modified example. In Figure 12, the wireless base station 41, traffic control center 42, and router 43 are omitted from the description. The information generation system 1a in Figure 12 has multiple edge servers 70, and in this modified example, the processing performed by the processing unit 21 in the above embodiment is divided between the multiple edge servers 70 and the processing unit 21.

[0137] The edge server 70 is installed, for example, in each designated area and collects probe information and signal information in that area. The edge server 70 communicates with the communication unit 12 of the information processing device 10 via the network N1. The edge server 70 collects probe information from vehicles 50 via the wireless base station 41 and transmits the collected probe information to the information processing device 10. The edge server 70 collects signal information from traffic signals 30 from the traffic control center 42 and transmits the collected signal information to the information processing device 10.

[0138] The edge server 70 executes each process from step ST11 to step ST12 in Figure 3, for example, and transmits the determination result to the information processing device 10 via the network N1. Based on the determination result, the information processing device 10 generates a travel time X (step ST13 or step ST14) and performs a route search based on the travel time X (step ST15). In other words, among the functions shown in Figure 2, the edge server 70 may implement the acquisition unit 25 and the determination unit 26, and the processing unit 21 may implement the generation unit 27 and the route search unit 28. By distributing each process among multiple edge servers 70 and the processing unit 21, the processing load on the processing unit 21 can be reduced.

[0139] <Vehicle Information Variation> In the embodiments described above, probe information is given as an example of vehicle information. In this disclosure, vehicle information is not limited to probe information, and may also be information based on image information acquired from various cameras that photograph road conditions, or information based on detection results from vehicle detectors installed on roads. Various cameras include, for example, in-vehicle cameras and cameras installed at intersections and along roads (e.g., security cameras).

[0140] [Additional Note] Furthermore, at least some of the embodiments and various modifications described above may be combined in any way. Also, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of symbols]

[0141] 1. Information Generation System 1a Information generation system 10 Information Processing Devices 11. Computer equipment 12 Communications Department 13 Map Database 14. Probe Information Database 15 Signal Information Database 16 Map Information 21 Processing Unit 22 Memory section 23 Computer Programs 24 Recording media 25 Acquisition Department 26 Judgment section 27 Generation part 28 Route Search Unit 30 Traffic lights 31 Light section 32 Control Unit 41 Wireless base stations 42 Traffic Control Center 43 Routers 50 vehicles 70 Edge Servers N1 Network ND node LK Link LK1 Link LK2 Link LK3 Link LK4 Compound Link LC link cost LD link distance A1 1st Intersection A2 2nd intersection B1 1st Intersection B2 2nd intersection B3 Third Intersection R11 Inflow channel R12 Inflow channel R21 Outflow channel R22 outflow channel R23 Outflow channel R31 Inflow channel R32 Inflow channel R51 Inflow channel R41 Outflow channel R42 Outflow channel R43 Outflow channel R44 Outflow channel X travel time X1 (Link LK1) Travel Time X2 (Combined Link LK4) Travel Time X3 (Link LK2) Travel Time X4 (Link LK3) Travel Time X5 (Link LK2) Travel Time X6 (Link LK3) Travel Time T1 1st cycle length T2 Second cycle length E1 Margin value (predetermined value) C1 coefficient C2 coefficient

Claims

1. The system includes a generation unit that generates the travel time of a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, The generating unit is When the absolute value of the difference between the first cycle length of the traffic signal installed at the first intersection and the second cycle length of the traffic signal installed at the second intersection is less than or equal to a predetermined value, multiple types of travel times for the link are generated for each inflow path to the link, each outflow path from the link, or each combination of an inflow path to the link and an outflow path from the link. An information generation system that generates one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value.

2. The system further includes an acquisition unit that acquires the first cycle length and the second cycle length, The generation unit generates multiple types or one type of travel time for the link based on the first cycle length and the second cycle length acquired by the acquisition unit. The information generation system according to claim 1.

3. The acquisition unit acquires vehicle information including the position of a vehicle traveling along the link and the time at which it passes that position, and acquires the first cycle length and the second cycle length as estimated results based on the vehicle information. The information generation system according to claim 2.

4. The system further includes an acquisition unit that acquires sub-area information that associates a plurality of intersections, including the first intersection and the second intersection, with the sub-areas to which each of the plurality of intersections belongs. The generation unit generates multiple types of travel times for the link, based on the sub-area information acquired by the acquisition unit, for each inflow path to the link, for each outflow path from the link, or for each combination of inflow paths to the link and outflow paths from the link, when the first intersection and the second intersection belong to the same sub-area. The information generation system according to claim 1.

5. The generation unit generates multiple types of travel times for a composite link, based on the sub-area information acquired by the acquisition unit, for each inflow path to the composite link, for each outflow path from the composite link, or for each combination of an inflow path to the composite link and an outflow path from the composite link, by treating multiple links connecting multiple intersections belonging to the same sub-area as a single composite link. The information generation system according to claim 4.

6. A communication unit that receives a search request from a user terminal including a starting point and a destination point, and transmits the route from the starting point to the destination point to the user terminal, A path search unit searches for the path based on the travel time of the link generated by the generation unit, Furthermore, The information generation system according to any one of claims 1 to 5.

7. A method for generating information to be executed by a computer, The system includes a generation step of generating the travel time of a link that enters from a first intersection and exits to a second intersection adjacent to the first intersection, The generation step is, The first step is to generate multiple types of travel times for the link for each inflow path to the link, each outflow path from the link, or each combination of inflow paths to the link and each outflow path from the link, when the absolute value of the difference between the first cycle length of the traffic signal installed at the first intersection and the second cycle length of the traffic signal installed at the second intersection is less than or equal to a predetermined value, A second step is to generate one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, Information generation method including

8. On the computer, The system executes a generation step to generate the travel time of a link that enters from the first intersection and exits to the second intersection adjacent to the first intersection. The generation step is, The first step is to generate multiple types of travel times for the link for each inflow path to the link, each outflow path from the link, or each combination of inflow paths to the link and each outflow path from the link, when the absolute value of the difference between the first cycle length of the traffic signal installed at the first intersection and the second cycle length of the traffic signal installed at the second intersection is less than or equal to a predetermined value, A second step is to generate one type of travel time for the link, regardless of the inflow path to the link and the outflow path from the link, when the absolute value of the difference between the first cycle length and the second cycle length is greater than the predetermined value, A computer program that includes [this].

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