JP2011209235A - Traffic support system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a sign and the like which are very important to a user, while suppressing complication of a map display.SOLUTION: Data showing regulation is prepared using a link and a node of a road network, for signs such as information for regulating traffic on a road, signs of road traffic for giving guidance useful for determining a path, road markings such as arrows drawn on a road, median strips of a road, direction boards, and signboards of various stores. The system sets related information L showing that the signs are displayed when a user is present in a specific link. The traffic support system refers to data of signs, and displays the signs which regulate traffic of a user and the signs specified by a related link in an embodiment in which the visibility of the signs is more enhanced than other signs. Thereby, the visibility at the time of displaying can be changed depending on the importance and the like, and information with high importance can be displayed to a user while avoiding complication of a map display.

Description

  The present invention relates to a traffic support system that supports traffic by displaying restriction information for a user traveling on a road.

  A navigation system that searches and guides a route from a specified departure point to a destination by using network data representing roads as links and nodes has become widespread. At the time of guidance, the navigation system not only displays the route on the map, but also displays a sign to notify the driver of traffic restrictions.

Prior art related to the display of signs includes the following.
Patent Document 1 discloses a technique for displaying only character information within a predetermined range from the vehicle position.
Patent Document 2 discloses a technique for transmitting a sign that the driver should recognize while traveling, such as speed regulation. In this technique, for each sign, information specifying a distance section in which the sign works effectively is provided to the navigation device, and the sign is displayed when the vehicle is in the distance section.
Patent Document 3 discloses a technique for suppressing the risk of a driver overlooking a sign such as “stop” while driving. In this technique, control information in which conditions for displaying each sign are represented in advance by the position and traveling direction of the vehicle is prepared in advance, and when the position and traveling direction of the own vehicle correspond to this control information, A technique for informing a driver of a sign to be recognized is disclosed.
Patent Document 4 prepares data in which display priorities are set for signs. For example, when traveling in a small car, a sign indicating a restriction on a large car lowers the display priority. And the technique which displays a sign with the priority according to the state of driving | running | working is disclosed.

JP-A-5-303331 JP-A-7-105479 JP 2001-34887 A JP 2009-110394 A

When displaying signs on a map, if too many signs are displayed, the map display becomes complicated, and the driver may overlook important information for himself. Therefore, when displaying a map, it is required to display information important for the driver without excess or deficiency.
In the technique described in Patent Document 1, since the display of character information is controlled by the positional relationship with the own vehicle, information that affects the determination of the route selection for the driver to go to, such as information that is far from the own vehicle position in advance. There is a risk that information that is highly necessary to be displayed on the screen will be lost. In addition, there is a problem that map display complexity is not sufficiently suppressed in that information that is not important even if it is nearby, such as information irrelevant to the traveling direction of the vehicle position, is displayed. .
Patent Documents 2 and 3 are techniques for reliably transmitting a sign to the driver, and do not take into account that the driver can easily display important map information on the map.
Since Patent Document 4 controls display regardless of the position and traveling direction of the host vehicle, it is insufficient in terms of suppressing complication of map display.

The problem of overlooking important information due to the complexity of the map display is not limited to the signs, but is provided on road markings (hereinafter referred to as “paint”) such as arrows drawn on the road surface and roads. The same applies to the presence or absence of the separation band.
In view of these problems, an object of the present invention is to provide a map display that allows a person who travels on a road to easily grasp important information, thereby assisting the travel.

The present invention can be configured as a traffic support system that supports road traffic by displaying signs together with a map. Signs refer to various features that provide information that regulates traffic when traveling on roads and provide useful guidance for determining routes. For example, road signs (hereinafter simply referred to as “signs”) There are also road markings such as arrows drawn on the road surface, road median strips, information boards, signs of various stores, and the like. The reason why the central separation band is included is that the direction in which the user can pass is regulated by the presence or absence of the separation band. The guide plate is included because the user provides guide information for determining the route. The signboard is included because the user can determine the destination, that is, the destination by looking at the signboard of the store, and can provide information for determining a route in a broad sense.
The traffic support system only needs to display the information of the signs together with the map, and does not necessarily need to display the route to the destination. However, as will be described later, it is also possible to combine with route search and route guidance.

The traffic support system includes a map database storage unit, a current position acquisition unit, and a guidance unit.
The map database storage unit stores network data representing roads as nodes and links, and sign data for storing positions and details of restrictions for signs that restrict road traffic. The positions of the signs may be represented by coordinate points such as latitude and longitude, or may be represented by nodes and links where the signs are located. The network data is prepared by mixing a main network that can be used for route search of automobiles in consideration of traffic regulations and a quasi network that can be used for route searches but is not completely prepared for traffic regulation information. Also good.
The current position acquisition unit acquires the current position of the user. For example, GPS (Global Positioning System) can be used.
The guide unit refers to the sign data, and among the signs within a predetermined range from the current position, the sign that will restrict the user's future direction of travel has higher visibility than the other signs. Display on the map in display mode. A map can be displayed by a method of drawing a road by giving a width to a link of network data. In order to display features such as buildings, feature data storing polygons for drawing them may be prepared in the map database storage unit. Further, the feature data may include polygon data for drawing a road. The display mode with high visibility means that the corresponding signs are displayed larger than the other signs or displayed with increased brightness or saturation. A mode in which other signs are not displayed is also included.

ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a label | marker is displayed excessively by making the label | marker in a predetermined range from a present position into a display object, and can suppress complication of map display. Since the predetermined range can be arbitrarily set, if the predetermined range is set sufficiently wide, information necessary for the user to travel can be provided in advance.
And for users traveling on the road, signs that regulate the direction of travel should be the most important. By displaying these signs in a highly visible display mode, important information is given priority. It is possible to display (hereinafter, the labels to be displayed in this manner are referred to as “visibility improvement targets”). By extracting the display target in this way, even if the predetermined range is set wide, it is possible to narrow down the labels that are targets for improving the visibility, and thus it is possible to suppress complication of map display.
The display mode of the present invention includes a mode in which other signs are not displayed. However, even when other signs are displayed, by providing a difference in visibility, the user can display information on important signs. It becomes possible to grasp easily.
In addition, when other signs are displayed, information by these signs can be displayed to the user for the time being. When the user decides whether the route is correct or not, the sign may be checked against the map regardless of the contents of the regulation, and if other signs are displayed, in this case It can also be used effectively.

  The traffic support system of the present invention is not necessarily limited to the one that performs route search. Even if the route that the user should take is unknown, if the current position is known, the link or node on which the user is proceeding can be specified. Therefore, the signs that restrict the passage of the link or the node, the links connected to the link or the node, and the signs that restrict the passage of the node may be targeted for visibility improvement.

The traffic support system of the present invention can also be used in combination with route search.
In this case, an input unit for inputting the designation of the departure point and the destination and a route search unit for searching for a route from the departure point to the destination with reference to the map database may be provided. For the route search, a known method such as the Dijkstra method can be used.
When performing a route search, the guide unit can display the searched route. In addition, since the route is known, it is preferable to determine signs that are targets for improving the visibility based on the current position and the user's traveling direction determined based on the route. By doing so, it is possible to exclude the signs at points where the user has already passed from the visibility improvement target, and to further suppress the complication of the map display.

When the map database includes feature data for drawing features including roads, the route search described above may be further performed in the following manner.
In the traffic support system, an arrival point acquisition unit is provided in addition to the route search unit described above. At the time of route search, the arrival point acquisition unit refers to the map database and refers to the above-mentioned main network, that is, a point on the road where the network data is prepared as a road on which a car can pass, and corresponds to the destination. It has a function of acquiring an arrival point, which is a point that can be reached from an object through any road.
The arrival point may be set for each feature such as a building as a part of the feature data. In this case, the arrival point acquisition unit need only read the arrival point data corresponding to the feature designated as the destination. When the destination is designated by the coordinate value, the arrival point acquisition unit may identify the feature corresponding to the designated coordinate and read the data of the arrival point corresponding to the feature.
On the other hand, it can also be set as the structure which does not prepare an arrival point beforehand. In this case, the arrival point acquisition unit finds the arrival point by route search starting from the destination. In this case, the route search can use a semi-network where the traffic regulation information is not completely prepared or a road where no network is established. For roads that do not have a network, it is possible to search for a route by treating the degree of connection of polygon data of roads included in the feature data as network data. In the feature data to be the destination, it is preferable to set information indicating an entrance for exiting from the feature to the road. In this way, it is possible to appropriately search and guide the route to the destination entrance / exit.
A system that performs route search in this manner may be used for guidance to a destination that is out of the main network. Streets outside the main network are generally narrow roads and are often subject to various regulations. Therefore, a display mode that narrows down the target for improving the visibility from among such many labels is particularly useful.

The sign data may include, for each sign, information capable of discriminating a sign that restricts the passage direction of the link and a sign that restricts the passage method of the node. As what regulates the direction of the link, one-way traffic can be cited as an example. Examples of restricting the direction of travel of the node include prohibition of traveling outside the specified direction, such as prohibition of turning left or right. Since the entry prohibition is prohibited from entering the corresponding link, it is preferable that the entry prohibition is information that regulates the traffic direction of the node that enters the link.
When classified in this way, the guide unit uses signs (hereinafter referred to as “link regulation”) for restricting the direction in which the link passes and signs (hereinafter referred to as “node regulation”) for regulating the passage method of the node. ) And the labels to be improved in visibility can be determined under different conditions. Since a plurality of links are connected to a node, a more complicated process may be required to determine whether or not node regulation will regulate user progress. By separating the link regulation and the node regulation as in the above aspect and separating the judgment process for determining whether or not to make the visibility improvement target, the judgment for the link regulation can be simplified and the processing load can be reduced. Can be planned.

The restriction contents of the node restriction can be given in various ways. For example, in a state where information that specifies a link that can be passed after passing through a node (hereinafter referred to as “exit link”) and information that specifies a link that can enter the exit link (hereinafter referred to as “entry link”) are combined. The method of inclusion can be taken. The combination of the exit link and the entrance link does not have to be 1: 1, and may be m: n (m and n are natural numbers). A plurality of combinations may be associated with one node.
Since the approach link means that the passage ahead is restricted by the exit link, the guide unit can determine the signs whose current position is located on the entrance link as the visibility improvement target. As described above, if the restriction information is stored in the combination of the entrance link and the exit link, various restrictions can be expressed, and whether the visibility should be improved only by comparing the entrance link and the current position. There is also an advantage that can be narrowed down.

In addition to the above-described control, the present invention can be configured to control the display of signs more broadly.
That is, the control is performed including not only signs for restricting traffic but also signs for displaying various guidance information.
In such a configuration, the sign data stores the position and guidance contents for the signs to be displayed to the user when the road passes. The guidance content includes not only the traffic regulation information but also the information given by the guidance version, that is, the content that gives the destinations when the intersection turns right, turns left, and goes straight. Further, information corresponding to a signboard such as a store, for example, information such as a type of restaurant such as Chinese food or Japanese food, a type of store such as an electronics store or a sports store, or information such as a store name may be stored.
In addition, the sign data stores information for controlling the display mode of each sign in association with the node and the link. The display mode broadly means not only display availability but also display in a mode with high or low visibility.
The guide unit displays the signs on the map in a display mode that is determined by referring to the signs data based on the link and node corresponding to the current position.

By doing so, the display mode of the signs can be controlled according to the current position of the user.
Since the nodes and links attached to the signs are not limited to those adjacent to the signs, there is an advantage that the signs located far from the current position can be controlled. Depending on the road on which the user is passing, the destination and purpose may be limited. For example, when the road on which the user is passing is a long single road like a country road and there is a village ahead of it, the destination of the user is assumed to be this village. In such a case, the one-way traffic and other regulatory information attached to the road in the village is important information for the user, and is information that the user wants to know early in order to determine the road to enter the village. . According to the above-described aspect, the signs can be displayed even when the current position of the user is far from the village simply by associating the signs in the village with the link of the single road following the village.
Conventionally, based on the idea that signs closer to the user are more important to the user, the signs to be displayed on the map are usually limited to signs closer to the user. However, the above-described aspect has been made by changing the idea that information that is important for the user is not necessarily limited to the nearby signs, apart from such a fixed idea.
As another example, when a user goes to Chinatown or an electronics store, the user wants to know information about a Chinese restaurant, an electronics store, a parking lot, and the like from an early stage. According to the above-mentioned aspect, by associating the display indications of stores and parking lots with links and nodes near the entrances to Chinatowns, electronic shopping streets, etc., these guidances are approached near the entrances. Display can be made. A user who has reached the vicinity of the entrance does not necessarily visit Chinatown or an electronic shopping street, but at least can provide useful information to a user who wants to visit Chinatown.

In this way, even when the display mode of a sign or the like is controlled in association with a link or a node, it can be combined with a route search. By doing so, the guide unit can control the display mode based on the traveling direction of the user determined based on the current position and the route.
For example, a sign or the like of an area that has already been passed by the user can be excluded from the display target, and the map display can be prevented from becoming complicated.

  The display mode control based on information associated with links and nodes and the control for improving the visibility of the signs that regulate the traveling direction are preferably performed with priority on the display mode with high visibility. When the display mode of the labels is controlled according to two conditions, the two controls may compete with each other. In such a case, if priority is given to the display mode on the side where the visibility is low, there is a possibility that information important to the user cannot be displayed accurately. According to the above-described aspect, priority is given to a display aspect with high visibility, so that important information can be accurately displayed even when control conflicts.

  In addition, the present invention may be configured as a traffic support method using a computer, or may be configured as a computer program for causing a computer to execute such route search. Moreover, you may comprise as a computer-readable recording medium which recorded such a computer program. Recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter printed with codes such as bar codes, computer internal storage devices (memory such as RAM and ROM), and Various media that can be read by a computer, such as an external storage device, can be used.

It is explanatory drawing which shows the structure of a traffic assistance system. It is explanatory drawing which shows the structure of a map database. It is explanatory drawing shown about the setting of an arrival point. It is explanatory drawing which shows the structure of marker data. It is a flowchart of a route guidance process. It is a flowchart of a signs display process. It is explanatory drawing which shows the example of a display of labels (1). It is explanatory drawing which shows the example of a display of labels (2). It is explanatory drawing which shows the example of a display of signs (3). It is explanatory drawing which shows the example of a display of labels (4).

Embodiments of the present invention will be described in the following order.
A. System configuration:
B. data structure:
B1. Network data:
B2. Character data:
B3. Feature data:
B4. Setting the arrival point:
B5. Signs data:
C. Route guidance process:
D. Sign display processing:
D1. Processing content:
D2. Example of sign display:
D3. Separation band display example:
D4. Separation band display example:

A. System configuration:
FIG. 1 is an explanatory diagram showing the configuration of the traffic support system. The traffic support system is configured as a navigation device 100. In this embodiment, the navigation apparatus 100 is connected to the server 200 that provides map data and the like through the network NE, and can receive the update of the map database from the server 200. The navigation device 100 may be configured to operate stand-alone, or may be configured to execute part of its functions on the server 200 or the like.

  The server 200 includes a map database storage unit 210, a transmission / reception unit 201, and a database management unit 202. Although the transmission / reception unit 201 and the database management unit 202 may be configured in hardware, in this embodiment, the transmission / reception unit 201 and the database management unit 202 are configured in software by installing a computer program that realizes these functions.

The transmission / reception unit 201 communicates with the navigation device 100 via the network NE. In the present embodiment, data stored in the map database storage unit 210, a command for requesting provision thereof, and the like are communicated.
The database management unit 202 reads the map information requested from the navigation device 100 from the map database storage unit 210. The map database storage unit 210 stores feature data 211, character data 212, network data 213, and signs data 214.
The feature data 211 is polygon data of features to be drawn on a map such as roads and buildings. The character data 212 is character information to be displayed on the map. For example, text information such as a building name and a place name is included. The network data 213 is data representing roads as nodes and links. The sign data 214 is data for storing the position and contents of road traffic signs and the like. The contents of these data will be described later.

The navigation device 100 includes various functional blocks that operate under the main control unit 101. In the present embodiment, the main control unit 101 and each functional block are configured by installing software that realizes the respective functions, but part or all of them may be configured by hardware.
The transmission / reception unit 102 communicates with the server 200 via the network NE. In this embodiment, transmission / reception of a map database and a command for receiving the map database are mainly performed.
The command input unit 103 inputs an instruction from the user through operations of buttons, levers, touch panels, and the like provided in the navigation device 100. Examples of instructions in the present embodiment include designation of a starting point and a destination for route search.
The GPS input unit 104 inputs a user's current position using GPS (Global Positioning System).
The map database storage unit 105 stores the map database provided from the server 200. In this embodiment, the entire map database stored in the map database storage unit 210 provided in the server 200 is also stored in the map database storage unit 105 in the navigation device 100. However, it is necessary for route search and map display. It is good also as what is acquired from the server 200 each time.
The route search unit 107 searches for a route with reference to the map database.
The display control unit 106 displays the map and the searched route on the display of the navigation device 100 using the map database storage unit 105.

B. data structure:
FIG. 2 is an explanatory diagram showing the structure of the map database. Among the data stored in the map database, the outline of the information stored in the feature data, character data, and network data is shown.

B1. Network data:
Network data is data representing roads as links and nodes. In this embodiment, two types of network data, main network data and semi-network data, are prepared. In the figure, links L1 to L4 and nodes N1 and N2 indicated by solid lines are main network data, and links L11 to L13 and nodes N11 and N12 indicated by broken lines are semi-network data.
Both main network data and semi-network data store link data and node data belonging to each. The link data records the coordinates of the point sequence forming each link, the type of national road / prefectural road, the number of lanes, other attribute information, and traffic regulation information. The node data records coordinate values, traffic regulation information, and the like.
However, the main network data is data for which traffic regulation information is sufficiently prepared by field surveys, and can be used without any trouble for vehicle route search. On the other hand, the quasi-network data is data that cannot be said to be sufficiently prepared for traffic regulation information, and is preferably data that is not used in the vehicle route search. Also in this embodiment, the route search is basically performed using the main network data.

B2. Character data:
The character data 212 is data defining a character for displaying a feature name or a place name. In the figure, an example of data for displaying the name of the building BLD is shown. Character data stores information such as contents, position, feature, font, size, and the like.
The content is a character string to be displayed, and in the example in the figure, is the company name “ΔΔ (stock)”.
The position is a position where a character is displayed. In this embodiment, the coordinate value is designated with the lower left point P5 of the character string as a reference point.
The feature is a polygon name of the feature data with which the character is associated.
The font and size are designation of the font and size for display.
In addition, various attributes such as color and bold may be specified.

B3. Feature data:
The structure of the feature data 211 is shown by taking the building H1 as an example. The feature data 211 is polygon data for drawing features such as buildings and roads, and stores names, shapes, representative points, doorway lines, arrival points, attributes, and the like.
The name is the name of the feature. An ID unique to the polygon may be used.
The shape is a sequence of coordinates indicating the vertexes of the polygon of the feature. In the illustrated example, the coordinates of the vertices P1, P2, P3, and P4 of the polygon of the building H1 are stored.
The representative point is the coordinates of the point C that represents the position of the feature. The representative point often uses the centroid of the feature, but can be set arbitrarily.
The entrance / exit line is information for associating a feature with a road. In the case of the building H1, a line segment D for exiting from the entrance to the road is registered as an entrance / exit line. Specifically, the coordinates of both ends of the line segment D are registered. As for the entrance / exit line, only the end point on the road among the line segment D may be registered. In addition, the entrance / exit line is set for a feature such as a building or a parking lot, and it is not necessary to set it for all the features. In the example in the figure, the entrance / exit line DB1 on the front side for the building BLD, the entrance / exit line DB2 on the parking lot BLDP side, the entrance / exit lines DH2 to DH4 for the buildings H2 to H4, and the entrance / exit line DPK for the parking lot PK are set. Has been.

The arrival point G is a point on the network that can be reached from an end point on the road of the feature entry / exit line via any road. In the case of the building H1, the arrival point G is set on the link L2 because it can reach the link L2 via the road R21 associated with the entrance / exit line D as indicated by the dotted line in the drawing. It is also possible to follow the road R21 from the entrance / exit line D in the right direction in the figure, turn right at the node N11 and take a route to the node N2, and use the node N2 as an arrival point. In the present embodiment, since the route from the building H1 to the node N2 is shorter than the route from the building H1 to the node N2, the setting is made in this way. Since the arrival point need not be limited to one, the node N2 may also be set as the arrival point.
In the example of the figure, the arrival point for the buildings H2 to H4 is set as a point GH. For the building BLD, the points GH and GBLD2 are set. The arrival point can be set in the parking lot as well as the entrance / exit line, and in the example shown in the figure, the arrival point GPK is set for the parking lot PK. Since the parking lot PK faces the link L2, the end point of the entrance / exit line DPK and the arrival point GPK coincide with each other.

B4. Setting the arrival point:
FIG. 3 is an explanatory diagram showing setting of arrival points. The arrival point for the entrance / exit line DB of the building BLD1 is shown.
As main network data around the building BLD1, there are a link L7, a node N7, links L5 and L6, and nodes N5 and N6. As the quasi-network data, there is a link L14 indicated by a broken line.
The route reaching the main network from the entrance / exit line DB of the building BLD1 via one of the roads includes three types shown by dotted lines in the figure. The route reaches the link L7 via the road R24, and the route reaches the link L6 and the link L5 via the road R25. The points where these routes reach links L7, L6, and L5 are arrival points G7, G6, and G5.

These arrival points can be obtained by route search. In this embodiment, each feature is associated with one of the roads by an entry / exit line, so the arrival point may be obtained by route search starting from the entry / exit point, that is, the end point on the road of the entry / exit line. .
This route search may use all of the main network data, quasi-network data, and road polygons. Road polygons are not composed of links and nodes, but because there is data specifying adjacent polygons, the relationship between polygons is defined, and as with links and nodes, routes It can be used for searching. As a result of the route search starting from the entrance / exit point, a point where the main network data is reached may be set as the arrival point.

When three arrival points G7, G6, and G5 are found as in the example of the figure, these three points may be used as the arrival point of the building BLD1, for example, the point where the road from the feature is the shortest , Even if you select by the criteria such as the point with the shortest distance from the feature, the point where there is a lot of overlap between the route from the feature to the arrival point and the quasi-network data, or the point close to the direction from the feature to the departure point Good.
In the example shown in the figure, if the route or distance from the feature is selected as a reference, the point G5 closest to the building BLD1 is the arrival point. If an overlapping portion with the quasi-network data is selected as a reference, the point G6 becomes the arrival point. If the departure point is in the leftmost direction in the figure, the point G7 becomes the arrival point if the direction of the departure point is selected as a reference.

  In this embodiment, the arrival point is set according to the above-described procedure, and is set in advance in the feature data 211. The arrival point may not be set in advance, but may be obtained in the course of processing such as route search.

B5. Signs data:
FIG. 4 is an explanatory diagram showing the structure of the tag data. The signs of the present embodiment include road traffic signs (hereinafter sometimes simply referred to as “signs”), road markings such as arrows drawn on the road surface (hereinafter referred to as “paints”), road median strips, Information boards, signs for various stores, and the like are included.
The label data is used to control the display mode of the labels as described later. In this embodiment, the display mode is switched in three stages. In the standard display mode, signs are displayed for the time being, but in a mode with low visibility, that is, displayed in a size, brightness, and saturation that do not give a complicated impression even if displayed on a map It is an aspect to do. On the other hand, the signs that display information related to traffic regulation to the user are displayed with high visibility. In this embodiment, it is larger than the standard display mode, and the brightness and saturation are also improved so that the display can be recognized at a glance. This display mode may be referred to as “visibility improvement display”. The third aspect is an intermediate display between the standard and the visibility improvement display. That is, although the signs are actively displayed to the user, the visibility is suppressed to such an extent that the visibility of the signs displayed with improved visibility is not impaired. Specifically, the size, brightness, and saturation of the signs may be set between the standard and the visibility improvement display. This mode is called an “intermediate mode” in the sense that it is intermediate between the standard display and the visibility improvement display.
Various settings can be made for the display mode. For example, the intermediate mode and the visibility improvement display may be the same mode. The standard state may be hidden. In this case, as an intermediate aspect, an aspect with low visibility like a standard display aspect can be used.

FIG. 4 illustrates the data structures of the signs S1, S2, S4, S6, the paint S3, and the median strip S5. The median strip S5 should be displayed so as to overlap with the links L46 and L48. However, in the drawing, these links L46 and L48 are shown in a deviated manner so as to be easily seen. The sign data stores data of type, position, incoming link (L), outgoing link (L), relevant link (L), relevant node (N), and related link (L).
The signs are classified into those relating to links, those relating to nodes, those relating to both, and those relating to neither. The ones that give restriction information for specific links, such as one-way traffic and maximum speed restriction, correspond to the links. Those that restrict the way the node passes, such as the right turn prohibition and the left turn prohibition at the intersection, correspond to the signs related to the node. Some also place restrictions on both links and nodes. In the sign data, the corresponding link (L) is recorded in the sign related to the link, and the corresponding node (N) is recorded in the sign related to the node.
Since the guide version and the signboard of the store are not restricted in traffic, it is sufficient that the corresponding link and the corresponding node are not recorded.

The content of the sign S1 will be described as an example.
The type represents the type of sign. In the case of the sign S1, it is “one-way”. The name and type of the store can be used for a store signboard or the like.
The position is recorded as (LAT1, LON1) in the form of the position coordinates of the signs (latitude, longitude). The signs may be represented by adjacent links or nodes.
Since the sign S <b> 1 is one-way, it is a sign that regulates the mode of passage of the link itself. Therefore, for the sign S1, a link L44 with restriction is recorded in the corresponding link (L). Since it does not restrict the traffic mode of the node, the corresponding node (N) is set to “None”, that is, there is no regulation.
The ingress link (L) and the egress link (L) are information for restricting the passage mode when the corresponding node (N) is defined. The sign S1 is “None” for both the incoming link (L) and the outgoing link (L) because the corresponding node (N) is not defined.
The related link (L) is information for controlling the display mode of the sign S1 regardless of the traffic regulation information. In the present embodiment, when the current position of the user is on the related link (L), the sign S1 is information indicating that it is displayed in an intermediate form between the standard and the visibility improving aspect. When the display of the sign S1 may be in the standard state, “None” is recorded. In this embodiment, only the related link (L) is provided, but a related node having the same function may be provided. However, since the current position is only on the relevant node for a moment, when using the relevant node, for example, a mode in which the user displays a corresponding sign after passing through the relevant node. It is preferable to take

The sign S2 is a kind of sign that the type is “prohibit traveling in the specified direction”, that is, so-called right turn prohibition. As for the position, the latitude and longitude (LAT2, LON2) are recorded. Since the right turn prohibition restricts the traffic mode of the intersection, the node S42 to which this restriction is applied is recorded as the corresponding node (N) in the sign S2. On the other hand, since the right turn prohibition does not restrict the passage of the link itself, “None” is recorded in the corresponding link (L).
Since the corresponding node (N) is recorded, the entry link (L) and the exit link (L) are recorded as information for defining this traffic mode.
The exit link (L) represents a link that can pass after passing through the node (N). In the case of the sign S2, after passing through the corresponding node N42, it is possible to pass the straight link L44 or the left turn link L43, so the links L43 and L44 are recorded as exit links.
The approach link (L) represents a link that can enter the node (N) when passing through the exit link (L). In the case of the sign S2, since travel from the link L45 to the exit links L43 and L44 is permitted, the link L45 is recorded in the approach link (L).
However, the incoming link (L) does not define all links that can pass through the outgoing link (L). In the example shown in the figure, the exit links L43 and L44 can be passed even when entering the node N42 from the link L46, but the sign S2 does not restrict traffic from the link L46. In (L), the link L46 is not recorded. The fact that the link L46 is not included in the approach link (L) does not mean that the passage from the link L46 to the links L43 and L44 is prohibited.
When the current position of the user is on the entry link, the exit link, or the link other than the corresponding node described above, if there is no need to display the intermediate mode on the sign S2, the related link (L) also indicates the sign S2. “None” is recorded.

  Paint S3 is a road marking that prohibits a straight turn right. In the sign data, the same contents as the sign S2 are recorded.

The type of the sign S4 is “prohibition of entry”, and the latitude and longitude of its position coordinates are (LAT4, LON4). Even in the link L45 where the entry prohibition is installed, traffic from the right to the left in the figure is allowed, so the sign S4 does not restrict the traffic of the link L45 itself, and passes through the node N42. Thereafter, it is restricted that a route entering the link L45 cannot be taken. Accordingly, for the sign S4, the corresponding link (L) is recorded as “None”, but the corresponding node (N) is recorded as the node N42.
And the traffic mode of the node N42 is prescribed | regulated by the approach link (L) and the exit link (L). The entry prohibition is a restriction that means that there is no link that can enter the link L45 after passing through the node (N). Therefore, the link L45 is recorded as the exit link (L) after passing through the corresponding node (N), and “None” is recorded indicating that there is no entry link (L) that can pass through the link L45. The

The type of the separation band S5 is “separation band closed”. “Closed” means provided in such a manner as to restrict the passage of the node N43. In the example shown in the figure, the separation band is set to extend to the links L46 and L48 across the node N43, and therefore a right turn from the link L47 to the link L48 and a right turn from the link L46 to the link L47 cannot be performed. In this embodiment, the restriction of traffic is expressed as “closed”. Conversely, those that do not restrict traffic are represented as “open”.
The position of the separation zone was recorded as the latitude and longitude of the representative point. The position may be defined by a point sequence representing the separation band.
The separation band is considered to restrict the right turn at the node N43 and at the same time restrict the traffic of the links L46 and L47 as in the one-way traffic. Accordingly, the node N43 is recorded as the corresponding node (N), and the links L46 and L47 are recorded as the corresponding link (L).
Further, the entrance link (L) and the exit link (L) representing the traffic regulation information for the node N43 are defined as follows. In the case of a separation band, unlike a single sign, traffic from a plurality of directions is restricted in a superimposed manner, so that a plurality of combinations of entrance links and exit links are also set. As the first set, when the exit link [1] is the link L46, the passage to the link L46 is allowed to turn left from the link L47 and go straight from the L48, so these are the entrance link [1]. To be recorded. As the second set, when the exit link [2] is the link L47, only the left turn from the link L48 is allowed to pass to the link 47. Therefore, the link L48 is recorded in the entrance link [2]. The As the third set, when the exit link [3] is the link L48, the passage to the link L48 is only allowed to go straight from the link L46, so the link L46 is recorded in the ingress link [3]. The
In addition, the user traveling on the link L47 is notified of the presence of the separation band S5 regardless of the user's route so that the user will not misunderstand that the user can make a right turn from the link L47 to the link L48. It is preferable to keep it. From this point of view, the link L47 is recorded in the related link (L). For the same reason, the link L46 may be set as a related link so that the presence of the separation band S5 can be notified regardless of the route of the user.

The sign S6 is one-way, and the same contents as the sign S1 are recorded. In this example, the example in which the link L42 is further recorded as the related link (L) is shown.
The related link L42 is a road toward the village AR as shown in the figure. It is considered that a user traveling on this road often goes to the village AR. For such users, it is preferable to display the signs in the settlement AR from an early stage. As shown in the figure, if regulation information such as one-way traffic in the village AR is displayed early, it will help you to determine which road will pass through the village AR and which route will pass through the village AR. It becomes. If the link L42 is recorded as a related link in the same way as the sign S6 for each sign in the settlement AR, the sign in the settlement AR can be displayed when the current position is on the link L42. It becomes.

C. Route guidance process:
FIG. 5 is a flowchart of route guidance processing. This is a process mainly executed by the route search unit 107 and the display control unit 106 of the navigation device 100, and is a process executed by a CPU (hereinafter simply referred to as “CPU”) of the navigation device 100 in terms of hardware.

The traffic support system of the present embodiment is not necessarily limited to a route search, and can be used in a mode in which a map around the current position is simply displayed. When the mode for performing the route search is set (step S10), the CPU inputs the departure place and the destination (step S12). The departure point may be specified by the user, or the current position acquired by GPS or the like may be set as the departure point.
As the destination, a feature may be designated, or a coordinate value may be designated.

The CPU acquires an arrival point for the designated destination (step S14). When a destination feature is designated, the arrival point may be read from the feature data corresponding to the designated feature. When the destination is designated by coordinates, it is only necessary to identify which polygon the coordinates are included in and to read the arrival point corresponding to the feature data of the identified polygon.
If the arrival point is not stored in advance in the feature data, the route search described in FIG. 3 may be performed to obtain the arrival point.
When the arrival point is acquired, the CPU searches for a route from the departure point to the arrival point (step S16).
In the mode in which route search is not performed (step S10), the above processing (steps S12 to S16) is skipped.

Next, the CPU performs route guidance.
First, the current position is input (step S20), and the route and the current position are displayed (step S22). If no route search is performed, a map around the current position may be displayed. When performing a route search, voice guidance may be performed along with the route display.
Then, the CPU performs a sign display process (step S30). This is a process of controlling the display mode of the signs displayed on the map with reference to the signs data. Details of the process will be described later.
Steps S22 and S30 may be performed in reverse order or in parallel.
The CPU repeatedly executes the above processing until it arrives at the destination (step S80).

D. Sign display processing:
D1. Processing content:
FIG. 6 is a flowchart of the sign display processing. This process corresponds to step S30 of the route guidance process.
In this process, the CPU specifies the link where the user is currently (current L) based on the current position of the user, and specifies the node (next N) through which the user passes next. If a route search is being performed, the next N is identified along the route because the user's direction of travel is known. If no route search is performed, the nodes at both end points of the current L may be handled as the next N.

The CPU sets the display mode of the signs corresponding to the current L (step S34). In this embodiment, the display mode is determined under the following four conditions. The conditions 1 to 4 are applied in priority order.
(Condition 1)
When the approach L set in the sign data coincides with the current L, the visibility is improved.
For example, if the current L is the link L45 with respect to the sign S2 in FIG.
(Condition 2)
When the corresponding N set in the sign data matches the next N, if the approach L is “None” and the exit link does not match the current L, the visibility is improved.
For example, this corresponds to the entry prohibition sign S4 in FIG. “None” of the approach L means that the exit link cannot be entered from any link, and is therefore a sign that should be displayed as a visibility improvement as information for restricting traffic. However, if the current L is equal to the exit L, the link is prohibited from entering, so that it is not affected by this restriction. In this sense, only when the exit link does not coincide with the current L, the visibility improvement display is made.
(Condition 3)
When the relation L matches the current L, the display is in an intermediate mode. An intermediate aspect is a display in the aspect which has the intermediate visibility of a visibility improvement display and a standard display.
This corresponds to the label S6 in FIG. Since the conditions 1 and 2 are preferentially applied, the signs determined to be displayed with improved visibility according to these conditions are not reset to the intermediate mode even if they meet the condition 3. . By setting the priority order in this way, it is possible to accurately convey to the user the signs (conditions 1 and 2) relating to traffic regulation.
(Condition 4)
About other labels, it is set as a standard aspect. It may be hidden.
The label S1 in FIG. 4 does not correspond to the conditions 1 and 2 because the corresponding N is not set, and does not correspond to the condition 3 because the related link is not set. Therefore, the label S1 is the restriction information for the corresponding L, but can only be displayed in the standard mode. This is because once the entry has entered the link L44, the restriction information that the link is one-way is information that does not need to be notified to the user.

If a route search is being performed, the CPU reads the route search result (step S36), and links other than the current L among the links on the route (hereinafter referred to as “route links”) are the corresponding L or related. The signs that are L are set to the intermediate mode (step S38).
Step S34 is a display mode setting based on the current position of the user, whereas step S38 is a display mode setting based on the route that the user plans to go ahead. If no route search is performed, the setting in step S38 is not performed.
The signs whose route link is the corresponding L or related L are displayed in an intermediate manner or the like according to the condition 4 shown in step S34 when the user travels along the route and reaches each route link. It should be. As a result of the processing in step S38, the signs that should eventually become the intermediate mode or the like can be set in the intermediate mode in advance, and appropriate information can be displayed to the user.

  When the display mode can be set by the above processing, the CPU displays the signs in the set mode (step S40).

D2. Example of sign display:
FIG. 7 is an explanatory view showing a display example (1) of signs.
It is assumed that the vehicle is at the current position P71 and moves from the right side to the left side in the drawing along the link L71. Currently L is the link L71, and the next N is the node N71.
The entry prohibition sign S71 restricts the passage of the node N71 (corresponding N = N71) and prohibits entry to the link L73 (exit link = L73, entry link = None).
Applicable N = next N = node N71, and approach L = None. Further, the exit L (= L73) is different from the current L (= L71). Accordingly, the sign S71 corresponds to the condition 2 in step S34 of the sign display process (FIG. 6), and thus is displayed in the visibility improving mode.
In the figure, an example is shown in which the sign S71 is displayed as a visibility improving mode with a large brightness and saturation.

The sign S72 does not correspond to the condition 1 because the approach L (= L73) is different from the current L (= L71).
The corresponding N (= N71) matches the next N (= N71), but the approach L is not None, and therefore does not correspond to the condition 2.
Since the relation L is not set, the condition 3 is not satisfied.
Accordingly, the label S72 is displayed in the standard mode. In the present embodiment, the image is displayed with a small size and reduced brightness and saturation.

Since the corresponding N is not set, the sign S73 does not correspond to the condition 1 and the condition 2, and the relation L is not set, and therefore does not correspond to the condition 3.
Therefore, the label S73 is displayed in the standard mode. Condition 4 may be further classified. Signs whose corresponding N matches the next N are signs related to the user's route, and it is preferable to display information to the user, while corresponding to the next N This is because such information display can be considered unnecessary if not.
According to this way of thinking, the condition 4 can be set in the following two stages.
(Condition 4-1) When the corresponding N = next N, display in the standard mode.
(Condition 4-2) Not displayed in other cases.
When the conditions 4-1 and 4-2 are used, since the corresponding N is not set, the sign S73 does not correspond to the condition 4-1, and is not displayed according to the condition 4-2. In the figure, the sign S73 is indicated by a dotted line to indicate that the sign S73 is not displayed.

For the user traveling on the link L71, the entry prohibition sign S71 is important in that it prohibits the left turn to the link L73. Does not matter.
According to the present embodiment, by setting the display mode based on the sign data, the visibility of the sign S71 having high importance for the user can be improved and displayed as shown in FIG. Since the sign is displayed in a mode with low visibility, it is possible to suppress complication of map display.

FIG. 8 is an explanatory view showing a display example (2) of signs.
It is assumed that the vehicle is at the current position P81 and moves from the lower side to the upper side in the drawing along the link L73. Currently L is the link L73, and the next N is the node N71.
The entry prohibition sign S71a restricts the passage of the node N71 (corresponding N = N71) and prohibits entry to the link L73 (exit link = L73, entry link = None).
Applicable N = next N = node N71, and approach L = None. However, the exit L (= L73) matches the current L (= L71), and therefore does not correspond to the condition 2 in step S34 of the signs display process (FIG. 6).
Further, since the relation L is not set, the condition 3 is not satisfied.
Therefore, the label S71a is displayed in the standard mode according to the condition 4. When the above-described condition 4-1 and condition 4-2 are applied, since the corresponding N = next N, it corresponds to the condition 4-1, and is displayed in a standard form.
The figure shows an example in which the label S71a is displayed in a standard mode, that is, small, with lightness and saturation suppressed.

On the other hand, the sign S72a satisfies the condition 1 because the approach L (= L73) matches the current L (= L73). Therefore, the sign S72a is displayed in the visibility improving mode.
In the figure, an example is shown in which the sign S72a is displayed with a large brightness and saturation as the visibility improving mode.

Since the corresponding N is not set, the sign S73 does not correspond to the condition 1 and the condition 2, and the relation L is not set, and therefore does not correspond to the condition 3. Therefore, the label S73 is displayed in the standard mode according to the condition 4.
When the above-described conditions 4-1 and 4-2 are used, the label S73 does not correspond to the condition 4-1, since the corresponding N is not set, and is not displayed according to the condition 4-2. In the figure, the sign S73 is indicated by a dotted line to indicate that the sign S73 is not displayed.

Even at the same intersection, important signs change depending on the current position of the user. As shown in FIG. 8, when passing through the link L73, prohibition of entering the link L73 is not important, and a sign S72a prohibiting traveling in the specified direction is important.
According to the present embodiment, even when the same label data as in FIG. 7 is used, as shown in FIG. 8, a highly important label can be displayed in a visibility improving mode.

FIG. 9 is an explanatory view showing a display example (3) of signs. The change of the display mode of the sign before and after passing the intersection was shown.
FIG. 9A shows a state in which the user is at the current position P101 before entering the node N101. Currently L is L101, and next N is N101.
The sign S101 that prohibits traveling in the designated direction satisfies the condition 1 (see step S34 in FIG. 6) because the approach L (= L101) matches the current L (= L101), and is displayed in a visibility improving manner.

FIG. 9B shows a state where the user is at the current position P102 after passing through the node N101. Currently L is L102. Although the next N is not shown, the link L102 is an end point node on the side different from N101.
In this state, the sign S102 does not correspond to the condition 1 because the approach L (= L101) is different from the current L (= L102).
Further, since the corresponding N (= N101) is different from the next N, the condition 2 is not satisfied.
Since the relation L is not set, the condition 3 is not satisfied.
Therefore, the label S102 is displayed in the standard mode according to the condition 4.
When the above-described conditions 4-1 and 4-2 are used, since the corresponding N does not match the next N, it does not correspond to the condition 4-1, and is not displayed by the condition 4-2. In the figure, an example of non-display is shown.

  After passing through the intersection, the sign S102 does not restrict the user's traffic, so the importance is reduced. As described above, even if the signs are the same, the importance differs before and after passing through the intersection (node N101). However, in this embodiment, the display mode can be changed according to the change in the importance, and the user can According to the traveling state of the vehicle, it becomes possible to display the information by the sign accurately.

D3. Separation band display example:
FIG. 10 is an explanatory view showing a display example (4) of signs. It is assumed that the route G91 is obtained by the route search when the user is at the current position P91. The user's destination is ahead of the link L94. At first glance, the route L92, L93, and L94 and a straight path G92 (hereinafter referred to as “straight course”) seem to be more suitable. However, since the separation band S91 exists in the node N92, it cannot go straight. The route G91 is a detour route obtained in consideration of the separation zone S91.

In such a state, if the separation band S91 is not displayed on the map, the user looks at the map and considers that the straight course is preferable to the route G91 and may go straight.
However, if all the separation zones are always displayed, the map display may become complicated.
In this embodiment, only the separation band that affects the user's route is displayed by the sign data.

In the separation band S91, as shown in the figure, in addition to the type and position, four sets of entry L and exit L, corresponding L, corresponding N, and related L data are set.
Consider the case where the user is at the current position P81. At this time, the current L becomes the link L92. Therefore, since the approach L [1] (= L92, L98) matches the current L (= L92), the condition 1 (see step S34 in FIG. 6) is satisfied, and the visibility is improved.

However, when the user is at the current position P81, the route G91 that has already been displayed has deviated. The separation band is preferably displayed at the time when the user is at the link L91 before reaching the node N91.
From this viewpoint, L91 is set as the relation L in the separation band S91. As a result, when the user is at the current position P91, the current L becomes the link L91, and the condition 3 is satisfied, so the separation band is displayed in an intermediate manner. Therefore, the user notices the presence of the separation zone S91 and can determine that it is preferable to travel along the route G91.

  When the relation L is used, it is possible to display necessary information in advance for the user. In the present embodiment, when a route search is being performed, a process is performed in which any link on the route corresponds to a related link and displayed in an intermediate manner (see step S38 in FIG. 6). By applying this process, the separation band S91 is displayed in an intermediate manner before the user reaches the link L91, so that information can be displayed to the user sufficiently in advance.

The display by the related link can be effectively used not only in the separation zone. For example, it is assumed that an entry prohibition sign S92 is installed on the link L96 in FIG. Without this sign S92, the user may consider going off the route G91 at the node N94 and going through the links L96 and L93. In this sense, the sign S92 is preferably displayed in advance to the user.
In such a case, if the link L91 is given as the related link of the sign S92, the sign S92 can be displayed in an intermediate manner when the user reaches the link L91. In addition, when a route search is performed, the sign S92 can be displayed in advance by setting the display mode (step S38 in FIG. 6) by comparing the route link and the related link described above. .

D4. Other display examples:
Related links can also be used in various ways.
As an example, there is an example for the village AR shown in FIG. By setting the link L42 as a related link for the signs in the settlement AR, even if the current position of the user is far from the settlement AR, these signs can be displayed in an intermediate manner.

The village AR can be used as an area such as Chinatown or an electronics store. A user heading to Chinatown or the like is considered to want information on stores such as Chinese restaurants and information on parking lots. Accordingly, a signboard or the like representing these stores and parking lots is prepared as sign data, and a road (corresponding to the link L42 in FIG. 4) that enters Chinatown etc. is set as a related link, so that the user It is possible to display information such as stores and parking lots.
Various techniques for acquiring location information of a store or a parking lot by a user heading for Chinatown or the like performing various settings and inputs have been conventionally displayed. On the other hand, the technique using the related link has an advantage that information is displayed without the user performing such setting and input.
In the embodiment, an example of switching whether or not to perform display in the intermediate mode by using a related link is shown. However, by recording the display mode setting in the sign data together with the related link, more various types are possible. Display may be possible.

According to the traffic support system of the present embodiment described above, information that is highly necessary for the user can be displayed in a visibility improving manner by setting the signs data.
Moreover, complication of map display can be avoided by displaying low-necessity information in a mode with low visibility. Information with low necessity may be completely unmarked. However, if the display is performed while the visibility is suppressed, it is preferable in that the user can utilize the display in such a manner that the user can pass using the displayed information about the signs.
Furthermore, when the related link is used, information that is estimated to be highly necessary can be displayed depending on the setting without the user performing various settings or inputs.

The present invention does not necessarily have all the functions of the above-described embodiments, and only a part may be realized. Moreover, you may provide an additional function in the content mentioned above.
Needless to say, the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the spirit of the present invention. For example, a part configured in hardware in the embodiment can be configured in software and vice versa.
Further, the display mode is not limited to the example described in the embodiment, and various settings are possible. For example, the intermediate mode may be shared with the visibility improving mode. The standard mode may be hidden. The display mode may be further subdivided and changed depending on the type of sign, separation band, guide plate, signboard, or the like.

The present invention may be configured as the following traffic support method.
By using a computer having a map database storage unit that stores network data representing roads as nodes and links and signs data for restricting road traffic, the signs and data for storing the location and the contents of the regulations, the signs are displayed together with the map. A traffic support method for displaying and supporting road traffic,
A current position acquisition step of acquiring a user's current position and storing it in a memory;
Referring to the signs data, among the signs within a predetermined range from the current position, the signs that will restrict the user's future traveling direction are targeted for visibility improvement, and are more visible than other signs. And a guidance step of displaying on a map in a highly display manner.

Moreover, it can also comprise as a computer program shown next.
By using a computer having a map database storage unit that stores network data representing roads as nodes and links and signs data for restricting road traffic, the signs and data for storing the location and the contents of the regulations, the signs are displayed together with the map. A computer program for displaying and supporting road traffic,
A current position acquisition function for acquiring a user's current position and storing it in a memory;
Referring to the signs data, among the signs within a predetermined range from the current position, the signs that will restrict the user's future traveling direction are targeted for visibility improvement, and are more visible than other signs. It is a computer program provided with a computer for making a computer implement | achieve the guidance function displayed on a map in a display mode with high property.

  INDUSTRIAL APPLICABILITY The present invention can be used to support traffic by displaying restriction information for a user traveling on a road.

DESCRIPTION OF SYMBOLS 100 ... Navigation apparatus 101 ... Main control part 102 ... Transmission / reception part 103 ... Command input part 104 ... GPS input part 105 ... Map database memory | storage part 106 ... Display control part 107 ... Path | route search part 200 ... Server 201 ... Transmission / reception part 202 ... Database management Section 210 ... Map database storage section 211 ... Feature data 212 ... Character data 213 ... Network data 214 ... Signs data

Claims (4)

A traffic support system that supports traffic on roads by displaying signs along with maps,
A map database storage unit for storing network data representing roads by nodes and links and signs data for storing the location and details of restrictions for signs that restrict road traffic;
A current position acquisition unit for acquiring the current position of the user;
Referring to the signs data, among the signs within a predetermined range from the current position, the signs that will restrict the user's future traveling direction are targeted for visibility improvement, and are more visible than other signs. A traffic support system comprising a guide unit that displays on a map in a highly display manner. The traffic support system according to claim 1,
An input section for entering a starting point and a destination,
With reference to the map database storage unit, a route search unit that performs a route search from the departure place to the destination,
The navigation unit displays the searched route, and determines the signs to be displayed based on the current position and the user's traveling direction determined based on the route. The traffic support system according to claim 1 or 2,
The signs data includes information for distinguishing the signs that regulate the passage direction of the link and the signs that regulate the passage method of the node for each of the signs,
The traffic guide support system, wherein the guide unit determines signs for which the visibility is to be improved according to different conditions for signs that regulate the passage direction of the link and signs that regulate the passage method of the node. The traffic support system according to claim 3,
The sign data defines information that designates a link that can be passed after passing through the node as an exit link, and a link that allows passage to the exit link among the links that enter the node is defined as an entrance link. In combination with the information to be
The guide unit is a traffic assisting system that determines signs for which the visibility is to be improved from signs having the current position on the approach link.

Images