Urban ground intersection traffic state alarm method based on links road section matching

Abstract

The invention discloses an urban ground intersection traffic state alarm method based on links road section matching. The method comprises the following steps: acquiring position information of each intersection of an urban ground road and links road section information; matching is carried out on the basis of road sections between the adjacent intersections and the information of the links road sections, and a path set which corresponds to the road sections and contains the information of a plurality of links road sections is obtained; according to the road section corresponding to the entrance included in each intersection, completing matching and binding of the intersection and the corresponding links road section information; and performing intersection traffic state evaluation based on the link road section information corresponding to the intersection, and giving an alarm when a preset alarm condition is met. According to the invention, a large amount of mixed vehicle links road section information can be accurately matched with the corresponding road section, so that the vehicle links road section information is matched and bound to the corresponding intersection, and the traffic state of the corresponding intersection can be evaluated and alarmed according to the links road section information; while the matching of the road section and the links road section is completed, the track spliced by the links road sections in the path set can approximately reflect the shape of the road section.

Description

Technical Field

[0001] The present invention relates to the field of intelligent transportation technology, and in particular to a method for alarming traffic status at urban ground intersections based on links road segment matching. Background Art

[0002] In the intelligent transportation system, accurate identification of the traffic status of the intersection of urban ground roads is helpful for macro-characterization of the traffic status of the road network, timely diagnosis of traffic congestion nodes, and convenient for formulating targeted traffic improvement measures. Defining the traffic status intensity index of the intersection to quantitatively characterize the traffic status of the intersection, that is, to digitally express the smooth or congested state of the intersection, can accurately indicate the traffic status of the intersection, so as to facilitate the tuning and control of the intersection signal and ensure the smooth flow of the road. In the existing technology, with the annual increase in the investment in intelligent transportation, various detection equipment on the road is becoming more and more abundant, which can generate a large amount of traffic data for relevant departments or units to judge the traffic status. Taking the currently widely used links section information as an example, the links section information of vehicles collected at various locations of the road network will be mixed and packaged together for transmission. Before judging the traffic status of the intersection based on the traffic data, it is necessary to match and bind the links section information to the corresponding intersection, and then perform subsequent judgment processing based on the links information corresponding to the intersection. Therefore, how to accurately match the links section information of a large number of mixed vehicles to their corresponding sections, and then match and bind them to the corresponding intersections has become an urgent problem to be solved.

[0003] The "method, system, medium and device for allocating lane identification data to Link" disclosed in Chinese patent literature has a publication number of CN116578659A and a publication date of 2023.08.11, including: obtaining a lane identification data set and a road-level road network Link data set of the road area to be tested; selecting any lane identification data from the lane identification data set; selecting any Link data from the road-level road network Link data set; matching any lane identification data with any Link data based on preset matching conditions, and allocating all lane identification data to the corresponding Link data according to the matching results; thus, the problem of allocating lane identification data to the corresponding Link can be solved. This technology actually allocates lanes based on the link data of the road and displays it on a high-precision map, and the road corresponding to the link data has been determined in advance. It does not solve the problem of how to accurately match the links section information of a large number of mixed vehicles to their corresponding sections, and then match and bind them to the corresponding intersections. Summary of the invention

[0004] The present invention aims to overcome the problem in the prior art that when judging the traffic status at an intersection of a ground road, a large amount of mixed vehicle links section information received needs to be accurately matched with its corresponding road section, so as to be matched and bound to the corresponding intersection, and provides a method for alarming the traffic status at an urban ground intersection based on links section matching.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for warning traffic status at urban ground intersections based on links road segment matching, comprising: Get the location information of each intersection of the city's ground roads and the links section information; Based on matching the road segments between adjacent intersections with the links segment information, a path set including a plurality of links segment information corresponding to the road segments is obtained; According to the road sections corresponding to the entrances contained in each intersection, the intersection and the corresponding links section information are matched and bound; The traffic status of the intersection is evaluated based on the links section information corresponding to the intersection, and an alarm is issued when the preset alarm conditions are met.

[0006] In the present invention, for the links section information (the links section information in the present invention refers to a short trajectory of a vehicle moving on a road collected by a detection device, and the corresponding vehicle driving data information, etc.) packaged together and received by the traffic status data processing department, first obtain the links section information belonging to the urban ground roads (screen out the links information with labels such as elevated, expressway and ramp, and only retain the links section information of the ground roads to avoid mismatching of elevated ramps and internal roads in the park), and then match the links section information according to the road sections between adjacent intersections when a road network relationship diagram containing the location information of the ground road intersections is known; judge and match based on the vector corresponding to the road section, the vector corresponding to the links section, and the relationship between the positions at both ends of the road section and the positions at both ends of the links section, and obtain a path set corresponding to the road section and containing the links section information, the trajectory formed by connecting all the links sections in the path set can approximately reflect the shape of the corresponding road section, and the links section information in the path set can reflect the driving status of the vehicle on the section. After completing the matching of each road segment (the road segments of the present invention have directionality, for example, for adjacent intersections A and B, the road segment from A to B and the road segment from B to A need to be separated into two for matching consideration) with the corresponding links segment, the matching and binding of the intersection and links segment information can be further completed according to the relationship that several road segments intersect and converge at the intersection. Thus, the purpose of accurately matching the received large amount of mixed vehicle links segment information to its corresponding segment is achieved, thereby matching and binding to the corresponding intersection.

[0007] Preferably, the matching process of the path set includes: Filter out a starting point segment set that meets the first matching condition with the starting point of the road segment from the links segment set; Taking each links segment in the starting segment set as the start of the path set, cyclically matching the links segments in the initial segment set NC0 that meet the second matching condition with the target segment, until the target segment meets the loop termination condition; The target segment of each loop is the links segment matched in the previous loop.

[0008] Preferably, the obtaining of the location information of each intersection and the links section information comprises: Get the longitude and latitude coordinates of the intersection, get the topological point coordinates of the links section, and convert them to the same coordinate system; Determine the starting point coordinates and the ending point coordinates of the road section based on the connection lines and directions between adjacent intersections; Determine the start and end coordinates of the links segment based on the direction in the links segment information.

[0009] Preferably, the matching process of the starting point road segment set includes: Filter out the initial segment set NC0 that meets the first screening condition with the road segments from the links segment set; Calculate the distance between the starting point of the road segment and the starting point of each link segment in NC0, as well as the vector angle between the corresponding vector of the road segment and the corresponding vector of each link segment; The first several links sections with the shortest distance and whose vector angle is less than the first preset angle are selected to form a starting point section set.

[0010] Preferably, the screening process of the initial road section set NC0 includes: Extending a first preset distance in all directions with a line segment corresponding to the road segment to form a buffer circle; Filter out links whose starting or ending points fall within the buffer circle to form the initial link set NC0; If NC0 is empty, a fixed distance step is cyclically extended and then a new NC0 is obtained by re-screening; When NC0 is still empty after extending to the second preset distance, the road segment has no matching links segment information.

[0011] Preferably, the links sections meeting the second matching condition in the initial section set NC0 include: The distance between the starting point St of the target section and the starting point Sl of the links section is less than the first distance threshold; and the distance from the end point El of the links section to St is greater than the distance from El to the end point Et of the target section; and The distance from the starting point Sl to St of the links is less than the distance from Sl to Et; and The angle between the vector pointing from St to S1 and the vector pointing from St to El is less than the second preset angle.

[0012] Preferably, the target section meets the cycle termination condition including: The end point of the target segment coincides with the end point of the road segment, or the distance between the end point of the target segment and the end point of the road segment is less than a second distance threshold.

[0013] As a preference, when a road segment is matched to obtain several path sets, the first priority is to take the path consisting of the links segments in the path set with the smallest average distance between the beginning and the end of the road segment; The minimum distance between the starting points of two adjacent links is the second priority; The minimum angle between the corresponding vectors of two adjacent links is the third priority; The fourth priority is the one with the smallest angle between the vector corresponding to the starting links segment and the vector corresponding to the road segment; select a path set.

[0014] Preferably, the intersection traffic status assessment includes an intersection congestion alarm: Get the links section information of the corresponding entrance of the intersection, extract the links status marked from 1 to 5 from smooth to congested, and the links speed; For each import, the links with the most severe congestion and the lowest speed are selected for judgment; When the links status of at least two imports is 3 or the links status of at least one import is greater than 3, a congestion alarm is issued.

[0015] Preferably, the intersection traffic status assessment includes an intersection imbalance alarm: Get the links section information corresponding to the entrance of the intersection, calculate the congestion delay index of the entrance and the intersection imbalance index of the intersection; When the intersection imbalance index is greater than the preset index threshold; and the links status corresponding to the entrance with the smallest congestion delay index is less than 3; and the links status corresponding to the entrance with the largest congestion delay index is greater than 3; an intersection imbalance alarm is issued.

[0016] The present invention has the following beneficial effects: a large amount of mixed vehicle links section information can be accurately matched to its corresponding road section, so as to match and bind to the corresponding intersection, so as to evaluate and alarm the traffic status of the intersection according to the links section information corresponding to the correctly matched intersection; in the process of matching the road section and the links section information, the starting links section that meets the conditions is screened according to the distance between the starting point of the links section and the starting point of the road section, and the vector angle between the two, and then the links section is cyclically matched according to the distance relationship and the vector angle relationship between adjacent links sections until the loop termination condition is met, so as to obtain a plurality of path sets corresponding to a certain road section, and for a large number of path sets, the path set that best meets the requirements can be selected according to the priority selection condition to match the road section, so that not only the matching of the road section and the links section can be completed, but also the trajectory spliced ​​and combined by the links sections in the path set can approximately reflect the specific shape of the road section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of the method for alarming the traffic status of urban ground intersections based on links road segment matching in the present invention.

[0018] Figure 2It is a flow chart of obtaining a path set by matching road segments with links segment information in the present invention.

[0019] Figure 3 It is a schematic diagram of the vector angle between the vector corresponding to the links section and the vector corresponding to the road section in the present invention.

[0020] Figure 4 It is a schematic diagram of the vector angle between the target segment and the links segment to be matched in the present invention.

[0021] Figure 5 It is a schematic diagram of matching the entrance and links section information according to the road sections corresponding to the entrances included in the intersection in the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0023] In the existing technology, with the increasing investment in intelligent transportation year by year, various detection equipment on the road is becoming more and more abundant, which can generate a large amount of traffic data for relevant departments or units to judge the traffic status. However, in the actual operation and judgment process, a large amount of traffic data is mixed together and transmitted to the data processing department for processing. Taking the currently widely used links section information as an example, the links section information of vehicles collected at various locations of the road network will be mixed and packaged together for transmission to relevant departments. Therefore, before judging the traffic status of the intersection based on the traffic data, it is necessary to first match and bind the links section information to the corresponding intersection, and then perform subsequent judgment processing based on the links information corresponding to the intersection. In the case of the road network relationship of the known intersection location information, the location coordinate information of the links section in a large amount of links section information is matched with the road section between adjacent intersections, so that the links section information is allocated to its corresponding road section for subsequent judgment of the traffic status of the intersection. The present invention is a specific technical solution proposed for this problem.

[0024] like Figure 1 As shown, a method for warning the traffic status of urban ground intersections based on links road segment matching includes: Get the location information of each intersection of the city's ground roads and the links section information; Based on matching the road segments between adjacent intersections with the links segment information, a path set including several links segment information corresponding to the road segments is obtained; According to the road sections corresponding to the entrances contained in each intersection, the intersection and the corresponding links section information are matched and bound; The traffic status of the intersection is evaluated based on the links section information corresponding to the intersection, and an alarm is issued when the preset alarm conditions are met.

[0025] It should be noted that, in the present invention, for the links section information packaged together and received by the processing department of the traffic status data, the links section information belonging to the urban ground roads is first obtained (the links information with labels such as elevated, expressway and ramp is screened out, and only the links section information of the ground roads is retained to avoid mismatching of elevated ramps and internal roads in the park). Then, when the road network relationship diagram containing the location information of the ground road intersections is known, the links section information is matched according to the road sections between adjacent intersections; the matching is judged and matched based on the vector corresponding to the road section, the vector corresponding to the links section, and the relationship between the positions at both ends of the road section and the positions at both ends of the links section, so as to obtain a path set corresponding to the road section and containing the links section information. The trajectory formed by connecting all the links sections in the path set can approximately reflect the shape of the corresponding road section, and the links section information in the path set can reflect the driving status of the vehicle on the section.

[0026] Links section information refers to a short track of a vehicle moving on the road collected by the detection equipment, as well as the corresponding vehicle driving data information. In the actual data collection process, the links section information of the vehicle is discontinuous. By matching the links section information with the road sections, the discontinuous links sections are matched and connected to obtain a path set corresponding to the road sections.

[0027] It is worth noting that after completing the matching of each road segment with the corresponding links segment, the matching and binding of the intersection and links segment information can be further completed based on the relationship of several road segments intersecting and converging at the intersection. Thereby achieving the purpose of accurately matching the received large amount of mixed vehicle links segment information with its corresponding road segment, thereby matching and binding to the corresponding intersection. The road segment of the present invention has directionality. For example, for adjacent intersections A and B, the road segment from intersection A to intersection B and the road segment from intersection B to intersection A need to be separated into two for matching consideration, and when considered as vectors, they are two vectors with opposite directions.

[0028] Specifically, firstly, the location information of each intersection is extracted based on the known road network relationship containing the intersection location information, and displayed on a latitude and longitude line graph; at the same time, a large amount of received links section information is also extracted to obtain the starting and ending point location information of each links section.

[0029] On the basis of the location information of each intersection, the connection line between any two adjacent intersections is taken to represent the road segment according to the road network relationship, and the vector corresponding to the road segment (including the direction, the starting point of the road segment, the end point of the road segment and the length, etc.) is obtained, and all the road segments are saved in the road segment set M. Similarly, corresponding to each links segment information, the vector corresponding to the links segment (including the direction, starting point, end point and length, etc.) can be obtained, and all the links segments are saved in the links segment set N.

[0030] The road segment set M contains all the road segments that need to be matched. Each road segment must be matched with the links segments in the links segment set N to obtain a path set that matches the road segment. The path set is composed of links segments that meet the matching conditions in the matching order during the matching process. Since there is a large amount of links segment information in the links segment set, there will also be many similar links segments. Therefore, there may be multiple links segments that meet the matching requirements at the same time. Therefore, there may be many possibilities for the final path set. All path sets obtained by matching with road segments can be used as alternatives for the subsequent selection of the best matching path set to obtain a path set that best matches the road segment.

[0031] When selecting the path set that best matches the road segment from several path sets, the corresponding screening conditions can be set in advance, and the different screening conditions can be prioritized, so that multiple path sets can be gradually screened from high to low according to the priority, and finally a path set that best meets the requirements is obtained. In this way, the road segment and the links segment are matched.

[0032] After matching and obtaining the path set of each road segment, the intersection and links segment information are matched and bound according to the intersection relationship of the road segments at the intersection. In the prior art, the traffic status of the intersection is analyzed by considering the traffic status of all the entrances contained in the intersection. Therefore, in the present invention, each entrance of the intersection corresponds to a road segment with the intersection as the end point. That is, all road segments with a certain intersection as the end point finally intersect at the intersection, and the path set matching these road segments is matched and bound to the corresponding intersection, thereby completing the matching and binding of the intersection and links segment information.

[0033] After completing the matching and binding of the intersection and links section information, the traffic status of the intersection can be analyzed and judged based on the vehicle driving data in the links section information. According to the links section information matched by the road section corresponding to each entrance included in the intersection, the traffic status of each entrance is first judged separately. For the links section information of each entrance, the links status and speed of the vehicle driving data are extracted, and it is determined whether an alarm is needed according to the corresponding intersection alarm conditions. The present invention specifically includes intersection congestion alarm and intersection imbalance alarm.

[0034] As a specific embodiment, obtaining the location information of each intersection and the links section information includes: Get the longitude and latitude coordinates of the intersection, get the topological point coordinates of the links section, and convert them to the same coordinate system; Determine the starting point coordinates and the ending point coordinates of the road section based on the connection lines and directions between adjacent intersections; Determine the start and end coordinates of the links segment based on the direction in the links segment information.

[0035] It should be noted that due to different data sources, the location information of intersections is generally expressed in longitude and latitude coordinates, so the starting and ending points of road sections between adjacent intersections are also expressed in longitude and latitude coordinates. The links section information comes from the collection and detection device on the road. The location information of each links section is expressed in specific topological point coordinates to represent its starting and ending points. In order to complete the matching between road sections and links sections, they must first be converted to the same coordinate system to accurately match road sections and links sections.

[0036] It is worth noting that, when matching road segments and links segments in the present invention, the corresponding matching conditions are mainly determined based on the vectors corresponding to the road segments and the vectors corresponding to the links segments. Therefore, the directionality of the vectors must be considered when obtaining the information of the road segments and the information of the links segments. For a road segment pointing from intersection A to intersection B, its starting point coordinates are the coordinates of intersection A, and its end point coordinates are the coordinates of intersection B. AB represents the vector corresponding to the road segment. On the contrary, for a road segment pointing from intersection B to intersection A, its starting point coordinates are the coordinates of intersection B, and its end point coordinates are the coordinates of intersection A. BA represents the vector corresponding to the road segment.

[0037] Specifically, collect and obtain the road segments and links segment information formed by adjacent intersections required for matching, where the road segment information formed by adjacent intersections includes the longitude and latitude of the intersections and the distance between the intersections; convert the starting point coordinates and the end point coordinates of the road segments formed by adjacent intersections and the topological point coordinates of the links segment information to the same coordinate system, the Mars coordinate system. The set of all road segments formed by adjacent intersections is recorded as M, and the set of all links segments is recorded as N.

[0038] In the actual matching application process, there are certain differences between the intersection position coordinates in the known road network relationship and the intersection position coordinates in the links section data system (for links section information applied to a certain navigation system, the position of the links intersection is the position of the intersection represented in the navigation system). In order to match more accurately, it is necessary to calculate the distance between each intersection in the adjacent intersections and the links intersection, and select the position coordinates of the nearest links intersection to update the longitude and latitude coordinates of all intersections in the adjacent intersections. In this way, the position correction of the intersection position information and the links section information is completed, so as to obtain more accurate matching results later.

[0039] As a specific example, Figure 2 As shown in the figure, the matching process of the path set includes: Filter out a starting point segment set that meets the first matching condition with the starting point of the road segment from the links segment set; Taking each links segment in the starting segment set as the start of the path set, cyclically matching the links segments in the initial segment set NC0 that meet the second matching condition with the target segment, until the target segment meets the loop termination condition; The target segment of each loop is the links segment matched in the previous loop.

[0040] It should be noted that, in the matching process of the path set of the present invention, when the starting point and the end point of the road segment have been determined, the starting point segment set that meets the first matching condition is first determined according to the position of the starting point of the road segment (including several links segments that meet the requirements, each links segment can be used as the starting segment of a path set), and when the starting segment is determined, the starting segment is used as the target segment to continue matching the next links segment as the second links segment of the path set, and then the second links segment is used as the target segment to continue cyclically matching the links segments, until the last links segment in the path set meets the loop termination condition, then a complete path set is formed from the starting segment to the last links segment.

[0041] Specifically, for the road segments to be matched, a set of starting segments that meet the first matching condition is screened out. This is mainly divided into two steps. The first step is to screen out an initial segment set that can match the road segments from all links segment sets. The second step is to match the initial segment set with the first matching condition to obtain the starting segment set corresponding to the final path set.

[0042] Since there may be multiple links in the matched starting segment set that can serve as starting segments, in the actual matching process, each links in the starting segment set needs to be matched to obtain a path set.

[0043] Taking any links segment in the starting segment set as an example, taking the current links segment as the starting segment of the path set (as the target segment for the first loop matching), find the links segment that meets the second matching condition with the target segment in the initial segment set NC0; then use the matched links segment as the target segment to continue matching the links segment that meets the second matching condition from the initial segment set NC0 (if multiple links segments that meet the requirements are matched, each links segment is subjected to subsequent matching processes to obtain multiple path set results), and so on, perform loop matching until the last links segment as the target segment meets the loop termination condition, and obtain the result of all optional path sets that match the road segment.

[0044] Optionally, the matching process of the starting road segment set RL0 includes: Filter out the initial segment set NC0 that meets the first screening condition with the road segments from the links segment set; Calculate the distance between the starting point of the road segment and the starting point of each link segment in NC0, as well as the vector angle between the corresponding vector of the road segment and the corresponding vector of each link segment; The first several road segments whose starting points are the shortest from the starting points of each links segment in the initial segment set NC0 and whose vector angles between the corresponding vectors of the road segments and the corresponding vectors of each links segment are less than a first preset angle are selected to form a starting segment set.

[0045] It should be noted that the starting segment set RL0 is the set of all links segments in the initial segment set NC0 that meet the first screening condition with the road segments. The links segments in the starting segment set are used as the starting points of the path set. When selecting, it is necessary to satisfy that the direction of the links segments is consistent with the overall direction of the road segments, and the starting position of the links segments is near the starting position of the road segments.

[0046] Based on the above reasons, when matching the links segments within the starting segment set RL0, it is necessary to consider the distance between the starting point of the road segment and the starting point of the links segment (the smaller the distance, the closer the starting points of the two are to each other, and the higher the degree of matching), as well as the vector angle between the corresponding vector of the road segment and the corresponding vector of the links segment (the smaller the vector angle, the more consistent the direction of the links segment and the straight line direction of the road segment).

[0047] In actual situations, due to the known road network relationship and intersection location information, the road segments obtained by connecting two adjacent intersections are all straight segments, but the actual road segments between adjacent intersections may be curved or curved in addition to being straight. In the case of curved road segments, the vector angle between the corresponding vector of the starting llinks segment and the corresponding vector of the road segment will be greater than the angle between the actual links segment and the road segment. Therefore, when setting the threshold of the vector angle, it is necessary to appropriately increase the range of the first preset angle to ensure the correctness of the final matching result. For the links segment added as noise after the first preset angle is increased, it can be excluded by the second matching condition through the subsequent cyclic matching process of the path set.

[0048] Specifically, when the initial segment set NC0 is obtained, the distance between the starting point of the road segment R and the starting point of the links segment in the initial segment set NC0 is calculated: Where (x Rs ,y Rs ) is the starting point coordinate of road section R, (x ls ,y ls ) is the starting point coordinate of the links segment in the initial segment set NC0; the distance between the road segment R and the starting points of all links segments in the initial segment set NC0 is calculated, and the links segments are sorted from small to large according to the distance.

[0049] like Figure 3 The figure shows the vector angle between the vector corresponding to the links segment and the vector corresponding to the road segment. Since the vector corresponding to the links segment and the vector corresponding to the road segment R may or may not intersect in the actual position coordinates, when they intersect, the vector angle is the angle between the intersecting parts, and when they do not intersect, it is the angle between the intersecting parts of the reverse extension lines. The vector corresponding to the road segment R can be expressed as Where (x Re ,y Re ) represents the end point coordinates of road segment R; the vector corresponding to the links segment can be expressed as Where (x le ,yle ) represents the end point coordinates of the links segment. Then the road segment R corresponds to the vector The vector corresponding to each links segment The vector angle AN can be expressed as: in represents the dot product of two vectors, Represents the product of the magnitudes of two vectors.

[0050] After the distance calculation between the road segment R and the starting points of all links in the initial segment set NC0 is completed, as well as the vector angle between the corresponding vectors of the two is calculated; the links whose vector angle AN is less than the first preset angle and whose distance between starting points is ranked in the top several places are selected and added to the starting segment set RL0. In this embodiment, because the actual road segment may be curved, the first preset angle is selected to be a larger value such as 70 degrees; for the distance sorting between starting points, the first three links with the shortest distance can be selected.

[0051] Furthermore, the screening process of the initial road segment set NC0 includes: Extending a first preset distance in all directions with a line segment corresponding to the road segment to form a buffer circle; Filter out links whose starting or ending points fall within the buffer circle to form the initial link set NC0; If NC0 is empty, a fixed distance step is cyclically extended and then a new NC0 is obtained by re-screening; When NC0 is still empty after extending to the second preset distance, the road segment has no matching links segment information.

[0052] It should be noted that the process of screening the initial segment set NC0 from the links segment set is actually a preliminary screening of links segments that may match the road segments. In order to reduce the amount of calculation and speed up the initial screening during the preliminary screening, the initial segment set NC0 can be screened directly according to the distance between the position of the road segment and the position of the links segment, and the links segments whose distance between the two is within a certain distance range are selected as elements of the initial segment set that meet the requirements.

[0053] Specifically, the line segments corresponding to the road segment from the starting point to the end point are extended in all directions by a first preset distance to form a buffer circle related to the road segment. Therefore, most types of roads from the starting point to the end point of the road segment and with the road segment shapes of straight lines, small arcs and multiple bends can be included in the buffer circle. Then, the area enclosed by the buffer circle and the links segments in the links segment set are selected, and the links segments whose starting points or end points fall within the buffer circle are added to the initial segment set NC0 to complete the screening of the initial segment set NC0.

[0054] In actual situations, there is a buffer circle surrounded by the first preset distance where no corresponding links section is screened out. In this case, the buffer circle range with a fixed distance step can be increased, and the corresponding links section can be screened out again. At the same time, a second preset distance is set (even if there is a distance error between the position of the links section and the position of the corresponding road section, there is an upper limit range for the distance error. If the position difference exceeds the range of the distance error, it means that the road section and the links section are not matched). When the fixed distance step is continuously increased in a cycle until the second preset distance is reached, if the buffer circle still does not screen out the corresponding links section, it means that the road section has no matching links section.

[0055] As a specific embodiment, the links segments in the initial segment set NC0 that meet the second matching condition include: the distance between the starting point St of the target segment and the starting point Sl of the links segment is less than the first distance threshold; and the distance from the end point El of the links segment to St is greater than the distance from El to the end point Et of the target segment; and The distance from the starting point Sl to St of the links is less than the distance from Sl to Et; and The angle between the vector from St to S1 and the vector from St to El is less than a second preset angle; The target segment of each loop is the links segment matched in the previous loop.

[0056] It should be noted that the second matching condition is used to match the path set. It is based on the previous links segment in the path set to match the next links segment that meets the second matching condition with the previous links segment, and the cycle is repeated until the last links segment in the matched path set meets the loop termination condition.

[0057] For the second matching condition, the purpose is to match the next links segment that is close in position and roughly in the same direction as the previous links segment and matches the corresponding vector direction of the road segment, and then sequentially connect each links segment in the path set to obtain the corresponding trajectory to match the road segment. Therefore, in addition to the distance between the starting point of the target segment and the starting point of the links segment being less than the first distance threshold, the distances between the two endpoints of the links segment and the target segment are also limited, and the range of the vector angle between the target segment and the links segment is also limited.

[0058] Specifically, a link segment in the starting segment set RL0 of the road segment is used as the starting segment for illustration, and the starting segment is used as the target segment. Its starting point St and end point Et can be expressed as (lo s , la s ;lo e , la e ), the coordinates before the semicolon represent the location of the starting point St, and the coordinates after the semicolon represent the location of the end point Et. The starting point S1 and the end point E1 of the links segment to be matched in the links segment set can be expressed as (lo sn , la sn ;lo en ,la en ).

[0059] In the second matching condition, the distance between the target segment and the starting point of the links segment is first calculated: Select the links section in the initial section set NC0 whose starting point S1 of the links section is less than the first distance threshold to the starting point St of the target section. In this embodiment, the first distance threshold can be selected as 150 meters, that is, select all the links sections in the initial section set NC0 whose dis1 is less than 150 meters.

[0060] After completing the above selection, select the end point of the links section El (lo en , la en ) to the starting point St(lo s ,la s ) is greater than the end point of the links segment E1(lo en , la en ) to the end point of the target section Et(lo e ,la e ) distance; and the starting point of the links segment Sl(lo sn , la sn ) to the starting point St(los ,la w ) is less than the starting point Sl(lo sn , la sn ) to the end point of the target section Et(lo e , la e ) links segment. This condition is set to ensure that the next links segment in the path set always moves in the vector direction of the road segment relative to the previous links segment, and the projections of two adjacent links segments in the direction of the road segment are connected or overlapped, that is, not discontinuous, thereby ensuring the continuity of the trajectory formed by the links segments in the final path set.

[0061] Finally, the vector angle between the target road segment corresponding vector and the links road segment corresponding vector to be matched is screened and matched, such as Figure 4 The figure shows a schematic diagram of the vector angle between the target section and the links section to be matched. When calculating the vector angle between the target section and the links section to be matched, the angle between the vector from the starting point St of the target section to the starting point S1 of the links section and the vector from the starting point St of the target section to the end point El of the links section is used as the vector angle ANc between the target section and the links section in the second matching condition. The specific calculation formula of the vector angle ANc is the same as the calculation formula of the vector angle AN, and is not described in detail here. Select the links section whose vector angle ANc is less than the second preset angle. In this embodiment, the second preset angle can also be set to 70 degrees or set according to actual needs.

[0062] The links segments that meet all the second matching conditions in the initial segment set NC0 are screened out and can all be used as the next links segment after the starting segment. Then the matched links segments are used as new target segments to continue matching subsequent links segments in the initial segment set NCO, until the last links segment in the final path set is used as the target segment and the loop termination condition is met, thus completing the matching of the entire path set.

[0063] Furthermore, the target road segment meets the cycle termination conditions including: The end point of the target segment coincides with the end point of the road segment, or the distance between the end point of the target segment and the end point of the road segment is less than a second distance threshold.

[0064] It should be noted that in order to complete the matching of road segments and links segments in the present invention, the trajectory formed by connecting the links segments in the matched path set can reflect the actual shape of the road segment. In this case, the last links segment in the path set should be the links segment closest to the end point of the road segment. The distance between the end point of the links segment and the end point of the road segment is used as the judgment condition for loop termination.

[0065] Specifically, the distance dis2 between the end point of the target section and the end point of the road section is calculated. The specific calculation method is the same as the calculation method of dis0 and dis1, so it is not described in detail. If the end point of the target section coincides with the end point of the road section, the distance between the two is zero, which also meets the condition of being less than the second distance threshold. Therefore, only the parameters of the second distance threshold need to be set (the second distance threshold can be selected as 100 meters in this embodiment). When the distance dis2 is less than the second distance threshold, the cyclic matching is stopped.

[0066] As a specific embodiment, when a road segment is matched to obtain several path sets, the first priority is the one whose trajectory composed of links segments in the path set has the smallest average distance from the beginning to the end of the road segment; The minimum distance between the starting points of two adjacent links is the second priority; The minimum angle between the corresponding vectors of two adjacent links is the third priority; The fourth priority is the one with the smallest angle between the vector corresponding to the starting links segment and the vector corresponding to the road segment; select a path set.

[0067] It should be noted that, firstly, there may be multiple links in the starting segment set, and each of the links is used as the starting segment to match the road segment to obtain a path set. Then, the number of path sets is at least the number of links in the starting segment set. Also, when the links in each starting segment set is used as the starting segment to match the second matching condition, each target segment may also have multiple links that meet the second matching condition. Therefore, each links is used as a subsequent target segment for matching according to the tree branch. By analogy, it can be seen that multiple path sets can actually be matched. In this case, different priority conditions can be used for screening and finally a path set can be selected to match the road segment.

[0068] Specifically, in the first priority, the average distance between the trajectory composed of links and the beginning and end of the road segment is calculated. In this embodiment, the average distance dis3 = (dis0 + dis2) / 2, that is, the average of the distance dis0 between the beginning of the road segment and the beginning of the starting segment and the distance dis2 between the end of the road segment and the end of the last links segment in the path set. The one with the smallest position difference between the beginning and the end is the highest priority.

[0069] In the second priority, the distance dis1 between the starting points of two adjacent links in the path set is calculated. Since a dis1 is calculated for each cyclic matching of a links in the path set, the dis1 of each match can be arranged according to the matching order of the links in the path set, and the smallest dis1 is selected according to the arrangement order. That is, for multiple path sets (each path set will have a first dis1 according to the order of cyclic matching, that is, the distance between the starting segment and the starting point of the second links; the second dis1, that is, the distance between the second links and the starting point of the third links; and so on), select the path set with the smallest first dis1. If there are still multiple path sets with the smallest first dis1, select the path set with the smallest second dis1 in order, and so on.

[0070] In the third priority, the vector angle ANc between the corresponding vectors of two adjacent links is calculated. The priority selection method of the vector angle ANc is the same as the selection method of the distance dis1 in the second priority; that is, the first path set with the smallest ANc is selected. If there are multiple path sets with the smallest first ANc, the second path set with the smallest ANc is selected in order, and so on.

[0071] The fourth priority calculation is to calculate the angle AN between the vector corresponding to the starting links segment and the vector corresponding to the road segment, and select the path set with the smallest vector angle AN. After screening the path sets of each priority, a path set that finally matches the road segment is obtained.

[0072] Finally, the matching credibility of each road segment at each adjacent intersection is scored based on ANc, dis1, AN and dis3. The scoring rule is that if dis3 is less than 20 meters, dis1 < 10 meters, AN < 50 degrees, and ANc < 50 degrees, the credibility is greater than 0.95, and in other cases it is less than 0.95.

[0073] Furthermore, according to the road sections corresponding to the entrances contained in each intersection, the intersection and the corresponding links section information are matched and bound.

[0074] like Figure 5 As shown, after matching and obtaining the path set of each road segment, the intersection and links segment information are matched and bound according to the intersection relationship of the road segments at the intersection. In the prior art, the traffic status of the intersection is analyzed by considering the traffic status of all the entrances contained in the intersection, so in the present invention, each entrance of the intersection corresponds to a road segment with the intersection as the end point. That is, all road segments with a certain intersection as the end point finally intersect at the intersection, and the path set matching these road segments is matched and bound to the corresponding intersection, thereby completing the matching and binding of the intersection and links segment information.

[0075] As an optional embodiment, the intersection traffic status assessment includes intersection congestion alarm: Get the links section information of the corresponding entrance of the intersection, extract the links status marked from 1 to 5 from smooth to congested, and the links speed; For each import, the links with the most severe congestion and the lowest speed are selected for judgment; When the links status of at least two imports is 3 or the links status of at least one import is greater than 3, a congestion alarm is issued.

[0076] It should be noted that the intersection congestion alarm in the present invention mainly reflects the degree of congestion at the intersection and is the main indicator reflecting the traffic status at the intersection. When evaluating the traffic status at the intersection, the specific traffic status of the entrances included in the intersection is comprehensively considered to obtain the final result.

[0077] It is worth noting that the links status can be classified into five levels using the existing traffic status classification method, namely "smooth", "basically smooth", "mild congestion", "moderate congestion" and "severe congestion". The specific classification method of traffic status can adopt the existing classification method, so it is not described in detail. After the congestion level is divided into five levels, 1, 2, 3, 4 and 5 are marked from low to high according to the congestion level to represent the links status. That is, the higher the value, the more congested the traffic state corresponding to the links status.

[0078] Specifically, step 1: obtain the links status of the entrance corresponding to the intersection; the links section information includes not only the starting and ending positions of the links section, but also the vehicle driving data corresponding to the links (such as vehicle speed, current traffic status, etc.). When evaluating the status of the intersection congestion alarm, first match the links status of the entrance corresponding to the intersection, that is, obtain the traffic status of the entrance.

[0079] Step 2: Determine whether it is the no-alarm period at night (the no-alarm period at night is a parameter that can be configured by yourself). If it is, it is determined to be a normal state and jumps to Step 5 output. That is, when there is no alarm at night, the corresponding data needs to be recorded. If it is not the no-alarm period at night, proceed with the subsequent operations.

[0080] Step 3: If each import contains multiple links status information, the link status with the most serious congestion status is selected for judgment (if no import is matched, the link is discarded). If it still contains multiple links status information, the one with the lowest speed is selected for subsequent judgment. If there is only one piece of data for this import and state = 5, the data is an abnormal value and does not enter the subsequent calculation.

[0081] Step 4: If the traffic status of at least two entrances is light congestion (state=3) or at least one entrance is severe congestion / moderate congestion (state>3), the intersection is recorded as congestion alarm state; Step 5: Output data and fill in the alarm information with the status of the links finally used by each import.

[0082] As an optional embodiment, the intersection traffic status assessment also includes an intersection imbalance alarm: Get the links section information corresponding to the entrance of the intersection, calculate the congestion delay index of the entrance and the intersection imbalance index of the intersection; When the intersection imbalance index is greater than the preset index threshold; and the links status corresponding to the entrance with the smallest congestion delay index is less than 3; and the links status corresponding to the entrance with the largest congestion delay index is greater than 3; an intersection imbalance alarm is issued.

[0083] It should be noted that the status evaluation of the intersection congestion alarm can be directly judged and evaluated based on the acquired links section information, while the evaluation is required after processing the links section information when performing the intersection imbalance alarm. Intersection imbalance means that at a certain intersection, there are several entrance directions with very congested vehicles and the road is not smooth, while the vehicles in the other entrance directions are less and very smooth. The uneven traffic flow in each direction requires adjustment of the signal timing.

[0084] Specifically, first calculate the congestion delay index of the import. According to the current road grade extracted from the links road section information, match the corresponding free flow speed according to the road grade. The specific calculation method of the free flow speed can be obtained by using any existing method, so no detailed description will be given. In the case of obtaining the corresponding free flow speed, for example, the free flow speed corresponding to the highway is 50 km / h, the free flow speed corresponding to the expressway is 40 km / h, the free flow speed corresponding to the main road is 25 km / h, and the free flow speed of the secondary road is 20 km / h.

[0085] Calculate the congestion delay index of the import = free flow speed / links speed; then perform a corrected assignment according to the calculation result: 1) If the value is less than 1, assign it as 1; 2) If the links speed is a null value, assign it as 1; 3) If 0 < links speed < free flow speed / 5, assign it as 6 - 5 * (link speed / free flow speed); 4) If links speed = 0 and state = 5, assign it as -1; 5) If links speed = 0 and state < 5, assign it as 5.99.

[0086] Calculate the average value of the intersection congestion index = the status value of the most congested import at the intersection + 0.15 * the sum of the congestion delay indexes of the imports (corresponding road sections) with data at the intersection / the number of imports with data (for example, the status of the most congested import state = 3, and the calculated average value of the import congestion index is 4, then the final output value is 3 + 0.15 * 4 = 3.6).

[0087] After calculating the congestion delay index of the import, step1: Calculate the intersection imbalance index of the intersection: intersection imbalance index = the maximum congestion delay index among all imports at the intersection / the minimum congestion delay index among all imports at the intersection.

[0088] Step2: Obtain the road section status of the import with the largest congestion delay index at the intersection and the road section status of the import with the smallest congestion delay index at the intersection. For each import, if it contains multiple links status information, take the most congested links status for judgment (if the import cannot be matched, discard the links). If there are still multiple links status information, take the lowest speed to enter the subsequent judgment.

[0089] Step3: Determine whether it is the non-alarm period at night (the non-alarm period at night is a parameter that can be configured by itself). If so, judge it as the normal state and jump to Step5 for output. That is, even in the case of no alarm at night, the corresponding data also needs to be recorded. If it is not the non-alarm period at night, perform subsequent operations.

[0090] Step 4: If the intersection imbalance index is greater than or equal to 3 (the intersection imbalance index threshold can be configured according to actual needs); and the traffic state of the corresponding section of the entrance with the smallest congestion delay index is normal or basically unobstructed (state<3); and the traffic state of the corresponding section of the entrance with the largest congestion delay index is moderately congested or severely congested (state>3); then it is recorded as an intersection imbalance alarm, and the entrance direction with the largest congestion delay index and the entrance direction with the smallest congestion delay index are recorded.

[0091] Step 5: Output the intersection number, start time, end time, intersection imbalance index, whether to issue an intersection imbalance alarm, the entrance direction with the largest congestion delay index and the entrance direction with the smallest congestion delay index, and update the current time.

[0092] The present invention can accurately match a large amount of mixed vehicle links section information with its corresponding road section, thereby matching and binding to the corresponding intersection, so as to evaluate and alarm the traffic status of the intersection according to the links section information corresponding to the correctly matched intersection; in the process of matching the road section and the links section information, the starting links section that meets the conditions is screened according to the distance between the starting point of the links section and the starting point of the road section, and the vector angle between the two, and then the links section is cyclically matched according to the distance relationship and the vector angle relationship between adjacent links sections until the loop termination condition is met, and a plurality of path sets corresponding to a certain road section are obtained. For a large number of path sets, the path set that best meets the requirements can be selected according to the priority selection condition to match the road section, which can not only complete the matching of the road section and the links section, but also the trajectory spliced ​​and combined by the links sections in the path set can approximately reflect the specific shape of the road section.

[0093] The above embodiments are further elaborations and illustrations of the present invention for ease of understanding, and are not limitations of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for warning the traffic status of urban ground intersections based on links section matching, characterized in that: include: Get the location information of each intersection of the city's ground roads and the links section information; Based on matching the road segments between adjacent intersections with the links segment information, a path set including a plurality of links segment information corresponding to the road segments is obtained; According to the road sections corresponding to the entrances contained in each intersection, the intersection and the corresponding links section information are matched and bound; The traffic status of the intersection is evaluated based on the links section information corresponding to the intersection, and an alarm is issued when the preset alarm conditions are met.

2. The method for warning the traffic status of urban ground intersections based on links road segment matching according to claim 1 is characterized in that: The matching process of the path set includes: Filter out a starting point segment set that meets the first matching condition with the starting point of the road segment from the links segment set; Taking each links segment in the starting segment set as the start of the path set, cyclically matching the links segments in the initial segment set NC0 that meet the second matching condition with the target segment, until the target segment meets the loop termination condition; The target segment of each loop is the links segment matched in the previous loop.

3. A method for warning traffic status at urban ground intersections based on links section matching according to claim 1 or 2, characterized in that: The acquisition of the location information of each intersection and the links section information includes: Get the longitude and latitude coordinates of the intersection, get the topological point coordinates of the links section, and convert them to the same coordinate system; Determine the starting point coordinates and the ending point coordinates of the road section based on the connection lines and directions between adjacent intersections; Determine the start and end coordinates of the links segment based on the direction in the links segment information.

4. The method for warning the traffic status of urban ground intersections based on links road segment matching according to claim 2 is characterized in that: The matching process of the starting point road segment set includes: Filter out the initial segment set NC0 that meets the first screening condition with the road segments from the links segment set; Calculate the distance between the starting point of the road segment and the starting point of each link segment in NC0, as well as the vector angle between the corresponding vector of the road segment and the corresponding vector of each link segment; The first several links sections with the shortest distance and whose vector angle is less than the first preset angle are selected to form a starting point section set.

5. The method for warning the traffic status of urban ground intersections based on links section matching according to claim 2 or 4, characterized in that: The screening process of the initial road section set NC0 includes: Extending a first preset distance in all directions with a line segment corresponding to the road segment to form a buffer circle; Filter out links whose starting or ending points fall within the buffer circle to form the initial link set NC0; If NC0 is empty, a fixed distance step is cyclically extended and then a new NC0 is obtained by re-screening; When NC0 is still empty after extending to the second preset distance, the road segment has no matching links segment information.

6. The method for warning the traffic status of urban ground intersections based on links road segment matching according to claim 2 is characterized in that: The links segments that meet the second matching condition in the initial segment set include: The distance between the starting point St of the target segment and the starting point Sl of the links segment is less than the first distance threshold; and The distance from the end point El to St of the links segment is greater than the distance from El to the end point Et of the target segment; and The distance from the starting point Sl to St of the links is less than the distance from Sl to Et; and The angle between the vector pointing from St to S1 and the vector pointing from St to El is less than the second preset angle.

7. A method for warning traffic status at urban ground intersections based on links section matching according to claim 2, 4 or 6, characterized in that: The target road section meets the cycle termination conditions including: The end point of the target segment coincides with the end point of the road segment, or The distance between the end point of the target segment and the end point of the road segment is less than a second distance threshold.

8. The method for warning the traffic status of urban ground intersections based on links road segment matching according to claim 7, characterized in that: When a road segment is matched to obtain several path sets, the first priority is to take the path consisting of the links segments in the path set with the smallest average distance between the beginning and the end of the road segment; The minimum distance between the starting points of two adjacent links is the second priority; The minimum angle between the corresponding vectors of two adjacent links is the third priority; The fourth priority is the one with the smallest angle between the vector corresponding to the starting links segment and the vector corresponding to the road segment; select a path set.

9. The method for warning the traffic status of urban ground intersections based on links road segment matching according to claim 1, characterized in that: The intersection traffic status assessment includes intersection congestion alarm: Get the links section information of the corresponding entrance of the intersection, extract the links status marked from 1 to 5 from smooth to congested, and the links speed; For each import, the links with the most severe congestion and the lowest speed are selected for judgment; When the links status of at least two imports is 3 or the links status of at least one import is greater than 3, a congestion alarm is issued.

10. The method for warning the traffic status of urban ground intersections based on links segment matching according to claim 9, characterized in that: The intersection traffic status assessment includes intersection imbalance alarm: Get the links section information corresponding to the entrance of the intersection, calculate the congestion delay index of the entrance and the intersection imbalance index of the intersection; When the intersection imbalance index is greater than the preset index threshold; and the links status corresponding to the entrance with the smallest congestion delay index is less than 3; and The links status corresponding to the import with the largest congestion delay index is greater than 3; an intersection imbalance alarm is issued.

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