A method for constructing a dynamic occlusion spatial model of the visible area of ​​a highway curve exit ramp

Abstract

The present invention discloses a dynamic occlusion space model of the visible area target area of ​​a curved exit ramp of a highway. First, the visible area target area of ​​the curved exit ramp is determined; secondly, the dynamic occlusion space model of the visible area target area of ​​the curved exit ramp is established, and the occlusion ratio and occlusion judgment model of the visible area target area are proposed; the present invention performs calculation and analysis on the actual road section to quantify the dynamic occlusion effect of the obstruction on the visible area target area of ​​the curved exit ramp. The dynamic occlusion space model of the visible area target area of ​​the curved exit ramp of the highway provided a basis for the setting of the curved exit ramp of the highway, the setting of the exit ramp area sign, the planting of plants, the scope of highway land acquisition, etc., and provides a reference for effectively solving the problem of the visible area of ​​the curved exit ramp of the highway being blocked.

Description

Technical Field

[0001] The invention belongs to the technical field of highway engineering, and in particular relates to a dynamic occlusion model and an occlusion judgment model for a visible target area of ​​a highway curve exit ramp. Background Art

[0002] The exit ramps of highways are connected to toll stations, service areas, hub interchanges and other facilities. Before entering the exit ramps, drivers need to perform complex actions such as turning, slowing down and weaving. Drivers need to obtain information from the road environment and make judgments in a very short time, and then take action. In accident analysis, although visual field obstruction is not the direct cause of the accident, if the visibility of the highway exit ramps is poor, especially the exit ramps at curves, the visual field will be blocked to a certain extent during the time when the driver obtains and judges the information. The driver cannot accurately obtain road information, cannot quickly make accurate judgments, decisions and take effective actions, which can easily lead to inaccurate judgments by the driver, causing operational errors and traffic accidents.

[0003] At the main exit of the expressway, lane changes, rear-end collisions, overtaking, rollovers, and driving behaviors that do not follow traffic signs and markings often occur. More than 40% of expressway accidents occur at the main exit, that is, within a certain distance upstream and downstream of the diversion area and at the exit ramp; 83% of interchange-related accidents occur at the entrance and exit of the expressway, of which 50% occur in the exit area. Affected by the topography and landforms, the exit site selection is limited, and the accidents occur more frequently. The visibility of the curved exit area is poor, and the occlusion problem is more serious. Most accidents occur within 300m upstream of the nose of the exit ramp, which is the area with the highest accident rate on the expressway. According to the accident data of the entrance and exit ramps of the Shanghai-Kunming Expressway (Hunan Section) from 2013 to 2015, the exit ramp accidents accounted for more than 70%, of which the exit ramp connected to the toll station accounted for 46.23%, the exit ramp connected to the service area accounted for 34.43%, and the exit ramp connected to the hub interchange accounted for 19.34%. According to statistics, 63% of accidents occurred between the main line and the deceleration lane, and 23% occurred in the triangle area at the nose of the diversion.

[0004] The statistics of the on-site obstruction of the exit ramps of 8 services, 25 toll stations, and 13 hub interchanges on the Shanghai-Kunming Expressway (Hunan Section) and the comparison with the accident-prone points found that the exit ramps with curved main lines are affected by the visual obstructions such as bridge piers, guardrails, slopes, plants, billboards, signs, monitoring facilities, etc. on the inner side of the curve, guardrails, anti-glare panels, plants, etc. on the median strip, and vehicles on the right traveling in the same direction, which are positively correlated with the accident rate. These visual obstructions not only interfere with the driver's information acquisition and reading, but also interfere with the driver's speed control, lane change, direction change and other vehicle operations.

[0005] The "Highway Grade Separation Design Regulations" (JTG / T D21-2014) stipulates that when there are objects such as bridge piers, guardrails, roadside slopes and plants that hinder visibility on the inside of the circular curve, and the radius of the circular curve is small, the lanes on the inside of the curve should be tested for parking sight distance, and the road section in front of the diverging nose should be tested for identification sight distance. When there are sight obstructions such as guardrails, anti-glare panels and plants on the dividing strip due to the small radius of the curve, the lanes on the outside of the curve close to the dividing strip should be tested for parking sight distance. This sight distance test is only a distance control measure to solve the problem of unobstructed visual domain. Therefore, it is urgent to determine the dynamic three-dimensional obstruction of the visual domain of the curved exit ramp by the obstruction through the study of the visual domain of the curved exit ramp, so as to propose effective measures to solve the problem of dynamic obstruction of the visual domain of the curved exit ramp. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for constructing a dynamic occlusion spatial model of the visible area target area of ​​a curved exit ramp of a highway. The present invention studies the problem of dynamic occlusion of the visible area of ​​a curved exit ramp. First, the visible area target area of ​​the curved exit ramp of the highway is determined, and a geometric model of the visual process is constructed, and the calculation equation of the visible area is derived; on this basis, a dynamic occlusion spatial model of the visible area target area of ​​the curved exit ramp of the highway is established; finally, the dynamic occlusion spatial model created is used to perform calculations and analysis on the Hunan section of the Shanghai-Kunming Expressway, and the results verify the correctness and effectiveness of the model.

[0007] The present invention is achieved through the following technical solutions:

[0008] A dynamic occlusion space model of a visible area target area of ​​a highway curve exit ramp is characterized in that the calculation equation of the occlusion ratio of the visible area target area of ​​the highway curve exit ramp of the model is:

[0009]

[0010] Where:

[0011] J z : Occlusion ratio, that is, the ratio of the volume of the invisible target area to the total volume;

[0012] V z : The volume of the target area that cannot be seen;

[0013] V: total volume of target area;

[0014] h: height of the target area;

[0015] S z : The bottom area of ​​the target area that cannot be seen;

[0016] S: bottom area of ​​the target area.

[0017] The method for constructing a dynamic occlusion space model of a visible area target area of ​​a highway curve exit ramp of the present invention comprises the following steps:

[0018] (1) Confirm the visible target area of ​​the curve exit ramp:

[0019] Based on the identification sight distance specified in the Highway Route Design Specifications (JTG D20-2017) and the Highway Intersection Design Specifications (JTG / T D21-2014), the identification process of the highway curve exit ramp is as follows: Figure 1 As shown in the figure, point F is the ground marking of the diverging nose. When the driver reaches the visual recognition point A, he finds the ground marking F of the diverging nose. After seeing the marking clearly, the vehicle drives at the main line speed v to the recognition point B. The distance traveled by the driver in this process is the visual recognition distance. This period of time is the visual recognition time t1; the time the driver needs to react from seeing the marking to taking action is the judgment time t2. During this period of time, the distance traveled to the action point C is the judgment distance. Starting from point C, the driver takes action. The distance from point C to point D where the driver observes the vehicle on the right and changes lanes is the action distance. The distance from point D to point F is the distance the driver travels during the vehicle deceleration process (possibly changing lanes), where the distance to find the gap to be inserted is The lane change distance for turning into the ramp is

[0020] According to the relevant provisions of the "Highway Grade Separation Design Regulations" (JTG / T D21-2014), the driver should be able to see the geometric structure of the fork ahead far beyond the recognition sight distance, and the exit ramp divergence nose should be placed within the effective viewing angle range of 10 to 20 degrees. What needs to be controlled is the lateral position of the nose within the viewing angle range. Therefore, the area area S of the visible area target of the curved exit ramp determined in this study is as follows: Figure 2 As shown, the area S is the range enclosed by the right side marking of the main lane of the deceleration section and the transition section to the rightmost roadbed edge line, that is, the range of S1 and S2.

[0021] The visual domain refers to the geographical range of a certain area of ​​three-dimensional space that can be seen by an observer. For the recognition process, the visual domain of the highway curve exit ramp starts from the visual recognition point A where the exit is visible, all the way to the action point C. The volume from the driver's visual height h to the visible target of the exit ramp is the volume of the visual domain, such as Figure 3 shown.

[0022] (2) Calculation of the visible target area of ​​the highway curve exit ramp;

[0023] The visible target area S of the highway curve exit ramp determined in this study is as follows: Figure 3 As shown in the figure, the area S is the area enclosed by the right side marking of the main lane of the deceleration section and the transition section to the rightmost side line of the highway, that is, the range of S1 and S2. When calculating the area S, it is divided into two parts, as shown in the figure. Figure 4 , Figure 5 , the area of ​​S1 is composed of q1L1q2L3. The area of ​​S2 is composed of q2L2q3L4.

[0024]

[0025] Where:

[0026] The area of ​​the sector enclosed by the radii R1+q1(=R) and R2+q2(=R);

[0027] The area enclosed by the arc length L1 and the chord length K1;

[0028] The area of ​​the triangle enclosed by R1, R2, and K1;

[0029]

[0030] From the cosine theorem we can get:

[0031]

[0032] Given the radius R and the length of the deceleration section L1, the chord length K1 is:

[0033]

[0034] at the same time:

[0035]

[0036]

[0037] According to Heron's formula:

[0038]

[0039] Where:

[0040] θ1: the angle between point D and the center of the circle and point F and the center of the circle (°);

[0041] R0: radius of the main line curve (m), value is determined according to the specification;

[0042] R: the radius of the right edge of the main curve lane (m), which is R0 minus the lane width; R1: the radius from point D to the center of the circle I1 (m), R1 = R-q1;

[0043] R2: The radius from point F to the center of circle I1 (m), R2 = R-q2;

[0044] q1: the distance from point D to the right sideline of the main lane (m), q1 = L0 × γ + l1 + l2;

[0045] q2: the distance from point F to the right sideline of the main lane (m), q2 = (L0 + L1) × γ + l1 + l2; γ: gradient rate;

[0046] l1: Width of hard shoulder on the right side of the speed change lane (m);

[0047] l2: width of the earth shoulder on the right side of the speed change lane (m);

[0048] L0: length of the gradient section (m), value is determined according to the specification;

[0049] K1: chord length of DF segment (m);

[0050] L3: arc length of the right sideline of the main lane of the DF section (m);

[0051] L1: deceleration section length (m), value is determined according to the specification. v0: initial speed of deceleration stage (km / h);

[0052] v1: speed of diversion nose passing (km / h);

[0053] α: deceleration in the transition section of running speed (m / s 2 ), the average value is 1.0m / s 2 .

[0054] S2 area calculation is as follows Figure 5 , the calculation formula is:

[0055]

[0056] Where:

[0057] The area of ​​the sector enclosed by the radii R2+q2(=R) and R3+q3(=R);

[0058] The area enclosed by the curve length L2 and the chord length K2;

[0059] The area of ​​the triangle enclosed by R2, R3, and K2;

[0060]

[0061] From the cosine theorem we can get:

[0062]

[0063] Where:

[0064] θ2: the angle between point F and the center of the circle and point G and the center of the circle (°);

[0065] K2: chord length of FG segment (m);

[0066] R3: The radius from point G to the center of circle I1 (R3 = R-q3);

[0067] q3: The distance from point G to the right edge of the main lane (m);

[0068] K2: chord length of FG segment (m);

[0069] L4: arc length of the right sideline of the main lane of FG section (m);

[0070] L2; transition section transition curve length (m), according to the specification, v2: Speed ​​at the end point of the transition curve segment (km / h).

[0071]

[0072] Where:

[0073] C: Easing curve constant (C = R4L2);

[0074] R4: Radius of the control curve connected to the transition curve (m);

[0075] β: tangent angle of curve length L2;

[0076] At the same time, there are:

[0077]

[0078] in:

[0079] W2=(K2+R2+R3) / 2

[0080]

[0081]

[0082] α=90-б-β

[0083]

[0084] Where:

[0085] б: split nose angle, i.e. outflow angle, i.e. the angle between the X tangent (axis) and the X1 tangent;

[0086] α: the angle between the chord length K2 and the Y axis;

[0087] p1: Y-axis distance of point G corresponding to the origin F (m);

[0088] p2 is the X-axis distance (m) from point G to the origin F.

[0089] (3) Establish a model to determine if the visible area of ​​a highway curve exit ramp is blocked

[0090] The occlusion ratio is defined as the ratio of the volume of the target area that cannot be seen due to line of sight occlusion to the total volume at a certain moment in the process of judging the visible area target. z ,like Figure 6 and Figure 7 shown.

[0091]

[0092] Where:

[0093] V: Total volume of the target area (m 3 );

[0094] V z ; Volume of the sight-blocked area (m 3 );

[0095] S z ; Area of ​​the sight-blocked area (m 2 );

[0096] S: Total area of ​​the target area (m 2 );

[0097] h: Driver’s visual height (m).

[0098] like Figure 8 The target area in the visible range is shown in Figure 1. The total area is known to be S. The target area can be divided into multiple n spline areas, each with a width of Δl and a length of q. i Obviously, when the number of splines n is larger, that is, the spline division is finer, the sum of the areas of n splines is closer to the total area S of the target area, and the deviation is smaller. Thus, the area of ​​the target area can be discretized.

[0099]

[0100] S i =Δl×q i

[0101] Assume that the occlusion ratio of the spline area is J zi , then the discrete expression of the target area occlusion ratio can be obtained:

[0102]

[0103] Where:

[0104] J z : total occlusion ratio;

[0105] J zi : The occlusion ratio of each spline area;

[0106] S i :The area of ​​each spline region (m 2 );

[0107]

[0108] Where:

[0109] S zi : The area of ​​each spline region blocked (m 2 );

[0110] q zi : The length of each spline area blocked (m);

[0111] The key to finding the occlusion ratio of each spline area is to find q i The length and q zi The length of q i Two-point equation of the line segment. Take the center of the circular curve I1 of the main line curve as the origin (0,0), and the axis from the sight point A to the center I1 as the Y axis to establish a coordinate system. The corresponding angle of the arc length from the sight point A to the action point C is θ3, the corresponding angle of the arc length from the action point C to the action completion point D gradient section is θ4, the corresponding angle of the main line arc length from the action completion point D to the deceleration section of the diverter nose F is θ1, and the corresponding angle of the main line arc length from the diverter nose F to the transition section of the end point G is θ2. Based on this, the rounded angle formula can be obtained:

[0112]

[0113]

[0114] Where: L0 is the length of the gradient section (m).

[0115] Calculate the deceleration section q i The length of Fig. 9 .

[0116] The equation of the main line circular curve is:

[0117] x 2 +y 2 =R2

[0118] θ 1i Value range (0~θ1), different angles θ 1i The corresponding q i The equation of the line is:

[0119]

[0120] Different angles θ 1i The corresponding length q i

[0121]

[0122] q i The coordinates of the two points are:

[0123] (Rsin(θ3+θ4+θ 1i ),Rcos(θ3+θ4+θ 1i ))

[0124] ((R i )sin(θ3+θ4+θ 1i ),(Rq i )cos(θ3+θ4+θ 1i ))

[0125] Calculate the transition segment q i The length of Fig. 9 .

[0126] The equation of the transition curve in the (x', y') coordinate system is:

[0127]

[0128] The equation of the transition curve converted to the (x, y) coordinate system is:

[0129]

[0130] The main line arc length corresponds to the angle θ2, θ 2i Value range (0~θ2), different angles θ 2i The corresponding q i The equation of the line is:

[0131]

[0132] Combined with the main line circular curve equation and the transition curve equation, the transition section q can be obtained. i The coordinates of two points and the distance between the two points.

[0133] Calculate the length q of each spline area blockedzi The key is to find the distance of the obstruction in the driver's line of sight. zi The projected coordinates on .

[0134] From the relationship between the arc length and angle of the sector, we can get:

[0135] Where:

[0136] v Main line running speed;

[0137] t i Any time within the visual recognition and judgment time t (the time t required for visual recognition and judgment is 5s);

[0138] is the angle corresponding to any moment in the coordinate system within the visual recognition and judgment time t;

[0139] Therefore, any time t within the visual judgment time t i The coordinates of the viewpoint are:

[0140]

[0141] Since the visible area target area seen by the driver's eye height is the ground marking of the exit ramp, the height in its visible area is lower than the driver's eye height, so it is only assumed that the obstruction has the characteristic of width, and the two coordinate points of the width are Φ1 and Φ2 respectively. Let the coordinates of the two points of the obstruction be (x φ1 ,y φ1 ) and (x φ2 ,y φ2 ), then at any time t within the visual recognition judgment time t i The equations of the lines formed by the viewpoint and the two points of the occluder.

[0142] The equation of the straight line is:

[0143]

[0144] The equation of the straight line is:

[0145]

[0146] The driver's sight line equations (1-19) and (1-20) are respectively related to q i The equations of the straight lines (1-13) and (1-17) are combined to find the intersection point, and determine the line segment and q formed by the two intersection points. i The overlapping part is q i The occluded part q zi , the obscured part q zi and q iThe ratio of is the occlusion ratio J of the area zi .

[0147] As a preferred technical solution, the model is suitable for application in determining the setting of obstructions for a direct exit ramp in a speed change lane.

[0148] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0149] (1) The model of the present invention fully considers the influence of factors such as vehicles, road environment, and obstructions. The established obstruction model is a dynamic space model, which can more accurately describe the situation of line of sight obstruction on the exit ramp of the curve. It is used to perform calculations and analysis on the Hunan section of the Shanghai-Kunming Expressway, and the results verify the correctness and effectiveness of the model.

[0150] (2) The calculation method of the present invention can calculate the visual area of ​​the deceleration lanes of different radii on the curved sections of highways using direct curve exit ramps, simulate different obstructions and quantify the impact of the obstructions on the driver's line of sight. Based on this, it can provide a design basis for the setting of highway interchange exits, plant planting, highway land acquisition scope, etc. It is also suitable for highway design planning and safety management, and provides a reference for effectively solving the problem of obstruction of the safe visual area of ​​highway curve exit ramps. BRIEF DESCRIPTION OF THE DRAWINGS

[0151] Figure 1 It is a schematic diagram of the visual recognition process of the curve exit ramp of the present invention.

[0152] Figure 2 It is a schematic diagram of the visible target of the curve exit ramp of the present invention.

[0153] Figure 3 Schematic diagram of the visible field volume of the present invention.

[0154] Figure 4 It is a schematic diagram of the calculation parameters of the visible area target area of ​​the present invention.

[0155] Figure 5 This is a parameter diagram for calculating the area of ​​the visible target area S2 of the present invention.

[0156] Figure 6 Schematic diagram of the obstructed area of ​​the visible area of ​​the curve exit ramp of the present invention.

[0157] Figure 7 It is a schematic cross-sectional view of the obstructed area of ​​the visible area of ​​the curve exit ramp of the present invention.

[0158] Figure 8 It is a schematic diagram of discrete expression of the visual field target area of ​​the present invention.

[0159] Fig. 9It is a schematic diagram of the visual field target area length parameters of the present invention.

[0160] Fig.10 The following are the simulation results of the shading ratio of different sized shading objects at the starting point of the gradient section (action point C) at a speed of 80 km / h.

[0161] Fig.11 The following are the simulation results of the shading ratio of different sized shading objects at the starting point of the gradient section (action point C) at a speed of 100 km / h.

[0162] Fig.12 The following are the simulation results of the shading ratio of different sized shading objects at the starting point of the gradient section (action point C) at a speed of 120 km / h.

[0163] Fig.13 The following are the simulation results of the occlusion ratio of a 1m obstruction at different positions at a speed of 80km / h.

[0164] Fig.14 The following are the simulation results of the shading ratio of 5m obstructions at different positions at a speed of 80km / h.

[0165] Fig.15 The following are the simulation results of the shading ratio of 10m obstructions at different positions at a speed of 80km / h.

[0166] Fig.16 The following are the simulation results of the occlusion ratio of a 1m obstruction at different positions at a speed of 100km / h.

[0167] Fig.17 The following are the simulation results of the shading ratio of a 5m obstruction at different positions at a speed of 100km / h.

[0168] Fig.18 The following are the simulation results of the occlusion ratio of a 10m obstruction at different positions at a speed of 100km / h.

[0169] Fig.19 The following are the simulation results of the occlusion ratio of a 1m obstruction at different positions at a speed of 120km / h.

[0170] Fig. 20 The following are the simulation results of the shading ratio of 5m obstructions at different positions at a speed of 120km / h.

[0171] Fig.21 The following are the simulation results of the shading ratio of 10m obstructions at different positions at a speed of 120km / h. DETAILED DESCRIPTION

[0172] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the present invention is not limited to its protection scope.

[0173] Example 1

[0174] The method for constructing a dynamic occlusion space model of a visible target area of ​​a highway curve exit ramp includes the following steps:

[0175] (1) Confirm the visible target area of ​​the curve exit ramp:

[0176] Based on the identification sight distance specified in the Highway Route Design Specifications (JTG D20-2017) and the Highway Intersection Design Specifications (JTG / T D21-2014), the identification process of the highway curve exit ramp is as follows: Figure 1 As shown in the figure, point F is the ground marking of the diverging nose. When the driver reaches the visual recognition point A, he finds the ground marking F of the diverging nose. After seeing the marking clearly, the vehicle drives at the main line speed v to the recognition point B. The distance traveled by the driver in this process is the visual recognition distance. This period of time is the visual recognition time t1; the time the driver needs to react from seeing the marking to taking action is the judgment time t2. During this period of time, the distance traveled to the action point C is the judgment distance. Starting from point C, the driver takes action. The distance from point C to point D where the driver observes the vehicle on the right and changes lanes is the action distance. The distance from point D to point F is the distance the driver travels during the vehicle deceleration process (possibly changing lanes), where the distance to find the gap to be inserted is The lane change distance for turning onto the ramp is

[0177] According to the relevant provisions of the "Highway Grade Separation Design Regulations" (JTG / T D21-2014), the driver should be able to see the geometric structure of the fork ahead far beyond the recognition sight distance, and the exit ramp divergence nose should be placed within the effective viewing angle range of 10 to 20 degrees. What needs to be controlled is the lateral position of the nose within the viewing angle range. Therefore, the area area S of the visible area target of the curved exit ramp determined in this study is as follows: Figure 2 As shown, the area S is the range enclosed by the right side marking of the main lane of the deceleration section and the transition section to the rightmost roadbed edge line, that is, the range of S1 and S2.

[0178] The visual domain refers to the geographical range of a certain area of ​​three-dimensional space that can be seen by an observer. For the recognition process, the visual domain of the highway curve exit ramp starts from the visual recognition point A where the exit is visible, all the way to the action point C. The volume from the driver's visual height h to the visible target of the exit ramp is the volume of the visual domain, such as Figure 3 shown.

[0179] (2) Calculation of the visible target area of ​​the highway curve exit ramp;

[0180] The visible target area S of the highway curve exit ramp determined in this study is as follows: Figure 3 As shown in the figure, the area S is the area enclosed by the right side marking of the main lane of the deceleration section and the transition section to the rightmost side line of the highway, that is, the range of S1 and S2. When calculating the area S, it is divided into two parts, as shown in the figure. Figure 4 , Figure 5 , the area of ​​S1 is composed of q1L1q2L3. The area of ​​S2 is composed of q2L2q3L4.

[0181]

[0182] Where:

[0183] The area of ​​the sector enclosed by the radii R1+q1(=R) and R2+q2(=R);

[0184] The area enclosed by the arc length L1 and the chord length K1;

[0185] The area of ​​the triangle enclosed by R1, R2, and K1;

[0186]

[0187] From the cosine theorem we can get:

[0188]

[0189] Given the radius R and the length of the deceleration section L1, the chord length K1 is:

[0190]

[0191] at the same time:

[0192]

[0193]

[0194] According to Heron's formula:

[0195]

[0196] Where:

[0197] θ1: the angle between point D and the center of the circle and point F and the center of the circle (°);

[0198] R0: radius of the main line curve (m), value is determined according to the specification;

[0199] R: The radius of the right edge of the main curve lane (m), which is R0 minus the lane width;

[0200] R1: The radius from point D to the center of circle I1 (m), R1 = R-q1;

[0201] R2: The radius from point F to the center of circle I1 (m), R2 = R-q2;

[0202] q1: the distance from point D to the right sideline of the main lane (m), q1 = L0 × γ + l1 + l2;

[0203] q2: The distance from point F to the right sideline of the main lane (m), q2 = (L0 + L1) × γ + l1 + l2;

[0204] γ: gradient rate;

[0205] l1: Width of hard shoulder on the right side of the speed change lane (m);

[0206] l2: width of the earth shoulder on the right side of the speed change lane (m);

[0207] L0: length of the gradient section (m), value is determined according to the specification;

[0208] K1: chord length of DF segment (m);

[0209] L3: arc length of the right sideline of the main lane of the DF section (m);

[0210] L1: deceleration section length (m), value is determined according to the specification. v0: initial speed of deceleration stage (km / h);

[0211] v1: speed of diversion nose passing (km / h);

[0212] α: deceleration in the transition section of running speed (m / s 2 ), the average value is 1.0m / s 2 .

[0213] S2 area calculation is as follows Figure 5 , the calculation formula is:

[0214]

[0215] Where:

[0216] The area of ​​the sector enclosed by the radii R2+q2(=R) and R3+q3(=R);

[0217] The area enclosed by the curve length L2 and the chord length K2;

[0218] The area of ​​the triangle enclosed by R2, R3, and K2;

[0219]

[0220] From the cosine theorem we can get:

[0221]

[0222] Where:

[0223] θ2: the angle between point F and the center of the circle and point G and the center of the circle (°);

[0224] K2: chord length of FG segment (m);

[0225] R3: The radius from point G to the center of circle I1 (R3 = R-q3);

[0226] q3: The distance from point G to the right edge of the main lane (m);

[0227] K2: chord length of FG segment (m);

[0228] L4: arc length of the right sideline of the main lane of FG section (m);

[0229] L2; transition section transition curve length (m), according to the specification, v2: Speed ​​at the end point of the transition curve segment (km / h).

[0230]

[0231] Where:

[0232] C: Easing curve constant (C = R4L2);

[0233] R4: Radius of the control curve connected to the transition curve (m);

[0234] β: tangent angle of curve length L2;

[0235] At the same time, there are:

[0236]

[0237] in:

[0238] W2=(K2+R2+R3) / 2

[0239]

[0240]

[0241] α=90-б-β

[0242]

[0243] Where:

[0244] б: split nose angle, i.e. outflow angle, i.e. the angle between the X tangent (axis) and the X1 tangent;

[0245] α: the angle between the chord length K2 and the Y axis;

[0246] p1: Y-axis distance of point G corresponding to the origin F (m);

[0247] p2: X-axis distance of point G relative to origin F (m).

[0248] (3) Establish a model to determine if the visible target area of ​​a highway curve exit ramp is blocked

[0249] The occlusion ratio is defined as the ratio of the volume of the target area that cannot be seen due to line of sight occlusion to the total volume at a certain moment in the process of judging the visible area target. z ,like Figure 6 and Figure 7 shown.

[0250]

[0251] Where:

[0252] V: Total volume of the target area (m 3 );

[0253] V z ; Volume of the sight-blocked area (m 3 );

[0254] S z ; Area of ​​the sight-blocked area (m 2 );

[0255] S: Total area of ​​the target area (m 2 );

[0256] h: Driver’s visual height (m).

[0257] like Figure 8 The target area in the visible range is shown in Figure 1. The total area is known to be S. The target area can be divided into multiple n spline areas, each with a width of Δl and a length of q. i Obviously, when the number of splines n is larger, that is, the spline division is finer, the sum of the areas of n splines is closer to the total area S of the target area, and the deviation is smaller. Thus, the area of ​​the target area can be discretized.

[0258]

[0259] S i =Δl×q i

[0260] Assume that the occlusion ratio of the spline area is J zi , then the discrete expression of the target area occlusion ratio can be obtained:

[0261]

[0262] Where:

[0263] J z : total occlusion ratio;

[0264] J zi : The occlusion ratio of each spline area;

[0265] S i :The area of ​​each spline region (m 2 );

[0266]

[0267] Where:

[0268] S zi : The area of ​​each spline region blocked (m 2 );

[0269] q zi : The length of each spline area blocked (m);

[0270] The key to finding the occlusion ratio of each spline area is to find q i The length and q zi The length of q i Two-point equation of the line segment. Take the center of the circular curve I1 of the main line curve as the origin (0,0), and the axis from the sight point A to the center I1 as the Y axis to establish a coordinate system. The corresponding angle of the arc length from the sight point A to the action point C is θ3, the corresponding angle of the arc length from the action point C to the action completion point D gradient section is θ4, the corresponding angle of the main line arc length from the action completion point D to the deceleration section of the diverter nose F is θ1, and the corresponding angle of the main line arc length from the diverter nose F to the transition section of the end point G is θ2. Based on this, the rounded angle formula can be obtained:

[0271]

[0272]

[0273] Where: L0 is the length of the gradient section (m).

[0274] Calculate the deceleration section q i The length of Fig. 9 .

[0275] The equation of the main line circular curve is:

[0276] x 2 +y 2 =R2

[0277] θ 1i Value range (0~θ1), different angles θ 1i The corresponding q i The equation of the line is:

[0278]

[0279] Different angles θ 1i The corresponding length q i

[0280]

[0281] q i The coordinates of the two points are:

[0282] (Rsin(θ3+θ4+θ 1i ),Rcos(θ3+θ4+θ 1i ))

[0283] ((R i )sin(θ3+θ4+θ 1i ),(Rq i )cos(θ3+θ4+θ 1i ))

[0284] Calculate the transition segment q i The length of Fig. 9 .

[0285] The equation of the transition curve in the (x', y') coordinate system is:

[0286]

[0287] The equation of the transition curve converted to the (x, y) coordinate system is:

[0288]

[0289] The main line arc length corresponds to the angle θ2, θ 2i Value range (0~θ2), different angles θ 2i The corresponding q i The equation of the line is:

[0290]

[0291] Combined with the main line circular curve equation and the transition curve equation, the transition section q can be obtained. i The coordinates of two points and the distance between the two points.

[0292] Calculate the length q of each spline area blockedzi The key is to find the distance of the obstruction in the driver's line of sight. zi The projected coordinates on .

[0293] From the relationship between the arc length and angle of the sector, we can get:

[0294] Where:

[0295] v: main line running speed;

[0296] t i : Any time within the visual recognition and judgment time t (the time t required for visual recognition and judgment is 5s);

[0297] θ 3i : Visualize and judge the angle corresponding to any moment in the coordinate system within the time t;

[0298] Therefore, any time t within the visual judgment time t i The coordinates of the viewpoint are:

[0299]

[0300] Since the visible area target area seen by the driver's eye height is the ground marking of the exit ramp, the height in its visible area is lower than the driver's eye height, so it is only assumed that the obstruction has the characteristic of width, and the two coordinate points of the width are Φ1 and Φ2 respectively. Let the coordinates of the two points of the obstruction be (x φ1 ,y φ1 ) and (x φ2 ,y φ2 ), then at any time t within the visual recognition judgment time t i The equations of the lines formed by the viewpoint and the two points of the occluder.

[0301] The equation of the straight line is:

[0302]

[0303]

[0304] The equation of the straight line is:

[0305]

[0306] The driver's sight line equations (1-19) and (1-20) are respectively related to q i The equations of the straight lines (1-13) and (1-17) are combined to find the intersection point, and determine the line segment and q formed by the two intersection points. i The overlapping part is q i The occluded part q zi , the obscured part qzi and q i The ratio of is the occlusion ratio J of the area zi .

[0307] (4) Verify the correctness and effectiveness of the model, including:

[0308] ① According to the G60 Shanghai-Kunming Expressway (Hunan Section), the main line design speeds are 120km / h, 100km / h and 80km / h respectively, the width of the l1 hard shoulder is 3.5m and the width of the l2 earth shoulder is 0.75m, and the visual field height h of the exit ramp is 1.2m for the driver's field of vision (2.0m for trucks); other parameter values ​​refer to Table 1, where the ramp control curve radius is the limit value, and the value in brackets is the general value. .

[0309] Table 1 Parameters for calculating visual occlusion of curved exit ramps

[0310]

[0311] ②Selection of occlusion parameters

[0312] Scenario 1: main line design speeds are 120km / h, 100km / h, and 80km / h; obstruction locations: all located on the main line radius at the starting point of the gradient section; obstruction sizes: 0.5m, 2m, 6m, 10m, 14m, 18m, and 28m.

[0313] Scenario 2: The design speed of the main line is 120km / h, 100km / h, and 80km / h; the position of the obstruction: 7 points from the visual point A to the action completion point D; the size of the obstruction: 1m, 5m, and 10m.

[0314] ③ Calculation of safe visual field and line of sight obstruction of highway curve exit ramp

[0315] Through MATLAB modeling, the relevant parameters are substituted into the target area occlusion ratio calculation equation:

[0316]

[0317] The occlusion conditions in different scenarios were simulated, and the occlusion ratio changes of different sizes at the same position corresponding to different main line speeds are shown in the figure below: Fig.10 , 11 As shown in 12, the occlusion ratio variation diagram of different positions with the same size corresponding to different main line speeds is as follows Fig.13 , 14 , 15, 16, 17, 18, 19, 20, 21.

[0318] from Figures 10-12It can be seen that at the same position, the larger the width of the obstruction, the greater the line of sight obstruction ratio and the longer the obstruction duration; when the main line radius is larger, the line of sight obstruction ratio and obstruction duration caused by the obstruction will decrease.

[0319] from Figures 13 to 21 It can be seen that the closer the occluder is to the visual point, the earlier it will block the line of sight; the larger the width of the occluder, the greater the occlusion ratio at the same time, and the longer the peak duration; when the main line radius is larger, the initial occlusion ratio and peak duration of the occluder are smaller.

[0320] Therefore, the key to improving the visual domain obstruction of the curve exit ramp is to set up the curve exit ramp on the section with a large main line radius so that it is located in the visual domain; avoid the appearance of obstructions on the main line side corresponding to the curve exit ramp identification and judgment section and the gradient section, such as slopes, plants, signs and other large-width obstructions, which will seriously obstruct the visual domain of the curve exit ramp.

Claims

1. A method for constructing a dynamic occlusion spatial model of the visible area of ​​a highway curve exit ramp, characterized in that: The construction of the model includes the following steps: (1) Determine the visible area of ​​the curve exit ramp: Based on the recognition sight distance specified in the Highway Route Design Specifications (JTG D20-2017) and Highway Grade Separation Design Detailed Rules (JTG / T D21-2014), the recognition process of the highway curve exit ramp, where point F is the diverging nose ground marking; when the driver drives to the recognition point A, the diverging nose ground marking F is found. After seeing the marking clearly, the vehicle drives at the main line speed v to the recognition point B. The distance traveled by the driver in this process is the recognition distance This period of time is the visual recognition time t1; the time the driver needs to react from seeing the marking to taking action is the judgment time t2. During this period of time, the distance traveled to the action point C is the judgment distance. Starting from point C, the driver takes action. The distance from point C to point D where the driver observes the vehicle on the right and changes lanes is the action distance. The distance from point D to point F is the distance the driver travels during the deceleration process of the vehicle, where the distance to find the insertable gap is The lane change distance for turning onto the ramp is According to the requirements of the "Highway Grade Separation Design Regulations", the driver can see the geometric structure of the fork ahead far beyond the identification sight distance. The diverging nose of the curve exit ramp should be placed within the effective viewing angle range of 10 to 20 degrees. What needs to be controlled is the lateral position of the nose within the viewing angle range; the area area S of the curve exit ramp visible area target to be determined is the area area S enclosed by the right side marking of the main line lane within the deceleration section and the transition section to the rightmost roadbed edge line, that is, the range of S1 and S2; (2) Calculation of the visible target area of ​​the highway curve exit ramp; The visible target area S of the highway curve exit ramp that needs to be determined is the area S enclosed by the right side marking of the main lane of the deceleration section and the transition section to the rightmost side line of the highway, that is, the range of S1 and S2; When calculating the area S, it is divided into two parts. The area of ​​S1 is composed of q1L1q2L3; the area of ​​S2 is composed of q2L2q3L4. Where: The area of ​​the sector enclosed by the radii R1+q1=R and R2+q2=R; The area enclosed by the arc length L1 and the chord length K1; The area of ​​the triangle enclosed by R1, R2, and K1; From the cosine theorem we can get: Given the radius R and the length of the deceleration section L1, the chord length K1 is: at the same time: According to Heron's formula: Where: θ1: the angle between point D and the center of the circle and point F and the center of the circle, unit: °; R0: The radius of the main line curve, in m, is determined according to the specification; R: the radius of the right edge of the main curve lane, in meters, which is R0 minus the lane width; R1: the radius from point D to the center of the circle I1, in meters, R1 = R-q1; R2: The radius from point F to the center of the circle I1, in meters, R2 = R-q2; q1: The distance from point D to the right sideline of the main lane, in meters, q1 = L0 × γ + l1 + l2; q2: the distance from point F to the right side of the main lane, in meters, q2 = (L0 + L1) × γ + l1 + l2; γ: gradient rate; l1: width of the hard shoulder on the right side of the speed change lane, in m; l2: width of the right earth shoulder of the speed change lane, in m; L0: Gradual section length, unit: m, value according to the specification; K1: chord length of DF segment, unit: m; L3: The arc length of the right side of the main lane of the DF section, in meters; L1: deceleration section length, unit: m, value according to the specification, v0: initial speed of deceleration stage, unit: km / h; v1: speed at the splitter nose, unit: km / h; α: deceleration of running speed transition section, unit: m / s 2 , the average value is 1.0m / s 2 ; The S2 calculation formula is: Where: The area of ​​the sector enclosed by the radii R2+q2=R and R3+q3=R; The area enclosed by the curve length L2 and the chord length K2; The area of ​​the triangle enclosed by R2, R3, and K2; From the cosine theorem we can get: Where: θ2: the angle between point F and the center of the circle and point G and the center of the circle, in degrees; K2: chord length of FG segment, unit: m; R3: The radius from point G to the center of circle I1, R3 = R-q3; q3: The distance from point G to the right edge of the main lane, in meters; K2: chord length of FG segment, unit: m; L4: The arc length of the right side of the main lane of the FG section, in meters; L2: Transition section transition curve length, unit: m, value according to the specification, v2: speed at the end point of the transition curve segment, unit: km / h; Where: C: Easing curve constant C = R4L2; R4: The radius of the control curve connected to the transition curve, in meters; β: tangent angle of curve length L2; At the same time, there are: in: W2=(K2+R2+R3) / 2 Where: The angle of the split nose, i.e., the outflow angle, is the angle between the X tangent / axis and the X1 tangent; α: the angle between the chord length K2 and the Y axis; p1: Y-axis distance of point G corresponding to origin F, unit: m; p2: The X-axis distance of point G corresponding to the origin F, in meters; (3) Establish a model to determine if the visible target area of ​​a highway curve exit ramp is blocked The occlusion ratio is defined as the ratio of the volume of the target area that cannot be seen due to line of sight occlusion to the total volume at a certain moment in the process of judging the visible area target. z ; Where: V: The total volume of the target area, in m 3 ; V z : The volume of the line of sight blocked area, unit: m 3 ; S z : The area of ​​the line of sight blocked area, unit: m 2 ; S: The total area of ​​the target area, in m 2 ; h: driver's eye height, unit: m; The target area can be divided into multiple n spline areas, each spline has a width of Δl and a length of q i ; When the number of splines n is larger, that is, the spline division is finer, the sum of the areas of n splines is closer to the total area S of the target area, and the deviation is smaller, thereby discretizing the area of ​​the target area; S i =Δl×q i Assume that the occlusion ratio of the spline area is J zi , then the discrete expression of the target area occlusion ratio can be obtained: Where: J z : Total occlusion ratio; J zi : The occlusion ratio of each spline area; S i : The area of ​​each spline region, unit: m 2 ; Where: S zi : The area blocked by each spline region; q zi : The length of each spline area blocked; The key to finding the occlusion ratio of each spline area is to find q i The length and q zi The length of q i Two-point equation of the line segment; take the center of the circular curve I1 of the main line curve as the origin (0,0), and take the axis from the sight point A to the center of the circle I1 as the Y axis to establish a coordinate system; the arc length from the sight point A to the action point C corresponds to an angle of θ3, the arc length from the action point C to the gradual transition section of the action completion point D corresponds to an angle of θ4, the main line arc length corresponding to the deceleration section from the action completion point D to the diverter nose F corresponds to an angle of θ1, and the main line arc length corresponding to the transition section from the diverter nose F to the end point G corresponds to an angle of θ2; Based on this, the rounded angle formula can be obtained: Where: L0: gradient length, unit: m; Calculate the deceleration section q i Length, The equation of the main line circular curve is: x 2 +y 2 =R 2 θ 1i The value range is 0~θ1, different angles θ 1i The corresponding q i The equation of the line is: Different angles θ 1i The corresponding length q i q i The coordinates of the two points are: (Rsin(θ3+θ4+θ 1i ),Rcos(θ3+θ4+θ 1i )) ((Rq i )sin(θ3+θ4+θ 1i ),(Rq i )cos(θ3+θ4+θ 1i )) Calculate the transition segment q i Length; The equation of the transition curve in the (x', y') coordinate system is: The equation of the transition curve converted to the (x, y) coordinate system is: The main line arc length corresponds to the angle θ2, θ 2i The value range is 0~θ2, different angles θ 2i The corresponding q i The equation of the line is: Combined with the main line circular curve equation and the transition curve equation, the transition section q can be obtained. i The coordinates of two points and the distance between the two points; Calculate the length q of each spline area blocked zi The key is to find the distance of the obstruction in the driver's line of sight. zi The projection coordinates on ; From the relationship between the arc length and angle of the sector, we can get: Where: v: main line running speed; t i : At any time during the visual recognition and judgment time t, the time required for visual recognition and judgment t is 5s; Visually recognize and judge the angle corresponding to any moment in the coordinate system within time t; Therefore, any time t within the visual judgment time t i The coordinates of the viewpoint are: Since the visible area target area seen by the driver's eye height is the ground marking of the exit ramp, the height in its visible area is lower than the driver's eye height, so it is only assumed that the obstruction has the characteristic of width, and the two coordinate points of the width are Φ1 and Φ2 respectively. Let the coordinates of the two points of the obstruction be (x φ1 ,y φ1 ) and (x φ2 ,y φ2 ), then at any time t within the visual recognition judgment time t i The equations of the lines formed by the viewpoint and the two points of the occluder; The equation of the straight line is: The equation of the straight line is: The driver's sight line equations (1-19) and (1-20) are respectively related to q i The equations of the straight lines (1-13) and (1-17) are used to find the intersection point, and the line segment formed by the two intersection points and q i The overlapping part is q i The occluded part q zi , the obscured part q zi and q i The ratio of is the occlusion ratio J of the area zi .

2. The method for constructing a dynamic occlusion space model of a visible target area of ​​a highway curve exit ramp according to claim 1 is characterized in that: It is used in the judgment of setting obstructions of the direct curve exit ramp in the speed change lane of the highway.

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