Highway path guidance method and system under event condition

Abstract

The present disclosure provides a highway path induction method and system under event conditions, relating to the technical field of transportation, obtaining the traffic flow in each road section of the highway road network in the current period, calculating the road section impedance under the path condition of the current event road section; updating the road section impedance of the entire road network, establishing a new impedance road network, judging whether the traffic capacity of the event road section can meet the traffic flow in the current period under the event level; if not, traffic flow distribution is carried out, and the path with short detour time and within the specified detour distance range is selected in turn as the objective function with the minimum path repetition degree; the total traffic capacity of the selected detour path is calculated, and it is judged whether the road network flow meets the condition and whether the traffic capacity of the event road section meets the detour path; if not, the path calculation is continued until the induced path flow is met, that is, the induced flow is successful. The traffic state problem under the event condition is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of traffic technology, in particular to a highway path induction method and system under event conditions. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute the prior art.

[0003] Traffic Guidance System (TGS) refers to a system that comprehensively considers traffic elements such as people, vehicles, and roads, and improves road traffic by inducing the behavior of travelers. It aims to prevent traffic congestion and reduce vehicle travel time on the road, and ultimately achieve the rational distribution of traffic flow on various road segments of the road network.

[0004] The highway path induction algorithm under event conditions is an important part of traffic induction. The highway induction method under event conditions significantly improves the road traffic state of the highway network and the surrounding road network. This method provides a scientific traffic control reference for traffic management departments, but there is currently no effective method.

[0005] However, existing research on highway network traffic induction and diversion mainly focuses on emergency traffic organization under emergency conditions, and research on network-level traffic induction and diversion methods mainly targets urban roads, with few studies on highway network traffic induction and diversion. At the same time, in practical applications, the development of induction measures is mainly based on the experience of traffic management personnel for manual decision-making, and a complete induction and diversion method has not yet been formed. SUMMARY

[0006] To solve the above problems, the present disclosure proposes a highway path induction method and system under event conditions, which uses an improved Logit algorithm to calibrate the flow of different grades of roads, proposes a path induction algorithm based on the minimum repetition degree of road segments, and selects road segment impedance, road segment delay, and road network traffic flow as indicators to evaluate the induction strategies given for different event levels in combination with VISSIM simulation traffic flow state.

[0007] According to some embodiments, the present disclosure adopts the following technical solutions:

[0008] A highway path induction method under event conditions, comprising:

[0009] Obtaining the traffic flow in each road segment of the highway network in the current period, and calculating the road segment impedance under the path condition of the current event road segment;

[0010] update the link impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event link can meet the traffic flow of the current period under the event level;

[0011] If not, traffic flow distribution is performed, and paths with short detour time and within a specified detour distance range are selected in turn as the objective function of minimum path repetition degree;

[0012] The total traffic capacity of the selected detour path is calculated, and it is determined whether the road network flow meets the condition and whether the traffic capacity of the event link meets the detour path. If yes, the iteration is stopped; if not, the path calculation is continued until the induced path flow is met, i.e., the induced flow is successful.

[0013] According to some embodiments, the present disclosure adopts the technical solutions as follows:

[0014] An expressway path induction system under event conditions comprises:

[0015] An initial data processing module is configured to obtain the traffic flow of each link in the expressway road network of the current period, and calculate the link impedance under the path condition of the event link currently occurring;

[0016] A road network updating module is configured to update the link impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event link can meet the traffic flow of the current period under the event level;

[0017] A path optimization module is configured to distribute traffic flow when the traffic capacity of the event link cannot meet the traffic flow of the current period, and select paths with short detour time and within a specified detour distance range in turn as the objective function of minimum path repetition degree;

[0018] A path induction module is configured to calculate the total traffic capacity of the selected detour path, determine whether the road network flow meets the condition and whether the traffic capacity of the event link meets the detour path. If yes, the iteration is stopped; if not, the path calculation is continued until the induced path flow is met, i.e., the induced flow is successful.

[0019] According to some embodiments, the present disclosure adopts the technical solutions as follows:

[0020] A computer readable storage medium, wherein a plurality of instructions are stored, the instructions being adapted to be loaded and executed by a processor of a terminal device.

[0021] According to some embodiments, the present disclosure adopts the technical solutions as follows:

[0022] A terminal device comprises a processor and a computer readable storage medium, the processor is used to realize instructions; the computer readable storage medium is used to store a plurality of instructions, the instructions are suitable for being loaded by the processor and performing the event condition highway path induction method.

[0023] Compared with the prior art, the beneficial effects of the present disclosure are:

[0024] (1) The present disclosure proposes path induction strategies for highways, national roads and provincial roads of different grades, performs path induction, and aims to provide a method and idea of inducing paths for traffic states under event conditions;

[0025] (2) The present disclosure obtains the relationship between the flow of highways, national roads and provincial roads in different time periods through highway network data and collected real road network data, and applies mathematical methods. For roads of different grades, when the number of lanes is constant, the flow range remains consistent, there is a clear range and other road grade proportion data distinction, and there is no boundary intersection. The data of the road network is calibrated;

[0026] (3) The present disclosure verifies the induction method by designing simulation experiments and combining simulation software, compares from the angles of path-section impedance time, delay time and vehicle passing volume, and verifies the effectiveness of the algorithm. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings accompanying the specification of the present disclosure serve to provide a further understanding of the present disclosure, and the schematic embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0028] Figure 1 The overall technical roadmap is designed for path induction in the embodiments of the present disclosure;

[0029] Figure 2 The Dial algorithm flowchart in the embodiments of the present disclosure;

[0030] Figure 3 The path induction algorithm flowchart based on minimum repetition in the embodiments of the present disclosure;

[0031] Figure 4 The road network delay index in the embodiments of the present disclosure;

[0032] Figure 5 The road network vehicle passing volume index in the embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] The present disclosure will be further described below in combination with the drawings and embodiments.

[0034] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in connection with the disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs.

[0035] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0036] Embodiment 1

[0037] In an embodiment of the present disclosure, a highway path induction method under event conditions is provided, comprising:

[0038] Step 1: Obtain the traffic flow in each road section of the highway road network in the current period, and calculate the road section impedance under the path condition of the current event section;

[0039] Step 2: Update the road section impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event section can meet the traffic flow in the current period under the event level;

[0040] Step 3: If not, traffic flow distribution is performed, and paths with short detour time and within the specified detour distance range are selected in turn as the objective function of minimum path repetition;

[0041] Step 4: Calculate the total traffic capacity of the selected detour path, determine whether the road network flow meets the condition and whether the traffic capacity of the event section meets the detour path, and if it does, stop iteration, and if it does not, continue path calculation until the induced path flow is met, i.e., the induced flow is successful.

[0042] As an embodiment, the method for obtaining the traffic flow in each road section of the highway road network in the current period includes obtaining the highway road network flow data, and collecting the calculated flow data of the real road network data, i.e.,

[0043] 1. The traffic flow is distributed using a non-equilibrium distribution Logit model, and the road impedance in the distribution model is selected as a comprehensive road impedance function to calculate the traffic flow in each road section.

[0044] Specifically, traffic impedance is an important indicator for measuring traffic state or traffic phenomenon, and its specific meaning is to describe the time spent by travelers on the road during the travel process. Traffic impedance generally includes link impedance and intersection delay. Traffic impedance is generally described by link impedance function, which is a comprehensive function for describing the relationship between traffic impedance, link capacity, link flow, intersection delay, etc.

[0045] Considering the traffic characteristics of different grades of roads, a comprehensive impedance function is selected to calibrate and calculate the road network flow, and the function form is shown in formula (1).

[0046]

[0047] In the formula, X w is the time impedance; Y w is the cost impedance. The different grades of roads include expressways, national roads, and provincial roads.

[0048] 2. Building a traffic assignment model

[0049] Traffic assignment models are mainly divided into balanced and unbalanced assignment. The balanced state completely satisfying the definition of Wardrop principle is called balanced assignment method. The assignment model using heuristic method or other approximate method is called unbalanced assignment method. The advantage of using Logit model for flow assignment in the present disclosure is that each cycle is based on path probability for multi-path traffic assignment, rather than assigning all traffic to the shortest path, which is more in line with the selection psychology of users. The specific expression is shown in formula (2).

[0050]

[0051] In the formula, o and d are the starting point and the ending point, c_k is the actual impedance of the path k, m is the selection correlation coefficient, and P is the probability of selecting path k.

[0052] In order to improve the IIA characteristic of Logit model, Dial algorithm is used to solve the Logit model. The algorithm idea of Dial algorithm is to solve the effective path between each OD. The present disclosure ignores the path due to too long distance, and selects the k short path (k<=5) for effective path selection. In each cycle, the selection probability of each path is calculated according to the Logit model, and the traffic flow is distributed according to the selection probability. The algorithm steps are as follows:

[0053] Step 1: Initialize the network. Add a column in the matrix mark to represent the proportion of adding each path selection mapping to the link. Initialize the path length matrix to store the impedance of k short path in each cycle.

[0054] Step two: calculate the cost of each road section. Yen's algorithm is used to solve the k-short path between adjacent OD pairs, and the proportion of each path is calculated according to the path impedance, which is converted into the label matrix.

[0055] Step three: traffic flow distribution is carried out on each road section according to the proportion.

[0056] Step four: loop distribution and accuracy check. If the set accuracy is met, the calculation stops and the final distribution result is obtained. If the accuracy is not reached, it will return to step two and continue to do traffic flow distribution. The higher the accuracy, the more iterations.

[0057] In step 1, the road section impedance under the path condition of the current event road section is calculated, which includes the current occurrence time level, traffic upstream and downstream density, and the current occurrence time clearance time.

[0058] In step 2, it is judged whether the traffic capacity of the event road section can meet the traffic flow of the current period under the event level. If it can meet, traffic induction is not needed, and the driver is only reminded to drive safely according to the shortest path; if it cannot meet, traffic flow induction is carried out.

[0059] The specific steps of traffic flow distribution are as follows: after excluding the current event road section, the shortest path algorithm and path search algorithm are used in the current updated impedance network to calculate other detour paths under the event condition, and the selected paths are compared, and the path with the minimum path repetition degree is selected as the objective function, and the path with short detour time within the specified detour distance range is selected in turn.

[0060] The specified detour distance range path is the path between 0-1.5 times the event path.

[0061] The path induction algorithm based on the minimum path repetition degree is as follows: assuming that in an abstract road traffic network, when a road section has a traffic event, the traffic capacity of the road section will be reduced according to the level and type of the event, and the road section impedance will also be different from other road sections. Due to the characteristics of traffic flow propagation, the upstream and downstream of the event road section will also be affected, which is reflected in the impedance function of the road section. The real induction starts from the upstream of the event road section, and the flow passing through the road section is induced and diverted. The most important thing in the induction is to determine the induction path. The disclosure determines the induction path based on the Floyd shortest path algorithm first, and solves the O-D (O is the abbreviation of origin, which refers to the departure point; D is the abbreviation of destination, which refers to the destination) path by using the actual impedance method and the node deletion method. The path repetition degree is used as a decision variable, and the path with the minimum repetition degree is searched in all paths. The path length and the path travel time are limited in a more appropriate proportion. The detour induction path is obtained by solving the operational optimization problem. The implementation steps of the algorithm are as follows:

[0062] S1: In the current traffic flow distribution balanced road network, the road section impedance under the condition of the current event path is calculated, the road section impedance (i.e. the time between nodes) of the entire network is updated, a new impedance network is established, and it is judged whether the traffic capacity of the event road section can meet the current period of traffic flow under the event level. If it can meet, no induction is needed, and the shortest path is continued to be driven, and only the driver is reminded to drive safely; if it cannot meet, step S2 is entered to recommend the detour path.

[0063] S2: After excluding the current event road section, the shortest path algorithm and the path search algorithm are used in the current updated impedance network to calculate other detour paths under the event condition. The selected paths are compared, the minimum path repetition degree is taken as the objective function, the detour time is short, and the path within the specified detour distance range is selected, i.e. the distance range of the detour path is between 0-1.5 times of the event path.

[0064] S3: The total traffic capacity of the selected detour path is calculated, and the road section impedance, traffic capacity, road section flow, and repetition degree index of the road network are calculated.

[0065] S4: It is judged whether the road network flow meets the condition and whether the traffic capacity of the event road section meets the detour path. If it meets, the iteration is stopped, and if it does not meet, it returns to step two and continues to execute the algorithm until the induction path flow is met, i.e. the induction flow is successful.

[0066] Specifically, the event occurrence has a great impact on the traffic impedance of the link, and has an impact on the upstream and downstream links, so the link impedance is recalculated. The total capacity of the selected detour path includes the calculation of link impedance, capacity, link flow, and the repetition index of the road network. The impact on the link can be calculated by formula (3), and the impact on the upstream and downstream links is calculated by the event occurrence time and the event clearance time.

[0067]

[0068] In the formula, C(a, t) is the link impedance of link a at time t, L is the length of the link, K jam is the jam density of the link, K a is the density of link a at time t, K s is the density of the upstream link of link a.

[0069] The repetition between paths is taken as the decision variable, and the path with the minimum repetition is searched in all paths. The minimum repetition R between paths is used to make a decision on the detour path, and the definition of the repetition is that the length of the common link of the selected detour path and the original path is divided by the total length of the original path, as follows:

[0070]

[0071]

[0072]

[0073] The decision formula is:

[0074]

[0075]

[0076] In the formula: is the repetition of the bth path between o and d, L is the length of the common link, l is the length of the original path, is the identification parameter, C o.d [b] is the remaining capacity of the bth detour path (design capacity * α - current link capacity, α is 0.85 for expressway and 0.80 for national and provincial highway, to avoid congestion of the detour path). T i is the travel time on the optimal path, and 1.5 times the optimal path time is used as the maximum detour time value in this study. The length of the detour path is less than twice the optimal path, and the total remaining capacity of the final detour path is greater than the link flow demand at that time.

[0077] Example 2

[0078] An event condition highway path induction system is provided in one embodiment of the present disclosure, comprising:

[0079] An initial data processing module is configured to acquire traffic flow in each road segment of the highway road network in a current period, and calculate road segment impedance under the path condition of the event road segment currently occurring;

[0080] A road network updating module is configured to update road segment impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event road segment can meet the traffic flow in the current period under the event level;

[0081] A path optimization module is configured to distribute traffic flow when the traffic capacity of the event road segment cannot meet the traffic flow in the current period, and sequentially select paths with short detour time and within a specified detour distance range as an objective function with minimum path repetition degree;

[0082] A path induction module is configured to calculate total traffic capacity of the selected detour path, determine whether the road network flow meets the condition and whether the traffic capacity of the event road segment meets the detour path, and stop iteration if the condition is met, or continue path calculation if the condition is not met until the induction path flow is met, i.e., the induction flow is successful.

[0083] The above system specifically executes the method steps in Embodiment 1 of the present disclosure.

[0084] Embodiment 3

[0085] A computer readable storage medium is provided in one embodiment of the present disclosure, wherein a plurality of instructions are stored, the instructions being adapted to be loaded and executed by a processor of a terminal device to implement the event condition highway path induction method steps.

[0086] Embodiment 4

[0087] A terminal device includes a processor and a computer readable storage medium, the processor being configured to implement instructions, and the computer readable storage medium being configured to store a plurality of instructions, the instructions being adapted to be loaded and executed by the processor to implement the event condition highway path induction method steps.

[0088] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0089] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0090] Although the present disclosure has been described with reference to the embodiments thereof, it is apparent that a variety of modifications or changes can be made thereto without departing from the scope of the present disclosure.

Claims

1. A method for guiding highway routes under event conditions, characterized in that, include: Obtain the traffic flow in each segment of the highway network during the current time period, and calculate the segment impedance under the path conditions of the segment where the current event occurred; Update the segment impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event segment can meet the traffic flow at the current time under the event level. If the conditions cannot be met, traffic flow allocation will be carried out, with the path redundancy as the objective function, and the path with the shortest detour time and within the specified detour distance will be selected in sequence. The total capacity of the selected detour route is calculated to determine whether the road network flow meets the conditions and whether the capacity of the event segment meets the detour route requirements. If they do, the iteration stops; otherwise, the path calculation continues until the induced path flow is met, i.e., the induced flow is successful. The calculation of the total capacity of the selected detour route includes the calculation of road network segment impedance, capacity, segment flow, and repetition index. For the impact on upstream and downstream segments, the event occurrence time and event clearance time are calculated. The formula for calculating segment impedance is as follows. ， In the formula: Let L be the impedance of road segment a at time t, and L be the length of the road segment. The congestion density of the road segment. Let be the density of road segment a at time t. The density of the upstream road segment of road segment a; The road segment impedance includes the current occurrence time level, upstream and downstream traffic density, and current occurrence time clearance time; The path redundancy is defined as the ratio of the length of the shared section between the selected detour path and the path where the current event occurred to the total length of the original path; the redundancy between paths is used as a decision variable to search for the path with the minimum redundancy with the selected path among all paths; Traffic flow is allocated using an unbalanced Logit model, and the Dial algorithm is used to solve the Logit model. In each iteration, the selection probability of each path is calculated based on the Logit model, and the traffic flow is allocated according to the selection probability.

2. The highway route guidance method under event conditions as described in claim 1, characterized in that, Determine whether the traffic capacity of the affected road segment can meet the current traffic flow under the event level. If it can, no traffic guidance is needed, and drivers can continue to follow the shortest path, only being reminded to drive safely. If it cannot meet the requirements, traffic flow allocation will be implemented.

3. The highway route guidance method under event conditions as described in claim 1, characterized in that, The specific steps for traffic flow allocation are as follows: After excluding the current event road segment, the shortest path algorithm and path search algorithm are used in the currently updated impedance network to calculate other detour paths under the event conditions. The selected paths are compared, and the path with the lowest path repetition is used as the objective function. Paths with the shortest detour time and within the specified detour distance are selected in sequence.

4. The highway route guidance method under event conditions as described in claim 1, characterized in that, The calculation of the total capacity of the selected detour route includes the calculation of road network segment impedance, capacity, segment flow, and repetition index.

5. A highway route guidance system under event conditions, employing the highway route guidance method under event conditions as described in any one of claims 1-4, characterized in that, include: The initial data processing module is used to obtain the traffic flow in each segment of the highway network during the current time period and calculate the segment impedance under the path conditions of the segment where the current event occurred. The road network update module is used to update the road segment impedance of the entire road network, establish a new impedance road network, and determine whether the traffic capacity of the event segment can meet the traffic flow at the current time under the event level. The route optimization module is used to allocate traffic flow when the capacity of the event road segment cannot meet the traffic flow of the current time period. It selects the routes with the shortest detour time and within the specified detour distance range in order of minimum route redundancy as the objective function. The route guidance module calculates the total capacity of the selected detour route, determines whether the road network traffic meets the conditions, and whether the traffic capacity of the event segment meets the detour route. If it meets the conditions, the iteration stops; if it does not meet the conditions, the route calculation continues until the traffic of the induced route is met, i.e., the traffic guidance is successful.

6. A computer-readable storage medium, characterized in that, It stores multiple instructions, which are adapted to be loaded and executed by the processor of a terminal device as a highway path guidance method under event conditions according to any one of claims 1-4.

7. A terminal device, characterized in that, It includes a processor and a computer-readable storage medium, the processor being used to implement various instructions; the computer-readable storage medium being used to store multiple instructions adapted to be loaded by the processor and executed as described in any one of claims 1-4, a highway path guidance method under event conditions.

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