EP0962004A1

EP0962004A1 - Device and method for reporting traffic jams

Info

Publication number: EP0962004A1
Application number: EP97951850A
Authority: EP
Inventors: Jochen Schaefer; Rudolf Messerschmidt
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-02-28
Filing date: 1997-12-12
Publication date: 1999-12-08
Anticipated expiration: 2017-12-12
Also published as: JP2001513235A; KR20000071119A; DE59710100D1; ES2200209T3; WO1998038617A1; DE19708106A1; EP0962004B1

Abstract

The invention relates to a method and device for reporting traffic jams comprising means for receiving traffic data picked up by sensors. The inventive method provides means for calculating output data describing the extent of traffic jams on the basis of traffic data received using a valid traffic flow density diagram for the traffic route concerned.

Description

Device and procedure for information about traffic incidents

The invention relates to a device for information about traffic disturbances with means for receiving traffic data recorded with sensors and a method for information about traffic disturbances.

Spoken traffic announcements have been known for a long time to inform motorists. These have various disadvantages, for example delays and inaccuracies, which are associated with the manual and therefore also subjective recording and forwarding of the information. So it happens, for example, that a driver gets into a traffic jam that has not (yet) been announced, or that despite a traffic jam warning, he can drive on the road in question realistically when he arrives at the designated point.

A more precise recording and faster transmission has become possible with the aid of the system for the transmission of digitally coded traffic reports that has become known in recent years. The structure and coding of these Traffic announcements and the location list are specified in CEN pr ENV / 278/7/1/0012 and pr ENV / 278/7/3/0004, which is based on the proposed standard ALERT C, June 1996, published by the RDS ATT ALERT Consortium. The essential elements of a traffic report are the location and the event. This information is cataloged, which means that a unique code is assigned to every traffic-relevant location and every traffic-relevant event. The chaining of the locations in the district sections along existing streets shows the course. In addition to the usual facilities of a receiving device with an RDS decoder, facilities for decoding, storing, further processing and outputting the traffic reports are required to use the traffic message channel TMC (Traffic Message Channel).

Digitally coded traffic reports - hereinafter also referred to as TMC messages - can be transmitted using the radio data system (RDS), which enables additional and inaudible transmission of digital data in parallel with radio programs in a data channel. Specifications of the radio data system for VHF radio can be found in Tech. 3244 - E, March 1984 of the European Runfunk Union (EBU). Broadcast receivers with suitable RDS decoders can record and decode transmitted data in addition to audio reception with the same receiver.

Digitally coded traffic announcements can also be transmitted in other ways than via radio transmitters and radio data signals. For example, it is possible to transmit the digitally coded traffic reports via mobile radio networks. With GSM (Global System for Mobile Communication), short messages can be transmitted parallel to the language, which can also contain digitally coded traffic reports. These known systems are used primarily for the transmission of traffic reports, but reports with other contents are not excluded, for example general danger warnings. The digital coding enables the received data to be processed before being output, for example a selection by area or street.

Even with such a system, the input data of which is essentially generated by sensors, incorrect assessments of the information output cannot be ruled out. For example, the information output in the known systems allows only limited conclusions to be drawn as to the speed that is possible despite the traffic disruption or the duration of a traffic disruption.

It is therefore an object of the present invention to make not only static information accessible to the driver, but also information which allows conclusions to be drawn about the actual traffic obstruction, for example the development over time of a traffic disruption or that which can be achieved despite traffic disruption

Average speed on the affected section.

This object is achieved in the device according to the invention in that means for calculating data to be output, which describe the effect of the traffic disruption, are provided from the received traffic data with the aid of a flow-density diagram which is valid for the respective route section.

The device according to the invention can be in or in connection with a terminal, for example a car radio or a mobile radio device, or in a central one Device be arranged. The flux density diagram used for the calculation is often also called

Fundamental diagram of road traffic is referred to and described for example in "How a traffic jam develops", Spectrum of Science, 11/89, p. 182. It represents the relationship between the traffic flow q - often also called traffic intensity - and the traffic density k. In order to calculate the data to be output with the aid of the flow-density diagram, different quantities can be used as input data, each of which is available from the available sensors and depends on the circumstances in individual cases. An advantageous embodiment of the invention is that the traffic data received describe the traffic density measured in each case, an identifier of the route section concerned and the extent of the traffic disruption measured in each case.

This embodiment can also be designed in such a way that the traffic data received further describe the flow-density diagram applicable in each case for the route section. This has the advantage that a central traffic computer can adapt the flow-density diagram to be taken into account in the calculation to the current road conditions (for example, single-lane traffic on a motorway). Since the flux density diagram is a parabola that passes through the coordinate zero point, a description by two variables is sufficient, for example by the coordinates of the maximum.

Another advantageous embodiment of the device according to the invention is that the traffic data received are expanded TMC messages. This means that the existing facilities of the TMC system can be used to a large extent. Furthermore, interference from existing TMC receivers can be excluded. An advantageous further development of the device according to the invention is that the data to be output describe the average speed and / or the travel time on a known section of the route. Additionally or alternatively, according to another advantageous development, it can be provided that the data to be output describe the change in the length of the traffic disruption.

As a result, a motorist is able to react to traffic disturbances much better than with the known information systems, for example to decide on which motorway exit an alternative route should be selected.

Another development of the device according to the invention is that data for describing the flux-density diagrams of sections of the route are stored in a memory. For those sections of the route for which there are no temporary changes, a transfer of the data describing the flux density diagram is not necessary. The data for the "normal" flowcharts can be stored in a simple manner in connection with the location tables which are required in any case for decoding TMC messages.

Programs to calculate route recommendations have become known to further facilitate the planning and implementation of, in particular, longer car journeys. Such programs are available on the market for personal computers, for example, or are integrated in navigation systems. The user enters the start and destination, possibly also other waypoints, and then receives a route recommendation either as a list or as a marker on a road map. Even if the road condition and possibly existing traffic disturbances are taken into account when calculating this route recommendation, one can unfavorable route calculation nevertheless take place, the driver being shown a route which turns out to be incorrect only at a waypoint which has been reached for a long time because of a traffic disturbance which has meanwhile increased considerably.

In another development of the device according to the invention, means for calculating route recommendations are therefore also provided, the calculated data to be output being taken into account.

In this development it can be provided that the device and the means for calculating route recommendations are arranged in a terminal which receives the traffic data from at least one central device. All that is required is a unidirectional data connection with the central device to the terminal, such as in the radio data system or in the broadcast channel of a mobile radio system. Alternatively, it can be provided in this development that the device and the means for calculating route recommendations are arranged in a central device, to which data on a desired journey can be fed from terminal devices and from which the calculated route recommendations can be transmitted to the terminal devices. This development requires a bidirectional data connection, such as that made available by mobile radio systems.

The object of the invention is achieved in a method according to the invention for information about traffic disruptions, traffic data being recorded with the aid of sensors, in that data which are to be output from the recorded traffic data are calculated with the aid of a flow-density diagram which is valid for the respective route section impact describe the traffic disruption.

The invention also includes a method for transmitting information about traffic disruptions, traffic data being recorded with the aid of sensors, in which it is provided that the recorded traffic data are transmitted to receivers and there with the aid of a flow-density diagram valid for the respective route section data to be output from the transmitted traffic data are calculated, which describe the effect of the traffic disruption.

Advantageous further developments and improvements of the method according to the invention are possible through the measures listed in further subclaims.

Exemplary embodiments of the invention are shown in the drawing using several figures and are explained in more detail in the following description. It shows:

Fig. 1 is a block diagram of an inventive

Device, which is preferably arranged in a terminal,

2 and FIG. 3 flow density diagrams,

Fig. 4 is a block diagram of a device according to a development of the invention in a terminal and

Fig. 5 in a central facility.

Identical parts are provided with the same reference symbols in the figures. The exemplary embodiment and parts thereof are shown as block diagrams. However, this does not mean that the device according to the invention is limited to implementation using individual circuits corresponding to the blocks. Rather, the device according to the invention can be implemented in a particularly advantageous manner with the aid of highly integrated circuits. In this case, digital signal processors can be used which, with suitable programming, carry out the processing steps shown in the block diagrams. The device according to the invention, together with further circuit arrangements within an integrated circuit, can form essential parts of a terminal, for example a radio receiver.

Broadcast signals containing RDS signals are received in a receiver 1, with demodulation, error correction and decoding of the RDS signals and subsequent decoding of the TMC messages also taking place. In addition, there is a device in the receiver 1 for selecting the TMC messages according to selection criteria which can be set by the user, for example according to individual streets and areas. The remaining TMC messages are then fed to a selection filter 2, which is connected to memories 3 to 5, 15 for the location LOC, the extent EXT, the characteristic values kmax, qmax of the flux density diagram, each with the TMC message transmitted current traffic density k and the also transmitted extent 1 of the traffic disruption. This information can be saved for several TMC messages.

At 7, the FDD characteristic value kmax, qmax and the route length ls stored for the respective location (= route section) are read out from the location list 6. The route length is temporarily stored in a memory 8, while at 14 a calculation of the FDD characteristic value in the event that the Several FDD parameters are stored in the location list. This can be the case if, for example, a route section has four, sometimes six lanes. This calculation can be made as a minimum (worst value) or as an average.

The FDD characteristic value thus calculated is temporarily stored at 9. At 10, a selection is made between the FDD characteristic value temporarily stored at 4 and at 9. The transmitted FDD characteristic value, which is temporarily stored at 4, has priority, so that the characteristic value read from the location list 6 is only used if no FDD characteristic value has been transmitted. This selection can also be made at 7, which is indicated by a dashed line. The result of the selection at 10 as well as the temporarily stored traffic density k and the extent 1 are evaluated at 11.

In particular, the evaluation can be carried out with the aid of the flow-density diagram, likewise calculated at 11, as described below with reference to FIGS. 2 and 3. The data to be output are then made visible using an output device (such as a display) 12 and / or can be e.g. be made available via voice output.

FIGS. 2 and 3 each show a flow-density diagram which shows the relationship between traffic flow q and traffic density k. The traffic flow in cars per unit of time is measured, while the traffic density means k cars per unit of route. The flux-density diagram represents a parabola that reaches its maximum starting from the coordinate origin at kmax and qmax and then drops again to k = 2 * kmax and q = 0. In Figures 2 and 3, three points A, B, C are highlighted for one low traffic density k1, medium traffic density k2 and high traffic density k3.

The slope of the straight line shown in dashed lines in FIG. 2 gives the average speed of the vehicles. In the exemplary embodiment explained in connection with FIG. 1, kmax and qmax were transmitted as a FDD identifier for a predetermined route section, from which the complete curve is calculated. If, for example, there is a traffic density k2 on the route section, which is also transmitted to the terminal, the traffic flow can be calculated. The gradient of the straight line through point B and thus the average speed is then calculated by dividing the flow of traffic by the traffic density. Since the length 1 of the traffic disruption was also transmitted, the time for driving through the part of the route section affected by the traffic disruption can in turn be calculated therefrom and made available by the output device 12. Other results can also be displayed, for example the delay compared to a journey at approximately "normal" speed or the time for the entire section of the route.

In Fig. 3, points A, B, C are tangents to the flux density diagram. The slope of these tangents gives the speed of density waves and the slope of a secant, as shown for example between points A and B, the speed of shock waves. Density waves continue with a positive slope of the tangents in the direction of travel, with a negative slope against the direction of travel, the latter thus influencing the following traffic. This makes it possible to calculate whether a traffic disruption has reached a junction of a motorway in the direction of travel or against the direction of travel within a predetermined time. Then, for example, a motorist can decide or recommend a terminal which connection point he uses to leave or drive up.

4 shows a device which is preferably also arranged in a terminal and is supplemented by a device 16 for calculating route recommendations. This includes a memory 17 with a so-called digital street map, which can optionally also be combined with the location list 6. With the aid of a keyboard 18, the user can enter the start, the destination and any intermediate waypoints that are to be passed on the journey. The selection of the TMC messages carried out in the receiver 1 can be controlled by the device 16 in such a way that all TMC messages which possibly influence the calculation of the route recommendation are selected. The relevant data for all these TMC messages are stored in memories 3 to 5 and 15.

The data belonging to a route section in each case can be called up by the device 16 from the memories, whereupon the result of the evaluation can be sent to the device 16 at 11. Traffic disturbances and their effects can thus be taken into account in the route calculation known per se. For example, it can be calculated whether a traffic disruption on a route section which is recommended per se by the route calculation and can be reached later by the vehicle represents a severe impairment, so that a different route may be recommended from the outset.

FIG. 5 shows a device according to the invention, which is arranged in a central unit, for example in a central traffic computer, and corresponds in its most important components to the device according to FIG. 4. Messages relating to individual route sections, which essentially contain the same information as in the exemplary embodiments already explained, are supplied via a communication network 21, for example ISDN, by a large number of sensors 22, which are only indicated in FIG. 5. The data present for each section of a road network are stored in the memories 3 to 5 and 15, so that the device 16 is able to take into account all reported traffic disruptions when calculating any route recommendations.

In the exemplary embodiment according to FIG. 5, requirements for calculating a route recommendation and the calculated route recommendations are transmitted to terminals 24 via a mobile radio network 23. The keyboard 18 and the display device 12 can be used for monitoring and maintenance tasks.

Claims

Expectations

1. A device for information about traffic disruptions with means for receiving traffic data recorded with sensors, characterized in that means for calculating data to be output, which describe the effect of the traffic disruption, from the received traffic data with the aid of a flow density that is valid for the respective route section Diagram are provided.

2. Device according to claim 1, characterized in that the traffic data received describe the respectively measured traffic density, an identifier of the route section concerned and the respectively measured extent of the traffic disruption.

3. Device according to claim 2, characterized in that the traffic data received further describe the flow-density diagram valid in each case for the route section.

4. Device according to one of the preceding claims, characterized in that the traffic data received are expanded TMC messages.

5. Device according to one of claims 1 to 4, characterized in that the data to be output describe the average speed and / or the travel time on a known route section.

6. Device according to one of claims 1 to 4, characterized in that the data to be output describe the change in the length of the traffic disruption.

7. Device according to one of the preceding claims, characterized in that data for describing the flux density diagrams of sections of the route are stored in a memory.

8. Device according to one of the preceding claims, characterized in that further means are provided for calculating route recommendations, wherein the calculated data to be output are taken into account.

9. Device according to claim 8, characterized in that the device and the means for calculating route recommendations are arranged in a terminal which receives the traffic data from at least one central device.

10. The device according to claim 8, characterized in that the device and the means for calculating route recommendations are arranged in a central device, the terminal data can be supplied to a desired trip and from which the calculated route recommendations can be transmitted to the terminals.

11. A method for information about traffic disruptions, traffic data being recorded with the aid of sensors, characterized in that from the recorded traffic data with the aid of one for the respective Section of the current flow-density diagram to be output is calculated, which describes the effect of the traffic disruption.

12. The method according to claim 11, characterized in that the traffic data received describe the respectively measured traffic density, an identifier of the route section concerned and the respectively measured extent of the traffic disruption.

13. The method according to claim 12, characterized in that the traffic data received further describe the flow-density diagram valid for the section in each case.

14. The method according to any one of claims 11 to 13, characterized in that the traffic data received are expanded TMC messages.

15. The method according to any one of claims 11 to 14, characterized in that the data to be output describe the average speed and / or the travel time on a known route section.

16. The method according to any one of claims 11 to 14, characterized in that the data to be output describe the change in the length of the traffic disruption.

17. The method according to any one of claims 11 to 16, characterized in that data for describing the flux-density diagrams of sections of the route for a predetermined area are stored in a memory.

18. A method for transmitting information about traffic disruptions, traffic data being recorded with the aid of sensors, characterized in that the recorded traffic data are transmitted to receivers and with the aid of a flow-density diagram valid for the respective route section, data to be output from the transmitted traffic data are calculated, which describe the effect of the traffic disruption.

19. The method according to claim 18, characterized in that the transmitted traffic data describe the respectively measured traffic density, an identifier of the route section concerned and the respectively measured extent of the traffic disruption.

20. The method according to claim 19, characterized in that the transmitted traffic data further describe the flow-density diagram valid in each case for the route section.

21. The method according to any one of claims 18 to 20, characterized in that the transmitted traffic data are expanded TMC messages.