EP0292897A2 - Evaluation method of the travel time measured in vehicles by means of a guidance and information device in a guidance and information system - Google Patents

Abstract

A digitized road network map can be stored in a location and navigation computer of the vehicle. Two nodes of the intermeshed road network form a route section, two guidance points form a sub-route with a separate address in each case. The travel time is measured using a travel time measuring device of the guidance and information device. The traffic congestion time contained in the travel time is calculated for each sub-route from the sum of all the time intervals during which the vehicle speed lies below a predetermined limit speed. In the location and navigation computer, the number of deceleration operations below the limit speed is measured for each sub-route and a weighting factor calculated therefrom. The respective weighting factors associated with the traffic congestion times are transmitted together with the latter to a central traffic and information controlling computer which evaluates the respective travel and traffic congestion time as a function of the size of the weighting factor. Using these evaluated travel times and traffic congestion times new alternative route recommendations are produced and evaluated for control of traffic light systems. <IMAGE>

Description

The invention relates to a method for evaluating the travel time measured in vehicles by means of a guidance and information device in a guidance and information system for individual traffic, with a digitized road network map that can be stored in a location and navigation computer of the guidance and information device, two of which A route section is formed in the nodes of the road network and a partial route is formed from two guidance points, each with its own address, and the travel time is measured with a travel time measuring device of the guidance and information device.

Traffic management and information systems are generally known. With such a control system, individual vehicles can be guided individually from a respective starting point to an inputable destination. European patent specification 00 21 060 describes a guidance system for individual traffic, in which guidance information for all vehicles in question is radiated from individual guidance beacons to all passing vehicles. The recommendation for a specific destination is selected in the vehicle. The guide beacons are each arranged at greater distances from one another. The routes between them are described as a sequence of path vectors. It is provided that guidance beacons are given to the vehicles in the form of a chain of guidance vectors.

European patent 00 29 201 describes a method for recording traffic data in a guidance and information system for individual traffic. The known method describes a travel time measuring device in the vehicle with which the travel time is measured individually between the individual guide points of a guide vector chain. The travel time within a section or section of a route is made up of several times. In addition to the driving time at which the vehicle is being driven, there is also a standstill, which may be due to traffic, such as is caused, for example, by traffic jams or stops in front of traffic signals. The standstill can also not be due to traffic, as can be caused, for example, by stopping with the engine running, because quick cigarettes or a newspaper are fetched or because, for example, a taxi driver pays the passenger with the engine running. Falsified travel times determined in this way are, however, not meaningful if travel time forecasts and situation-related route optimizations are to be created with the aid of a central control computer. In the above-mentioned patent it has already been proposed to reduce such false travel times by averaging the measured values of several vehicles. However, such smoothing inevitably requires longer reaction times to real traffic jams. Delays in reaction are undesirable, however, because the benefits of a dynamic traffic control system depend to a large extent on its ability to react quickly to unexpected traffic jams.

It is therefore an object of the invention to provide a method in a control and information system for traffic detection and control of the type mentioned above, in which the travel time is measured for respective sections of the route, which allows the credibility of traffic jam time measurements to be assessed and for such measurements who are very likely to avoid real traffic jams, to respond without delay by recommending alternative routes.

This object is achieved in such a system in that the congestion time contained in the travel time per partial route is calculated from the sum of all time intervals at which the vehicle speed is below a predetermined limit speed, that in the location and navigation computer the number of deceleration processes below Limit speed is measured for each section and a weight factor is formed, that the respective weight factors associated with the congestion times are transmitted to a central traffic and information control computer, that the respective travel and congestion time is evaluated as a function of the size of the weight factor, and that with These evaluated travel and traffic jam times, on the one hand, new alternative route recommendations are worked out and, on the other hand, they are evaluated for traffic light control systems.

With the method according to the invention, an analysis of the vehicle movement forms a weight factor that describes the credibility of a traffic jam message. The measured congestion times are evaluated depending on the size of the associated weight factor and only congestion times with sufficiently large weight factors are used for further processing in the host computer.

This has the advantage that the guidance and information system for dynamic traffic control can react to real traffic jams relatively early by offering special route recommendations the individual vehicles are there or by better adapting the switching program of a traffic light system to the actual traffic in order to reduce the length of the traffic jams.

For the method according to the invention, it is expedient to form a plurality of speed classes to form the weight factor, which, for example, comprise a speed range of 5 km each per hour. Six speed ranges result in a limit speed of 30 km per hour. The number of transitions from one speed range to the next lower speed range is now advantageously determined, this number of transitions corresponding to the weight factor.

In a further development of the invention, the weighting factors for evaluating the measured congestion time are standardized by dividing the number of transitions from one speed range to a next lower one in the area of a partial distance by the number of transitions that are necessary for a stopping process from a speed exceeding the limit speed is inevitably given. If the standardized weight factor is greater than or equal to a limit value, for example two, the associated congestion time is assessed as the real congestion time. If the normalized weight factor has a value which is below this limit value, for example two, the congestion time can be evaluated in a known manner by continuously averaging.

To evaluate the measured travel time within a section of the route, it is advisable to add up the weighting factors of all congestion times of the individual sections, that is to say a section of the route, in the traffic and information control computer and to use the size of this sum factor for route optimization.

With the method according to the invention, the weight factors added to the traffic jam time measurements are used to assess the credibility of travel times. The congestion times are measured separately for each section, which are limited by two control points, which are generally two signaling systems. Travel times are generally for entire sections of the route, i.e. Routes between two nodes in the main node network, measured. They can contain several control points or light signal systems. The addition of the weight factors of all congestion times of a route section in the central control computer makes sense, because the weight factors are nothing else than the number of (standard) deceleration processes during the slow movement of a pent-up column.

It is extremely unlikely that long travel times combined with high weight factors can be attributed to causes other than traffic. Since a longer traffic jam requires certain times to build up and take down and no longer allows individual driving behavior, such a mathematical treatment of travel times with larger weight factors is useful for travel time forecasts, because a travel time with a large weight factor will only change from time interval to time interval Can change time constants that are characteristic for each section and can be determined by measurements. It is also possible to automatically detect road traffic disruptions due to high weight factors and to have the host computer carry out traffic management measures automatically.

• Fig. 1 schematisch das Funktionsprinzip eines Leit- und Informationssystems (ALI-SCOUT),
• Fig. 2 ein Schema eines Straßennetzes in einem begrenzten Bereich,
• Fig. 3 ein typisches Geschwindigkeitsprofil für ein Fahrzeug im Stau,
• Fig. 4 und 6 ein Geschwindigkeitsprofil im Rückstaubereich einer überlasteten Lichtsignalanlage und
• Fig. 5 und 7 ein Geschwindigkeitsprofil, verursacht durch nicht verkehrsbedingte Halte.

The method according to the invention is described in more detail with reference to the drawing. Show

• 1 schematically shows the functional principle of a control and information system (ALI-SCOUT),
• 2 shows a diagram of a road network in a limited area,
• 3 shows a typical speed profile for a vehicle in a traffic jam,
• 4 and 6 a speed profile in the backwater area of an overloaded traffic signal system and
• 5 and 7 a speed profile caused by non-traffic stops.

The functional principle of the control and information system is shown schematically in FIG. In the vehicle FZ there is a guidance and information device LIE which has a locating device 0 with a magnetic field probe MS and a wheel pulse generator RIG, and a navigation device N with an operating device BG, with a travel time measuring device RZM and with an infrared transmitter SF and an infrared receiver EF. The operating device BG has an input keyboard ET, a target memory ZSp and, for example, a direction indicator ANZ. The common travel and congestion times, including the weight factors, are transmitted via the vehicle transmitter SF of the vehicle FZ to the beacon LB, which is mounted on the roadside, for example on a mast SM on a light signal system LSA. Likewise, data is transmitted in the opposite direction from the beacon LB to the vehicle FZ and received by the vehicle receiver EF. The beacon LB is connected to the beacon electronics BE, which can be accommodated in the VSG traffic switching device. The traffic switching device VSG is connected to the traffic and information control computer VLR, which is located in a traffic control and information center VLZ, via a data line DL. The known traffic control and information system need not be described further here.

Fig. 2 shows the scheme of a road network in a limited area. The are shown Intersections or nodes K1, K2 and K3, each with a beacon. For better understanding, their functions of sending control information (LB1, LB2) and receiving time measurements (MB1, MB2, MB3) are shown separately. A vehicle FZ1 approaching the node K1 receives the guidance recommendation from the beacon LB1 to use the route to the node K2 described by the guidance point LP1, LP2 to LP5. During the journey, the control and information device LIE in the vehicle FZ measures the respective travel times between the mentioned control points LP1 to LP5. When passing the node K2, it transmits the measured travel times to the beacon MB2, which in turn forwards it to the traffic control computer VLR. The vehicle FZ3 is routed from the node K1 via the through the control points LP1, LP2, LP3 and LP7 to the node K3 and there reports the measuring beacon MB3 which sections and which times it has in common on these. Further details of the known travel time measurement are described in European patent specification 00 29 201.

3 shows the typical course of a speed profile v = F (s) from a vehicle moving in a column. The speed v (km / h) is plotted over the distance s covered in meters (m). The congestion time tSt per section is determined from the sum of all time intervals tStn, tSt (n + 1) at which the vehicle travels at a speed which is below a certain limit speed vSt.

FIG. 4 also shows a speed profile of a vehicle over the distance s using an example of a measurement run in the backflow area in front of an overloaded traffic light system. The travel time tR is also plotted as a function of the path s in FIG. The path s is plotted in meters (m) on the abscissa, the zero point being entered on the right and the stop line HL being drawn in on the left of the zero point (traffic signal system). The speed v is plotted on the right ordinate in kilometers per hour (kmih). The travel time tR in seconds (sec) is plotted on the left coordinate.

This example shows that the vehicle meets the end of a pent-up column about 520 m in front of the stop line HL and then moves with it according to the switching rhythm of the signaling system at intervals of approximately 60 seconds in this example and decelerates again (tR = F (s)). Accordingly, the speed v is shown.

If one now looks at FIG. 5, which also shows a speed profile, for a test run of a vehicle that stops once and then has to wait a second time in front of a traffic light system at the stop line HL, it can be seen that a completely different situation must exist. As in FIG. 4, the vehicle also stops about 520 m in front of the stop line using the example of FIG. 5. In contrast to Fig. 4, however, it only starts again after a time of approx. Four minutes (240 sec), before finally having to wait in front of the traffic light system (HL) in order to continue driving after about 40 more seconds.

In both examples, the travel time is approximately 360 seconds. In the first case (Fig. 4) it is due to traffic, in the second case (Fig. 5) it is most likely due to other reasons. In the first case the control system to a traffic-related congestion must recognize and respond IN THE OWNER ^T prechend, in the second case it would be wrong and an alternative route recommendation unfounded. The typical difference between the two routes is striking. The speed profile v in FIG. 4 is characterized by a relatively large number of acceleration and deceleration processes. The speed curve v shown in FIG. 5 even runs through a larger speed range between the two stops, but has significantly fewer changes.

The method according to the invention therefore measures the number of transitions from one speed class to the next lower one and uses this as a weight factor for evaluating the measured congestion time. FIGS. 6 and 7, which correspond to FIGS. 4 and 5, show n = 6 speed classes, namely a first speed class v1, which corresponds to the speed range from 0 to 5 km per hour, a second class v2, which corresponds to the speed range of 5 up to 10 km per hour, etc. So there are six speed classes v1 to v6 up to the limit speed vSt = 30 km / h. The navigation computer ONR of the guidance and information device LlE in the vehicle FZ determines the number of transitions ü from one speed class to the next lower speed class as a weight factor G by measuring the wheel revolutions in a time unit with the wheel pulse generator RIG. These transitions ü are identified by small crosses on the speed curve . For the example of the pent-up column according to FIG. 6, this results in a ü = 39, that is to say a weight factor of G = 39. For the example of the non-traffic-stopping vehicle according to FIG. 7, there are 16 transitions (ü), that is to say a weight factor from G = 16.

In order to obtain smaller and clearer numerical values, it is advisable to form a standardized weighting factor GN. The normalization is based on the number of "normal stops". Decelerates a vehicle from a trip with a speed v = 30 km per hour to a standstill, there are a total of n + 1 = 7 border crossings with n = 6 speed classes v1 to v6. The standardized weight factor GN thus results from the relationship GN =, with Ü = number of border crossings (corresponds to the weight factor G).

For the example of the pent-up columns according to FIG. 6, this calculation gives GN = 6. For the case of non-traffic-related stops in the example of FIG. 7, GN = 2 results. These numbers are correct with the number in the two examples given above of stops (v = 0) match. This is marked with small rings in FIGS. 6 and 7. You would also get the same result if you simply count the number of stops. However, this would have the disadvantage that vehicles which are driven economically by accelerating less in the column and not braking to a speed of v = 0 would provide a weighting factor of zero when the stops were counted. The standardized weight factor GN is therefore used with the method according to the invention and is used for the measurement of the congestion time.

Each congestion time TSt, which is measured by the navigation computer ONR and the travel time measuring devices RZM in the vehicles FZ, is supplemented with a weight factor G or GN. The weight factors can be calculated relatively easily from the temporal density of the path impulses in the vehicle navigation computer. Measurements with normalized weight factors of 0 and 1 are expediently dealt with by continuous averaging, as is already known. In green waves, the frequency of occurrence of standardized weighting factors GN> - 1 can be used for a first rough assessment of the quality of the green wave.

Weight factors of GN k 2 mean that vehicles entering the backwater area of an intersection with a red signal cannot pass through the next green. Weight factors of GN k-2 are therefore used to record traffic jam time lines in the traffic control computer for all the entrances to the traffic light system in question. Significantly different weighting factors for the traffic flows at an intersection can be a clear indication, in contrast to the normally measured congestion time, that the green time distribution no longer corresponds to the actual traffic volume.

The measured travel time is also evaluated with the weight factors added to the traffic jam time measurements. The congestion times are measured separately for each section, which is limited by two control points. The travel time is for entire sections of the route, i.e. the distance between two nodes in the road network, measured. The travel times can include several guiding points or light signal systems. The weighting factors of all congestion times of a section of the route are added in the central control computer. An addition makes sense because the weight factors are nothing other than the number of (standard) deceleration processes in a pent-up column. The length of a traffic jam can also be derived indirectly if one assumes that the speed curve v shown is typical for a pent-up column according to FIG. 4, and that a switching cycle of the signal system of e.g. 60 seconds often occurs, it can be seen that the weight factor GN increases by one value in each 100 m of stowage length. The sum of the weight factors for a route section or a partial route can therefore serve as an indirect measure of the amount of the pent-up vehicles on this route.

Claims (5)

1. Method for evaluating the travel time (TR) measured in vehicles (FZ) by means of a guidance and information device (LIE) in a guidance and information system for individual traffic, with in a location and navigation computer (ONR) of the guidance and information device (LIE) storable, digitized road network map, whereby a route section is formed from two nodes (K1, K2, ...) of the meshed road network and a partial route is formed with two control points (LP1, LP2, ...) and each with the travel time (TR) is measured with a travel time measuring device (RZM) of the control and information device (LIE),
characterized in that for each section the congestion time (TSt) contained in the travel time (TR) is calculated from the sum of all time intervals (tSt1, tSt2, ...) at which the vehicle speed (v) is below a predetermined limit speed (vSt) is that in the location and navigation computer (ONR) the number of deceleration processes below the limit speed (vSt) is measured for each section and a weighting factor (G) is formed from it that the respective weighting factors (G) associated with the congestion times (TSt) together These are transmitted to a central traffic and information control computer (VLR) that the respective travel and traffic jam time is evaluated depending on the size of the weight factor, and that on the one hand new travel route recommendations are developed with these evaluated travel and traffic jam times and on the other hand for a traffic light system control be evaluated. 2. The method according to claim 1,
characterized in that to form the weight factor (G) several (n) speed classes (v1 to vn) are formed and the number of transitions (ü) to the next lower speed class is determined, the number of transitions (ü) being the weight factor (G ) corresponds. 3. The method according to claim 2,
characterized in that from the number (n + 1) of the border crossings of the speed classes (v1 to vn) and from the weight factor (G

ü) a standardized weighting factor (GN) according to the following relationship
is calculated, and that standardized weighting factors GN, which are greater than or equal to a certain limit value (e.g. 2), show the associated congestion time (TSt) as real congestion time, and thereby trigger an immediate reaction by the traffic control computer VLR to influence traffic signal systems. 4. The method according to claim 3,
characterized in that the measured congestion times (TSt) with an associated standardized weighting factor (GN), which is below the specific limit value (for example 2), are evaluated by running averaging, thereby limiting an undesirable influence of non-traffic-related stopping processes. 5. The method according to any one of the preceding claims,
characterized in that with the weight factors (G or GN) of the associated congestion times (TSt) the measured travel time (TR) within a section of the route is evaluated by adding the weight factors of all congestion times of the individual sections in the traffic and information control computer, and in Depending on the size of this calculated sum factor, the response of the central traffic control computer (VLR) to excessive travel times is accelerated when selecting alternative routes.

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