Method for evaluating applicability of single left turn of non-motor vehicle and setting left turn induction area

Abstract

The present invention discloses a method for evaluating the applicability of non-motor vehicle one-time left turns and setting left-turn induction areas, which relates to the technical field of urban road traffic safety design, and includes: obtaining the traffic flow operation video at the intersection; establishing a rectangular coordinate system for the intersection area and rasterizing it; determining the high-frequency occupied areas of the outer wheel tracks of left-turning motor vehicles in each direction; judging whether the intersection meets the spatial requirements for non-motor vehicles to make a one-time left turn on the opposite side of this road; for roads suitable for non-motor vehicles to make a one-time left turn on the opposite side, completing the setting of the non-motor vehicle left-turn safety induction line at the intersection; comprehensively considering the scene geometric characteristics and traffic flow operation characteristics of the intersection, judging whether the intersection can meet the lateral safety clearance requirements for non-motor vehicles to make a one-time left turn in each direction in terms of space, and for intersections meeting the conditions for non-motor vehicle one-time left turns, setting the inner and outer boundary lines of the non-motor vehicle left-turn passing induction area to clarify the right-of-way division between left-turning motor vehicles and non-motor vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of urban road traffic safety design, and particularly to a method for evaluating the applicability of non-motor vehicles making a one-time left turn and setting a left-turn induction area. Background Art

[0002] Urban road intersections, as key nodes of the urban road network, are not only the inducing points of traffic congestion but also the frequent accident points. In intersections, multi-directional traffic flows coexist in the same space, and various traffic participants frequently interfere with each other, which is extremely likely to cause traffic accidents. In China, a considerable number of traffic accidents related to non-motor vehicles occur in urban road intersections.

[0003] In recent years, with the increase in the number of non-motor vehicles in China, the traffic flow of non-motor vehicles at urban road intersections has also continued to increase significantly. At intersections without dedicated non-motor vehicle signal phases, non-motor vehicles generally travel according to the motor vehicle signal rules. At present, the planning, design, and management of urban roads still focus on motor vehicle traffic. When planning and constructing intersections, the spatial requirements of non-motor vehicle traffic operation are not fully considered, and there is still a lack of traffic control measures for non-motor vehicles, resulting in frequent problems of unclear road rights and mutual interference between left-turning motor vehicles and non-motor vehicles at intersections, which greatly affects the safety and efficiency of urban road traffic operation.

[0004] In actual scenarios, urban road intersections are diverse in type and characteristics, and different intersections vary in dynamic and static characteristics such as geometric dimensions and traffic flow composition. If the traffic organization method of non-motor vehicles making a one-time left turn or a two-time crossing the road is uniformly adopted without distinguishing the differences in intersection scenarios, it will inevitably lead to a waste of road resources or an increase in traffic operation risks. Therefore, an effective method is needed to effectively evaluate whether a non-motor vehicle one-time left turn is applicable to an urban road intersection. For intersections that can meet the needs of non-motor vehicles making a one-time left turn, it is also necessary to induce the passage of left-turning non-motor vehicles through traffic markings to clarify the road right division between left-turning motor vehicles and non-motor vehicles, reduce the lateral interference between motor vehicles and non-motor vehicles, and ensure the safety of motor vehicle and non-motor vehicle interaction.

[0005] Currently, the technical solutions around non-motor vehicle left turns at urban road intersections mainly focus on the interference of left-turning non-motor vehicles on straight-through motor vehicles, and mainly carry out technical solution design from two aspects: optimizing the geometric design of intersections and traffic organization.

[0006] In terms of geometric design optimization, aiming at the traffic conflict between left-turning non-motor vehicles and straight-going motor vehicles at continuous flow intersections, Zhao Jing et al. [1] proposed an optimized design method for left-turn non-motor vehicle lanes, setting the left-turn non-motor vehicle lanes between the motor vehicle exit lanes and the left-turn lanes, and completing left-turns following the motor vehicle signals. Song Lang et al. [2] optimized and improved the geometric layout of intersections, set up a left-turn non-motor vehicle waiting area in the non-motor vehicle crosswalk area on the side close to the main signal between the shifted left-turn lanes and the exit lanes, and optimized the signal phase settings of intersections with the maximum motor vehicle throughput as the optimization goal. Yu Haiming [3] aimed at four-phase urban road intersections, and proposed a method for adjusting the traffic path of left-turn motor vehicles from the perspective of the design of the motor vehicle stop line at the approach, by analyzing the expansion characteristics of left-turn non-motor vehicle flows in the intersection and their impact on the traffic capacity of the intersection.

[0007] In terms of traffic organization, Gu Chenyang [4] took two-phase intersections as the research scenario, analyzed the differences in safety costs and delay costs between the two traffic organization methods of non-motor vehicle one-time left-turn and two-time crossing at intersections, and gave the traffic flow thresholds applicable to different non-motor vehicle left-turn traffic organization methods. Zhang Wenkai [5] qualitatively analyzed the applicable conditions of non-motor vehicle one-time left-turn crossing from the perspectives of the separation form between motor vehicles and non-motor vehicles, non-motor vehicle traffic volume, non-motor vehicle approach width, left-turn phase duration, etc., and proposed a method for setting non-motor vehicle left-turn phases considering the traffic characteristics of non-motor vehicles. Zhang Weihua et al. [6] proposed a regulation method for non-motor vehicle left-turn dedicated lanes based on the expansion characteristics of non-motor vehicle traffic flows, determined the maximum collision width and the shortest distance between trajectories of left-turn non-motor vehicle flows according to the left-turn trajectories of non-motor vehicles, and then adjusted the number and red-light duration of non-motor vehicle left-turn dedicated lanes according to the safety distance requirements.

[0008] In summary, the existing technical solutions mainly focus on how to apply non-motor vehicle one-time left-turn to urban road intersections from the perspectives of intersection optimization design, traffic organization, etc., but there is still a lack of an effective method for evaluating the applicability of non-motor vehicle one-time left-turn at urban road intersections with independent left-turn phases for motor vehicles, and there is also a lack of a marking setting method for safely guiding the left-turn path of non-motor vehicles in the intersection. Summary of the Invention

[0009] In order to make up for the deficiencies of existing technical problems, the purpose of the present invention is to provide a method for evaluating the applicability of non-motor vehicle one-time left-turn and setting a left-turn induction area, comprehensively considering the geometric characteristics of the intersection scene and the traffic flow operation characteristics, judging whether the intersection can meet the lateral safety clearance requirements for one-time left-turn of non-motor vehicles in all directions in space. For intersections that meet the conditions for non-motor vehicle one-time left-turn, the inner and outer boundary lines of the non-motor vehicle left-turn traffic guidance area are set by using spline curve fitting and optimization methods, clarifying the right-of-way division between left-turn motor vehicles and non-motor vehicles.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for evaluating the applicability of non-motor vehicle one-time left-turn and setting a left-turn induction area, comprising the following steps:

[0012] (1) Obtain the traffic flow operation video of the intersection

[0013] For any urban road intersection with an independent left-turn phase for motor vehicles, use a drone to orthographically capture a long-time traffic operation video;

[0014] (2) Establish a rectangular coordinate system for the intersection area and rasterize it;

[0015] (3) Determine the high-frequency occupancy areas of the outer wheel tracks of left-turning motor vehicles in each direction

[0016] According to the video data in step (1), obtain the trajectory bands of all left-turning motor vehicles, calculate the grid cell positions occupied by each left-turning motor vehicle trajectory band, count all the left-turn trajectories obtained from the aerial photography, obtain the occupancy frequencies of all grid cells G in the intersection area, screen out the high-frequency occupancy areas of the left-turn motor vehicle trajectory bands, and screen out the high-frequency occupancy areas of the outer wheel tracks of left-turning motor vehicles in each direction from the high-frequency occupancy areas;

[0017] (4) Evaluation of the applicability of non-motor vehicle one-time left-turn at the intersection

[0018] Determine the pair of grid cells GS1 and GS2 with the smallest distance, compare the distance between GS1 and GS2 with the minimum lateral safety distance required for oncoming non-motor vehicles to turn left simultaneously in the intersection, and judge whether the intersection meets the spatial requirements for oncoming non-motor vehicles to turn left once on this road;

[0019] (5) Setting of the non-motor vehicle left-turn induction area

[0020] For roads suitable for oncoming non-motor vehicles to turn left once, according to the positions of the exit lane and the entrance lane of left-turning non-motor vehicles in the intersection and the position of the minimum distance between the high-frequency occupancy areas of the outer wheel tracks of oncoming left-turning motor vehicles, fit spline curves respectively to determine the function expressions of the inner and outer boundaries of the non-motor vehicle left-turn induction line, and complete the setting of the non-motor vehicle left-turn safety induction line at the intersection.

[0021] The establishment of the rectangular coordinate system for the intersection area is specifically as follows:

[0022] For two intersecting roads at the intersection, with the intersection point of the axes of the intersecting roads as the origin, the axis direction of one of the intersecting roads as the positive x-axis, and the direction obtained by rotating the x-axis counterclockwise by 90 degrees as the positive y-axis, establish a plane coordinate system xOy.

[0023] Grid division of the intersection area is as follows:

[0024] According to the conversion ratio r between the size of the aerial image of the intersection and the actual scene size, calculate the image projection length δ of the actual size L, and use δ as the unit length to rasterize the aerial image of the intersection into m*n grid cells, where m and n are the number of grid rows and columns respectively, and use the center point coordinates of each grid as the grid coordinates.

[0025] Determination of the trajectory band of left-turn motor vehicles:

[0026] 1.1) Take the centroid of the motor vehicles in the intersection as the tracking point, and extract the continuous trajectory point coordinates of all left-turn motor vehicles on two intersecting roads;

[0027] 1.2) Identify the type of motor vehicle corresponding to each trajectory respectively, assign values to the body widths of different types of motor vehicles, and offset the trajectory points 1 / 2 of the body width inward and outward along the radial direction of the trajectory respectively;

[0028] 1.3) Connect the discrete trajectory points after inner and outer offsets in sequence to obtain inner and outer wheel tracks and connect their heads and tails to form a closed area, and obtain the trajectory bands of all left-turn vehicles.

[0029] Determination of the high-frequency occupied area of the outer wheel track of each left-turn motor vehicle is as follows:

[0030] 2.1) Calculate the grid cell positions occupied by each left-turn motor vehicle trajectory band,

[0031] 2.2) Statistically analyze all K left-turn trajectory bands obtained from the aerial photography to obtain the occupancy frequency of all grid cells G in the intersection area. For the grid cell in the i-th row and j-th column, use f i,j / K to represent its occupancy frequency; screen all grid cell sets θ with an occupancy frequency f i,j / K greater than or equal to 85% to obtain the high-frequency occupied area of the left-turn motor vehicle trajectory band;

[0032] 2.3) For the left-turn trajectory where the y coordinate of the trajectory point gradually increases as the motor vehicle turns left, only retain the cell with the largest x value among the grid cells with the same y coordinate in the high-frequency occupied area Θ of the trajectory band; for the left-turn trajectory where the y coordinate of the trajectory point gradually decreases as the motor vehicle turns left, only retain the cell with the smallest x value among the grid cells with the same y coordinate in the high-frequency occupied area Θ of the trajectory band, and obtain the high-frequency occupied areas of the outer wheel tracks of left-turn motor vehicles in each direction respectively.

[0033] Evaluation of the applicability of a single left turn of non-motor vehicles at the intersection is as follows:

[0034] 3.1) The high-frequency occupied areas of the outer wheels of left-turning motor vehicles in two directions on the same road are respectively denoted as M1 and M2. Calculate the distances between pairwise grid cells in M1 and M2, and determine the pair of grid cells GS1 and GS2 with the minimum distance.

[0035] The minimum value d of the distance between the grid pairs min :

[0036]

[0037] where: (x s1 , y s1 ), (x s2 , y s2 ) are the coordinates of a pair of grid cells G S1 and G S2 with the minimum distance;

[0038] 3.2) The minimum lateral safety distance required for oncoming non-motor vehicles to turn left simultaneously at the intersection:

[0039] d saf = 2L 非机动车 + 2h 1 + h 2 (2)

[0040] L 非机动车 is the width of the non-motor vehicle, and h 1 , h 2 are respectively the minimum lateral safety distances when the non-motor vehicle travels in parallel with the oncoming motor vehicle and the oncoming non-motor vehicle;

[0041] 3.3) Compare the magnitudes of d min and d saf . If d min < d saf , it indicates that the intersection cannot meet the spatial requirements for oncoming non-motor vehicles to turn left once on this road, and it is not applicable for oncoming non-motor vehicles to turn left once in this direction; if d min ≥ d saf , it indicates that the intersection meets the spatial requirements for oncoming non-motor vehicles to turn left once on this road, and it is applicable for oncoming non-motor vehicles to turn left once in this direction.

[0042] The specific setting of the safety guiding line for non-motor vehicles turning left at the intersection is as follows:

[0043] 4.1) For the grid pair G S1 and G S2 with the minimum distance between the high-frequency occupied areas of the outer wheels of oncoming left-turning motor vehicles, take the midpoint C of the line connecting their center points, and calculate its coordinates according to the following formula:

[0044]

[0045] 4.2) On the shortest distance connection line G S1 G S2 Take two points at a distance of 1 / 2h from point C on both sides of point C 2 and denote them as C 1 and C 2 points respectively, and their coordinates are (x C1 , y C1 ), (x C2 , y C2 ), where C 1 , C 2 are close to G S1 , G S2 respectively; take two points at a distance of h S1 , G S2 from the two end points of G 1 and denote them as C 3 and C 4 , and their coordinates are (x C3 , y C3 ), (x C4 , y C4 );

[0046] 4.3) Denote the inner and outer edge points of the end cross-section of the non-motor vehicle exit lane where non-motor vehicles turning left in the same driving direction as the motor vehicles turning left in the grid cell occupying G S1 as D I and D E points respectively, and their coordinates are (x DI , y DI ), (x DE , y DE ), and the tangent slope of the non-motor vehicle exit lane end point is k D ; denote the inner and outer edge points of the starting cross-section of the non-motor vehicle entrance lane where non-motor vehicles turning left in this direction as S I and S E points respectively, and their coordinates are (x SI , y SI ), (x SE , y SE ), and the tangent slope of the non-motor vehicle entrance lane end point is k S ;

[0047] Using point S E and point D E as the starting point and the end point respectively, and using point C 1 as the control point, fit a cubic spline curve. The spline curve equations of the S E C 1 section and the C 1 D E section are as shown in Equation (4) and Equation (5) respectively:

[0048] F 1 F(x) = a 1 + b 1 (x - x SE ) + c 1 (x - x SE ) 2 + d 1 (x - x SE ) 3 (4)

[0049] F 2 F(x) = a 2 + b 2 (x - x C1 ) + c 2 (x - x C1 ) 2 + d 2 (x - x C1 ) 3 (5)

[0050] Where: a 1 , a 2 , b 1 , b 2 , c 1 , c 2 , d 1 , d 2 are all undetermined parameters;

[0051] The spline curve needs to satisfy the following formula:

[0052]

[0053] Where: F’(x) and F”(x) are the first-order and second-order derivatives of the spline curve respectively;

[0054] Based on the above conditions, the Lagrange multiplier method is used to optimize the calculation of the undetermined parameters of the spline curves F 1 (x) and F 2 (x). The optimization boundary constraints include: ① The absolute value of the tangent slope of the spline curve F 1 (x) at x = x SE is less than or equal to |k S |, and greater than or equal to the absolute value of the slope of the line connecting the center points of two adjacent grids corresponding to y = y 1 in the high-frequency occupied grid M SE of the inner wheel track of the motor vehicle turning left in this direction; ② The tangent slope of the spline curve F 2 (x) at x = x DE is greater than or equal to |k D |, and less than or equal to the absolute value of the slope of the line connecting the center points of two adjacent grids corresponding to x = x 1 in the high-frequency occupied grid MDE The absolute value of the slope of the line connecting the centers of two adjacent grid cells corresponding to the grid; ③ The spline curve F 1 (x) and F 2 (x) are equally divided along the x-axis direction from the starting point by a distance τ. For any equally divided point, find the grid cell with the closest Euclidean distance to M 1 and ensure that the sum of the distances between all equally divided points and their closest grid cells is minimized; On this basis, determine all undetermined parameters a 1 、a 2 、b 1 、b 2 、c 1 、c 2 、d 1 、d 2 values to obtain the spline curve formula, which is used as the inner edge line of the non-motorized vehicle left-turn induction area in this direction, on the side closer to the intersection center area;

[0055] Similarly, taking point D I and point S I as the starting point and the ending point respectively, and taking point C 3 as the control point, fit a cubic spline curve. The spline curve equations of section S E C 1 and section C 1 D E are as shown in equations (7) and (8) respectively:

[0056] F 3 (x) = a 3 + b 3 (x - x SI ) + c 3 (x - x SI ) 2 + d 3 (x - x SI ) 3 (7)

[0057] F 4 (x) = a 4 + b 4 (x - x C3 ) + c 4 (x - x C3 ) 2 + d 4 (x - x C3 ) 3 (8)

[0058] In the formula: a 3 、a 4 、b 3 、b 4 、c 3 、c4 , d 3 , d 4 are all parameters to be determined;

[0059] The spline curve needs to satisfy the following formula:

[0060]

[0061] Where: F’(x) and F”(x) are the first-order and second-order derivatives of the spline curve respectively;

[0062] Based on the above conditions, the Lagrange multiplier method is used to optimize the calculation of the parameters to be determined of the spline curves F 3 (x) and F 4 (x). The optimization boundary constraints include: ① The absolute value of the tangent slope of the spline curve F 3 (x) at x = x SI is less than or equal to |k S |, and greater than or equal to the absolute value of the slope of the line connecting the centers of two adjacent grids corresponding to the grid where y = y 1 in the high-frequency occupied grid M of the inner wheel track of the motor vehicle turning left in this direction; ② The absolute value of the tangent slope of the spline curve F SI 4 (x) at x = x DI is greater than or equal to |k D |, and less than or equal to the absolute value of the slope of the line connecting the centers of two adjacent grids corresponding to the grid where x = x 1 in the high-frequency occupied grid M of the outer wheel track of the motor vehicle turning left in this direction; ③ The spline curves F DI 3 (x) and F 4 (x) are equally divided along the x-axis direction from the starting point according to the distance τ. For any equally divided point, find the grid unit with the closest Euclidean distance to it in M 1 , and ensure that the distance between all equally divided points and the grid unit closest to them is greater than h 1 and the sum of all distances is the smallest; On this basis, determine the values of all parameters to be determined a 3 , a 4 , b 3 , b 4 , c 3 , c 4 , d 3 , d 4 , and obtain the spline curve formula, which is used as the outer edge line of the non-motor vehicle left-turn induction area in this direction, on the side close to the sidewalk area; So far, the setting of the non-motor vehicle left-turn induction line in this direction is completed; According to the above, the setting of the non-motor vehicle left-turn induction line in the other direction of this road can be realized.

[0063] Compared with the prior art, the beneficial effects of the present invention are:​​

[0064] (1) For any intersection with a dedicated left-turn phase for motor vehicles, based on obtaining the spatial occupancy characteristics of the left-turn motor vehicle flows in all directions, by determining the actual lateral clear distance available for non-motor vehicles turning left, the evaluation of the applicability of non-motor vehicles turning left once is completed, making the evaluation process and results of the applicability of non-motor vehicles turning left once more in line with the actual requirements of the safe operation of non-motor vehicle traffic flows.

[0065] (2) For any intersection applicable to non-motor vehicles turning left once, on the premise of fully ensuring the requirements for the lateral safety distance of left-turning non-motor vehicles and the smoothness of the driving trajectory, the functional expressions of the inner and outer boundaries of the safe induction area for left-turning non-motor vehicles can be determined according to the geometric characteristics of the intersection scene and the traffic operation state, which can be actually used for the measurement and painting of the induction markings for left-turning non-motor vehicles within the intersection, and can effectively clarify the road right-of-way allocation between non-motor vehicles and motor vehicles within urban road intersections from the infrastructure level, thereby reducing traffic conflicts between left-turning non-motor vehicles and motor vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is the flowchart of the method of the present invention.

[0067] Figure 2 is the schematic diagram of the construction and rasterization of the coordinate system in the intersection area of the present invention.

[0068] Figure 3 is the schematic diagram of the minimum lateral distance of the high-frequency occupancy area of the outer wheel track of oncoming left-turning non-motor vehicles of the present invention.

[0069] Figure 4 is the schematic diagram of the setting of the induction area for non-motor vehicles turning left once of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0071] As Figures 1-4 shown, the present invention discloses a method for evaluating the applicability of non-motor vehicles turning left once and setting a left-turn induction area, which is specifically as follows:

[0072] (1) Technical Overview

[0073] The technical framework of the method for evaluating the applicability of non-motor vehicles turning left once and setting a safe induction line at urban road intersections proposed by the present invention is as Figure 1 shown.

[0074] For any urban road intersection with an independent left-turn phase for motor vehicles, use an unmanned aerial vehicle (UAV) to orthogonally capture long-term traffic operation videos, establish a rectangular coordinate system for the intersection area, and rasterize it. Extract the driving trajectories of left-turn motor vehicles in each direction from the videos, determine the high-frequency occupied areas of the outer wheel tracks of left-turn motor vehicles, and calculate the minimum lateral distance between the high-frequency occupied areas of the outer wheel tracks of oncoming left-turn motor vehicles. Then, determine whether this minimum distance meets the minimum lateral distance requirement for non-motor vehicles to make a single left turn within the intersection. If it does not meet the requirement, it indicates that this intersection is not suitable for the traffic organization method of non-motor vehicles making a single left turn; if it meets the requirement, according to the positions of the exit lanes and entrance lanes of left-turn non-motor vehicles within the intersection and the position of the minimum distance between the high-frequency occupied areas of the outer wheel tracks of oncoming left-turn motor vehicles, fit spline curves respectively to determine the function expressions of the inner and outer boundaries of the non-motor vehicle left-turn guiding line, and complete the setting of the non-motor vehicle left-turn safety guiding line at the intersection. The following will detail each step of the technical solution of the present invention.

[0075] (2) Rasterization of the intersection area and construction of the left-turn motor vehicle trajectory band

[0076] If it is desired that non-motor vehicles can cross the intersection in a single left-turn manner, it is necessary to ensure that the area between oncoming left-turn motor vehicle flows within the intersection can meet the safety passage space requirements of left-turn non-motor vehicles.

[0077] For urban road intersections that allow oncoming traffic flows to turn left simultaneously, use a UAV to capture the traffic flow operation video at the intersection. For the image of the intersection area captured by the UAV, as Figure 2 shown, for two intersecting roads A and B at the intersection, with the intersection point of the axes of the intersecting roads as the origin, the axis direction of one of the intersecting roads as the positive x-axis, and the direction obtained by rotating the x-axis counterclockwise by 90 degrees as the positive y-axis, establish a plane coordinate system xOy. According to the conversion ratio r between the size (cm) of the intersection aerial image and the actual scene size (m), calculate the image projection length δ of the actual size of 10 cm, and use δ as the unit length to rasterize the intersection aerial image into m*n grid cells, where m and n are the number of grid rows and columns respectively, and use the center point coordinates of each grid as the grid coordinates.

[0078] Taking the centroid of motor vehicles within the intersection as the tracking point, the coordinate of consecutive trajectory points of all left-turning motor vehicles on two intersecting roads are extracted. The type of motor vehicle corresponding to each trajectory (compact car, large bus, large truck) is identified respectively, and the trajectory points are offset 1 / 2 vehicle body width towards the inside and outside along the radial direction of the trajectory. Specifically, for compact motor vehicles, large buses and large trucks, the actual offset distances are 0.9 m, 1.0 m and 1.25 m respectively, and the offset distances in the image space are 0.9r, 1.0r and 1.25r (the unit is cm). Then, the discrete trajectory points after inner and outer offset are connected in sequence to obtain the inner and outer wheel tracks, and their heads and tails are connected to form a closed area, obtaining the trajectory bands of all left-turning vehicles.

[0079] (3) Determination of the high-frequency occupancy area of the outer wheel track of each left-turning motor vehicle

[0080] Calculate the grid cell positions occupied by each left-turning motor vehicle trajectory band, that is, for any grid cell, if the trajectory band covers its center point, it is considered that the grid cell is occupied; otherwise, it is considered that the trajectory band does not occupy the grid cell. Statistics are carried out on all K left-turning trajectory bands obtained from aerial photography to obtain the occupancy frequency of all grid cells G in the intersection area. For the grid cell in the i-th row and j-th column, it is characterized by f i,j / K to represent its occupancy frequency. Screen the set θ of all grid cells where the occupancy frequency f i,j / K is greater than or equal to 85%, obtaining the high-frequency occupancy area of the left-turning motor vehicle trajectory band.

[0081] For the left-turning trajectory where the y coordinate of the trajectory point gradually increases as the motor vehicle turns left, only retain the cell with the largest x value among the grid cells with the same y coordinate in the high-frequency occupancy area θ of the trajectory band; for the left-turning trajectory where the y coordinate of the trajectory point gradually decreases as the motor vehicle turns left, only retain the cell with the smallest x value among the grid cells with the same y coordinate in the high-frequency occupancy area θ of the trajectory band. Then, the high-frequency occupancy areas M of the outer wheel tracks of left-turning motor vehicles in each direction are obtained respectively.

[0082] (4) Applicability evaluation of non-motor vehicle one-time left turn at intersection

[0083] Taking the intersecting road A as an example, as Figure 3 shown, the high-frequency occupancy areas of the outer wheel tracks of left-turning motor vehicles in two driving directions calculated according to the above method are M 1 and M 2 respectively. Further calculate the distances between pairwise grid cells in M 1 and M 2 , determine the grid cell pair G S1 and G S2 with the smallest distance, and calculate the minimum value d min of the grid pair distance according to the following formula:

[0084]

[0085] Where: (x s1 , y s1 ), (x s2 , y s2 ) are the coordinates of a pair of grid cells G S1 and G S2 with the smallest spacing.

[0086] Take the width of non-motor vehicles as 0.7 m, and denote the minimum lateral safety spacing when non-motor vehicles are running parallel to motor vehicles in the same direction and non-motor vehicles in the oncoming direction as h 1 and h 2 (in m). Calculate the minimum lateral safety distance (in m) required for oncoming non-motor vehicles to turn left simultaneously in the intersection according to the following formula:

[0087] d saf = 1.4 + 2h 1 + h 2 (2)

[0088] Compare the magnitudes of d min and d saf . If d min < d saf , it indicates that the intersection cannot meet the spatial requirements for oncoming non-motor vehicles to turn left once on this road, and it is not applicable for non-motor vehicles to turn left once in this direction; if d min ≥ d saf , it indicates that the intersection can meet the spatial requirements for oncoming non-motor vehicles to turn left once on this road, and it is applicable for non-motor vehicles to turn left once in this direction.

[0089] (5) Setting of non-motor vehicle left-turn induction area

[0090] If it is determined through applying Technical Step 4 that the intersection can meet the spatial requirements for oncoming non-motor vehicles to turn left once on Intersecting Road A, then set a left-turn induction area for left-turning non-motor vehicles. For the grid pair G S1 and G S2 with the smallest spacing in the area with high-frequency occupancy of the outer wheel tracks of oncoming left-turning motor vehicles, take the midpoint C of the line connecting their center points, and calculate its coordinates according to the following formula:

[0091]

[0092] For example Figure 4 , on this shortest distance connection line, take two points at a distance of 1 / 2h 2 from point C on both sides of point C and denote them as C 1 and C 2 points, and their coordinates are (x C1 , y C1), (x C2 , y C2 ); Take two points with a distance h 1 from both endpoints and denote them as C 3 and C 4 , and their coordinates are (x C3 , y C3 ), (x C4 , y C4 ).

[0093] Denote the inner and outer edge points at the end cross-section of the non-motor vehicle exit lane where left-turn non-motor vehicles drive out in a certain driving direction on the intersecting road A as D I and D E points, and their coordinates are (x DI , y DI ), (x DE , y DE ), and the tangent slope of the non-motor vehicle exit lane endpoint is k D ; Denote the inner and outer edge points at the starting cross-section of the non-motor vehicle entrance lane where left-turn non-motor vehicles drive in as S I and S E points, and their coordinates are (x SI , y SI ), (x SE , y SE ), and the tangent slope of the non-motor vehicle entrance lane endpoint is k S .

[0094] Taking point S E , point D E as the starting point and the ending point respectively, and taking point C 1 as the control point, fit a cubic spline curve. The spline curve equations of the S E C 1 section and the C 1 D E section are respectively as shown in Equation (4) and Equation (5):

[0095] F 1 (x) = a 1 + b 1 (x - x SE ) + c 1 (x - x SE ) 2 + d 1 (x - x SE ) 3 (4)

[0096] F 2 (x) = a 2 + b 2 (x - x C1 ) + c 2 (x - xC1 ) 2 +d 2 (x - x C1 ) 3 (5)

[0097] where: a 1 、a 2 、b 1 、b 2 、c 1 、c 2 、d 1 、d 2 are all undetermined parameters.

[0098] The spline curve needs to satisfy the following formula:

[0099]

[0100] where: F’(x) and F”(x) are the first - order and second - order derivatives of the spline curve respectively.

[0101] Based on the above conditions, the Lagrange multiplier method is used to optimize the calculation of the undetermined parameters of the spline curves F 1 (x) and F 2 (x). The optimization boundary constraints include: ① The absolute value of the tangent slope of the spline curve F 1 (x) at x = x SE is less than or equal to |k S |, and greater than or equal to the absolute value of the slope of the line connecting the center points of two adjacent grids corresponding to the grid where y = y 1 in the high - frequency occupied grid M of the inner wheel track of the motor vehicle turning left in this direction; ② The tangent slope of the spline curve F SE 2 (x) at x = x(x) at x = x DE is greater than or equal to |k D |, and less than or equal to the absolute value of the slope of the line connecting the center points of two adjacent grids corresponding to the grid where x = x 1 in the high - frequency occupied grid M of the outer wheel track of the motor vehicle turning left in this direction; ③ The spline curves F DE 1 (x) and F(x) and F 2 (x) are equally divided along the x - axis direction from the starting point by a distance of τ. For any equally - divided point, find the grid cell in M 1 with the closest Euclidean distance, and ensure that the sum of the distances between all equally - divided points and their closest grid cells is minimized. On this basis, determine all undetermined parameters a 1 、a 2 、b 1 、b 2 、c 1 、c 2 、d 1 、d2 The value of is used to obtain the spline curve formula, which is used as the inner edge line of the non-motor vehicle left turn induction area in that direction (close to the center area of ​​the intersection).

[0102] Similarly, with D I Point, S I The points are the starting point and the end point, with C 3 Points are control points, and cubic spline curves are fitted. E C 1 Duan and C 1 D E The spline curve equations of the segments are as follows:

[0103] F 3 (x) = a 3 +b 3 (xx SI )+c 3 (xx SI ) 2 +d 3 (xx SI ) 3 (7)

[0104] F 4 (x) = a 4 +b 4 (xx C3 )+c 4 (xx C3 ) 2 +d 4 (xx C3 ) 3 (8)

[0105] Where: a 3 、a 4 、b 3 、b 4 、c 3 、c 4 ,d 3 ,d 4 All parameters are pending.

[0106] The spline curve must satisfy the following formula:

[0107]

[0108] Where: F'(x) and F"(x) are the first and second order derivatives of the spline curve respectively.

[0109] Based on the above conditions, the Lagrange multiplier method is used to calculate the spline curve F 3 (x) and F 4The undetermined parameters of (x) are optimized and calculated. The optimized boundary constraints include: ① The spline curve F 3 (x) when x=x SI The absolute value of the slope of the tangent line at is less than or equal to |k S |, and greater than or equal to the left turn to the high-frequency occupancy grid M of the inner wheel track of the motor vehicle in this direction 1 y=y SI The absolute value of the slope of the line connecting the center points of two adjacent grids; ② Spline curve F 4 (x) when x=x DI The absolute value of the slope of the tangent line at is greater than or equal to |k D |, and is less than or equal to the high-frequency occupancy grid M of the outer wheel track of the motor vehicle in this direction 1 x=x DI The absolute value of the slope of the line connecting the center points of two adjacent grids; ③ The spline curve F 3 (x) and F 4 (x) is divided equally from the starting point along the x-axis according to the distance τ. For any equally divided point, find its distance from M 1 The nearest grid unit in the Central European style ensures that the distance between all equally divided points and the nearest grid unit is greater than h 1 And the sum of all spacings is the smallest. On this basis, determine all the parameters a to be determined 3 、a 4 、b 3 、b 4 、c 3 、c 4 d 3 d 4 The value of is used to obtain the spline curve formula, which is used as the outer edge line of the non-motor vehicle left turn induction area in this direction (close to the side of the sidewalk area). So far, the setting of the non-motor vehicle left turn induction line in this direction is completed.

[0110] On this basis, the same method is used to set a left-turn guidance line for non-motor vehicles turning left in the other direction on the intersecting road A. The same idea is used to determine whether non-motor vehicles on the intersecting road B can safely make a left turn. If so, the same method is used to set a left-turn guidance line.

[0111] References

[0112] [1] Zhao Jing, Xu Haijun, Gao Xing, Wang Tao. Optimal design method for left-turn non-motor vehicles at continuous flow intersections[J]. Transportation Systems Engineering and Information, 2018, 18(06): 178-186.

[0113] [2] Song Lang, Wang Jian, Yang Binyu, An Shi. Innovative Design of Left-turn Traffic Organization for Non-motor Vehicles at Continuous-flow Intersections [J]. Journal of Transportation Systems Engineering and Information Technology, 2022, 22(01): 225-233+242.

[0114] [3] Yu Haiming. Characteristics of Left-turn Traffic Flow of Non-motor Vehicles at Intersections and Spatial Planning Methods [D]. Hefei: Hefei University of Technology, 2021.

[0115] [4] Gu Chenyang. Research on Evaluation and Scheme Comparison of Left-turn Traffic Organization for Non-motor Vehicles at Two-phase Intersections [D]. Chengdu: Southwest Jiaotong University, 2017.

[0116] [5] Zhang Wenkai. Research on Traffic Organization of Left-turn Cross-street for Non-motor Vehicles at Urban Road Plane Intersections [J]. Municipal Engineering Technology, 2022, 40(9): 79-84.

[0117] [6] Zhang Weihua, Gan Yangyang, Bai Haijian, Zhang Fan, Shi Kang, Tian Libin, Zhu Wenjia, Zhu Kai. Regulation Method of Exclusive Left-turn Lane for Non-motor Vehicles Based on Expansion Characteristics of Bicycle Traffic Flow [P]. July 14, 2023, published.

[0118] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and the inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A method for evaluating the applicability of non-motor vehicle single left-turn and setting left-turn induction areas, characterized in that, it includes the following steps: (1) Obtain the traffic flow operation video of the intersection For any urban road intersection with an independent left-turn phase for motor vehicles, use an unmanned aerial vehicle to orthographically capture a long-term traffic operation video; (2) Establish a rectangular coordinate system for the intersection area and rasterize it; (3) Determine the high-frequency occupied areas of the outer wheel tracks of left-turning motor vehicles in each direction According to the video data in step (1), obtain the trajectory bands of all left-turning motor vehicles, calculate the grid cell positions occupied by each left-turning motor vehicle trajectory band, count all the left-turn trajectories obtained from the aerial photography, obtain the occupancy frequencies of all grid cells G in the intersection area, screen out the high-frequency occupied areas of the left-turning motor vehicle trajectory bands, and screen out the high-frequency occupied areas of the outer wheel tracks of left-turning motor vehicles in each direction from the high-frequency occupied areas; (4) Evaluation of the applicability of non-motor vehicle single left-turn at the intersection Determine the grid cell pair GS1 and GS2 with the smallest distance, compare the distance between GS1 and GS2 with the minimum lateral safety distance required for oncoming non-motor vehicles to turn left simultaneously at the intersection, and judge whether the intersection meets the spatial requirements for oncoming non-motor vehicles to make a single left-turn on the road; (5) Setting of non-motor vehicle left-turn induction areas For roads suitable for oncoming non-motor vehicles to make a single left-turn, according to the positions of the exit lanes and entrance lanes of left-turning non-motor vehicles in the intersection and the position of the minimum distance between the high-frequency occupied areas of the outer wheel tracks of oncoming left-turning motor vehicles, fit spline curves respectively to determine the function expressions of the inner and outer boundaries of the non-motor vehicle left-turn induction line, and complete the setting of the non-motor vehicle left-turn safety induction line at the intersection; The evaluation of the applicability of non-motor vehicle single left-turn at the intersection is specifically as follows: 3.1) The high-frequency occupied areas of the outer wheel tracks of oncoming left-turning motor vehicles on the same road are respectively denoted as M1 and M2, calculate the distances between pairwise grid cells in M1 and M2, and determine the grid cell pair GS1 and GS2 with the smallest distance, The minimum value d of the grid pair spacing min : Where: (x s1 , y s1 ), (x s2 , y s2 ) are the coordinates of a pair of grid cells G S1 and G S2 with the smallest spacing; 3.2) The minimum lateral safety distance required for oncoming non-motor vehicles to turn left simultaneously at the intersection: d saf = 2L 非机动车 + 2h 1 + h 2 (2) L 非机动车 is the width of non-motor vehicles, h 1 , h 2 are respectively the minimum lateral safety clearances when non-motor vehicles are running parallel to motor vehicles in the same direction and to non-motor vehicles moving in the opposite direction; 3.3) Compare d min with d saf . If d min < d saf , it indicates that the intersection cannot meet the space requirement for the oncoming non-motor vehicles to make a left turn at one time on this road, and the one-time left turn of non-motor vehicles in the corresponding direction is not applicable; if d min ≥ d saf , it indicates that the intersection meets the space requirement for the oncoming non-motor vehicles to make a left turn at one time on this road, and the one-time left turn of non-motor vehicles in the corresponding direction is applicable.

2. According to the method for evaluating the applicability of non-motor vehicle single left-turn and setting left-turn induction areas according to claim 1, characterized in that, the establishment of the rectangular coordinate system for the intersection area is specifically as follows: For two intersecting roads at the intersection, with the intersection point of the axes of the intersecting roads as the origin, the axis direction of one of the intersecting roads as the positive x-axis, and rotating 90 degrees counterclockwise from the x-axis as the positive y-axis, establish a plane coordinate system xOy.

3. According to the method for evaluating the applicability of non-motor vehicle single left-turn and setting left-turn induction areas according to claim 1, characterized in that, the rasterization of the intersection area is specifically as follows: According to the conversion ratio r between the size of the intersection aerial photography image and the actual scene size, calculate the image projection length δ of the actual size L, and use δ as the unit length to rasterize the intersection aerial photography image into m*n grid cells, where m and n are the number of grid rows and columns respectively, and use the center point coordinates of each grid as the grid coordinates.

4. According to the method for evaluating the applicability of non-motor vehicle single left-turn and setting left-turn induction areas according to claim 3, characterized in that, Determination of the trajectory band of left-turning motor vehicles: 1.1) Taking the centroid of the motor vehicle in the intersection as the tracking point, extract the coordinates of consecutive trajectory points of all left-turning motor vehicles on two intersecting roads; 1.2) Identify the motor vehicle types corresponding to each trajectory respectively, assign values to the body widths of different types of motor vehicles, and offset the trajectory points 1 / 2 of the body width inward and outward along the radial direction of the trajectory respectively; 1.3) Connect the discrete trajectory points after the inner and outer offsets in sequence to obtain the inner and outer wheel tracks and connect their heads and tails to form a closed area, thereby obtaining the trajectory band of all left-turning vehicles.

5. According to the non-motor vehicle one-time left-turn applicability evaluation and left-turn induction area setting method described in claim 4, it is characterized in that the determination of the high-frequency occupancy area of the outer wheel track of each left-turning motor vehicle is specifically as follows: 2.1) Calculate the grid cell positions occupied by each left-turning motor vehicle trajectory band, 2.2) Statistically analyze all K left-turn trajectory bands obtained from aerial photography to obtain the occupancy frequencies of all grid cells G in the intersection area. For the grid cell in the i-th row and j-th column, use f i,j / K to represent its occupancy frequency; screen all grid cell sets θ whose occupancy frequency f i,j / K is greater than or equal to 85% to obtain the high-frequency occupancy area of the left-turn motor vehicle trajectory band; 2.3) For the left-turn trajectory where the y coordinate of the trajectory point gradually increases as the motor vehicle makes a left turn, only retain the cell with the largest x value among the grid cells with the same y coordinate in the high-frequency occupancy area θ of the trajectory band; for the left-turn trajectory where the y coordinate of the trajectory point gradually decreases as the motor vehicle makes a left turn, only retain the cell with the smallest x value among the grid cells with the same y coordinate in the high-frequency occupancy area θ of the trajectory band, and obtain the high-frequency occupancy areas of the outer wheel tracks of left-turning motor vehicles in each direction respectively.

6. According to the non-motor vehicle one-time left-turn applicability evaluation and left-turn induction area setting method described in claim 1, it is characterized in that the setting of the left-turn safety induction line for non-motor vehicles at the intersection is specifically as follows: 4.1) For the grid pair G with the smallest center distance in the high-frequency occupied area of the outer wheel track of the oncoming left-turning motor vehicle S1 and G S2 , take the midpoint C of the line connecting their center points, and calculate its coordinates according to the following formula: 4.2) On the shortest distance connection line G S1 G S2 On it, take two points at a distance of 1 / 2h from point C on both sides of point C 2 and denote them as C 1 and C 2 respectively. Their coordinates are (x C1 , y C1 ), (x C2 , y C2 ), where C 1 and C 2 are close to G S1 and G S2 respectively; take two points at a distance of h S1 from the two end points of G S2 and denote them as C 1 and C 3 respectively. Their coordinates are (x 4 , y C3 ), (x C3 ), (x C4 , y C4 ); 4.3) The left-turn non-motor vehicle exiting in the same driving direction as the left-turn motor vehicle occupying grid cell G S1 The inner and outer edge points of the end cross-section of the non-motor vehicle exit lane where the left-turn non-motor vehicle in the same driving direction exits are respectively denoted as D I and D E points, and their coordinates are respectively (x DI , y DI ), (x DE , y DE ). The tangent slope of the end point of the non-motor vehicle exit lane is k D ; The inner and outer edge points of the starting cross-section of the non-motor vehicle entrance lane where the left-turn non-motor vehicle in this direction enters are respectively denoted as S I and S E points, and their coordinates are (x SI , y SI ), (x SE , y SE ). The tangent slope of the end point of the non-motor vehicle entrance lane is k S ; Taking point S E and point D E as the starting point and the ending point respectively, and taking point C 1 as the control point, a cubic spline curve is fitted. The spline curve equations of segment S E C 1 and segment C 1 D E are respectively as shown in Equation (4) and Equation (5): F 1 f(x) = a 1 + b 1 (x - x SE ) + c 1 (x - x SE ) 2 + d 1 (x - x SE ) 3 (4) F 2 f(x) = a 2 + b 2 (x - x C1 ) + c 2 (x - x C1 ) 2 + d 2 (x - x C1 ) 3 (5) where: a 1 、a 2 、b 1 、b 2 、c 1 、c 2 、d 1 、d 2 are all undetermined parameters; The spline curve needs to satisfy the following formula: In the formula: F’(x) and F”(x) are the first and second derivatives of the spline curve respectively; Based on formulas (4), (5), and (6), the Lagrange multiplier method is used to optimize the calculation of the undetermined parameters of spline curves F 1 (x) and F 2 (x). The optimization boundary constraints include: ① The absolute value of the tangent slope of spline curve F 1 (x) at x = x SE is less than or equal to |k S | and greater than or equal to the absolute value of the slope of the line connecting the center points of two adjacent grids corresponding to the grid where y = y 1 in the high-frequency occupied grid M of the inner wheel track of the motor vehicle turning left in this direction; ② The SE of spline curve F 2 (x) at x = x DE is The tangent slope is greater than or equal to |k D | and less than or equal to the high-frequency occupied grid M of the outer wheel track of the motor vehicle turning left in this direction 1 where x = x DE the absolute value of the slope of the line connecting the centers of two adjacent grids of the corresponding grid; ③ Divide the spline curves F 1 (x) and F 2 (x) equally along the x-axis direction from the starting point according to the distance τ. For any equal division point, find the grid cell with the closest Euclidean distance to the equal division point in M 1 and ensure that the sum of the distances between all equal division points and their closest grid cells is the smallest; On this basis, determine all undetermined parameters a 1 、a 2 、b 1 、b 2 、c 1 、c 2 、d 1 、d 2 values to obtain the spline curve formula, which is used as the inner edge line of the non-motor vehicle left-turn induction area in this direction, on the side closer to the intersection center area; Taking D I point and S I point as the starting point and the ending point respectively, and taking C 3 point as the control point, fitting a cubic spline curve, S E C 1 section and C 1 D E section of the spline curve equations are respectively as shown in Equation (7) and Equation (8): F 3 f(x) = a 3 + b 3 (x - x SI ) + c 3 (x - x SI ) 2 + d 3 (x - x SI ) 3 (7) F 4 f(x) = a 4 + b 4 (x - x C3 ) + c 4 (x - x C3 ) 2 + d 4 (x - x C3 ) 3 (8) Where: a 3 、a 4 、b 3 、b 4 、c 3 、c 4 、d 3 、d 4 are all parameters to be determined; The spline curve needs to satisfy the following formula: In the formula: F’(x) and F”(x) are the first and second derivatives of the spline curve respectively; Based on formulas (7)-(9), the Lagrange multiplier method is used to optimize the calculation of the undetermined parameters of the spline curves F 3 (x) and F 4 (x). The optimization boundary constraints include: ① The absolute value of the tangent slope of the spline curve F 3 (x) at x = x SI is less than or equal to |k S | and greater than or equal to the absolute value of the slope of the line connecting the centers of two adjacent grids corresponding to y = y 1 in the high-frequency occupied grid M SI of the inner wheel track of the motor vehicle turning left in this direction; ② The absolute value of the tangent slope of the spline curve F 4 (x) at x = x DI is greater than or equal to |k D | and less than or equal to the absolute value of the slope of the line connecting the centers of two adjacent grids corresponding to x = x 1 in the high-frequency occupied grid M DI of the outer wheel track of the motor vehicle turning left in this direction; ③ The spline curves F 3 (x) and F 4 (x) are equally divided along the x-axis direction from the starting point by a distance of τ. For any equally divided point, find the grid cell in M 1 with the closest Euclidean distance to the equally divided point, and ensure that the distance between all equally divided points and the grid cell closest to them is greater than h 1 and the sum of all distances is minimized; on this basis, determine the values of all undetermined parameters a 3 , a 4 , b 3 , b 4 , c 3 , c 4 , d 3 , d 4 to obtain the spline curve formula, which is used as the outer edge line of the non-motor vehicle left-turn induction area in this direction, on the side close to the sidewalk area; thus, the setting of the non-motor vehicle left-turn induction line in this direction is completed; according to the above settings, the setting of the non-motor vehicle left-turn induction line in the other direction of this road is realized.

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