EP1902435A1

EP1902435A1 - Method and computer for calculating actual and future motor vehicle traffic status

Info

Publication number: EP1902435A1
Application number: EP06764099A
Authority: EP
Inventors: Paul Mathias
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2005-07-14
Filing date: 2006-07-06
Publication date: 2008-03-26
Also published as: WO2007023019A1; DE102005032975A1

Abstract

The invention relates to a method for estimating the actual motor vehicle traffic status and/or for forecasting the future traffic status thereof in a road network (1). In the calculation, the road network (1) disturbance is taken into consideration in such a way that a delay between the occurrence, modification and/or removal of the disturbance (S) is taken into account until a corresponding information is received by a driver. In such a manner, a real delay is advantageously taken into account in the information degree of drivers during a disturbance modelling and the calculation accuracy is increased. A corresponding road traffic computer (11) used by a traffic-managing central station (3) is also disclosed.

Description

description

Method and traffic computer for calculating a current or future traffic condition

The invention relates to a method for calculating an estimate of the current traffic status comprising several links and / or multiple traffic nodes and / or a prognosis of a future traffic condition in a road network comprising a plurality of links and / or multiple traffic nodes, wherein the calculation is a disturbance in the road network is taken into account. The invention further relates to a traffic ^computer for a traffic management center for calculating a multiple link and / or several traffic nodes comprising current or future traffic conditions in a road network.

Traffic managers are confronted with daily growing demands on traffic engineering and traffic telematics. An important task moder ^¬ ner systems this is to guarantee individual mobility under the simultaneous consideration of environmental aspects. Higher-level traffic management systems are becoming increasingly important. The data on traffic network burdens is becoming increasingly important.

An important starting point is the reduction and relocation of traffic. This applies particularly to the case where in a road network, for example in an urban road network, or in a highway network, a fault occurs, for example caused by a Ver ^¬ road accident or by a different induced complete or partial road closure, such as due to a construction work or a severe weather event. In the event of such an accident, the capacity of a so-called link in the network, ie, a road between two network nodes or intersections, decreases. from a maximum value to a reduced value (teilge ^¬ locked street) or zero (fully blocked road).

It has already been recognized that a time delay between see a disturbance in traffic and the corresponding information of the road users to control or manage the traffic is significant. Based on this finding, DE 197 08 106 ^A1 specifies a special ^method for informing about traffic disturbances, eg via car radio.

It is also disclosed in DE 102 61 172 B4 to evaluate the period of slow collapse of the traffic in such a way so-called FCD test cars (Floating Car Data) with a punctual fault detection that they themselves do not experience unnecessary delay and a fault message with minimal Data effort succeeds.

In DE 100 36 364 C2 it is stated that inherent reaction times of a traffic system are significant for the traffic simulation and prognosis, whereby it is taken into account that for a traffic data prognosis a prognosis error constantly results from target / actual value comparisons and from this permissible temporal forecast horizon is determined.

The invention has for its object to provide a method and a traffic computer, with which the accuracy of the calculation of a current or future traffic condition is improved in the event of an incident.

This object is based on the aforementioned procedural ^¬ the invention ren solved according to the disturbance is taken into account in the road network in such a manner that a delay with a time delay ^¬ between an occurrence of a change and / or cancellation of the interference to reception of a corresponding information is included in the calculation for the road user. The inventor has recognized that it is important for the calculation of traffic conditions to consider that an actual traffic system has a certain inertia with respect to the responsiveness of its road users, for example 15 to 90 minutes. This is mainly due to the fact that not all road users are immediately informed about accidents or blockages and usually takes some time until the information - usually via radio or appropriate signaling devices passed - arrive at the road users. Such

Inertia often causes larger backwater effects that can spread over an environment of the accident. With the method according to the invention, a corresponding dynamic modeling of the accident is possible taking into account this inertia.

Thus, the invention goes beyond the known findings through ^¬ out. It is used not only the realization exist that inhä ^¬ pension delay times, and from this example, the necessity derived, a valid maximum Prog ^¬ nosehorizont for simulation and / or prognosis of Verkehrszu ^¬ determine object, but it is this delay when calculating even be in the simulation and / or prediction model ^¬ taken into account, for example, to increase the forecast horizon, and not only to determine the upper limit. The prognosis is improved, not only rated.

The delay can be e.g. composite out

- Delay times of measuring sensors for traffic data acquisition, and / or

- Delay times of computer software at the headquarters, and / or

- Delay times when forwarding the calculation to downstream systems and road users.

The simulated and / or predicted traffic condition be ^¬ true, for example the entire road network or subnet here- out. A network comprises at least several nodes, for example intersections or branches and / or at least several links, ie connecting roads or routes between nodes.

According to a preferred embodiment, a first time delay from the occurrence of the disturbance to the receipt of information about the occurrence of the disturbance and a second time delay from the cancellation of the disturbance to the receipt of information about the cancellation of the disturbance flows into the calculation.

The disturbance is preferably taken into account as the time course of a reduced capacity of a link. The capaci ^¬ ty, for example, expressed as the number of passable over a road or a link vehicles per unit of time.

According to a particularly preferred embodiment, a continuous first course of the capacitance is used as a time characteristic. Jumps in the capacity curve are thereby avoided because they do not correspond to the real state of knowledge of the participants - because the inertia described above is not included. In the first course of the capacitance values so do not change abruptly, but gradually descend ^¬ Lich. For example, they decrease linearly after the occurrence of the disturbance, and linearly return to the original value after the disturbance has been eliminated.

Specifically, the first curve after the occurrence, the Än ^¬ alteration or the cancellation of the interference in each case a delay time range decreases, changing and increasing capacity.

The length of the delay range and thus, for example, the slopes in the ascent or descent of the capacity may vary depending on the type of fault: In an accident, they are approximately in the range between 5 and 360 minutes, preferably in the range of 15 to 90 minutes, in the case of a construction site by ^¬ out in the range of a few days.

According to a very particularly preferred development, in the method according to the invention as a time course a sudden or faster than the first course vary ^¬ the second course of the capacity used. Preferably, the disturbance in the calculation method in two different union under ^¬ species is modeled, namely as a continuous first course and as erratic or varying rapidly ^¬ the second course.

The computing method for calculating the traffic condition comprises, according to a particularly preferred embodiment, the following computation methods communicating with one another:

a) a choice of route calculation for calculating the currently selected by road users traveling routes, and traffic data from the measured at certain points true and is assumed, and b) a traffic simulation model to calculate the zeitli ^¬ chen development of the traffic condition.

In addition to these cooperating process components, further components may be present. The traffic model can be play realized at ^¬ in the form of a microscopic or macroscopic ^¬'s traffic simulation and mapping of the dynamics of the traffic situation on the road network bewerkstel ^¬ time, for example for a short-term dynamics of a aktuel- len condition or for a longer term prognosis.

According to a very particularly preferred embodiment, the fault is taken into account in the route selection calculation with the first course. Therein lies the realization that the drivers only change their route decision once they have received the corresponding fault message. This applies not only to short-term accidents but also to a long-term The same time scale of several days also applies to the installation or abolition of construction sites. By using the first course in the choice of route calculation method, the route choice and possibly traffic assignment method can be seen as a dynamic process, because it shows dynamic effects of the accident, gently, for example, by the time delay Doomed? ^¬ backwater effects in the flow of traffic. Such a dynamic route selection calculation method leads as a result of calculation only to gradually reorienting routes, which correctly reflects the slowly increasing degree of information of the road users.

According to a further particularly preferred embodiment, the disturbance is taken into account in the traffic simulation model with the second course of the capacity. At the component

This is based on the inventor's finding that for a high-precision calculation of the traffic condition in the traffic model the physical reality, eg a closed road, is reflected immediately and without delay need, because it - in contrast to the route selection calculation method - does not depend on the degree of information of the road users.

The object mentioned above is based on the aforementioned traffic computer according to the invention, achieved by input means for inputting a time delay and / or a memory for storing predefined time delays, wherein the traffic computer is programmed such that the

Time delay (EN) for simulating a real time delay between an occurrence, a change and / or a cancellation of a disturbance in the road network until the reception of corresponding information in a road user is usable. An embodiment of a method and a traffic ^¬ computer according to the invention will be explained in more detail with reference to Figures 1 and 2. Show it:

1 shows a road network with a traffic computer for calculating a traffic condition of the road network, and FIG 2 is a schematic representation of the modeling of an incident occurred in the road network of Figure 1 accident with the method according to the invention.

FIG. 1 shows a road network 1 with several intersections or network nodes NK1, NK2, to each of which a schematically represented signaling system S1, S2 is installed. At measuring points M1, M2, M3, the traffic volume and the speed of the vehicles are measured by means of detectors. Corresponding ^¬ the detector data D are supplied leads 3 ^¬ over wired or drahtlo ^¬ se data links of a traffic management center, which, starting from this state a current traffic ^¬ and calculates its time development. As a measure for the resolution or avoidance of detected or predicted unfavorable traffic conditions, for example a traffic jam as a result of a heavily increased traffic on a link L ₁ , the traffic management center 3 intervenes via the signal systems Sl, S2 in the traffic.

For a highly accurate estimate of the traffic conditions in Stra ^¬ infra- structures already in one, according to a knowledge of the inventor, according to the proper treatment of a disorder southeast of importance. Such a disturbance S is shown in FIG. 1 by way of example on a road or a link L ₁ with index i. The information about such an accident or a disturbance S usually arrives by telephone calls of the road users or radio conversations of the police authorities to the traffic center 3, so that the disturbance S in the traffic condition calculation system 10 formed there with its traffic computer 11 can be taken into account. The traffic condition calculation system 10, in which the calculation method according to the invention is implemented, is shown in detail in FIG. It includes a Verkehrssi ^¬ simulation model 12 as well as a transport position calculation module 14, which includes, in turn, a route selection calculation module 16 and a traffic assignment module 18th

The traffic simulation model works on the principle of movement of individual vehicles, which follow macroscopic laws.

Further details and alternative embodiments are e.g. described in:

Matti Pursula, "Simulation of Traffic Systems - an Over- view", Journal of Geography Information and Decision Analysis, vol. 3, no. 1, pp. 1-8, 1999.

The traffic condition calculation system 10 estimates the current traffic situation based on a dynamic route selection and traffic assignment model. The calculation is based on the De ^¬ tektordaten D, on target functions Z (for example, system, user, optimum), Verkehrsnachfragematrizen, and to be stored in the traffic computer 11 topology data T (traffic engineering parameters) about the road network. 1

In the choice of route calculation module 16, a method is introduced ^¬ which weight assignment is based on an iteratively applied equi-. The controlling variable of the iteration process are path resistances. Downstream of the iterative method is in the traffic ^{allocation module} 18 a so-called dynamic measured value propagation, which serves to extrapolate the values of traffic intensity and speed measured at individual points in the road network 1 to the entire road network 1.

The route calculation module 16 returns the result Routenda ^¬ R th of the routes Rl, R2 (see Figure 1) on which the post- question in the road network 1 is currently being processed and their average static load. The route data R is provided to the traffic simulation model 12. This supplies data about a current traffic state V _act to the route selection calculation module 16.

Execution details and variants for route selection calculation can be found e.g. in the following literature:

Cascetta, E., Cantarella, G.E. (1993) Modeling dynamics in transportation networks: State of the Art and Future Devel- opments, Simulation Practice and Theory, Volume 1, pp. 65-91; Elsevier; Ran, B. and Boyce, D. (1996) Modeling Dynamic Transportation Networks. Springer-Verlag, Berlin;

Wie, B. -W., Friesz, T.L. and Tobin, R.L. (1990) Dynamic user optimal traffic assignment on congested multidistence networks. Transportation Research 24B, pp. 431-442;

Bell, M.G.H. (1995): Stochastic User Equilibrium Assignment in Networks with Queues. Transpn. Res.-B., Vol. 29B, No 2, pp. 125-137;

Daganzo, CF. , Sheffi, Y. (1977): On Stochastic Models of Traffic Assignment. Transportation Science, Vol. 3, pp. 253-274; Sheffi, Y. (1986): Urban Transportation Networks: Equilib ^¬ Ministry Analysis with mathematical Programming Methods. Prentice Hall.

As a result, the traffic condition calculation system 10 provides an estimate of the current traffic condition in the road network and its dynamic development on a short-term or long-term basis, that is, estimates for future traffic conditions. All traffic conditions can be displayed graphically on a display device 20 (FIG. 2) which is arranged in the traffic management center 3 (FIG. 1).

In the traffic state calculation system 10, the accident S represented in FIG. 1 is attributed to two different types of traffic. decomposed. These differ in the type of Modellie ^¬ tion of the time course of the so-called K ₁ capacity of the network links L _1, measured in the number of motor vehicles per hour, which describes the instantaneous maximum flow capacity of the link _L1. In the case of the fault S, ie in an accident, a construction site or a blockage, the capacity K _{1 is} reduced in the course over time t. The capacity K _{1 of} the link L ₁ decreases from a value of undisturbed maximum capacity K _{1 / max} to a value of reduced capacity K _{1, s} in the event of a fault S. The reduced capacity K ₁ , _s prevails at the link L ₁ from the time t _s of Occurrence of the disturbance S until the time t _{A of} the cancellation of the disturbance S. The two different types of modeling are the following:

a) In the route selection calculation module 16, the accident S is modeled with a first curve 22 of the capacitance K ₁ , which has a gradual transition from the maximum capacity K _{1 / max} to the reduced capacity K _{1, s} in the event of a fault and vice versa. The modeled capacity K ₁ follows the actual capacity K ₁ with a first Zeitverzöge ^¬ tion Δti after the instant t _s of occurrence of the fault S and with a second time delay At ₂ after the time t _A of the cancellation of the disturbance S. This the only reflects slowly increasing level of information among road users after the occurrence or elimination of a disturbance. The route selection calculation module 16 thus calculates only dynamically reoriented routes R ₁ , R ₂ .

b) In the traffic simulation model 12, which is intended to map the actual dynamics of the traffic in the network, the course of the capacity K ₁ over the time t is modeled without delays with a step-shaped and erratic second course 24. The second course of 24 spat ^¬ gelt the actual capacity of the course again.

Instead of the linear ramps shown in the first curve 22 in FIG. 2 in the region of the time delays Δti, At ₂ Smooth or continuously differentiable curves are also possible. In a very short fault S, it is also possible that in the first course 22, the capacity K _{1 ^ 3 is} not reached in case of failure, and / or results in the case of linear course, for example, a V-shaped profile.

Essential to the invention is the special treatment of the time course of the capacity K _{1 of} the disturbed link L ₁ in the road network 1 with regard to their use in dynamic see route selection and traffic transfer method. To the

To simulate inertia of the real system, so the road users, the capacitance values concerned are not sudden, but gradually changed so that the calculation ^¬ Neten route changes first minimal and are later herein. These slow changes are applied both to the initial reduction of the capacity K ₁ and to the later restoration of the capacity K ₁ .

When the message on the incident S in the traffic management center 3 is received, the interference S is periodic computer in the local Ver ^¬ 11 summarizes the local operator in accordance ER. For this purpose, the operators use corresponding entranc ^¬ bemittel IIB (see Figure 1) is available, for example, a specially programmed input mask with input fields for entering the time delays Δti, At. ₂ Alternatively or additionally, the operator thereby on the input mask in a memory IIA (Figure 1) stored experience for different types of accident (light accident, severe accident, small construction site, large construction site, fallen tree, water pipe break, etc.), for example in the form of a PuIl - Down menus, offered. Alternatively, only the type of fault is entered and the traffic computer 11 gets corresponding empirical values from the memory IIA.

Claims

claims

1. A method for calculating an estimate of the plurality of links and / or multiple traffic nodes comprising current traffic condition and / or a prognosis of a multiple links and / or multiple traffic nodes comprehensive future traffic condition in a road network (1), wherein the Be ^¬ bill a Disturbance (S) in the road network (1) is taken into account such that a time delay between a occurrence, a change and / or a cancellation of the disturbance (S) until receipt of a corresponding information flows to the road user.

2. The method of claim 1, wherein a first time delay (.DELTA.ti) from the occurrence of the disturbance (S) to the receipt of information about the occurrence of the disturbance (S) and a second time delay (At ₂ ) of the cancellation of the disturbance (S) until receipt of information about the cancellation of the fault (S) flows.

3. The method of claim 1 or 2, wherein the disturbance (S) as a time course (22, 24) of a reduced capacity (K ₁ ) of a link (L ₁ ) is taken into account.

4. The method of claim 3, wherein as a time course, a continuous first curve (22) of the capacitance (K ₁ ) is used.

5. The method of claim 4, wherein the first course after the occurrence, the change or the cancellation of the disturbance (S) each have a delay time ^{¬ range} (.DELTA.ti, At ₂ ) with decreasing, changing or increasing capacity (K ₁ ) having.

6. The method of claim 5, wherein the delay region (Δti, At ₂ ) is a length from the

Range between 5 minutes and a few days.

7. The method of claim 3, wherein as a time course, a sudden or faster than the first course (22) varying second curve (24) of the capacitance (K ₁ ) is used.

8. The method according to any one of claims 1 to 7, wherein the following ^{miteinan ¬} the communicating computational methods are used for calculating the traffic condition: a) a route selection calculation (16) for calculating the currently selected by the road users driving routes (Rl, R2), wherein of the at certain measuring points

(Ml, M2, M3, ...) measured actual traffic data being ^¬ is expected, and b) a traffic simulation model (12) for calculating the temporal evolution of the traffic condition.

9. The method of claim 8 and claim 4, 5 or 6, wherein the disturbance (S) in the route selection calculation (16) with the first curve (22) of the capacity (K ₁ ) is taken into account.

10. The method of claim 8 or 9 and claim 7, wherein the interference (S) in the traffic simulation model (12) with the second course (24) of the capacity (K ₁ ) is taken into account ^¬ tigt.

11. traffic computer (11) for a traffic management center (3) for calculating a plurality of links and / or multiple Ver ^¬ periodic knot comprehensive current or future Verkehrszu ^¬ article in a road network (1) with input means (IIB) for inputting a time delay (Δti, At ₂ ) and / or with a memory (IIA) for storing predefined time delays (.DELTA.ti, .DELTA.t ₂ ), wherein the traffic computer (11) such program- is that the time delay (s) (Δti, At ₂ ) for after ^¬ formation of a real time delay between an occurrence, a change and / or cancellation of a fault (S) in the road network (1) until receiving a corresponding information at a road user is usable.