A method for estimating highway OD matrix by using historical ETC gantry data
By utilizing highway ETC gantry data and combining it with geographic location calculations, an OD matrix is constructed, solving the problems of high cost and inaccuracy in existing OD matrix construction technologies, and achieving fast and accurate OD matrix construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGAN UNIV
- Filing Date
- 2024-06-25
- Publication Date
- 2026-06-12
AI Technical Summary
Existing methods for constructing OD matrices rely on manual surveys or traditional traffic flow data, which are costly and inaccurate, making it difficult to effectively utilize ETC gantry data for accurate construction.
By utilizing highway ETC gantry data, a basic travel network is established, and geographic location is used to construct an OD matrix. This process includes data cleaning, preprocessing, and travel data estimation, resulting in an upper and lower triangular OD matrix.
It enables rapid and accurate OD matrix construction, reduces costs, improves the universality and accuracy of data, and eliminates the need for manual surveys.
Smart Images
Figure CN118840793B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of traffic engineering technology, and in particular relates to a method for estimating the OD matrix of highways using historical ETC gantry data. Background Technology
[0002] An OD matrix is a way to describe travel flow. It is usually a two-dimensional table where the rows and column headers represent the origin and destination, respectively. The elements in the table represent the number of trips from one origin to one destination. It reflects the characteristics of vehicle flow direction and quantity in the highway network and has certain reference value for highway management and future traffic planning.
[0003] Traditional OD matrices are typically constructed based on individual traffic travel survey data. However, traditional manual survey methods are time-consuming, costly, and complex. Alternatively, traffic flow data can be used to infer the OD matrix, reducing the cost of manual surveys to some extent. However, the results are influenced by various factors, making it difficult to obtain an accurate OD matrix. Existing patents use traffic volume survey sections to obtain traffic volume data for inferring the OD matrix. In recent years, new detection equipment has optimized OD matrix construction methods. Existing patents use toll station monitoring data to construct the OD matrix, but this still requires data from the start and end points of the OD matrix to complete its construction.
[0004] In the process of intelligent highway construction, ETC gantries are gradually being put into use. ETC gantries are built along highway sections and have the function of recording vehicle passage data. This vehicle passage data is different from traffic volume data and is more accurate, with each vehicle having its own individual data record. However, since gantries are located upstream and downstream of interchanges, they do not directly provide vehicle passage data at the interchanges. Considering the shortcomings of previous OD matrix construction methods, this paper proposes a new method for constructing highway OD matrices by utilizing detailed, accurate, and real-time highway gantry data and extrapolating travel trajectories based on the geographical locations of gantries and interchanges. Summary of the Invention
[0005] The purpose of this invention is to provide a method for estimating the OD matrix of highways using historical ETC gantry data, aiming to solve the problems raised in the third part of the background art.
[0006] This invention is implemented as follows: a method for estimating the OD matrix of a highway using historical ETC gantry data includes the following steps:
[0007] Step S1: Locations A and B are connected by a highway with two-way interchanges and ETC gantries. Establish a basic travel network based on the locations of locations A and B, as well as the gantries and interchanges. Number a total of n interchanges from H1 to H2 in the A-to-B direction. n There are a total of n+1 gantries numbered from 1 to n+1, with A, B and each bidirectional interchange as OD matrix nodes; each interchange is composed of an exit ramp a and an entry ramp b from A to B, and an exit ramp c and an entry ramp d from B to A.
[0008] Step S2: Clean and preprocess the historical ETC gantry data collected within a day, distinguish different driving directions, form separate data files for each gantry, and establish the data foundation required for the OD matrix.
[0009] Step S3: First, calculate the OD data from A to B, selecting A as the starting point and all downstream interchanges and B as the ending point. Use the data file of the adjacent gantry downstream of A, i.e., gantry 1, as the starting point data table for A. Iterate through each vehicle data entry in the starting point data table and compare it with the data file of gantry 2 to determine whether the vehicle has passed through the gantry. If not, the vehicle exits the highway via ramp a of interchange H1 between gantry 1 and gantry 2, generating a travel data entry with A as the starting point and interchange H1 as the ending point. Remove the vehicle data entry of vehicles exiting interchange H1 from the starting point data table. Then, compare the starting point data table with the data file of gantry 3 again to determine whether the vehicle has passed through gantry 3. If not, the vehicle exits the highway via ramp a of interchange H2 between gantry 2 and gantry 3. After removing the exiting vehicles, continue to compare with the data files of each downstream gantry to obtain travel data. After summarizing, all vehicle travel data starting from A can be obtained.
[0010] Step S4: Change the starting point to H1 interchange. Iterate through the vehicle data of the adjacent No. 2 gantry downstream of H1 interchange to see if it appears in the data file of the adjacent No. 1 gantry upstream of H1 interchange. If it does not appear, it is determined that the vehicle entered the highway from ramp b of H1 interchange. Summarize and build a starting point data table. Continue according to step S3 to obtain all vehicle travel data with H1 interchange as the starting point, and change the starting interchange in turn for calculation. After all interchanges are calculated as starting points, summarize and build an upper triangular OD matrix in the direction from A to B.
[0011] Step S5: Then calculate the OD data from B to A. Taking B and its downstream interconnection as the starting point, calculate all travel data from B to A according to steps S3 and S4, and summarize to construct a complete OD matrix.
[0012] Preferably, in step S1, the starting and ending points of the travel network are locations A and B, and the interchange is a two-way interchange consisting of entrance and exit ramps in two directions, existing on both sides of the same location on the road; the geographical relationship between the highway gantries and the interchanges is intertwined, with the interchange located between two adjacent gantries, and it is necessary to calculate the vehicles originating from the interchanges through gantry data.
[0013] Preferably, in step S2, the collected vehicle passage data includes "gantry stake number", "passage time", "license plate number", "driving direction" and "vehicle type". Data cleaning requires deleting incorrectly identified passage data, preprocessing to select data within the time range required by the OD matrix, distinguishing driving directions, and forming separate data files for each gantry.
[0014] Preferably, in step S3, when distinguishing travel directions and calculating the OD matrix from A to B, the gantry data file from A to B is used. When calculating from A to B, since A is the starting point of the travel network, all vehicles in the data file of gantry 1 downstream of A take A as their starting point. The starting point data table contains data of all vehicles traveling from this point. Traversing the starting point data table, it is determined whether the same "license plate number" appears in the data file of gantry 2 downstream. If it does, the vehicle has passed through gantry 2. Due to the closed nature of the highway, it can only exit the highway at the interchange. Therefore, vehicles that have not passed through gantry 2 can only exit the highway from the H1 interchange ramp a between gantry 1 and gantry 2. If a vehicle has already exited the highway from the H1 interchange, travel data is formed and needs to be removed from the starting point data table to avoid affecting subsequent calculations. When comparing with the data file of the last gantry, i.e., gantry n+1, vehicles from H1 are removed. n After the vehicles leave the interchange, all remaining vehicles in the starting point data table will have B as their destination.
[0015] Preferably, in step S4, when the interchange is taken as the starting point, there are vehicles coming from upstream and vehicles entering the expressway from interchange ramp b. Therefore, it is necessary to compare the upstream and downstream adjacent gantry data files of the interchange to determine the vehicles entering the expressway from the interchange and establish a starting point data table. The order of selecting the starting point in the direction from A to B is A, H1 interchange, H2 interchange, and so on up to H. n Interconnection, when the starting point is selected as H n During interconnection, H n All vehicles in the interchange starting point data table have B as their destination.
[0016] Preferably, in step S5, when distinguishing travel directions and calculating the OD matrix from B to A, the gantry data file from B to A is used; when constructing the OD matrix from B to A, the starting point interconnection sequence is selected as B, H. n Interconnection, H n-1 Interconnection, H n-2The interchange continues until the H1 interchange. After changing direction, the entrance and exit ramps of the interchange become c and d. After the calculation is completed, the lower triangular OD matrix data from B to A is obtained, and the complete OD matrix is constructed by summarizing them.
[0017] Preferably, the downstream interconnection is H n Go to H1.
[0018] Beneficial effects of the embodiments of the present invention:
[0019] 1. This invention utilizes highway ETC gantry data to estimate the OD matrix, and proposes a new method for OD matrix estimation using novel data. It fully considers the current status of highway data collection equipment, is more universal and applicable, and reduces costs.
[0020] 2. This invention uses ETC gantry data located upstream and downstream of interconnected systems to propose a new method for estimating the OD matrix based on geographical location.
[0021] 3. The construction method of the present invention eliminates the manual investigation step in the previous method, completes the construction of OD matrix more scientifically and quickly, and is more accurate than the OD matrix reverse calculation method. Attached Figure Description
[0022] Figure 1 This is a flowchart of a method for estimating the OD matrix of a highway using historical ETC gantry data, according to the present invention.
[0023] Figure 2 This is a schematic diagram of the highway research conducted in this invention.
[0024] Figure 3 This is a flowchart for determining the start and end points of a vehicle according to the present invention. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0026] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first script may be referred to as a second script, and similarly, a second script may be referred to as a first script.
[0027] like Figure 1-3As shown, an embodiment of the present invention provides a method for estimating the OD matrix of a highway using historical ETC gantry data, comprising the following steps:
[0028] Step S1: Locations A and B are connected by a highway with two-way interchanges and ETC gantries. Establish a basic travel network based on the locations of locations A and B, as well as the gantries and interchanges. Number a total of n interchanges from H1 to H2 in the A-to-B direction. n There are a total of n+1 gantries numbered from 1 to n+1, with A, B and each bidirectional interchange as OD matrix nodes; each interchange is composed of an exit ramp a and an entry ramp b from A to B, and an exit ramp c and an entry ramp d from B to A.
[0029] Step S2: Clean and preprocess the historical ETC gantry data collected within a day, distinguish different driving directions, form separate data files for each gantry, and establish the data foundation required for the OD matrix.
[0030] Step S3: First, calculate the OD data from A to B, selecting A as the starting point and all downstream interchanges and B as the ending point. Use the data file of the adjacent gantry downstream of A, i.e., gantry 1, as the starting point data table for A. Iterate through each vehicle data entry in the starting point data table and compare it with the data file of gantry 2 to determine whether the vehicle has passed through the gantry. If not, the vehicle exits the highway via ramp a of interchange H1 between gantry 1 and gantry 2, generating a travel data entry with A as the starting point and interchange H1 as the ending point. Remove the vehicle data entry of vehicles exiting interchange H1 from the starting point data table. Then, compare the starting point data table with the data file of gantry 3 again to determine whether the vehicle has passed through gantry 3. If not, the vehicle exits the highway via ramp a of interchange H2 between gantry 2 and gantry 3. After removing the exiting vehicles, continue to compare with the data files of each downstream gantry to obtain travel data. After summarizing, all vehicle travel data starting from A can be obtained.
[0031] Step S4: Change the starting point to H1 interchange. Iterate through the vehicle data of the adjacent No. 2 gantry downstream of H1 interchange to see if it appears in the data file of the adjacent No. 1 gantry upstream of H1 interchange. If it does not appear, it is determined that the vehicle entered the highway from ramp b of H1 interchange. Summarize and build a starting point data table. Continue according to step S3 to obtain all vehicle travel data with H1 interchange as the starting point, and change the starting interchange in turn for calculation. After all interchanges are calculated as starting points, summarize and build an upper triangular OD matrix in the direction from A to B.
[0032] Step S5: Then calculate the OD data from B to A. Taking B and its downstream interconnection as the starting point, calculate all travel data from B to A according to steps S3 and S4, and summarize to construct a complete OD matrix.
[0033] In this embodiment, based on gantry data of the Chengdu-Nanchong Expressway, which has 19 interchanges and 20 gantries, and using Chengdu, Nanchong, and each interchange as nodes, vehicle travel is estimated based on geographical location to establish an estimated expressway OD matrix. A method for estimating the expressway OD matrix using historical ETC gantry data according to the present invention includes the following steps:
[0034] Step S1: Establish a basic travel network based on the locations of gantries and interchanges along the city and highways, with the location relationships as follows: Figure 2 As shown, there are a total of 19 bidirectional interchanges and 20 gantries. The 19 interchanges in the Chengdu to Nanchong direction are numbered H1 to H19, and the 20 gantries are numbered 1 to 20. Chengdu, Nanchong and each bidirectional interchange are used as OD matrix nodes.
[0035] Step S2: Clean and preprocess the historical ETC gantry data collected within one day (0:00 to 24:00), distinguish different driving directions, form separate data files for each gantry, and establish the data foundation required for the OD matrix;
[0036] Step S3: First, calculate the OD data from Chengdu to Nanchong, selecting Chengdu as the starting point and all downstream interchanges and Nanchong as the ending point. Use the data file of the adjacent gantry downstream of Chengdu, i.e., gantry 1, as the starting point data table. Iterate through each vehicle data entry in the starting point data table and compare it with the data file of gantry 2 to determine whether the vehicle has passed through the gantry. If not, the vehicle exits the highway via ramp a of interchange H1 between gantry 1 and gantry 2, generating a travel data entry with Chengdu as the starting point and interchange H1 as the ending point. Remove vehicles exiting interchange H1 from the starting point data table. Compare the starting point data table with the data file of gantry 3 again to determine whether the vehicle has passed through gantry 3. If not, the vehicle exits the highway via ramp a of interchange H2 between gantry 2 and gantry 3. After removing exiting vehicles, repeat this process and compare with the data files of each downstream gantry to generate travel data. After summarizing, all vehicle travel data originating from Chengdu can be obtained.
[0037] Step S4: Change the starting point to H1 Interchange, iterate through the vehicle data of the adjacent No. 2 gantry downstream of H1 Interchange, and check if it appears in the data file of the adjacent No. 1 gantry upstream of H1 Interchange. If it does not appear, it is determined that the vehicle entered the expressway from ramp b of H1 Interchange. Summarize and build a starting point data table, and continue according to step S3 to obtain all vehicle travel data with H1 Interchange as the starting point, and calculate the starting interchange in turn. After all interchanges are calculated as starting points, summarize and build an upper triangular OD matrix in the direction from Chengdu to Nanchong.
[0038] Step S5: Calculate the OD data from Nanchong to Chengdu, and sequentially establish interconnection between Nanchong and its downstream areas (H). 19Starting from H1), according to steps S3 and S4, calculate all travel data from Nanchong to Chengdu, and summarize to construct a complete OD matrix, as shown in Appendix Table 2.
[0039] As a preferred embodiment of the present invention, such as Figure 1-3 As shown, in step S1, the starting and ending points of the travel network are locations A and B. The interchange is a two-way interchange, consisting of entrance and exit ramps in two directions, existing on both sides of the same location on the road. The geographical relationships between the highway gantries and the interchanges are intertwined, with the interchange located between two adjacent gantries. It is necessary to calculate the vehicles originating from the interchanges using gantry data.
[0040] In this embodiment, the starting and ending points of the travel network are Chengdu and Nanchong. The interchanges are bidirectional, consisting of entrance and exit ramps in both directions, existing on both sides of the same location on the road. The geographical relationships between the highway gantries and the interchanges are intertwined, with interchanges located between two adjacent gantries. Therefore, it is necessary to calculate the vehicles originating from the interchanges using gantry data. The positional relationships are shown in the attached figure. Figure 2 As shown.
[0041] As a preferred embodiment of the present invention, such as Figure 1-3 As shown, in step S2, the collected vehicle passage data includes "gantry stake number", "passage time", "license plate number", "driving direction" and "vehicle type". Data cleaning requires deleting incorrectly identified passage data, preprocessing to select data within the time range required by the OD matrix, distinguishing driving directions, and forming separate data files for each gantry.
[0042] In this embodiment, in step S2, the collected vehicle passage data includes "gantry stake number", "passage time", "license plate number", "driving direction" and "vehicle type". Data samples are shown in Table 1. Data cleaning requires deleting incorrectly identified vehicle passage information, preprocessing to select data within the time range required by the OD matrix, and distinguishing the driving direction to form separate data files for each gantry.
[0043] Table 1. Examples of gantry traffic data
[0044] gantry staking number Through time license plate number driving direction Vehicle type G004251**********10102 2023-07-0100:00:06.154815947 Zhejiang A****9 Up small car G004251**********10102 2023-07-0100:00:08.600115214 Sichuan R****5 Up cart G004251**********10102 2023-07-0100:00:15.594610948 SichuanA****0 Up cart G004251**********10102 2023-07-0100:00:28.602111884 Sichuan R****4 Up cart
[0045] As a preferred embodiment of the present invention, such as Figure 1-3As shown, in step S3, when distinguishing travel directions and calculating the OD matrix from A to B, the gantry data file from A to B is used. When calculating from A to B, since A is the starting point of the travel network, all vehicles in the data file of gantry 1 downstream of A take A as their starting point. The starting point data table contains data of all vehicles traveling from this point. Traversing the starting point data table, it is determined whether the same "license plate number" appears in the data file of gantry 2 downstream. If it does, the vehicle has passed through gantry 2. Due to the closed nature of the highway, it can only exit the highway at the interchange. Therefore, vehicles that have not passed through gantry 2 can only exit the highway from the ramp a of interchange H1 between gantry 1 and gantry 2. If a vehicle has already exited the highway from interchange H1, travel data is formed and needs to be removed from the starting point data table to avoid affecting subsequent calculations. When comparing with the data file of the last gantry, i.e., gantry n+1, vehicles from H1 are removed. n After the vehicles leave the interchange, all remaining vehicles in the starting point data table will have B as their destination.
[0046] In this embodiment, in step S3, it is necessary to distinguish the travel direction. When calculating the OD matrix for the Chengdu to Nanchong direction, the gantry data file for the Chengdu to Nanchong direction is used. When calculating the Chengdu to Nanchong direction, since Chengdu is the starting point of the travel network, vehicles in the No. 1 gantry data file downstream of Chengdu are all considered to have Chengdu as the starting point. The starting point data table contains data of all vehicles traveling from this point. Traversing the starting point data table, it is determined whether the same "license plate number" appears in the downstream No. 2 gantry data file. If it does, the vehicle has passed through No. 2 gantry. Due to the closed nature of the highway, it can only exit the highway from the interchange. Therefore, vehicles that have not passed through No. 2 gantry can only exit the highway from the H1 interchange a ramp between No. 1 and No. 2 gantry. If the vehicle has already exited the highway from the H1 interchange, travel data has been formed and needs to be removed from the starting point data table to avoid affecting subsequent calculations. When comparing with the data file of the last gantry, namely No. 20 gantry, vehicles from H1 interchange a ramp are removed. 19 After vehicles depart from the interchange, all remaining vehicles in the starting point data table will have Nanchong as their destination.
[0047] As a preferred embodiment of the present invention, such as Figure 1-3 As shown, in step S4, when the interchange is taken as the starting point, there are vehicles coming from upstream and vehicles entering the expressway from interchange ramp b. Therefore, it is necessary to compare the upstream and downstream adjacent gantry data files of the interchange to determine the vehicles entering the expressway from the interchange and establish a starting point data table. The order of selecting the starting point in the direction from A to B is A, H1 interchange, H2 interchange, and so on up to H. n Interconnection, when the starting point is selected as H n During interconnection, H n All vehicles in the interchange starting point data table have B as their destination.
[0048] In this embodiment, in step S4, when the interchange is taken as the starting point, there are vehicles coming from upstream and vehicles entering the expressway from interchange ramp b. Therefore, it is necessary to compare the upstream and downstream adjacent gantry data files of the interchange to determine the vehicles entering the expressway from the interchange and establish a starting point data table. The starting point order selected for the Chengdu to Nanchong direction is Chengdu, H1 interchange, H2 interchange, and so on up to H1 interchange. 19 Interconnection; select starting point H 19 During interconnection, H 19 All vehicles listed in the interchange starting point data table have Nanchong as their destination.
[0049] As a preferred embodiment of the present invention, such as Figure 1-3 As shown, in step S5, when distinguishing travel directions and calculating the OD matrix from B to A, the gantry data file from B to A is used; when constructing the OD matrix from B to A, the starting point interconnection order is selected as B, H. n Interconnection, H n-1 Interconnection, H n-2 The interchange continues until the H1 interchange. After changing direction, the entrance and exit ramps of the interchange become c and d. After the calculation is completed, the lower triangular OD matrix data from B to A is obtained, and the complete OD matrix is constructed by summarizing them.
[0050] In this embodiment, in step S5, when calculating the OD data from Nanchong to Chengdu, the starting point is selected in the order of Nanchong, H 19 Interconnection, H 18 The interchange continues until the H1 interchange, with the starting point selection order reversed from that used when calculating the Chengdu to Nanchong direction. After changing the direction, the entrance and exit ramps of the interchange become c and d. After the calculation is completed, the lower triangular OD matrix data in the B to A direction is obtained, and the complete OD matrix is constructed by summarizing them. The final OD matrix calculated in this embodiment is shown in Table 2.
[0051] Table 2 OD Matrix of Examples
[0052]
[0053]
[0054] This invention utilizes historical data from ETC gantries on highways and combines it with the geographical locations of interchanges and gantries to propose a new OD matrix estimation method. This method has the advantages of being easy to generalize and promote, and it improves efficiency, expands the range of available data, increases accuracy, and reduces costs compared to traditional OD matrix methods.
[0055] It should be understood that although the steps in the flowcharts of the various embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the various embodiments may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.
[0056] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.
[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0058] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.
[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for estimating the OD matrix of a highway using historical ETC gantry data, characterized in that, Includes the following steps: Step S1: Locations A and B are connected by a highway with two-way interchanges and ETC gantries. Establish a basic travel network based on the locations of locations A and B, as well as the gantries and interchanges. Number a total of n interchanges from H1 to H2 in the A-to-B direction. n There are a total of n+1 gantries numbered from 1 to n+1, with A, B and each bidirectional interchange as OD matrix nodes; each interchange is composed of an exit ramp a and an entry ramp b from A to B, and an exit ramp c and an entry ramp d from B to A. Step S2: Clean and preprocess the historical ETC gantry data collected within a day, distinguish different driving directions, form separate data files for each gantry, and establish the data foundation required for the OD matrix. Step S3: First, calculate the OD data from A to B, selecting A as the starting point and all downstream interconnections and B as the ending point. Using the data file of the adjacent gantry downstream of A, namely gantry 1, as the starting data table of A, each vehicle passage data in the starting data table is traversed and compared with the data file of gantry 2 to determine whether the vehicle has passed through the gantry. If not, the vehicle exits the highway via ramp a of interchange H1 between gantry 1 and gantry 2, generating a travel data line with A as the starting point and interchange H1 as the ending point. The vehicle passage data of vehicles exiting interchange H1 is removed from the starting data table. The starting data table is then compared with the data file of gantry 3 to determine whether the vehicle has passed through gantry 3. If not, the vehicle exits the highway via ramp a of interchange H2 between gantry 2 and gantry 3. After removing the exiting vehicles, this process continues to compare with the data files of each downstream gantry to obtain travel data. After summarizing, all vehicle travel data starting from A can be obtained. Step S4: Change the starting point to H1 Interchange, iterate through the vehicle data of the No. 2 gantry downstream of H1 Interchange, and check if it appears in the data file of the No. 1 gantry upstream of H1 Interchange. If it does not appear, it is determined that the vehicle entered the expressway from ramp b of H1 Interchange. Summarize and build the starting point data table, and continue to follow step S3 to obtain the travel data of all vehicles starting from H1 Interchange, and change the starting interchange in turn for calculation. After all interconnections are calculated as the starting point, the upper triangular OD matrix in the direction from A to B is established by summarizing the results. Step S5: Then calculate the OD data from B to A. Taking B and its downstream interconnection as the starting point, calculate all travel data from B to A according to steps S3 and S4, and summarize to construct a complete OD matrix. In step S2, the collected vehicle passage data includes "gantry stake number", "passage time", "license plate number", "driving direction" and "vehicle type". Data cleaning requires deleting incorrectly identified passage data, preprocessing to select data within the time range required by the OD matrix, and distinguishing the driving direction to form a separate data file for each gantry. In step S3, when distinguishing travel directions and calculating the OD matrix from A to B, the gantry data file from A to B is used. Since A is the starting point of the travel network, all vehicles in the downstream gantry 1 data file originating from A are considered to have A as their starting point. The starting point data table contains data for all vehicles traveling from this point. The starting point data table is traversed to determine if the same license plate number appears in the downstream gantry 2 data file. If it does, the vehicle has passed through gantry 2. Due to the closed nature of the highway, vehicles can only exit the highway at the interchange. Therefore, vehicles that have not passed through gantry 2 can only exit the highway at the H1 interchange ramp a between gantry 1 and 2. If a vehicle has already exited the highway at the H1 interchange, travel data is generated and needs to be removed from the starting point data table to avoid affecting subsequent calculations. When comparing with the data file of the last gantry, i.e., gantry n+1, data from H1 is removed. n After the vehicles leave the interchange, all remaining vehicles in the starting point data table will use B as their destination. In step S4, when the interchange is taken as the starting point, there are vehicles coming from upstream and vehicles entering the expressway from interchange ramp b. Therefore, it is necessary to compare the upstream and downstream adjacent gantry data files of the interchange to determine the vehicles entering the expressway from the interchange and establish a starting point data table. The order of selecting the starting point in the direction from A to B is A, H1 interchange, H2 interchange, and so on up to H. n Interconnection, when the starting point is selected as H n During interconnection, H n All vehicles in the interchange starting point data table have B as their destination.
2. The method for estimating the OD matrix of a highway using historical ETC gantry data according to claim 1, characterized in that, In step S1, the starting and ending points of the travel network are locations A and B. The interchange is a two-way interchange, consisting of entrance and exit ramps in two directions, existing on both sides of the same location on the road. The geographical relationships between the highway gantries and the interchanges are intertwined, with the interchange located between two adjacent gantries. It is necessary to calculate the vehicles originating from the interchanges using gantry data.
3. The method for estimating the OD matrix of a highway using historical ETC gantry data according to claim 1, characterized in that, In step S5, when distinguishing travel directions and calculating the OD matrix from B to A, the gantry data file from B to A is used; when constructing the OD matrix from B to A, the starting point interconnection order is selected as B, H. n Interconnection, H n-1 Interconnection, H n-2 The interchange continues until the H1 interchange. After changing direction, the entrance and exit ramps of the interchange become c and d. After the calculation is completed, the lower triangular OD matrix data from B to A is obtained, and the complete OD matrix is constructed by summarizing them.
4. The method for estimating the OD matrix of a highway using historical ETC gantry data according to claim 1, characterized in that, The downstream interconnection is arrive .