EP1628274B1 - Method and system for providing traffic information and controlling traffic - Google Patents

Abstract

The equipment takes spot samples of vehicle-specific traffic data, especially vehicle position, speed and route, from vehicles (1) approaching the road crossing (4). The information is transmitted wirelessly to the controller (2) of the traffic lights (3). All fixed data transmission equipment is local to the crossing. Route data includes starting point and destination, journey time and turning rules at the crossing. Data is transmitted to a central computer for further processing. An independent claim is included for the corresponding system.

Description

The invention relates to a method for determining traffic information in a road network with at least one intersection at which the traffic flow is controlled by means of a traffic signal having a control device for turning on signaling lights performing signal traffic correlated with the traffic flow and from this traffic information, in particular a traffic demand, for at least part of the road network.

The invention further relates to a method for controlling the traffic in a road network with at least one intersection at which the traffic flow is controlled by a traffic signal system in which vehicle-carrying road users are influenced by light signals represented by signal generators of the traffic signal system, wherein the signal transmitters according to a in a control unit of the traffic signal running signal schedule, which is calculated on the basis of determined traffic information.

Finally, the invention relates to a system for carrying out the method.

Traffic information, in particular traffic demand data, is essential in order to make estimates about the current and future traffic conditions of a road network. Furthermore, they are necessary to be able to identify and apply traffic control procedures that are optimized with regard to the entire road network or to define appropriate traffic management strategies.

Traffic demand data has so far been derived, especially in offline planning processes, from archived historical values of traffic detectors of the road network. For this purpose, demand matrices for various types of days, such as working days, weekends, holidays, vacation periods and for different hour groups, such as morning and evening peak hours, daily traffic and night traffic are usually derived from a static demand matrix, which comes from a survey. However, very little is known about the extent to which such derived traffic demand data is in line with reality. In addition, such traffic demand data can not reflect short-term changes in traffic demand arising from current events such as events, construction sites or incidents.

The document US 6654681 describes a method for obtaining traffic information and for dynamic route recommendation.

In order to improve the timeliness and reliability of a traffic demand database formed by manual traffic counts and roadside traffic detector data, it is known to utilize the vehicle specific traffic data of vehicles of a sampling fleet equipped with route guidance systems. The Patent DE 100 18 562 C1 discloses a method for detecting and monitoring the traffic situation on a road network. The reporting vehicles of a sampling fleet that are involved in traffic are usually referred to as so-called "floating cars" because they "swim" in traffic. Accordingly, the traffic data obtained from such vehicles are referred to as "floating car data", abbreviated as FCD. In order to be able to win such FCD for a traffic network with traffic-controlled network nodes with reasonably little effort such that they are well suited for further evaluation, particularly with regard to the determination of the current and future traffic situation in metropolitan areas, it is proposed in the known method that data acquisition operations at least for successively operated network nodes are triggered, specifically in each case to a certain extent Time after leaving a line edge that opens into the associated network node. In this case, a time stamp information is obtained in the respective data acquisition process as traffic data indicating a reporting time related to the respective network node.

A disadvantage of the FCD-based method is the high expense of transmitting the traffic data from the vehicles of the sampling fleet to a traffic control center. Namely, the communication links are established, for example, via route guidance systems of the vehicles, using fee-based telecommunications standards such as GMS or UMTS. Depending on the size of the sample fleet or the road network, frequency, volume and speed of data transmission, this involves enormous costs.

The invention is therefore based on the object to provide methods and a system of the type mentioned, which work economically and thus find the necessary acceptance in user and operator circles.

A subtask is achieved according to the invention by a generic method for determining traffic information, wherein vehicle-specific traffic data is detected by the intersection approaching vehicles of a sampling fleet vehicle-specific traffic data locally limited to the intersection, wireless transmission from the vehicle to the control unit of the traffic signal. As with the FCD, it uses a fleet of selected vehicles to track the traffic flow in the road network as a carrier of traffic data. Anonymized vehicle-specific data are transmitted directly to the control unit of a traffic signal system using a local communication while avoiding the costly telecommunications standards (GSM, UMTS), which regulates the traffic of the intersection to which the respective vehicle is currently approaching. It is therefore sufficient to use a - possibly for the driver of the sample vehicle free - communication, which is limited to the vicinity of the approached intersection and therefore may be short-range trained. The traffic data acquired in this way could be termed a local FCD, around which the data base for traffic demand information is enriched.

In a preferred embodiment of the method according to the invention, the current position and speed of a vehicle are transmitted as vehicle-specific traffic data. If this traffic data is recorded with the respective transmission time and an identifier identifying the sampling vehicle, the travel of this vehicle with regard to route and travel time can be tracked at points along such road intersections which can receive these vehicle-specific traffic data.

In an advantageous embodiment of the method according to the invention, route data of a vehicle are transmitted as vehicle-specific traffic data. For example, all data available via a vehicle's route guidance system could be sent to the upcoming intersection controller.

Preferably, as route data of a vehicle, source-destination information and / or previous travel times and / or turn decisions for the approached road intersection are transmitted. On the basis of this data, based on the entire recorded road network, traffic forecasts can be derived promptly and reliably.

In a preferred embodiment of the method according to the invention, count values of road-side traffic detectors are detected as further traffic data describing the traffic state in the area of the road intersection and transmitted to the control device. In this way, the data base for traffic demand estimates is also extended by traffic data, the vehicles not belonging to the sample fleet. For example, these data could serve to verify the validity of the data limited to sample fleet vehicles. In addition, such traffic detectors can also obtain traffic data around intersections outside the short-range reception area.

In an advantageous embodiment of the method according to the invention, the traffic data recorded in the control unit are aggregated and transmitted to a central traffic computer for further processing. In a traffic control center or traffic management center, the traffic data of all in the road network locally around their crossing area receiving control units are processed. Thus, the central traffic computer for the considered road network from the historical data as well as from the currently transmitted data define new traffic strategies that can satisfy the current transport demand. Such a traffic strategy for the road network is implemented in signal plans for the control devices of the individual intersections, which are each optimally matched to each other.

Another sub-problem is solved by a method for controlling the traffic of the type mentioned, in which the traffic information is determined according to a method of the type described above. In the context of a partially or fully traffic-dependent local control of traffic at a light signal-controlled road intersection, the locally recorded traffic data can be processed directly in the control unit of the traffic signal system. This is done essentially by influencing the running in the control unit signal time schedule, according to which the signal generator of the traffic signal system are turned on, wherein within a predetermined frame signal plan, the duration of release and blocking phases are variable.

According to an advantageous embodiment of the method according to the invention, the traffic data in the control unit are converted into traffic-technical variables for controlling the traffic light system. Thus, for example, the vehicle-specific traffic data transmitted by vehicles of the sampling fleet - such as current positions, speeds and route data - can be converted into traffic volumes, average speeds and directional divisions of the traffic flows passing through the intersection. Optionally supplemented by traffic data from roadside traffic detectors in the area of the intersection, queue lengths in the individual access roads to the intersection can also be determined.

In a preferred embodiment of the method according to the invention, with the transmission of traffic data, a vehicle approaching a road intersection requires a release time in the signal time schedule. In the case of a traffic-dependent control of a traffic signal system, a traffic data transmission interpreted as a request signal can cause an extension of the green time in the ongoing signal program.

In an advantageous embodiment of the control method according to the invention, release time requirements are prioritized according to vehicle types. Here, the sample fleet is extended to include vehicle types that log on to a light signal-controlled road intersection by data transmission at the light signal system control unit in order to request a preferential treatment - for example in the form of a free passage. The prioritization can be staggered, so that, for example, public transport vehicles are preferred at a crossroads over private vehicles, while emergency vehicle, emergency services, fire brigade or police emergency vehicles enjoy the highest priority in the allocation of release times.

In a preferred embodiment of the method according to the invention, control units of neighboring traffic signals exchange traffic information. By exchanging information with traffic light control systems in the traffic flow of preceding or succeeding intersections, the signal times can be optimally adapted to the current local traffic demand. There is even a network-wide self-organizing control possible, which is able to control the traffic flows in a road network according to a network-wide target function as a fully distributed calculation scheme when locally receives at the respective road intersections traffic information about the destinations of the incoming vehicles. In this case, only local calculations are carried out in the control devices of each road intersection and are communicated with the control devices of the next adjacent road intersections, the road network being mapped onto a recurrent neural network, as described, for example, in "Static and Dynamic Traffic Allocation with Recurrent Neural Networks", ISBN3- 8265-6720-X, thesis by P. Mathias, published 1999.

Finally, a final sub-problem is solved by a system for carrying out a traffic information determination method and a control method in which control units of traffic signals are each in communication with a road-side communication device, whereby vehicles of a sampling fleet are equipped with vehicle-side communication devices via the traffic data locally, respectively a close range around a road junction to the associated roadside communication device are wirelessly transferable.

Preferably, the vehicles of the sampled fleet in question are each equipped with a destination guidance system.

FIG 1

ein System zum Durchführen eines Ermittlungsverfahrens für Verkehrsinformation und eines Verkehrssteuerungsverfahrens, und in

FIG 2

ein Ablaufdiagramm der erfindungsgemäßen Verfahren

schematisch veranschaulicht sind.An embodiment and further advantages of the invention will be explained in more detail below with reference to the drawings, in which

FIG. 1

a system for carrying out a traffic information determination method and a traffic control method, and in

FIG. 2

a flowchart of the inventive method

are illustrated schematically.

Essential for a system according to the invention for carrying out a traffic information determination method and a traffic control method is the provision of cost-effective data transmission from vehicles 1 of a sampling fleet to a control unit 2 of a traffic signal system 3 FIG. 1 Such a traffic signal system 3 regulates the traffic flow at a road junction 4, which has four crossing arms in the illustrated example. The vehicle 1 leading road user is influenced by light signals that are generated by signalers 5 of the traffic signal 3 or displayed. For the sake of simplicity, only one signal generator 5 is shown, whereas in reality a large number of signal generators 5 corresponding to the topology of the road intersection 4 are used. Thus, signal generator 5 may be provided for different lanes of access roads to the intersection 4 and for pedestrians, cyclists or trams. The light signals of the signal generator 5 are turned on by a programmable running in the control unit 2 Signal Schedule 6 according to specifiable release and blocking times.

To FIG. 1 For example, a vehicle 1 of the sampling fleet has a vehicle-side communication device 7, via which traffic data can be transmitted wirelessly to a roadside communication device 8. The roadside communication device 8 is connected to the control unit 2 of the traffic signal system 3 in connection. By avoiding cost-intensive telecommunications standards, such as GSM or UMTS, the data transmission according to the invention is locally limited, namely within a short range 4R around the intersection 4. In this way, vehicle-specific traffic data of vehicles 1 of a sampling fleet can be cost-effectively transmitted directly wirelessly to the control unit 2 of the traffic signal system 3 as soon as the vehicle 1 has entered the vicinity 4R. To transmit current position, speed and route data, the vehicles 1 of the sampling fleet may be equipped with navigating guidance systems 9 which operate by means of communication with a satellite system 10.

The control unit 2 of the traffic signal system 3 has according to FIG. 1 a number of other important connections. First of all, the control device 2, as well as control devices, not shown, of further light signal installations installed in the road network are connected to a control center 11, which comprises a traffic computer 12. The central unit 11 may be a traffic computer or traffic management center, which receives the traffic data received in the control unit 2 for further processing. Conversely, updated from such centers 11 by means of the traffic computer 12 updated traffic strategies and transmitted in the form of optimized signal time schedules 6 to the control units 2 in the road network. Furthermore, the control unit 2 communicates via data lines 13 - or via radio links - with control units of traffic lights of adjacent intersections. Thus, recorded traffic data and the current switching states of the signal generator 5 can be exchanged for the mutual coordination of the control processes among the adjacent control devices 2. Finally, the control unit 2 is connected to roadside arranged traffic detectors 14, such as induction loops, radars, infrared sensors or video cameras, via which additional traffic data both within the near range 4R and outside can be detected. Incidentally, these traffic detectors 14 detect not only vehicles 1 of the sampling fleet, but all vehicles forming a traffic flow. For short-range data transmission between the communication devices 7 and 8 are for example infrared, radio or microwave into consideration.

In FIG. 2 the traffic information determination method according to the invention and the traffic control method in system levels are illustrated. In a first level, vehicles, in particular vehicles 1 of a sampling fleet, interact with various sensors and actuators. According to the invention, vehicle-specific traffic data are transmitted wirelessly locally within a vicinity around a road intersection to a roadside communication device 8. These traffic data are anonymized vehicle-specific data, which originate, for example, from vehicle-side destination guidance devices with a GPS system and are transmitted to the traffic light control with a vehicle-specific identifier. Specifically, this may be current position, speed or route data - such as source-destination information, previous travel times or planned turn decisions - of a vehicle 1. In addition, 14 counts are detected by roadside traffic detectors, which characterize the traffic flows at the considered road intersection in terms of traffic intensity and average speed.

In the in FIG. 2 represented central level is the control unit 2, which receives the detected traffic data of the roadside communication device 8 and the traffic detectors 14. The traffic data is aggregated in the control unit 2, ie accumulated and compressed and possibly to traffic technical parameters such as traffic volumes, average speeds, directional divisions and queue lengths in the access and possibly exits the considered intersection.

The traffic information determined in this way is forwarded by the control units 2 in the given road network to a superordinate traffic computer or traffic management center 11 of a third level. There, the traffic information obtained is evaluated and further processed to define traffic strategies for the road network. These pursue the goal of satisfying the currently ascertained traffic demand in the road network according to specific strategy specifications. In addition to the currently recorded traffic data of the sample fleet and the traffic detectors, 11 archived historical traffic data are also used in the central office.

The method for determining traffic information described above can advantageously be used for a method for traffic control in a traffic-signal-controlled road network. In a first approach, updated signal time schedules 6 for the various control devices 2 of the traffic signal systems in the road network can be calculated by a central traffic computer in the center 11 and transmitted to the control devices 2. In the control unit 2, such a signal time schedule 6 runs programmatically. After the release, lock and split times defined in the signal program, the signal transmitters 5 of the first described level are turned on. The influencing of the road users in this level takes place via light signals represented by the signal transmitters 5, in the signal phases of which vehicles are allowed to pass the intersection or are prevented from entering the intersection.

According to FIG. 2 However, another traffic control approach is possible. In this case, data transmissions from vehicles 1 to the roadside communication device 8 are interpreted by the control unit 2 as a request signal for a green phase. If a so-called frame signal plan runs from the fully traffic-dependent control in the control unit 2 as the signal time schedule 6, the controller can issue such request signals take into account, for example, a prolonged green phase is extended. For competing request signals from different accesses, the controller may also prioritize. Such prioritization is done, for example, by types of vehicles, emergency vehicles such as police, fire or ambulance being given top priority, while public transport vehicles such as trams or buses are given medium priority and private cars are given the lowest priority.

Another advantage arises when control units 2 of adjacent road intersections exchange traffic information such as the detected traffic data or the instantaneous switching state in the running signal program with each other. By suppression of the central level, this control can control the traffic flows in the road network according to a network-wide predefinable destination function via exclusively locally performed calculations by communication with the next adjacent control unit, if it receives local traffic information about the destinations of the incoming vehicles. A similar approach is published in the previously cited publication "Static and dynamic traffic sharing with recurrent neural networks".

Claims (11)

1. Method for ascertaining traffic information in a road network having at least one intersection (4) at which the traffic flow is controlled by means of a traffic-light signal system (3) which has a control device (2) for turning on signal generators (5) representing traffic light signals, with traffic data correlating with the traffic flow being acquired and traffic information, in particular traffic demand, being ascertained therefrom for at least a part of the road network,
   characterised in that vehicle-specific traffic data from vehicles (1) of a sample vehicle fleet that are approaching the intersection (4) is acquired by wireless transmission, limited locally around the intersection (4), from the vehicle (1) to the control device (2) of the traffic-light signal system (3), that count values serving as further traffic data describing the traffic conditions in the area of the intersection (4) are acquired by roadside traffic detectors (14) and transmitted to the control device (2), and that the traffic data acquired in the control device (2) is aggregated and transmitted to a central traffic computer (12) in which said data is analysed and processed further in order to define traffic strategies for the road network.
2. Method according to claim 1,
   characterised in that the current position and speed of a vehicle (1) are transmitted as vehicle-specific traffic data.
3. Method according to claim 1 or 2,
   characterised in that route data of a vehicle (1) is transmitted as vehicle-specific traffic data.
4. Method according to claim 3,
   characterised in that source-destination information and/or previous journey times and/or turning decisions for the approached intersection (4) are transmitted as route data of a vehicle (1).
5. Method for controlling the traffic in a road network having at least one intersection (4) at which the traffic flow is controlled by means of a traffic-light signal system (3), wherein vehicle-driving road users are influenced by traffic light signals represented by signal generators (5) of the traffic-light signal system (3), with the signal generators (5) being switched on in accordance with a signal timetable (6) running in a control device (2) of the traffic-light signal system (3), said signal timetable (6) being calculated on the basis of ascertained traffic information,
   characterised in that the traffic information is ascertained by means of a method according to one of claims 1 to 4.
6. Method according to claim 5,
   characterised in that the traffic data is converted in the control device (2) into traffic-related parameters for controlling the traffic-light signal system (3).
7. Method according to claim 5 or 6,
   characterised in that with the transmission of traffic data an approaching vehicle (1) requests a green time in the signal timetable (6).
8. Method according to claim 7,
   characterised in that green-time requests are prioritised according to vehicle types.
9. Method according to one of claims 5 to 8,
   characterised in that control devices (2) of neighbouring traffic-light signal systems (3) exchange ascertained traffic information.
10. System for performing a method according to one of claims 1 to 9, wherein control devices (2) of traffic-light signal systems (3) are in each case connected to a roadside communication apparatus (8), wherein vehicles (1) of a sample vehicle fleet are equipped with onboard communication apparatuses (7) via which traffic data can be wirelessly transmitted locally, in each case within a local area (4R) around an intersection (4), to the associated roadside communication apparatus (8).
11. System according to claim 10,
    characterised in that the vehicles (1) of the sample vehicle fleet are each equipped with a route guidance system (9).

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