# Patent

## Title
Onboard unit and method for providing information to a driver

## Abstract

An onboard unit for a vehicle for providing information to the driver when travelling on a road portion with at least two adjacent lanes forming a common traffic area, the onboard unit having a position detection device for determining the position thereof and having a measured value of the speed thereof, comprising a lane detector, connected to the position detection device, with a map memory for a digital road map for locating in the road map a lane corresponding to the determined position, a traffic jam detector for detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and an evaluation and output unit, which is connected to the lane detector and the traffic jam detector and which is configured, upon detection of a traffic jam, to output direction of travel information specific for the located lane.

## Background
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims priority to European Patent Application No. 14 151 027.1, filed on Jan. 14, 2014, the entirety of which is incorporated by reference herein.
BACKGROUND
Technical Field
The present subject matter relates to an onboard unit for a vehicle for providing information to the driver when travelling on a road portion with at least two adjacent traffic lanes forming a common traffic area, wherein the onboard unit has a position detection device for detecting the position thereof and has a measured value of the speed thereof. The subject matter also relates to a method for an onboard unit of this type.
Background Art
In road traffic, the driver of a vehicle is often heavily burdened in order to register information going beyond the actual steering of the vehicle under consideration of the surrounding traffic and to respond to said information. In order to make it easier, more efficient and safer to travel on roads in road networks, modern vehicles carry technical apparatuses having different specific functions. By way of example, there are thus onboard units for handling road tolls or onboard navigation apparatuses for orientation, which each, by determination of the position of said onboard units with the aid of a position detection device, for example a satellite navigation system (global navigation satellite system, GNSS), identify vehicle travel on a road portion and where applicable levy toll charges and/or plan additional routes. This relieves the burden on the driver and at the same increases safety in road traffic.
BRIEF SUMMARY
It is an object of the present subject matter to create an onboard unit and a method which inform or advise the driver efficiently and in a precise manner in the case of a traffic jam.
The object may be achieved in accordance with a first aspect with an onboard unit of the type mentioned in the Technical Field, which is characterised by
a lane detector, connected to the position detection device, with a map memory for a digital road map for locating in the road map a lane corresponding to the determined position,
a traffic jam detector for detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and
an evaluation and output unit, which is connected to the lane detector and the traffic jam detector and which is configured, with detection of a traffic jam, to output direction of travel information specific for the located lane.
In the case of a traffic jam, lane-specific information for the driver is thus output for the first time, by means of which the driver is guided to drive in a certain direction within the lane or to change lane. The onboard unit thus assists the correct driving of the individual vehicle and the coordination of all vehicles equipped with such an onboard unit in the case of a traffic jam. For example, the creation of an “emergency lane” for the access of emergency vehicles to an accident causing the traffic jam is thus assisted, more specifically under consideration of the actual structural circumstances of the used road portion and also under consideration of local or regional requirements.
In accordance with an embodiment, the lane-specific direction of travel information for each lane of the road portion is stored in the map memory and can be read out by the evaluation and output unit. The storage of the direction of travel information concerning each lane in the map memory means that this information can be read out directly and output immediately at the output unit. An evaluation going beyond the mere locating of the direction of travel information in the map memory is not necessary here, thus saving computing effort. If no direction of travel information for the used road portion is stored in the map portion, there is thus also no output. Road portions without emergency lane obligation in the case of a traffic jam are thus also taken into consideration correctly, that is to say without outputting information to the driver.
Alternatively, the lane-specific direction of travel information can be determined by the evaluation and output unit from the position of the located lane relative to all lanes of the road portion and from a stored set of evaluation rules. Such an evaluation does not require much memory space, since the evaluation unit can quickly determine the specific direction of travel information on the basis of simple evaluation steps according to the set of evaluation rules, for example with the aid of an evaluation table. The determined direction of travel information is then output at the output unit without storing separately in the map memory such information concerning each lane of each road portion. Memory volume is thus saved. Furthermore, an adaptation to modified ambient conditions is easily possible in this case by modifying the set of evaluation rules, for example with the aid of a new evaluation table, without replacing the entire digital road map with direction of travel information stored therein.
In accordance with an embodiment, the onboard unit for this purpose further comprises a transceiver for receiving the set of evaluation rules. The set of evaluation rules can thus be adapted easily to regional or local requirements in a memory-space-saving manner. A transceiver, which for example is stationary, for transmitting the new set of evaluation rules to the onboard unit passing by, for example in accordance with the standards ETSI ITS-G5, DSRC, IEEE 802.11 p or WAVE, but also GSM, UMTS, LTE, WLAN etc., can thus be provided for example at borders between regions or countries having different rules for forming an emergency lane and thus having different sets of evaluation rules. Onboard units for road toll systems usually have radio interfaces of the aforementioned type and are therefore particularly suitable.
In accordance with an alternative embodiment, at least two different sets of evaluation rules each assigned to different road portions are stored in the onboard unit. The onboard unit, when determining the lane-specific direction of travel information, can thus select the set of evaluation rules that is assigned to the used road portion. A separate transceiver in the onboard unit can be omitted, and the onboard unit, when determining and outputting the direction of travel information, is not reliant on the transmission quality of the radio connection, which may incur costs, but rather, for example when passing the border of a region or country, the direction of travel information can thus be determined automatically on the basis of the correct set of evaluation rules assigned to the road portion.
It is particularly easy and clearly understandable for the driver if the direction of travel information output by the evaluation and output unit is an instruction to drive to the left/right, optionally with graphical representation. The small variety of options in this case also requires only a very low amount of memory or evaluation effort. Such an instruction to drive to the left/right can also quite simply be output acoustically and/or optically at the output unit. Furthermore, the direction of travel information, if desired, can be visualised by a graphical representation, for example of the lanes of the used road portion and supplemented by the valid set of rules for creating an emergency lane for the driver, whereby the understanding of the situation and the response of the driver are accelerated.
In an embodiment, a speed measured value can be received with the aid of a transceiver of the onboard unit from at least one further onboard unit carried by a further vehicle, wherein the traffic jam detector additionally takes into consideration the received speed measured value for detection of the traffic jam. Onboard units, in particular onboard unit for road toll systems, are nowadays equipped frequently with transceivers of this type for establishing a radio connection to similar onboard units, for example within the scope of a traffic telematics system in accordance with the standards IEEE 802.11 p, DSRC, WAVE or ETSI ITS-G5, and for example form an ad hoc network comprising a plurality of adjacent onboard units, wherein various pieces of information concerning the running state of the vehicle carrying the respective onboard unit are exchanged. It is thus possible in a quite simple manner to detect a traffic jam with assistance by onboard units carried by other vehicles and to attain a greater accuracy in the detection of a traffic jam by comparison or by averaging. Furthermore, by information exchange with the onboard units of vehicles travelling ahead, a traffic jam can already be identified in good time, and the response thereto can thus be better prepared or a traffic jam can be responded to earlier.
In another aspect, the subject matter creates a method for providing information to the driver of a vehicle carrying an onboard unit when travelling on a road portion with at least two adjacent lanes forming a common traffic area, said method comprising the following steps:
determining the position of the vehicle with the aid of a position detection device of the onboard unit and determining a measured value of the speed of the vehicle;
detecting a traffic jam when at least the speed measured values falls below a predefined threshold value, and,
upon detection of a traffic jam,
locating in a digital road map stored in the onboard unit a lane corresponding to the determined position and
outputting direction of travel information specific for the located lane at an output unit of the onboard unit.
With regard to the advantages and further embodiments of the method, reference is made to the previous statements concerning the onboard unit. Here, it is favourable if the lane-specific direction of travel information is determined only in the case that the road portion is marked in the road map for output of direction of travel information. The output of direction of travel information is thus omitted when the vehicle is travelling on a road portion for which no special requirements are provided in the case of a traffic jam. The output of superfluous direction of travel information at the output unit is avoided and the driver is not loaded unnecessarily with information.
The onboard unit, in embodiments, reads out a speed measured value, received via a radio connection from at least one further onboard unit carried by a further vehicle, from a Common Awareness Message in accordance with standard ETSI ITS-G5 or a Basic Safety Message in accordance with standard IEEE 802.11p or WAVE. There is thus no need to establish a bidirectional radio connection or an adhoc network between the vehicles or onboard units thereof; speed and where necessary position of the further onboard unit can be deduced easily from the received message emitted periodically.



BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
The present subject matter will be explained in greater detail hereinafter on the basis of exemplary embodiments illustrated in the accompanying drawings, in which:
FIG. 1 shows a schematic plan view of two road portions, each used by a number of vehicles, with detection of a traffic jam, according to an embodiment.
FIG. 2 shows a block diagram of an onboard unit, according to an embodiment.
FIGS. 3a-3d show various embodiments of the digital road map of the onboard unit of FIG. 2 with lane-specific direction of travel information (FIGS. 3a, 3b) and lane-specific marking (FIGS. 3c, 3d).



Embodiments will now be described with reference to the accompanying drawings.
DETAILED DESCRIPTION
In accordance with FIG. 1, a number of vehicles C1, C2, . . . , generally Ci, on a road 1 are travelling in two parallel road portions S1, S2, . . . , generally Sn, with opposite directions of travel 2, 3. The road portions Sn each have at least two adjacent lanes T1,1, T1,2, T1,3, T2,1, T2,2, . . . , generally Tn,m, forming a common traffic area. In the example of FIG. 1, the road portion S1 has three adjacently arranged lanes T1,1, T1,2, T1,3 with a direction of travel 2, whereas the second road portion S2 has two adjacently arranged lanes T2,1, T2,2 with the opposite direction of travel 3 and also has a breakdown lane or hard shoulder T2,0.
Each vehicle Ci carries an onboard unit 4 according to FIG. 2. The onboard unit 4 has a position detection device 5, for example a satellite receiver determining the position P of the onboard unit 4 with the aid of satellites 5′ of a global navigation satellite system (GNSS). Alternatively, the position detection device 5 could also determine the position P with the aid of terrestrial radio beacons, for example short-range radio beacons according to standards ETSI ITS-G5, DSRC (dedicated short range communication), IEEE 802.11p or WAVE (wireless access in vehicular environments) and/or mobile radio stations (not illustrated).
The onboard unit 4 also has a measured value of the speed v thereof; this speed measured value v can be provided by the position detection device 5 and/or by another sensor, for example a sensor 6 of the vehicle Ci, said sensor being connected to the onboard unit 4.
In order to increase the accuracy of the determined position P and speed v, the onboard unit 4 may also average a number of measured values and/or further sensor measured values, for example from an acceleration sensor (not illustrated), or may use computing units for the predictive or corrective estimation of the course of movement (trajectory) of said onboard unit.
In order to inform the driver, in the case of a traffic jam, about the creation of a free emergency lane E1, E2, . . . , generally Ek, to be used for example by emergency vehicles, the onboard unit 4 has a lane detector 7, a traffic jam detector 8 and an evaluation unit 9 with connected output unit 10.
The lane detector 7 connected to the position detection device 5 has a map memory 11 for a digital road map 12 and accesses this in order to locate in the stored digital road map 12 the lane Tn,m corresponding to the determined position P. The digital road map 12 may be an image of the road 1 illustrating the lanes accurately, for example by means of vectors or polygon courses or another geoobject definition method known to a person skilled in the art, for example in accordance with the standards of the International Organisation for Standardisation ISO 19115, ISO 19119, ISO 14825 or ISO 17575, part 3. The lane detector 7 locates the lane Tn,m corresponding to the position P directly in the digital road map 12. Alternatively, the digital road map 12 could show the road 1 without lanes Tn,m, for example again in the form of vectors or a polygon course, and could contain, for each road portion Sn, the associated lane number Tcn, from which the lane detector 7 calculates the used lane Tn,m on the basis of the distance of the determined position P from the respective vector or polygon course of the road portion Sn and a known lane width.
The traffic jam detector 8 detects a traffic jam on the basis of at least the speed measured value v, more specifically on the basis of the fact that this falls below a predefined threshold value, for example 10 or 20 km/h. The traffic jam detector 8, in accordance with FIG. 2, can additionally take into consideration a distance measured value d from a vehicle travelling ahead, for example from a distance sensor 13 of the vehicle Ci and/or further speed measured values in order to detect the traffic jam, as explained in detail further below with reference to road portion S2 of FIG. 1.
The evaluation and output unit 9, 10 connected to the lane detector 7 and traffic jam detector 8 is controlled by the traffic jam detector 8. Upon detection of a traffic jam, the evaluation and output unit 9, 10 accesses the map memory 11 and thereupon outputs at the output unit 10 direction of travel information In,m for the driver, said information being specific for the lane Tn,m located by the lane detector 7.
In the simplest case, the direction of travel information In,m output at the output unit 10 is an instruction to drive to the left/right L, R, which is output via a display 10′ and/or a loudspeaker 10′′ of the output unit 10. Alternatively or additionally, the output unit 10, on the display 10′ thereof, could also output for example a graphical illustration of the road portion Sn with lanes Tn,m thereof and a detailed, lane-specific illustration of the driving instruction or the locally valid set of rules for creating an emergency lane Ek. In order to output the direction of travel information In,m, loudspeakers or displays, for example of a car radio or navigation system, provided in a vehicle Ci could optionally also be used, and the onboard unit 4 could be connected for this purpose to these built-in elements of the vehicle Ci.
The locating of the lane Tn,m by means of the lane detector 7, similarly to the determination of the position P of the vehicle Ci with the aid of the position detection device 5 and/or the determination of the speed v, is repeated or performed periodically in the illustrated examples, but could alternatively also be triggered merely as required, for example by an external controller or manually. The lane detector 7, similarly to the evaluation and output unit 9, 10, is controlled by the traffic jam detector 8 of the onboard unit 4 and is activated thereby only in the event of detection of a traffic jam, but alternatively could also operate continuously.
It goes without saying that the onboard unit 4 can be integrated in an existing electronic device of the vehicle Ci or can be formed thereby, for example a toll onboard unit for a road toll system, or can be constructed as a modularised (“virtual”) onboard unit by networking modules already provided in a vehicle Ci. The connection or networking of the modules can be implemented in a wired manner, for example by means of FlexRayTM or CAN bus (controller area network), or wirelessly, for example by means of Bluetooth or WLAN.
In example of FIG. 1, the vehicles C1 to C8, of which the onboard units 4 have located in the road map 12 one of the two right-hand lanes T1,1, T1,2 of the road portion S1 as the lanes corresponding to the respective determined position P, in view of the traffic jam developing in the road portion S1 (on the right-hand side in FIG. 1), that is to say as a result of the low speed measured value v of said onboard units, obtain an instruction to drive to the right R. On the other hand, the vehicles C11 and C12, of which the onboard units 4 have located the lanes T1,3 as the lanes corresponding to the determined position P, obtain an instruction to drive to the left L as direction of travel information I1,3. By contrast, the onboard units 4 of the vehicles C9 and C10, as a result of the (previously also) higher speed measured values v thereof, do not detect a traffic jam and therefore also do not output any direction of travel information. The vehicles C1 to C8, C11 and C12 travelling on the first road portion S1 in the example of FIG. 1 thus form the free emergency lane E1 to be used by emergency vehicles in the case of a traffic jam.
If desired, different lane-specific direction of travel information In,m can also be output. For example, the vehicles C6 to C8, C11, C12 in the two left lanes T1,2, T1,3 could thus receive an instruction to drive to the left L and only those vehicles on the right lane T1,1 could receive an instruction to drive to the right R, etc.
In accordance with FIG. 2, the onboard unit 4 of a vehicle Ci may also have a transceiver 14, with which said onboard unit establishes a radio connection 15, for example in accordance with the standards ETSI ITS-G5, DSRC, IEEE 802.11p or WAVE, to at least one further onboard unit 4 carried by a further vehicle Ci+1. The first-mentioned onboard unit 4 of the vehicle Ci receives a speed measured value v from the further onboard unit 4 of the vehicle Ci+1, which is additionally taken into consideration by the traffic jam detector 8 of the first-mentioned onboard unit 4 during the detection of the traffic jam for the creation of the emergency lane Ek. The speed measured value v of the further onboard unit 4 of the further vehicle Ci+1 can be read out from a Common Awareness Message (CAM) of the further onboard unit 4 received in the first-mentioned onboard unit 4 in accordance with the standard ETSI ITS-G5 or from a Basic Safety Message (BSM) of the further onboard unit 4 in accordance with the standards IEEE 802.11p or WAVE.
In this way, the onboard unit 4 of a vehicle Ci is provided with an additional speed measured value v from at least one onboard unit 4 of a vehicle Ci+1, for example travelling ahead, such that the first-mentioned onboard unit can already identify the development of a traffic jam in good time, as is illustrated in FIG. 1 for the vehicle C13 of the road portion S2 communicating via the radio connection 15 with the vehicle C14, said vehicle C13 thus being able to already determine in good time a driving instruction—here the instruction to drive to the left L. The onboard unit 4 of the vehicle Ci identifies a vehicle travelling ahead Ci+1, for example on the basis of the position P of the vehicle Ci+1 relative to the position P of said vehicle Ci, this position of the vehicle Ci+1 being received by the onboard unit of the vehicle Ci for example in the CAM or BSM.
FIGS. 3a-3d show various examples for the determination of the lane-specific direction of travel information In,m by the evaluation unit 9.
In the example of FIG. 3a, an instruction to drive to the left/right L or R respectively is stored in the road map 12 separately for each lane Tn,m of each road portion Sn as direction of travel information In,m, which the evaluation unit 9 reads out directly for the located lane Tn,m in the case of a detected traffic jam—for example the instruction to drive to the right R for the vehicle C6 on the lane T1,2. Alternatively, as illustrated in the example of FIG. 3b, the lane-specific direction of travel information In,m could be stored in coded form in the road map 12 as a road-portion-specific data field Isn. Here, the evaluation unit 9 determines the direction of travel information In,m corresponding to the used lane Tn,m from the character sequence—for example for the vehicle C6 on the second lane T1,2 of the road portion S1, the second position of the data field Is1=“RRL”, therefore the instruction to drive to the right R.
If a road portion Sn, for example the road portion S3 in FIGS. 3a and 3b, contains no lane-specific direction of travel information In,m, for example because it is a single-lane or inner city road portion Sn, where no emergency lane Ek is to be created, the onboard unit 4 thus does not output any information to the driver, even in the event of a traffic jam.
According to FIGS. 3c and 3d, in a further alternative variant, merely one marking Mn may be stored in the digital road map 12 for each road portion Sn in addition to a road-portion-specific lane number Tcn. A set marking Mn=“Y” signals here that direction of travel information In,m is to be determined for this road portion Sn. In this case, the evaluation unit 9 of the onboard unit 4 of the vehicle Ci accesses a set of evaluation rules K stored for example in the map memory 11 or in another memory (not shown in FIG. 2) of the onboard unit 4, said set of evaluation rules linking the lane number Tcn to a lane-number-dependent data field IT comprising the direction of travel information In,m for example as illustrated in FIG. 3d, and determines from this, for the vehicle Ci, on the basis of the position of the located lane Tn,m relative to all lanes of the road portion Sn, the associated direction of travel information In,m in the manner described with reference to the examples of FIG. 3a or 3b. For example for the vehicle C6 in the middle lane of three lanes T1,1, T1,2, T1,3 of the road portion S1, the instruction to drive to the right R stored in the middle of the data field IT=“RRL” valid for Tcn=3 is thus determined as direction of travel information In,m.
The set of evaluation rules K or the lane-number-dependent data field IT of the set evaluation rules K can be received via the transceiver 14 or another interface of the onboard unit 4, for example at country or region borders, and stored in the onboard unit 4 for adaptation to different sets of rules for creating an emergency lane, for example in different countries or regions. Here, the onboard unit 4 may store beforehand a set of evaluation rules K corresponding to the country of the approval authority and, with each journey into a country or region with different sets of rules, can store the additionally received set of evaluation rules K instead or in addition.
Alternatively, the onboard unit 4 could store at least two different sets of evaluation rules K each assigned to different road portions Sn and, when determining the lane-specific direction of travel information In,m, could select the set of evaluation rules K assigned to the road portion Sn detected as the used road portion.
For example, all road portions Sn of a certain geographic area, for example of a country or a region having uniform sets of rules for creating an emergency lane may thus be assigned a first set of evaluation rules K, and the road portions Sn of another geographic area with different emergency lane rules can thus be assigned a different second set of evaluation rules K. The onboard unit 4, in the case of an area change, for example the passing of a border from one country into another, can thus select “automatically” so to speak the set of evaluation rules K to be applied, on the basis of the determined position P of said onboard unit.
If, by contrast, as shown in FIG. 3c for the road portion S3, the marker Mn is not set for a road portion Sn (Mn=“N”), no direction of travel information In,m is determined or output.
CONCLUSION
Accordingly, the invention is not limited to the presented embodiments, but comprises all variants and modifications falling within the scope of the accompanying claims.

## Claims

1. An onboard unit for a vehicle for providing information to a driver of the vehicle when travelling on a road portion with at least two adjacent lanes forming a common traffic area, wherein the onboard unit has a position detection device for determining a position thereof and has a measured value of a speed thereof, wherein the onboard unit comprises:
a lane detector, connected to the position detection device, with a map memory, in which a digital road map and lane-specific direction of travel information for each lane of the road portion are stored, for locating in the road map a lane corresponding to the determined position,
a traffic jam detector for detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and
an evaluation and output unit, which is connected to the lane detector and the traffic jam detector and which is configured, upon detection of a traffic jam, to read out, for the located lane, the lane-specific direction of travel information stored in the map memory, and to output the read-out direction of travel information for the driver.

2. The onboard unit according to claim 1, wherein the direction of travel information output by the evaluation and output unit is an instruction to travel to the left or to the right.

3. The onboard unit according to claim 2, wherein the instruction includes a graphical illustration.

4. The onboard unit according to claim 1, wherein a speed measured value can be received with the aid of a transceiver of the onboard unit from at least one further onboard unit carried by a further vehicle, wherein the traffic jam detector additionally takes into consideration the received speed measured value for detection of the traffic jam.

5. An onboard unit for a vehicle for providing information to a driver of the vehicle when travelling on a road portion with at least two adjacent lanes forming a common traffic area, wherein the onboard unit has a position detection device for determining a position thereof and has a measured value of a speed thereof, wherein the onboard unit comprises:
a lane detector, connected to the position detection device, with a map memory, in which a digital road map and a road-portion-specific number of lanes are stored, for locating in the road map a lane corresponding to the determined position,
a traffic jam detector for detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and
an evaluation and output unit, which is connected to the lane detector and the traffic jam detector and which is configured, upon detection of a traffic jam, to determine, for the located lane, the lane-specific direction of travel information by accessing a set of evaluation rules stored in the onboard unit, which set of evaluation rules links the road-portion-specific number of lanes of said road portion to a lane-number-dependent data field comprising the direction of travel information, and to output the determined direction of travel information for the driver.

6. The onboard unit according to claim 5, wherein the onboard unit further comprises a transceiver for receiving the set of evaluation rules.

7. The onboard unit according to claim 5, wherein at least two different sets of evaluation rules each assigned to different road portions are stored in the onboard unit.

8. A method for providing information to a driver of a vehicle carrying an onboard unit when driving on a road portion with at least two adjacent lanes forming a common traffic area, said method comprising the following steps:
determining the position of the vehicle with aid of a position detection device of the onboard unit;
determining a measured value of the speed of the vehicle;
detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and,
upon detection of the traffic jam,
locating a lane, corresponding to the determined position, in a digital road map stored in the onboard unit, and
outputting at an output unit of the onboard unit direction of travel information specific for the located lane, wherein lane-specific direction of travel information for each lane of the road portion is stored in the digital road map and the direction of travel information specific for the located lane is read out from the digital road map.

9. The method according to claim 8, wherein the direction of travel information is determined only in the case that the road portion is marked in the digital road map for output of direction of travel information.

10. The method according to claim 8, wherein the output unit, as direction of travel information, outputs an instruction to drive to the left or to the right, optionally with graphical illustration.

11. The method according to claim 10, wherein the instruction includes a graphical illustration.

12. The method according to claim 8, wherein the onboard unit further receives, via a radio connection, a speed measured value from at least one further onboard unit carried by a further vehicle, wherein the received speed measured value is additionally taken into consideration with detection of the traffic jam.

13. The method according to claim 12, wherein the onboard unit reads out the received speed measured value from a Common Awareness Message according to the standard ETSI ITS-G5 or from a Basic Safety Message according to the standard IEEE 802.11p or WAVE.

14. A method for providing information to a driver of a vehicle carrying an onboard unit when driving on a road portion with at least two adjacent lanes forming a common traffic area, said method comprising the following steps:
determining the position of the vehicle with aid of a position detection device of the onboard unit;
determining a measured value of the speed of the vehicle;
detecting a traffic jam when at least the speed measured value falls below a predefined threshold value, and,
upon detection of the traffic jam,
locating a lane, corresponding to the determined position, in a digital road map stored in the onboard unit, and
outputting at an output unit of the onboard unit direction of travel information specific for the located lane, wherein a road-portion-specific number of lanes is stored in the digital road map, and the lane-specific direction of travel information is determined from a stored set of evaluation rules which links the road-portion-specific number of lanes of said road portion to a lane-number-dependent data field comprising the direction of travel information.

15. The method according to claim 14, wherein the onboard unit receives and stores the set of evaluation rules via a radio connection.

16. The method according to claim 14, wherein the onboard unit stores at least two different sets of evaluation rules each assigned to different road portions, wherein, when determining the lane-specific direction of travel information, the set of evaluation rules assigned to the used road portion is selected.