JP2015228081A - Travel time estimation system and travel time estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate estimated travel time in respective zones easily, based on shortest travel time and occupancy.SOLUTION: A traffic signal control system estimates estimated travel time T from an A point on an upstream side of a road to a B point on a downstream side of the road, and displays the estimated travel time T which has been estimated on an information plate 10 installed in the vicinity of the A point being the uppermost point. Vehicle detectors 21-23 disposed on small zones D1-D3 respectively, are connected to a travel time estimation device 30 in a traffic management center C by wired connection or wireless connection. The travel time estimation device 30 calculates occupancy X in each small zone Dn and small zone estimated travel time Tn based on vehicle detection information inputted from the vehicle detectors 21-23. In calculation of the small zone estimated travel time Tn, the occupancy X of the vehicle detector in the small zone Dn is used as a variable in estimation processing, and a travel time estimation formula in which a sigmoid function is applied to the occupancy X, is used.

Description

  The present invention relates to a travel time estimation system and a travel time estimation method for estimating a travel time between an upstream point and a downstream point on a road on which a vehicle travels.

  Patent Document 1 discloses a travel time providing device that calculates travel time based on data obtained from a vehicle sensor. In Patent Document 1, a vehicle detector is provided for each link formed by dividing a predetermined upstream point on a road and a predetermined downstream point far from the upstream point into a predetermined link length. The vehicle speed is calculated using the traffic volume Q obtained from the vehicle detector and the road occupation ratio X.

  By dividing the link length (Li) by the calculated speed, the travel time Ti for each link is obtained, and the travel time Ti for each of these links is totaled to obtain the provided travel time (T) between the upstream point and the downstream point. presume. The provided travel time (T) estimation process is updated every predetermined time, and the provided travel time (T) estimated for the driver is displayed on an information board installed near the upstream point as needed.

JP-A-9-35175

  In this conventional travel time calculation method, the provided travel time (T) increases in proportion to the increase in the occupation ratio X. However, in the road conditions from the time when it is actually quiet to the time when the vehicle runs continuously, the provided travel time (T) is second-order while the occupation ratio X is increased linearly. It is known to increase functionally and exponentially. Furthermore, in a road situation from a certain level of congestion to a traffic congestion state in which stop and start are alternately repeated, the provided travel time ( Conversely, T) increases logarithmically.

  Accordingly, there is no error between the provided travel time (T) and the actual travel time when it is quiet. However, there is an error between the travel time provided (T) calculated by the conventional calculation formula and the actual travel time between the time when the road condition is quiet and the time of congestion and from the time of congestion to the time of congestion. There's a problem.

  Further, even if the traveling vehicle V is in a traffic situation such as a traffic jam where the stop and start are alternately repeated, the occupancy X is about 30% when viewed from the entire traveling section, and the vehicle after the occurrence of a traffic accident or the like. Occupancy rate X is a value exceeding 30% in the case of an extreme traffic jam that stops traveling.

  In the occupancy ratio X calculated based on the vehicle detection information from the vehicle detector, a value that the occupancy ratio X temporarily exceeds 30% may be measured. In this case, the road condition at the time of the above extreme congestion Is almost not applicable, and most of the times are in traffic jams where stop and start are repeated alternately. Since the vehicle detector measures the occupancy rate X at a pinpoint on the road, the occupancy rate X is temporarily measured to exceed 30% when the vehicle stops continuously under the vehicle detector. This is because there are cases.

  In the conventional formula for calculating the travel time (T), if the occupancy rate X temporarily exceeds 30% in spite of a traffic jam where the stop and the start are alternately repeated, the travel rate provided using this occupancy rate X is used. Since the time (T) is presented, a numerical value far from the actual travel time is displayed on the information board, which causes a complaint from the driver.

  Further, depending on the installation location of the vehicle detector, it may be necessary to set a weighting factor for the occupation ratio X. For example, in a vehicle detector installed at a place where an intersection exists behind, the occupation ratio X is calculated to be higher than the actual occupation ratio of the entire section due to the influence of the intersection. In such a case, the occupancy rate X is corrected by multiplying the occupancy rate X by a weighting factor in order to approach the true value. This weighting factor is set based on the experience of a professional engineer.

  An object of the present invention is to solve the above-described problems and provide a travel time estimation system and a travel time estimation method for estimating an accurate travel time based on a road occupation ratio.

  In order to achieve the above object, a travel time estimation system according to the present invention calculates a road occupancy rate from vehicle detection information of a vehicle detector installed in a predetermined section on a road and applies a sigmoid function to the occupancy rate. A travel time estimation system for calculating an estimated travel time of the predetermined section by multiplying the output value by a set value consisting of a minimum travel time and a weighting factor of the predetermined section, and equipped with a narrow area communication terminal The set value is corrected using a link travel time obtained from a travel history of the vehicle.

  The travel time estimation method according to the present invention includes a step of calculating a road occupancy rate from vehicle detection information of a vehicle detector installed in a predetermined section on the road, and an output value obtained by applying a sigmoid function to the occupancy rate In contrast, a travel time estimation method comprising a step of calculating an estimated travel time of the predetermined section by multiplying a set value consisting of a minimum travel time and a weighting factor of the predetermined section, and is equipped with a narrow area communication terminal The step of correcting the set value using a link travel time obtained from a travel history of the vehicle is characterized.

  According to the travel time estimation system and the travel time estimation method according to the present invention, the accurate estimated travel time of each section can be calculated based on the shortest travel time and the road occupation rate.

  In addition, the weighting factor used to calculate the estimated travel time can be corrected and set using the accumulated link travel time, so that it is not necessary to set the weighting factor based on the experience of a professional engineer as in the past, A weighting factor can be easily set.

It is a system block diagram of an Example. It is a signal waveform diagram of vehicle detection of a vehicle detector. It is a graph showing the output of the sigmoid function with respect to an occupation rate. It is a flowchart figure which sets minimum travel time and a weighting coefficient. It is explanatory drawing of the small area between A point-B point, a link area, and travel time.

The present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 is a system block diagram of the embodiment. The travel time estimation system estimates the estimated travel time T of the section from the point A on the upstream side of the road to the point B on the downstream side, and estimates it on the information board 10 installed in the vicinity of the point A, which is the most upstream point in this section. The estimated travel time Tm is displayed.

  The information board 10 is a large display board such as an LED type or a liquid crystal type, and is installed above the road. For example, the information board 10 outputs and displays “to the point B ** minutes”. The driver of the traveling vehicle V can recognize the characters even from a distance, and can know the approximate arrival time at the point B.

  The section from point A to point B is divided into a plurality of small sections, and one or more vehicle detectors 20 are arranged in the small sections. In the example of FIG. 1, the small section is divided into three sections D1 to D3, and the boundaries of the small sections D1 to D3 are intersections. Further, the small sections D1 to D3 may be divided and set at the same distance interval, or may be set by distributing an appropriate distance according to the road environment.

  In addition, even if the intersection which has a traffic signal is arrange | positioned in the middle of the road in the small sections D1-D3, there is no trouble in the calculation process of the small section estimated travel time Tn mentioned later. Further, since the accuracy of estimating the small section estimated travel time Tn is improved by further subdividing the small sections D1 to D3 and arranging a large number of vehicle detectors 20, the estimation is the sum of the plurality of small section estimated travel times Tn. The travel time Tm approaches the true value.

  The vehicle detectors 21 to 23 arranged in the small sections D1 to D3 are connected to the travel time estimation device 30 in the traffic control center C by wire or wireless. The travel time estimation device 30 receives vehicle detection information from the vehicle detectors 21 to 23 in real time and accumulates them in a storage unit or the like. Based on the vehicle sensing information, the occupation ratio X and the small section estimated travel time Tn are calculated.

  The place where the information board 10 is installed is a main trunk road, and a narrow-area communication device 40 that performs narrow-area communication by radio communication or optical communication with a specific vehicle Vt described later is installed on such a main road. . Each narrow area communication device 40 is connected to a traffic information device 50 in the traffic control center C by radio or wire.

  The narrow area communication device 40 is usually arranged several tens of meters before the approach of the intersection. In the example of FIG. 1, two narrow area communication devices 41 to 46 are arranged for one small section Dn. Link sections L1 to L6 are set between the intersections of these narrow area communication apparatuses 41 to 46.

  The specific vehicle Vt that can receive the traffic information providing service from the narrow area communication device 40 is not widely spread, and the ratio of traveling is smaller than the entire traveling vehicle V. The vehicle Vt is equipped with a narrow area communication terminal and performs two-way wireless communication between the narrow area communication devices 40. The vehicle information including the vehicle ID and the like is transmitted from the vehicle Vt entering the narrow area communication area to the traffic information apparatus 50 via the narrow area communication apparatus 40, and the traffic information such as the traffic jam link information is narrowed from the traffic information apparatus 50. It transmits to the vehicle Vt via the communication device 40.

  From the travel history of the vehicle Vt obtained by the continuous narrow area communication device 40, that is, the difference in the reception time of the vehicle ID information at the narrow area communication device 40, the link travel time t required for passing between the narrow area communication devices is calculated. Can be calculated. For example, the link travel time t2 of the link section L2 can be obtained in the traffic information device 50 from the reception time of the fixed vehicle ID information of the narrow area communication devices 41 and 42.

  The travel time estimation device 30 and the traffic information device 50 in the traffic control center C are connected, and various data such as the link travel time t can be exchanged between the travel time estimation device 30 and the traffic information device 50. it can. Further, the estimated travel time Tm calculated by the travel time estimation device 30 can be transmitted as traffic information from the traffic information device 50 to the vehicle Vt via the narrow area communication device 40.

  The vehicle detector 20 is an ultrasonic vehicle detector or the like that detects the traveling vehicle V by using the reflection of ultrasonic waves. From the head portion of the vehicle detector 20 installed above the road, the vehicle detector 20 moves toward the road. Sound waves can be emitted, and the presence or absence of a vehicle on the main road can be determined from the response time of the reflected wave from the road surface.

  When the response time of the reflected wave is equal to or greater than a predetermined value, no detection is made that the traveling vehicle V is not present under the vehicle detector 20, and when the response time is equal to or less than the predetermined value, the traveling vehicle V is located under the vehicle detector 20. By detecting the presence, the detection of the traveling vehicle V can be displayed as a waveform diagram of on / off information with time on the horizontal axis as shown in FIG.

  Based on the on / off information obtained from the vehicle detection information from the vehicle detector 20, the ratio of the total time of the on information T11 to T14 per predetermined time K is the occupation ratio X. This occupancy rate X is updated every predetermined time K, which is an interval of several minutes. Generally, when the traveling speed of the traveling vehicle V decreases, the occupancy rate X increases, and the actual travel time increases as the occupancy rate X increases. To do.

  In FIG. 1, the occupation ratio X from one vehicle detector is calculated for each small section Dn. However, when a plurality of vehicle sensors 20 are included in the small section Dn, The occupation ratio X of the small section Dn is calculated based on the average value of the occupation ratio X and the ratio of the occupation ratio X of each vehicle detector 20. Further, in the case of a road having a plurality of lanes, a head portion is installed for each lane. In this case as well, the occupation ratio X is calculated by setting an average value and a ratio ratio for each head portion. .

For calculating the small section estimated travel time Tn of the small section Dn, the following travel time estimation formula using the occupation ratio X of the vehicle detector 20 in the small section Dn as a variable and applying a sigmoid function to the occupation ratio X is used. .
r = 1 / [1 + exp {(15−X) /2.5}] (1)
Tn = a + a × b × r (2)

  Where Tn: small section estimated travel time (seconds), X: small section Dn occupancy (%), a: minimum section Dn travel time (seconds), b: small section Dn weighting factor.

  The sigmoid function is known as a function that represents the input / output of a neural network model and the effect of medication on the dose of medicine, and becomes an S-shaped curve in coordinates as shown in FIG. The left and right curves centering on the inflection point g at the center of this curve are point objects.

  FIG. 3 is a graph of a sigmoid function that represents the relationship between r and occupancy ratio X in equation (1). When the occupancy ratio X is greater than a certain value, a value close to 1 is output. If it is small, a value close to 0 is output.

  As described above, even if the traveling vehicle V is an extremely heavy traffic jam that repeatedly stops and starts, the occupancy rate X is maintained at about 30%, and the actual occupancy rate X is actually increased until the road becomes congested. The travel time increases exponentially, and the actual travel time increases logarithmically with respect to the occupation ratio X from the congestion situation. When this increase phenomenon is graphed, it approximates to a curve of a sigmoid function. Therefore, it is possible to estimate a travel time close to a true value by using the sigmoid function in a travel time estimation formula.

  In order to set the occupancy ratio X to 30%, which is the convergence value of the sigmoid function, as well as the congestion situation g of the occupancy ratio X of about 15% to the inflection point g of the sigmoid function, The value of is set. Moreover, about 2.5 of the denominator of Formula (1), it shows the steepness of the S-shaped graph characteristic of FIG. 3, and an appropriate value can be adopted.

  The minimum travel time a and the weighting factor b in Expression (2) need to be defined for each small section Dn. In collecting the small section estimated travel time Tn from the small section Dn, first, the default values are set to the minimum travel time a and the weighting factor b, and the correction is made using the link travel time t stored in the traffic information device 50. Do. Note that the default value of the minimum travel time a is set based on the distance and the average speed, and the default value of the weighting factor b is set to 2.

  Since vehicles Vt equipped with narrow area communication terminals are not widely used at present, on the main roads in the suburbs, etc., except for the time zone when the traffic volume at the time of commuting rush is high with respect to the estimated travel time Tm updated as needed Then, the sample number of the link travel time t cannot be collected sufficiently. Therefore, in many cases, it cannot be used as information on the estimated travel time Tm to be provided to the information board 10.

  However, by using the past link travel time t accumulated in the traffic information device 50, it is possible to correct the minimum travel time a and the weighting factor b. The travel time estimation device 30 connected to the traffic information device 50 in the traffic control center C corrects the minimum travel time a and the weighting factor b in Expression (2).

  FIG. 4 is a flowchart for correcting the minimum travel time a and the weighting factor b in the small section Dn. The link travel time t in the small section Dn from the traffic information device 50 is used. Since the minimum travel time a and the weighting factor b change greatly due to the installation of a new intersection or the opening of a road, it is necessary to periodically correct the minimum travel time a and the weighting factor b.

  In steps S <b> 1 to S <b> 3, processing related to the correction processing for the minimum travel time a is performed. In the first step S 1, the traveling vehicle V is the most in the day within the minimum travel time a of the small section Dn set in the travel time estimation device 30 in advance and the past link travel time t stored in the traffic information device 50. Compared with the actual travel time tn corresponding to the small section Dn in the quiet time, which is a small time zone, for example, at night or in the morning time zone.

  FIG. 5 is an explanatory diagram showing the relationship between the small section Dn and the link section Ln and the relationship of the travel time for each section with respect to the system block diagram of the points A to B in FIG. Taking the small section D1 shown in FIG. 5 as an example, the minimum travel time a1 of the small section D1 and the link travel time t1 of the link section L1 and the link travel time t2 of the link section L2 collected in the past in step S1. The total measured travel time t12 is compared.

  Since the occupation ratio X is almost 0% in a quiet time, r in equation (1) is 0, and the small section estimated travel time T1 in equation (2) is equal to the minimum travel time a1. Moreover, the average value of the link travel time t1 and t2 collected between 3:00 and 4 o'clock in the middle of the night for several days, etc. are utilized for the measured value of the link sections L1 and L2 at the off time.

  In the next step S2, it is determined whether or not the difference between the minimum travel time a1 and the actually measured travel time t12 of the link sections L1 and L2 is within a predetermined range. If it is within the predetermined range, for example, within ± 5%, the set value of the set minimum travel time a1 is assumed to be appropriate, and the process proceeds to step S4. When the difference between the minimum travel time a1 and the actual travel time t12 is outside the predetermined range, the process proceeds to step S3, and after correcting the value of the minimum travel time a1 with the value of the actual travel time t12, the process proceeds to step S4.

  Next, in steps S4 to S6, the weighting factor b is corrected. In step S4, the link travel time t in the time zone in which the traveling vehicle V is large in one day is used. And, for example, the small section estimated travel time T1 of the equation (2) in which the occupation rate X collected by the vehicle detector 21 near 8:00 am in the commuting rush of the small section D1 and the link section L1 in the same time zone, The actual travel time t12 obtained by adding the link travel times t1 and t2 of L2 is compared.

  Next, in step S5, it is determined whether or not the difference between the small section estimated travel time T1 and the actually measured travel time t12 is within a predetermined range. If it is within the predetermined range, for example, within ± 5%, it is determined that the set value of the set weight coefficient b is appropriate, and the correction process is terminated. If the difference between the small section estimated travel time T1 and the actually measured travel time t12 is outside the predetermined range, the process proceeds to step S6, and the weighting factor b is corrected so that the small section estimated travel time T1 becomes the same value as the actually measured travel time t12. The correction process is finished later.

  The correction process of the flowchart shown in FIG. 4 needs to be performed for each small section Dn. For example, in the system diagram shown in FIG. 1, the minimum travel times a1 to a3 and the weighting factors b1 to b3 are added to the calculation formulas of the small section estimated travel times T1 to T3 in the formula (2) of each of the small sections D1 to D3. Set and input the values of the occupation ratios X1 to X3 collected by the vehicle detectors 21 to 23 into the formulas (1) and (2), and calculate the small section estimated travel times T1 to T3 of the small sections D1 to D3. presume.

  Then, the estimated travel time Tm, which is the total value of the small section estimated travel times T1 to T3, is transmitted to the information board 10, and the time required from point A to point B is displayed. In the present embodiment, a description has been given using a plurality of small sections D, but the small section D may be only one section.

  In this embodiment, after correcting the minimum travel time a and the weighting factor b based on the flowchart shown in FIG. 4, the estimated travel time Tm from the point A to the point B is determined only by the occupation ratio X from the vehicle detectors 21 to 23. Can be estimated.

  Further, even when the occupation ratio X is calculated to be 30% or more, the small section estimated travel time Tn in which the occupation ratio X indicating the traffic congestion where the traveling vehicle V repeats stopping and starting is 30% is calculated. Accordingly, the difference from the actual travel time is smaller than the estimated travel time Tm when the occupation rate exceeds 30% according to the conventional estimation formula.

  Conventionally, the setting of the weighting factor b has been set by the experience of a specialist engineer. However, in this embodiment, the optimum weighting factor b is set even by an unskilled person by using the accumulated link travel time t. It becomes possible to do.

DESCRIPTION OF SYMBOLS 10 Information board 20-23 Vehicle detector 30 Travel time estimation apparatus 40-46 Narrow area communication apparatus 50 Traffic information apparatus

Claims (8)

A road occupancy ratio is calculated from vehicle detection information of a vehicle detector installed in a predetermined section on the road, and a minimum travel time and a weighting coefficient of the predetermined section are output for an output value obtained by applying a sigmoid function to the occupancy ratio. A travel time estimation system for calculating an estimated travel time of the predetermined section by multiplying a set value consisting of:
A travel time estimation system, wherein the set value is corrected using a link travel time obtained from a travel history of a vehicle equipped with a narrow area communication terminal.   The travel time estimation system according to claim 1, wherein the set value of the minimum travel time is corrected using the link travel time in a time zone in which the vehicle travels less.   The travel time estimation system according to claim 1 or 2, wherein the set value of the weighting factor is corrected using the link travel time in a time zone in which the vehicle travels frequently.   The total estimated travel time obtained by summing up the estimated travel time of one or a plurality of predetermined sections is output and displayed on an information board installed at the most upstream point of the one or more predetermined sections. The travel time estimation system according to any one of the preceding claims. Calculating a road occupancy rate from vehicle detection information of a vehicle detector installed in a predetermined section on the road; and for an output value obtained by applying a sigmoid function to the occupancy ratio, a minimum travel time of the predetermined section and A travel time estimation method comprising: multiplying a set value consisting of a weighting factor to calculate an estimated travel time of the predetermined section,
A travel time estimation method comprising the step of correcting the set value using a link travel time obtained from a travel history of a vehicle equipped with a narrow area communication terminal.   6. The travel time estimation method according to claim 5, further comprising a step of correcting a set value of the minimum travel time using the link travel time in a time zone in which the vehicle travels less.   The travel time estimation method according to claim 5, further comprising a step of correcting the set value of the weighting factor using the link travel time in a time zone in which the vehicle travels frequently.   6. A step of outputting and displaying a total estimated travel time obtained by summing up estimated travel times of one or a plurality of predetermined sections on an information board installed at the most upstream point of the one or more predetermined sections. The travel time estimation method according to any one of? 7.

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