JP2875520B2 - Traffic flow simulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traffic flow simulator, and more particularly to a traffic flow simulator with a reduced amount of calculation for a traffic network.

[0002]

2. Description of the Related Art It is possible to quantitatively evaluate the effect of introducing measures when modifying or newly constructing roads and traffic facilities for the purpose of eliminating traffic congestion and smoothing traffic,
There is a need for a traffic simulation system that can support planning. In the planning of facilities for regional development and revitalization, such as parking lots, station square maintenance and redevelopment projects, and distribution centers, and facilities for improving the local environment, such as Incineration plants and waste disposal sites, Evaluation by traffic simulation is becoming indispensable in order to minimize the load on surrounding roads and the environment while guiding traffic smoothly.

A traffic flow simulation system is roughly classified into a micro simulation system and a macro simulation system, but each has conflicting features and problems. In other words, the micro-simulation system has the advantage of modeling that a discrete vehicle follows the running, making it easy to implement route selection and traffic regulation. However, the calculation amount is large, so a large-scale network model is constructed. And it is difficult to adjust the parameters of the behavior of the vehicle to match the link capacity.

[0004] On the other hand, the macro simulation system treats traffic as an approximation of a continuous fluid, and thus can perform a simulation based on link capacity. However, it is generally difficult to select a route of a vehicle or express traffic regulation. There is a problem with the simulation accuracy.

The applicant of the present application has developed a traffic flow simulator based on a hybrid block density method which is an improvement of a block density method simulation system which is a typical example of a macro simulation system (Japanese Patent Application No. Hei 7-300969).
No.). Reproduction of traffic flow in the conventional block density method is performed by calculating the amount of movement between blocks from the set traffic volume-density curve and the possible outflow and inflow of vehicles in each block, and revising the vehicle density in the block. According to the hybrid block density method, each block in a link is divided into lanes to make blocks in lanes into multiple inputs and multiple outputs, and at the same time, attributes such as traffic regulation information are given to each block to move traffic. The simulation is performed by selectively moving the number of individual vehicles according to the amount based on the traffic regulation information.

[0006] This makes it possible to express the influence of various traffic regulations such as the regulation of the traveling direction of the lane, the bus lane, and the displacement of the Chuo Line on the overall traffic, and to improve the simulation accuracy and versatility in the street network. Have achieved.

In the above hybrid block density method (hereinafter referred to as HBDM), a link is divided into blocks at a fixed distance. This distance is set equal to the distance that the vehicle on the link moves at the free running speed during the unit scan interval, and is usually a block having a length of 10 to 20 m with the scan interval being one second.

By the way, in HBDM, the amount of calculation is proportional to the number of blocks. Therefore, when the total link length of the network to be simulated becomes longer, the amount of calculation increases, and a large amount of time is required for the simulation, thereby limiting the size of the network. On the other hand, if the scan interval is lengthened and the link is divided into longer blocks, the amount of calculation is reduced, but in the section controlled by the signal, the length of the scan interval increases the difference between the calculation result and reality. There are reciprocal problems.

Therefore, in the HBDM, it is possible to reduce the calculation amount of the traffic volume while securing the reproducibility of the traffic flow at the signalized intersection, to improve the simulation speed, and to simulate a larger-scale road network model. Technical problems to be solved arise to provide a traffic flow simulator, and an object of the present invention is to solve the above problems.

[0010]

SUMMARY OF THE INVENTION The present invention proposes to achieve the above object, and a hybrid road model having an arbitrary number of lanes and a road network shape by connecting a plurality of links as a road model. Can be constructed, the link is divided into blocks of a certain length, each block is provided with an attribute that describes a route restriction, a vehicle type restriction, etc., and a vehicle model, a vehicle type, a traveling direction, a destination, a passenger vehicle conversion coefficient, etc. Is provided, and the vehicle outflow and inflow possible amounts of each block are calculated and calculated according to the vehicle density of each block and the preset traffic-density curve for each unit scan interval. Based on the outflowable amount and the inflowable amount, the block attribute and the vehicle attribute, from one or more upstream blocks adjacent to the own block,
When the link is divided into blocks in a traffic flow simulator based on the hybrid block density method in which only a vehicle satisfying the vehicle outflow possible amount and the inflowable amount and the block attributes and the vehicle attributes is selectively moved to express a traffic flow. In addition, a block of the unit scan interval is arranged at the most downstream of the link, a scan interval of an integral multiple of the downstream block is given to each of the upstream blocks, and each block is assigned a scan interval assigned to each block and a link assigned to the link. Processing function of dividing the link as a length determined from the free running speed of the vehicle and adjusting the number of blocks of each length so that the sum of the lengths of all the blocks is equal to the length of the link Is provided.

In the above traffic flow simulator,
At the connection between the most downstream block of the upstream link and the most upstream block of the downstream link, the block density revision is calculated for each scan interval of the downstream link of the upstream link, and the calculated traffic volume is calculated based on the upstream link. A processing function is provided for moving the most upstream block of the downstream link from the most downstream block to the most upstream block of the downstream link, and changing the vehicle inflowable amount of the most upstream block of the downstream link to a value obtained by subtracting the movement amount from an original value. It is intended to provide a traffic flow simulator characterized in that:

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

1. 1 shows a system configuration of a traffic flow simulator. A computer 1 executes a simulation process by an expert system 2. Expert system 2
Is constituted by an interface 3, a knowledge database 4, an inference mechanism 5, and a working memory 6, and stores a multi-scan hybrid block density method simulation program of variable block length / multi-scan interval.

All components of the traffic network are modeled and stored as objects, and the objects are all displayed as icons on the screen of the CRT 9 by operating the keyboard 7 and the pointing device 8. By inputting road network data, signal control parameters, OD (departure / destination) traffic volume and the like in accordance with the menu, a road network model in which desired objects are developed on a screen as shown in FIG. 2 is constructed. be able to.

The simulation results can also be displayed on the screen as a graph, as well as travel time, traffic congestion length,
External storage device 1 stores data such as passing traffic volume at regular intervals.
Write to file 0.

FIG. 3 shows the basic class structure of an object. A link 11 corresponds to a road portion, and is a directed branch connecting the nodes 12. Geometric attributes such as length and lane configuration, capacity attributes such as traffic capacity and saturation density, and direction display attributes for storing information for route selection are defined.
4

The node 12 corresponds to an intersection or an end point of the network when the road network is represented by a graph, and is connected to the link 11 to form a road network. The subclasses of the nodes 12 include an OD node (departure point / destination node) 15 which is an end point of a network where traffic flows occur and concentrate, and a signal intersection node 16 controlled by a signal.

The block 13 corresponds to one section when the road is divided into sections, and has a length of an integral multiple (including an equal size) of a unit length determined from the free running speed of the vehicle on the link and the scan interval. That's it. The block 13 itself has a relationship with blocks adjacent upstream and downstream, and has a relationship with vehicles existing in the block 13. The block density is calculated by using these relationships, and the vehicle is moved.

The block 13 has an attribute that describes a route restriction, a vehicle type restriction and the like, and can constitute a multi-input multi-output hybrid block in which a plurality of lanes are arranged in parallel. In block 13, a prototype of a routine for selectively moving a vehicle from the upstream block is defined, and the behavior of changing lanes from the upstream block to the downstream block can be incorporated into the model.

The subclass of the block 13 includes a control block 17 corresponding to a section in which the traffic flow is controlled by the display of the traffic light, and a section in which the traffic flow is restricted in accordance with traffic rules such as regulation of the traveling direction set in the lane. There is a block 18 with lane regulation corresponding to.

The lane 14 has various traffic regulation attributes such as a traveling direction regulation and a bus-only regulation, and has a relationship with a lane regulation block 18 to be regulated.

The traffic controller 19 has a function of stopping, starting, or decelerating traffic depending on its own state, and has a relationship with the control block 17 to be controlled. In the sub-class of the traffic controller 19, there is a signal light 20.
Displays the signal status of blue, yellow and red.

The signal controller 21 controls the display of the signal lamp 20 in each direction in accordance with the set cycle, split, offset time, and the present state, and controls the signal intersection node 16 to be controlled and the signal lamp 20 in each direction. Having.

The vehicle 22 moves on the block 13 to calculate speed and acceleration, select a route, change a traveling direction, and the like. Attributes such as a vehicle type, a passenger vehicle conversion coefficient, and the presence or absence of an in-vehicle information terminal are defined. The subclass includes various vehicles having different behaviors such as a passenger vehicle 23, a truck 24, and a bus 25.

Since the basic class for modeling is defined as an object, it is possible to add various traffic control systems and traffic regulation functions by adding or changing the minimum functions. it can. For example, when incorporating a bus-only lane, block 1 with lane regulation
As a subclass of 8, a class of a block that moves only a bus from an upstream block may be additionally defined.

By describing the restriction on the traveling direction in the block 13, only vehicles satisfying the restriction of the own block are selected and moved from a plurality of adjacent upstream blocks when the vehicle moves. .

In the example of FIG. 4, the restriction on the direction of travel imposed on each block is indicated by an arrow, and among the vehicles in block A, those turning left are in block B and those turning right are in C. Only the vehicle can move, and the straight-ahead vehicle can move to both B and C. In addition, since the right-turning vehicle among the vehicles in D is set so as not to go straight and move to E, the right-turn lane F is always moved at the next scan.

[0027] Further, a vehicle to which the block of the lane corresponding to the traveling direction of the downstream intersection is suitable is obtained, and the lane is changed as necessary. For example, as shown in FIG. 5, when a right-turning vehicle is stagnant in a block B in the straight traveling direction of the block A due to the influence of the signal, if the block A is related to the diagonally forward block C, the block A Can change lanes to block C. On the other hand, the block C is also associated with the block D obliquely forward because the straight traveling direction is blocked, but the left turn vehicle in the block C does not satisfy the restrictions of the block D and does not change lanes.

The most downstream block reaching the signalized intersection is constituted by a control block 17 which is restricted by a signal, and is connected to the most upstream block of the downstream link connected to the intersection. Each control block 17 changes the outflowable amount according to the indication of the signal light concerned. In addition, for right-turn traffic, the vehicle is moved in consideration of the clearance and gap at the turn of the present.

The control block 17 refers to the signal light 20 corresponding to the own block, and is associated with the most upstream block of the left turn link and the most upstream block of the straight ahead link. When the signal light turns blue, the block can drain the vehicle.The most upstream block at the left turn selects the left-turning vehicle, and the most upstream block at the straight ahead selects and moves the straight-ahead vehicle. Each vehicle enters the appropriate link. When the current indication is red, the possible outflow amount of the own block is 0, and the vehicle does not move.

The simulation program is configured to execute a route search at an arbitrary time interval set in advance, and changes a destination direction display attribute of each link object. When the vehicle enters the link, the vehicle determines the next link to enter by referring to the destination display attribute of the link. The travel time of the link is expressed as a function of the traffic volume of the link, and the difference between the simulated travel time value and the value of the function is given as a penalty for each of right and left turns and straight traffic. Then, each vehicle is distributed to the shortest route obtained based on this information.

2. Decision of block length and link division The accuracy of reproduction and prediction of the entire target network by traffic simulation depends on the reproduction and prediction accuracy of traffic flow of a supersaturated link. Conversely, it can be said that the effect of reproduction / prediction accuracy on the links around the network where the number of vehicles is small and the traffic volume is small has little effect on the reproduction / prediction accuracy of the entire network.

Therefore, the downstream block of the link that requires the accuracy of traffic flow reproduction has a small scan interval,
If the scan interval is increased in the other upstream blocks that do not require much accuracy, the calculation amount can be reduced while maintaining the reproducibility of the entire network.

In view of the above, the traffic flow simulator of the present invention is configured such that a scan interval is individually set for each block by an algorithm of link division. The scan interval of a block is a time interval during which the block is subjected to traffic volume calculation. According to the definition of HBDM, the length of the block is the distance that the vehicle on the link travels at the free running speed within the scan interval. Is taken equal to Therefore, each block will have a length proportional to its scan interval.

When dividing a link into blocks, the scan interval of each block is first determined. That is, the scan interval is set to a minimum of, for example, 1 second in consideration of the control by the signal at the lowest block of the link. ) Is set to have a scan interval.

At this time, the number of blocks is adjusted so that the total length of the blocks is equal to the length of the link. In consideration of practicality, the maximum scan interval, that is, the maximum value of the length of one block can be specified by the user. An algorithm for determining the block scan interval from the downstream side when dividing a link will be described below.

1) Algorithm of link division (recursive definition) Explanation of variables L: = link length dT: = scan interval of block n: = radix of block division (integer of 2 or more) MaxdT: = maximum scan interval (user) ScanList: = List in which scan intervals of blocks are stored Main Procedure call Sub Proc1 (L, MaxdT, ScanList, 1); Sort elements of ScanList from the smallest one; Loop1: ScanList of each block i from link downstream End element is taken out as a scan interval of block i; End of Loop1; End of Main Proc SubProc1 (L, MaxdT, ScanList, dT) L = L−dT; dT is put into ScanList; if ((L ≧ dT * N) and (dT * n≤MaxdT)) then call Sub Proc1 (L, MaxdT, ScanList, dT * n); else if (L≥dT) then call Sub Proc1 (L, MaxdT, ScanList, dT); else if (L> 0) then call Sub Pro c2 (L, ScanList, dT); return; End of SubProc1 SubProc2 (L, ScanList, dT) if (dT> 1) then dT = dT / n; Loop1: while (L> dT) L = L−dT End of Loop1; if (L> 0) then call Sub Proc2 (L, ScanList, dT); return; End of Sub Proc2

FIGS. 6 (a) and 6 (b) show an example of the arrangement of blocks when a link is divided by, for example, MaxdT = 10 according to the above-described link division algorithm.
(B) is the case where n = 3, and the scan interval and the block length are n times (or 1 time due to the limitation of the maximum scan interval) from the most downstream block to the upstream, respectively. It has become. For reference, FIG. 1C shows an arrangement of isometric blocks in the conventional HBDM.

3. Limitation of Radix of Division In general, the radix n of division in the link division algorithm is limited to an arbitrary value and used. However, in practice, n = 2 is optimal. When n is 3 or more, the scan interval of the block sharply increases toward the upstream side.
MaxdT or less ”and the constraint that“ the sum of the block lengths and the link length become equal ”must be satisfied. Therefore, the number of blocks in the short scan interval on the downstream side increases, and n = This is because the number of blocks increases as compared with the case of 2, and the effect of reducing the amount of calculation decreases.

4. Matching between Main Lane and Auxiliary Lane In the link division algorithm described above, the link is divided into blocks for each lane, similarly to the HBDM. On actual roads, auxiliary lanes shorter than the main lane are often attached due to vehicles turning right and left, but this difference in length must be taken into account when dividing into blocks. In other words, the main lane and the auxiliary lane are divided separately, but the boundary of the block on the main lane must be located at the most upstream position of the auxiliary lane, and the upstream block at that position on the main lane must be scanned. The interval must be arranged to satisfy the constraint of being equal to or double the scan interval of the most upstream block in the auxiliary lane.

5. Block Density Revision In the block density revision algorithm, the blocks on the link are each represented by a scan interval dti and a length dLi
And the number i from the downstream (i.
= 0, 1,...), And the attributes of the block critical density Kci and the block jam upper limit density Kji.

The i-th block is based on the vehicle density Ki, the block critical density Kci, and the block jam upper limit density Kji only when the time t is a multiple of its own scan interval dti. , The traffic volume A ^out i that can flow ^{out of} the block and the traffic volume A that can flow in the block
ⁱⁿ i, and the flow rate Q from the upstream block i + 1 of the own block
i + 1, i is calculated, and the vehicle density Ki in the block and the vehicle density Ki + 1 in the block are revised. Furthermore, when moving the traffic volume, the outflowable amount A ^out i + 1 of the upstream block i + 1
Is subtracted from the flow rate Qi + 1, i that has been moved. The details of this algorithm are shown below.

1) Algorithm of block density revision Loop1: For each time t Loop2: For each block i, if (t is a multiple of dti) then A ^out i = min (Kci, Ki) dLi / dti; End of Loop2; Loop3 : for each block i if ((t is a multiple of the dti) and (Ki <Kci) ) then a in i = min (Kci, Kji-Ki) dLi / dti; else if ((t is a multiple of the dti) and ( ^{Ki <Kji)) then a in} i = Kci (Kji-Ki) / (Kji-Kci) · dLi / dti; End of Loop3; Loop4: multiple if (t is dti for each of the downstream block i) then Qi + ^{1, i = min (A out} i + 1, A in i); KidLi = KidLi + Qi + 1, idti; Ki + 1dLi + 1 = Ki + 1dLi + 1 -Qi + 1, idti; A out i + 1 = A ^out i + 1 -Qi + 1, i; End of Loop4; End of Loop1;

6. Exception Handling The above block density revision algorithm is effective when the scan interval of the upstream block is higher than that of the downstream, such as a single link, but the upstream block, such as a link between links, is effective. That is, where the scan interval dti of the downstream block, that is, the block of the most upstream block of the downstream link is longer than the scan interval dti of the most downstream block of the upstream link, exceptional processing must be performed. That is, Loop4 of the above algorithm
At time t, when the time t becomes a multiple of the scan interval dti of the lowermost block of the upstream link, the density revision is calculated, and the inflowable amount of the downstream block is calculated as the traffic amount shifted from the original value. This is a process of changing the value to a deducted value. The algorithm of the exception processing part of Loop 4 is shown below.

1) Algorithm of exception processing part of block density revision Loop 4 ′: When block i is located at the most upstream of the downstream link and block i + 1 is located at the most downstream of the upstream link, if (t is dti + 1 of multiples) then Qi + 1, i = min (a out i + 1, a in i); KidLi = KidLi + Qi + 1, idti; Ki + 1dLi + 1 = Ki + 1dLi + 1 -Qi + 1, idti ^{; A in i = A in i} -Qi + 1, i; End of Loop4 ';

Actually, since the scan interval of the block at the lowermost stream of the upstream link is fixed to one second, this exception processing is performed every second. Block from the scan interval
The dti moves traffic to the uppermost block of the longer downstream link.

7. Difference from the conventional hybrid block density method The above link division algorithm and block density revision algorithm smooth the density distribution for long blocks, but enable density management based on the set traffic-density curve become. As for the amount of calculation, not only the number of blocks is reduced as compared with the case where the blocks are divided into blocks of a fixed distance, but also not all the blocks are necessarily included in the calculation for each scan interval, so that the amount of calculation is greatly reduced.

When a real network having 31 nodes, 193 links, and a total link length of 73 km was simulated by this traffic flow simulator, the number of blocks was reduced to 20% as compared with the conventional HBDM, and the number of blocks per scan was reduced. Has been reduced to 15%, and the actual calculation time has been reduced to about 1/4.

[0048]

As described above, the traffic flow simulator of the present invention, in the simulation based on the hybrid block density method, makes the scan interval of the block into which the link is divided variable, thereby improving the reproduction / prediction accuracy of the traffic flow of the entire network. The scan interval and the block length of the upstream block that have little effect are configured to be integral multiples of the downstream block. This gives 1
The number of blocks to be calculated in the scan interval is reduced, and the calculation amount is significantly reduced as compared with the traffic flow simulator based on the conventional hybrid block density method.

Therefore, when comparing with the conventional hybrid block density method traffic flow simulator while securing the reproduction accuracy of the traffic flow at the signal intersection in the lowermost block, the amount of calculation is reduced in the same scale road network model. The calculation time is shortened, and a larger-scale road network model can be simulated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a traffic flow simulator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a CRT display screen of a traffic flow simulator.

FIG. 3 is an object class hierarchy diagram of a traffic flow simulator.

FIG. 4 is an explanatory diagram of lane change of a traffic flow simulator.

FIG. 5 is an explanatory diagram of lane change of a traffic flow simulator.

FIG. 6 is an explanatory diagram of a link divided into blocks;
(A) shows the case where the division radix n = 2, and (b) shows the case where the division radix n = 3. (C) is an explanatory diagram of a link divided into blocks of a fixed length by a conventional link dividing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Computer 2 Expert system 3 Interface 4 Knowledge database 5 Inference mechanism 6 Working memory 7 Keyboard 8 Pointing device 9 CRT 10 External storage device

────────────────────────────────────────────────── ─── Continued on the front page (73) Patent holder 000001317 Kumagaya Gumi Co., Ltd. 2-6-1-8 Chuo, Fukui City, Fukui Prefecture (72) Inventor Masao Kuwahara 2-1-1-4 Mizuho Hanamigawa-ku, Chiba City, Chiba Prefecture −306 (72) Inventor Masahiko Katakura 2-9-2 Tomigaya, Shibuya-ku, Tokyo (72) Inventor Hirokazu Akabane 7-4-7, Higashikasai, Edogawa-ku, Tokyo 703 Corp. 703 (72) Inventor Haruo Ozaki Tokyo 3-72-6-302, Akatsuka Shinmachi, Itabashi-ku (72) Inventor Kunihiko Oshima 2-1 Tsukudocho, Shinjuku-ku, Tokyo Tokyo Main Office (72) Inventor Ryota Horiguchi 2 Tsukudocho, Shinjuku-ku, Tokyo No. 1 Kumagaya Gumi Tokyo Head Office (72) Inventor Kotaro Kumagai 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo, Japan Kumagaya Gumi Tokyo Head Office (56) References JP-A-5-28394 (JP) JP-A-6-259407 (JP, A) JP-A-5-250594 (JP, A) JP-A-6-4510 (JP, A) JP-A-9-147285 (JP, A) Ryota Horiguchi, "Development of AVENUE, a Traffic Simulator for Urban Street Networks," Proceedings of the Conference on Traffic Engineering Research, Japan Society for Traffic Engineering, November 1993, Vol. 13, p. 33-36 (58) Field surveyed (Int. Cl. ⁶ , DB name) G08G 1/00 G06F 17/00 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A hybrid road model having an arbitrary number of lanes and a road network shape can be constructed by connecting a plurality of links as a road model, and the link is divided into blocks of a certain length. Attributes that describe route restrictions and vehicle type regulations are provided, and attributes that individually describe the vehicle type, traveling direction, destination, and passenger car conversion coefficient are provided in the vehicle model.The vehicle density of each block in each unit scan interval The vehicle outflow possible amount and the inflowable amount of each block are obtained in accordance with the traffic volume-density curve set in advance and the calculated vehicle outflow possible amount and inflowable amount, and the block attribute and the vehicle attribute. Only one vehicle that satisfies the vehicle outflow possible amount and inflowable amount and the block attribute and the vehicle attribute is selectively transferred from one or a plurality of adjacent upstream blocks. In the traffic flow simulator based on the hybrid block density method for expressing a traffic flow by moving, when dividing the link into blocks, a block of a unit scan interval is arranged at the most downstream of the link, and each of the upstream blocks has its downstream block. Is given by an integer multiple of the scan interval, each block is divided into a scan interval assigned to each block and a length determined from the free running speed of the vehicle assigned to the link, and the link is divided. A traffic flow simulator provided with a processing function of adjusting the number of blocks of each length so that the sum of the lengths is equal to the length of the link. 2. The traffic flow simulator according to claim 1, wherein a connection between the most downstream block of the upstream link and the most upstream block of the downstream link calculates a block density revision for each scan interval of the downstream block of the upstream link. Then, the obtained traffic is moved from the most downstream block of the upstream link to the most upstream block of the downstream link, and the possible vehicle inflow of the most upstream block of the downstream link is calculated from the original value by the amount of movement. 2. The traffic flow simulator according to claim 1, further comprising a processing function for changing the value to a value obtained by subtracting.