CN105741551A - Method for evaluating traffic safety of unsignalized intersection - Google Patents

Abstract

The invention discloses a method for evaluating the traffic safety of an unsignalized intersection. The method includes the steps of selecting an intersection to researched, obtaining basic data, processing basic data of the intersection, establishing a coordinate system and carrying out grid division, obtaining the conflict probability of each grid, assigning inner grids of the entire intersection to form a conflict probability matrix, obtaining the severe degree of conflict probability of each grid according to a conflict severe degree kinetic energy loss model, assigning the grids in the entire intersection, determining the safety evaluation index of each grid in the entire intersection by using a grey cluster method and taking conflict probability and conflict severe degree into consideration, assigning equivalent codes to each grid and constructing a grade code matrix, and realizing visualized output of the safety evaluation result through a programming language. Comprehensive safety evaluation index determination and visualized output of safety evaluation of the entire intersection are realized.

Description

A kind of unsignalized intersection Traffic safety evaluation method

Technical field

The present invention relates to the technical field of urban road intersection safe design and evaluation, refer in particular to a kind of unsignalized intersection Traffic safety evaluation method incorporating collision probability and crash severity.

Background technology

Intersection at Grade of Urban Road is urban road network's " throat ", is the convergent point of artificial abortion, bicycle flow and Vehicle flow；Meanwhile, they are also the nodes that road user changes travel direction, are traffic conflict centrostigma and vehicle accident point occurred frequently.Its safety problem is always up the focus that people pay close attention to, and crossing conflict analysis and safety evaluation become one highly important content of traffic engineering research field.

At present, the method both at home and abroad intersection traffic being evaluated safely is broadly divided into multi-intersection grade classification and Single Intersection conflict point evaluates two aspects.In multi-intersection grade classification, research method is many based on vehicle accident number or number of collisions, traffic conflict is evaluated as evaluation points with the ratio (TC/MPCU) mixing the equivalent volume of traffic: Guan Xiaowei et al. have studied with time equal traffic conflict and traffic data be foundation Traffic Conflict grey cluster safe evaluation method；Cheng Wei et al. proposes the intersection traffic safety evaluation method of the Fuzzy C-Means Clustering based on the traffic conflict technique.And the method for Single Intersection intramural conflict safety evaluation is mainly evaluated with traffic conflict dot characteristics, collision probability and critical collision probability for data basis: Wang Ying etc. propose the intersection evaluation model based on safety level of service in conjunction with conflict point kind Yu number；Zhou Jiaxiang et al. have studied the fuzzy synthetic appraisement method of mixed row crossing.Although the method comparison in safety evaluation is comprehensive both at home and abroad, still suffer from several respects problem: although an existing research is more to the research of crossing collision probability, but Single Intersection safe evaluation method based on this is less, its reason is in that the collision probability research of existing crossing is many with conflict point for object of study, it is impossible to relatively comprehensively evaluate whole crossing situation；Two, whole crossing safety grade classification is focused in research, and relatively have ignored the conflict situations within crossing and level of security, less for the regulation contribution of crossing stain；Three, safety evaluation index is comparatively single, and what utilize data mode presents evaluation result more, is unfavorable for when data volume is big reading and storing.

Summary of the invention

It is an object of the invention to overcome the shortcoming and defect of prior art, a kind of unsignalized intersection Traffic safety evaluation method incorporating collision probability and crash severity is provided, the method only traffic conflict being carried out grade classification and evaluation with the ratio (TC/MPCU) mixing the equivalent volume of traffic or collision probability when breaking through conventional cross mouth safety evaluation, it is achieved that the safety evaluation index of synthesization is determined and the visualization output of safety evaluation within the scope of whole crossing relatively.

For achieving the above object, technical scheme provided by the present invention is: a kind of unsignalized intersection Traffic safety evaluation method, comprises the following steps:

1) crossing of selected research, obtains basic data, altogether includes the data of four aspects: crossing geological information, intersection traffic management strategy, intersection traffic flow data and vehicle related parameters；

2) crossing basic data processes, and sets up coordinate system and carries out grid division；

3) solve the collision probability of each grid, to the grid assignment within whole crossing, construct collision probability matrix；

4) according to conflict order of severity kinetic energy rejection model, each grid is solved it may happen that the order of severity of conflict, and to the grid assignment in whole crossing；

5) consider collision probability and the conflict order of severity, utilize grey clustering method, it is determined that the safety evaluation index of each grid in whole crossing, equivalence code is assigned to each grid, construction class code matrices；

6) programming language is utilized to realize the visualization output of safety evaluation result.

In step 1) in, described crossing geological information include intersection type, crossing scope, the number of track-lines of each entrance driveway and width arrange, design radial, it is possible to obtain geological information data from crossing basic design scheme；Described intersection traffic management strategy includes the lane function of crossing and arranges, turns to restriction, design speed, it is possible to obtain management strategy data from intersection traffic Managed Solution；Described intersection traffic flow data refers to the vehicle arriving rate of each entrance driveway in crossing, it is possible to from traffic volume forecast data obtain research crossing respectively flow to traffic data, thus calculating each arrival rate flowing to vehicle；Described vehicle related parameters includes the side-play amount of the length of vehicle, the width of vehicle, vehicle.

In step 2) in, according to selected crossing, it is carried out grid process, specifically includes following steps:

2.1) coordinate system is set up: with crossing East and West direction and north-south centrage intersection for zero, east-west direction is x-axis, and North and South direction is that y-axis sets up plane right-angle coordinate；

2.2) grid division: arbitrarily inserting n-1 branch on two coordinate axess of crossing respectively, if crossing length is 2a, width is 2b；

-a=x₀< x₁< x₂< ... < x_n-1< x_n=a ,-b=y₀< y₁< y₂< ... < y_n-1< y_n=b

Crossing has been divided into N number of grid, and grid Rec (ij) is designated as Rec (ij)={ x_i-1,x_i,y_i-1,y_i, as grid quantity n → ∞, then grate area S [Rec (ij)] → 0, therefore the probability of the grid centre of form can be occurred in vehicle and occur in the probability in this grid cell as vehicle；

In step 3) in, solve grid collision probability within the scope of crossing, specifically include following steps:

3.1) calculating vehicle collision probability, the probability that grid Rec (ij) clashes is:

$\begin{array}{c}{P}_{ij}conflict=P_{Aij}^a\&CenterDot;P_{Aij}^b+P_{Aij}^b\&CenterDot;P_{Aij}^c+P_{Aij}^a\&CenterDot;P_{Aij}^c\\ =\underset{k_1\&NotEqual;k_2}{\underset{k_2=a,b,c}{\underset{k_1=a,b,c}{\&Sigma;}}}{P}_{Aij}^{k_1}\&CenterDot;P_{Aij}^{k_2}\end{array}$

In formula: a, b, c be likely at most in a grid cell through the numbering of three track of vehicle lines；

The probability of grid Rec (ij) is occurred in along track k；

3.2) collision probability result of calculation is assigned to each grid, constructs collision probability matrix；

In step 4) in, according to conflict order of severity kinetic energy rejection model, solve each grid it may happen that the order of severity of conflict, and to the grid assignment in whole crossing, specifically include following steps:

4.1) order of severity calculates: characterize crash severity by the energy loss of vehicle collision, with worst situation for basis, namely calculates the kinetic energy of loss during vehicle does not take brake measure to collision to stopped process；

In formula: m₁, m₂Respectively collide the quality of two cars；v₁, v₂Speed before the two cars that respectively collides collision；v_CloseSum velocity after colliding for two cars；

It is assumed hereinafter that under condition:

A) vehicle mass is close, and before collision, speed is the speed each via crossing；

B) being in uniform speed motion state before vehicle collision, bonding force suffered by system is zero, and when vehicle collides endogenetic process suffered by system much larger than External Force Acting；

Under rectangular coordinate system, decompose crashing vehicle speed, and in conjunction with principle of conservation of momentum, set up kinetic energy rejection model, calculate each grid units mass dynamic energy loss vector:

$\frac{\mathrm{\&Delta;}E}{\stackrel{\&OverBar;}{m}}=\frac{1}{4}({v_1}^2+{v_2}^2)-\frac{1}{2}{v}_1{v}_{2}cos({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)$

In formula:For crashing vehicle average quality；v₁, v₂Speed before the two cars that respectively collides collision；θ₁, θ₂Respectively collide the velocity attitude of first two and the angle counterclockwise of x-axis positive direction；

4.2) severity level divides: the data statistics result according to kinetic energy loss and crash severity, the order of severity is divided into slight conflict, general conflict, more serious conflict and Serious conflicts level Four, divides the order of severity of each grid potentially conflicting accordingly；

In step 5) in, adopt grey clustering method to set up the Model for Safety Evaluation based on collision probability and crash severity two indices, grid all of within the scope of crossing is carried out safety status classification；Determine safety evaluation index and result of calculation Visualization；Specifically include following steps:

5.1) collision probability matrix and conflict order of severity matrix are converted into safety evaluation matrix；

5.2) determining the clear figure of ash class and correspondence, be safety, criticality safety, danger and five grey classes of special hazard by the safety status classification of grid, the clear figure that collision probability is corresponding tries to achieve λ by About Safety Cities grading evaluation criteria₁=0, λ₂=0.001, λ₃=0.025, λ₄=0.036；Conflict clear figure corresponding to the order of severity is according to step 4) obtain λ '₁=0, λ '₂=50, λ '₃=100, λ '₄=150；

5.3) calculating clear figure, obtain the clear figure of corresponding ash class according to whitened weight function, computing formula is as follows:

$\begin{array}{cc}{f}_z^1=\left\{\begin{array}{cc}1& (x<{\mathrm{\&lambda;}}_1)\\ \frac{{\mathrm{\&lambda;}}_1-x}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ 0& (x>{\mathrm{\&lambda;}}_2)\end{array}\right.& f_z^2=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_1)\\ \frac{x-{\mathrm{\&lambda;}}_1}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ 0& (x>{\mathrm{\&lambda;}}_3)\end{array}\right.\end{array}$

$\begin{array}{cc}{f}_z^3=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ \frac{{\mathrm{\&lambda;}}_4-x}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 0& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.& f_z^4\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_3)\\ \frac{x-{\mathrm{\&lambda;}}_3}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 1& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.\end{array}$

Wherein: z is index number；

5.4) cluster power is determined: having motor vehicles collision probability and conflict two evaluation indexes of the order of severity, based on collision probability, the order of severity is auxiliary, and cluster power takes η respectively₁=0.6, η₂=0.4；

5.5) calculating Cluster Evaluation value: grid Rec (ij) for the Cluster Evaluation value belonging to kth ash class is:

${\mathrm{\&sigma;}}_{\mathrm{Re}c\left(ij\right)}^k=\underset{z=1}{\overset{2}{\&Sigma;}}{f}_z^k\left(\mathrm{Re}c{\left(ij\right)}_z\right)\&CenterDot;{\mathrm{\&eta;}}_z$

Wherein: Rec (ij)_zThe z of grid Rec (ij) refers to target value；

η_zThe weight of z index；

Whitened weight function；

5.6) ash class belonging to grid is determined: if the grey Cluster Evaluation value of certain grid meetsThen belonging to this grid, ash class is that safe class is k；Safe class is assigned to each grid, construction class code column vector

[k₁₁,…,k_1n,k₂₁,…,k_2n,…,k_n1,…,k_nn]^T

5.7) level code column vector is changed into level code matrix；

5.8) providing the safety evaluation index of whole crossing, take the area shared by the grid of each safe class, its computing formula is:

S_k=n_kab/N

S in formula_kRepresent the area in the region that safe class is k, n_kRepresent the number of the grid that safe class is k；

5.9) for more intuitively presenting safety evaluation result, according to corresponding relation, color value corresponding for each level code is assigned to each grid, constructs color code matrix.

The present invention compared with prior art, has the advantage that and beneficial effect:

1, breakthrough only carries out safe evaluation method by collision probability, by two aspects of risk of collision: collision probability and the conflict order of severity compose cluster weights respectively, carry out integrating cluster.Solve but the problem of the regional evaluation distortion that conflict serious little for probability of happening, improve the comprehensive and reliability of safety evaluation.

2, conventional grey cluster it is different from for evaluating the level of security of whole crossing, safe class within the scope of crossing is refined by the present invention, four grades it are divided into inside one crossing, specify the accurate picture of accident black-spot in crossing, significant for single crossing safety evaluation and improvement.

3, visual image form is utilized to express crossing safety situation, safe class is distinguished by color, visual in image, technical staff is made to be no longer limited to be observed and analytical data information by relation database table, Intersection Safety data and structural relation thereof can also be seen in more intuitive mode, be conducive to its analysis accident origin cause of formation, propose solution targetedly.There is stronger practical value.

4, built crossing can both have been evaluated, safety evaluation can also be carried out for the crossing of design phase, before the construction of crossing, its design safety is evaluated, effectively reduces the conflict brought because of its design problem after crossing puts into construction, be conducive to crossing design to improve perfect.

Accompanying drawing explanation

Fig. 1 is the flow chart of the inventive method.

Fig. 2 is grid division schematic diagram.

Fig. 3 is collision schematic diagram.

Fig. 4 is striking momentum decomposing schematic representation.

Fig. 5 is present situation safety evaluation result schematic diagram.

Fig. 6 is scheme 1 safety evaluation result schematic diagram.

Fig. 7 is scheme 2 safety evaluation result schematic diagram.

Fig. 8 is scheme 3 safety evaluation result schematic diagram.

Detailed description of the invention

Below in conjunction with specific embodiment, the invention will be further described.

As it is shown in figure 1, the unsignalized intersection Traffic safety evaluation method described in the present embodiment, comprise the following steps:

1) crossing of selected research, obtains basic data, altogether includes the data of four aspects: crossing geological information, intersection traffic management strategy, intersection traffic flow data and vehicle related parameters；

2) crossing basic data processes, and sets up coordinate system and carries out grid division；

3) solve the collision probability of each grid, to the grid assignment within whole crossing, construct collision probability matrix；

4) according to conflict order of severity kinetic energy rejection model, each grid is solved it may happen that the order of severity of conflict, and to the grid assignment in whole crossing；

5) consider collision probability and the conflict order of severity, utilize grey clustering method, it is determined that the safety evaluation index of each grid in whole crossing, equivalence code is assigned to each grid, construction class code matrices；

6) programming language is utilized to realize the visualization output of safety evaluation result.

In step 1) in, described crossing geological information include intersection type, crossing scope, the number of track-lines of each entrance driveway and width arrange, design radial, geological information data can be obtained from crossing basic design scheme；Described intersection traffic management strategy includes the lane function of crossing and arranges, turns to restriction, design speed, can obtain management strategy data from intersection traffic Managed Solution；Described intersection traffic flow data refers to the vehicle arriving rate of each entrance driveway in crossing, can from traffic volume forecast data obtain research crossing respectively flow to traffic data, thus calculating each arrival rate flowing to vehicle；Described vehicle related parameters includes the side-play amount of the length of vehicle, the width of vehicle, vehicle, and the present invention, with standard vehicle for object, adopts the data of standard vehicle to be modeled calculating.

In step 2) in, according to selected crossing, it is carried out grid process, comprises the following steps:

2.1) coordinate system is set up: with crossing East and West direction and north-south centrage intersection for zero, east-west direction is x-axis, and North and South direction is that y-axis sets up plane right-angle coordinate.

2.2) grid division: arbitrarily insert n-1 branch (setting crossing length as 2a, width is 2b) on two coordinate axess of crossing respectively

-a=x₀< x₁< x₂< < x_n-1< x_n=a ,-b=y₀< y₁< y₂< < y_n-1< y_n=b

Crossing has been divided into N number of grid, and grid Rec (ij) is designated as Rec (ij)={ x_i-1,x_i,y_i-1,y_i(see accompanying drawing 2).As grid quantity n → ∞, then grate area S [Rec (ij)] → 0, therefore the probability of the grid centre of form can be occurred in vehicle and occur in the probability in this grid cell as vehicle.

Step 3) in, solve grid collision probability within the scope of crossing, be mainly calculated assignment according to the method proposed in patent " a kind of unsignalized intersection motor vehicles collision probability determination methods " (patent No. 201610032796.8).

3.1) calculating vehicle collision probability, the probability that grid Rec (ij) clashes is:

$\begin{array}{c}{P}_{ij}conflict=P_{Aij}^a\&CenterDot;P_{Aij}^b+P_{Aij}^b\&CenterDot;P_{Aij}^c+P_{Aij}^a\&CenterDot;P_{Aij}^c\\ =\underset{k_1\&NotEqual;k_2}{\underset{k_2=a,b,c}{\underset{k_1=a,b,c}{\&Sigma;}}}{P}_{Aij}^{k_1}\&CenterDot;P_{Aij}^{k_2}\end{array}$

In formula: a, b, c be likely at most in a grid cell through the numbering of three track of vehicle lines；

Occur in the probability of grid Rec (ij) along track k, its circular is shown in patent 201610032796.8.

3.2) collision probability result of calculation is assigned to each grid, constructs collision probability matrix.

In step 4) in, according to conflict order of severity kinetic energy rejection model, solve each grid it may happen that the order of severity of conflict, and to the grid assignment in whole crossing, specifically include following steps:

4.1) order of severity calculates: characterize crash severity by the energy loss of vehicle collision, with worst situation for basis, namely calculates the kinetic energy of loss during vehicle does not take brake measure to collision to stopped process.

In formula: m₁, m₂Respectively collide the quality of two cars；v₁, v₂Speed before the two cars that respectively collides collision；v_CloseSum velocity after colliding for two cars.

It is assumed hereinafter that under condition:

A) vehicle mass is close, and before collision, speed is the speed each via crossing.

B) being in uniform speed motion state before vehicle collision, bonding force suffered by system is zero, and when vehicle collides endogenetic process suffered by system much larger than External Force Acting.

Under rectangular coordinate system, decompose crashing vehicle speed (see accompanying drawing 3).In conjunction with principle of conservation of momentum (see accompanying drawing 4), set up kinetic energy rejection model, calculate each grid units mass dynamic energy loss vector:

$\frac{\mathrm{\&Delta;}E}{\stackrel{\&OverBar;}{m}}=\frac{1}{4}({v_1}^2+{v_2}^2)-\frac{1}{2}{v}_1{v}_{2}cos({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)$

In formula:For crashing vehicle average quality；v₁, v₂Speed before the two cars that respectively collides collision；θ₁, θ₂Respectively collide the velocity attitude of first two and the angle counterclockwise of x-axis positive direction.

4.2) severity level divides: the data statistics result according to kinetic energy loss and crash severity, the order of severity is divided into slight conflict, general conflict, more serious conflict and Serious conflicts level Four, and table 1 below is shown in by corresponding unit mass kinetic energy rejection table respectively.Divide the order of severity of each grid potentially conflicting accordingly.

Table 1 crash severity table corresponding to unit mass kinetic energy rejection

In step 5) in, adopt grey clustering method to set up the Model for Safety Evaluation based on collision probability and crash severity two indices, grid all of within the scope of crossing is carried out safety status classification；Determine safety evaluation index and result of calculation Visualization.Specifically include following steps:

5.1) collision probability matrix and conflict order of severity matrix are converted into safety evaluation matrix.

5.2) clear figure of ash class and correspondence is determined.It is safety, criticality safety, danger and five grey classes of special hazard by the safety status classification of grid.The clear figure that collision probability is corresponding tries to achieve λ by About Safety Cities grading evaluation criteria₁=0, λ₂=0.001, λ₃=0.025, λ₄=0.036.Conflict clear figure corresponding to the order of severity obtains λ ' according to step 4₁=0, λ '₂=50, λ '₃=100, λ '₄=150.

5.3) clear figure is calculated.Obtain the clear figure of corresponding ash class according to whitened weight function, computing formula is as follows:

$\begin{array}{cc}{f}_z^1=\left\{\begin{array}{cc}1& (x<{\mathrm{\&lambda;}}_1)\\ \frac{{\mathrm{\&lambda;}}_1-x}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ 0& (x>{\mathrm{\&lambda;}}_2)\end{array}\right.& f_z^2=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_1)\\ \frac{x-{\mathrm{\&lambda;}}_1}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ 0& (x>{\mathrm{\&lambda;}}_3)\end{array}\right.\end{array}$

$\begin{array}{cc}{f}_z^3=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ \frac{{\mathrm{\&lambda;}}_4-x}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 0& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.& f_z^4\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_3)\\ \frac{x-{\mathrm{\&lambda;}}_3}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 1& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.\end{array}$

Wherein: z is index number.

5.4) cluster power is determined.This method has motor vehicles collision probability and conflict two evaluation indexes of the order of severity, and based on collision probability, the order of severity is auxiliary, and cluster power takes η respectively₁=0.6, η₂=0.4.

5.5) Cluster Evaluation value is calculated.Grid Rec (ij) for the Cluster Evaluation value belonging to kth ash class is:

${\mathrm{\&sigma;}}_{\mathrm{Re}c\left(ij\right)}^k=\underset{z=1}{\overset{2}{\&Sigma;}}{f}_z^k\left(\mathrm{Re}c{\left(ij\right)}_z\right)\&CenterDot;{\mathrm{\&eta;}}_z$

Wherein: Rec (ij)_zThe z of grid Rec (ij) refers to target value；

η_zThe weight of z index；

Whitened weight function.

5.6) ash class belonging to grid is determined.If the grey Cluster Evaluation value of certain grid meetsThen belonging to this grid, ash class is that safe class is k.Safe class is assigned to each grid, construction class code column vector

[k₁₁,…,k_1n,k₂₁,…,k_2n,…,k_n1,…,k_nn]^T

5.7) level code column vector is changed into level code matrix.

5.8) providing the safety evaluation index of whole crossing, take the area shared by the grid of each safe class, its computing formula is:

S_k=n_kab/N

S in formula_kRepresent the area in the region that safe class is k, n_kRepresent the number of the grid that safe class is k.

5.9) for more intuitively to present safety evaluation result, color value corresponding for each level code is assigned to each grid by corresponding relation shown in table 2 below, constructs color code matrix.

Table 2 safe class and color corresponding relation

Grade name	Safety	Criticality safety	Dangerous	Special hazard
					Level code	1	2	3	4
Color	Green	Yellow	Crocus	Red

We are for Kunming below, and the unsignalized intersection Traffic safety evaluation method that the present invention is above-mentioned is specifically described.

The happiness one plane unsignalized intersection northwestward, tunnel, riverine North Road, Kunming is a building vacant lot, and the north is building for sale, and it is less that north and south flows to motor vehicle flow；But a happy curb road commercial facility is more, and it is bigger that thing flows to motor vehicle flow.For its traffic safety situation, provide three Analysis of Nested Design schemes.

Scheme 1: reduce thing and flow to motor vehicle flow.

Scheme 2: forbid that thing flows to motor vehicles.

Scheme 3: reduce design speed.

Through consulting related data, the length L=4 of standard vehicle, width B=2 of standard vehicle.Analogy method is adopted to obtain average value mu=0.011 of vehicle shift amount, variances sigma=0 of vehicle shift amount_.572.Taking grid be the length of side is 1m.

The basic data of this plane unsignalized intersection present situation and three designs is as shown in table 3 below.

The basic data of this plane unsignalized intersection present situation of table 3 and three designs

Use matlab language to achieve this evaluation methodology, programming process have employed modularity and top-down method for designing.For testing the operability of method described in these works, choose the present situation of riverine North Road, Kunming happiness one tunnel plane unsignalized intersection and to improve design be that case has been evaluated, by in the basic data input system of collection, obtain safety evaluation result such as shown in Fig. 5～Fig. 8.

The region area such as table 4 below of each safe class of each scheme.

Each safe class region area (the unit m of table 4²)

Project	Safety	Criticality safety	Dangerous	Special hazard	The gross area
						Present situation	1511	142	10	18	1681
Scheme 1	1533	140	7	1	1681
						Scheme 2	1611	59	3	8	1681
Scheme 3	1520	135	17	9	1681

There is more conflict in this crossing present situation, scheme 2 can significantly eliminate the motor vehicles conflict within the scope of whole crossing, and scheme 1 can reduce thing and flow to the conflict that motor vehicles causes, and the contention situation of scheme 3 is the same with present situation situation.Therefore, the level of security of scheme 2 is the highest, and effect is best.

The examples of implementation of the above are only the preferred embodiments of the invention, not limit the practical range of the present invention with this, therefore all changes made according to the shape of the present invention, principle, all should be encompassed in protection scope of the present invention.

Claims (3)

1. a unsignalized intersection Traffic safety evaluation method, it is characterised in that comprise the following steps:

1) crossing of selected research, obtains basic data, altogether includes the data of four aspects: crossing geological information, intersection traffic management strategy, intersection traffic flow data and vehicle related parameters；

2) crossing basic data processes, and sets up coordinate system and carries out grid division；

3) solve the collision probability of each grid, to the grid assignment within whole crossing, construct collision probability matrix；

4) according to conflict order of severity kinetic energy rejection model, each grid is solved it may happen that the order of severity of conflict, and to the grid assignment in whole crossing；

5) consider collision probability and the conflict order of severity, utilize grey clustering method, it is determined that the safety evaluation index of each grid in whole crossing, equivalence code is assigned to each grid, construction class code matrices；

6) programming language is utilized to realize the visualization output of safety evaluation result.

2. a kind of unsignalized intersection Traffic safety evaluation method according to claim 1, it is characterized in that: in step 1) in, described crossing geological information include intersection type, crossing scope, the number of track-lines of each entrance driveway and width arrange, design radial, it is possible to obtain geological information data from crossing basic design scheme；Described intersection traffic management strategy includes the lane function of crossing and arranges, turns to restriction, design speed, it is possible to obtain management strategy data from intersection traffic Managed Solution；Described intersection traffic flow data refers to the vehicle arriving rate of each entrance driveway in crossing, it is possible to from traffic volume forecast data obtain research crossing respectively flow to traffic data, thus calculating each arrival rate flowing to vehicle；Described vehicle related parameters includes the side-play amount of the length of vehicle, the width of vehicle, vehicle.

3. a kind of unsignalized intersection Traffic safety evaluation method according to claim 1, it is characterised in that: in step 2) in, according to selected crossing, it is carried out grid process, specifically includes following steps:

2.1) coordinate system is set up: with crossing East and West direction and north-south centrage intersection for zero, east-west direction is x-axis, and North and South direction is that y-axis sets up plane right-angle coordinate；

2.2) grid division: arbitrarily inserting n-1 branch on two coordinate axess of crossing respectively, if crossing length is 2a, width is 2b；

-a=x₀< x₁< x₂< ... < x_n-1< x_n=a ,-b=y₀< y₁< y₂< ... < y_n-1< y_n=b

Crossing has been divided into N number of grid, and grid Rec (ij) is designated as Rec (ij)={ x_i-1,x_i,y_i-1,y_i, as grid quantity n → ∞, then grate area S [Rec (ij)] → 0, therefore the probability of the grid centre of form can be occurred in vehicle and occur in the probability in this grid cell as vehicle；

In step 3) in, solve grid collision probability within the scope of crossing, specifically include following steps:

3.1) calculating vehicle collision probability, the probability that grid Rec (ij) clashes is:

$\begin{array}{c}{P}_{ij}conflict=P_{Aij}^a\&CenterDot;P_{Aij}^b+P_{Aij}^b\&CenterDot;P_{Aij}^c+P_{Aij}^a\&CenterDot;P_{Aij}^c\\ =\underset{k_1\&NotEqual;k_2}{\underset{k_2=a,b,c}{\underset{k_1=a,b,c}{\&Sigma;}}}{P}_{Aij}^{k_1}\&CenterDot;P_{Aij}^{k_2}\end{array}$

In formula: a, b, c be likely at most in a grid cell through the numbering of three track of vehicle lines；

The probability of grid Rec (ij) is occurred in along track k；

3.2) collision probability result of calculation is assigned to each grid, constructs collision probability matrix；

In step 4) in, according to conflict order of severity kinetic energy rejection model, solve each grid it may happen that the order of severity of conflict, and to the grid assignment in whole crossing, specifically include following steps:

4.1) order of severity calculates: characterize crash severity by the energy loss of vehicle collision, with worst situation for basis, namely calculates the kinetic energy of loss during vehicle does not take brake measure to collision to stopped process；

In formula: m₁, m₂Respectively collide the quality of two cars；v₁, v₂Speed before the two cars that respectively collides collision；v_CloseSum velocity after colliding for two cars；

It is assumed hereinafter that under condition:

A) vehicle mass is close, and before collision, speed is the speed each via crossing；

B) being in uniform speed motion state before vehicle collision, bonding force suffered by system is zero, and when vehicle collides endogenetic process suffered by system much larger than External Force Acting；

Under rectangular coordinate system, decompose crashing vehicle speed, and in conjunction with principle of conservation of momentum, set up kinetic energy rejection model, calculate each grid units mass dynamic energy loss vector:

$\frac{\mathrm{\&Delta;}E}{\stackrel{\&OverBar;}{m}}=\frac{1}{4}({v_1}^2+{v_2}^2)-\frac{1}{2}{v}_1{v}_{2}cos({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)$

In formula:For crashing vehicle average quality；v₁, v₂Speed before the two cars that respectively collides collision；θ₁, θ₂Respectively collide the velocity attitude of first two and the angle counterclockwise of x-axis positive direction；

4.2) severity level divides: the data statistics result according to kinetic energy loss and crash severity, the order of severity is divided into slight conflict, general conflict, more serious conflict and Serious conflicts level Four, divides the order of severity of each grid potentially conflicting accordingly；

In step 5) in, adopt grey clustering method to set up the Model for Safety Evaluation based on collision probability and crash severity two indices, grid all of within the scope of crossing is carried out safety status classification；Determine safety evaluation index and result of calculation Visualization；Specifically include following steps:

5.1) collision probability matrix and conflict order of severity matrix are converted into safety evaluation matrix；

5.2) determining the clear figure of ash class and correspondence, be safety, criticality safety, danger and five grey classes of special hazard by the safety status classification of grid, the clear figure that collision probability is corresponding tries to achieve λ by About Safety Cities grading evaluation criteria₁=0, λ₂=0.001, λ₃=0.025, λ₄=0.036；Conflict clear figure corresponding to the order of severity is according to step 4) obtain λ '₁=0, λ '₂=50, λ '₃=100, λ '₄=150；

5.3) calculating clear figure, obtain the clear figure of corresponding ash class according to whitened weight function, computing formula is as follows:

$\begin{array}{cc}{f}_z^1=\left\{\begin{array}{cc}1& (x<{\mathrm{\&lambda;}}_1)\\ \frac{{\mathrm{\&lambda;}}_1-x}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ 0& (x>{\mathrm{\&lambda;}}_2)\end{array}\right.& f_z^2=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_1)\\ \frac{x-{\mathrm{\&lambda;}}_1}{{\mathrm{\&lambda;}}_2-{\mathrm{\&lambda;}}_1}& ({\mathrm{\&lambda;}}_1<x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ 0& (x>{\mathrm{\&lambda;}}_3)\end{array}\right.\end{array}$

$\begin{array}{cc}{f}_z^3=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_2)\\ \frac{x-{\mathrm{\&lambda;}}_2}{{\mathrm{\&lambda;}}_3-{\mathrm{\&lambda;}}_2}& ({\mathrm{\&lambda;}}_2<x<{\mathrm{\&lambda;}}_3)\\ \frac{{\mathrm{\&lambda;}}_4-x}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 0& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.& f_z^4=\left\{\begin{array}{cc}0& (x<{\mathrm{\&lambda;}}_3)\\ \frac{x-{\mathrm{\&lambda;}}_3}{{\mathrm{\&lambda;}}_4-{\mathrm{\&lambda;}}_3}& ({\mathrm{\&lambda;}}_3<x<{\mathrm{\&lambda;}}_4)\\ 1& (x>{\mathrm{\&lambda;}}_4)\end{array}\right.\end{array}$

Wherein: z is index number；

5.4) cluster power is determined: having motor vehicles collision probability and conflict two evaluation indexes of the order of severity, based on collision probability, the order of severity is auxiliary, and cluster power takes η respectively₁=0.6, η₂=0.4；

5.5) calculating Cluster Evaluation value: grid Rec (ij) for the Cluster Evaluation value belonging to kth ash class is:

${\mathrm{\&sigma;}}_{\mathrm{Re}c\left(ij\right)}^k=\underset{z=1}{\overset{2}{\&Sigma;}}{f}_z^k\left(\mathrm{Re}c{\left(ij\right)}_z\right)\&CenterDot;{\mathrm{\&eta;}}_z$

Wherein: Rec (ij)_zThe z of grid Rec (ij) refers to target value；

η_zThe weight of z index；

Whitened weight function；

5.6) ash class belonging to grid is determined: if the grey Cluster Evaluation value of certain grid meetsThen belonging to this grid, ash class is that safe class is k；Safe class is assigned to each grid, construction class code column vector

[k₁₁,…,k_1n,k₂₁,…,k_2n,…,k_n1,…,k_nn]^T

5.7) level code column vector is changed into level code matrix；

5.8) providing the safety evaluation index of whole crossing, take the area shared by the grid of each safe class, its computing formula is:

S_k=n_kab/N

S in formula_kRepresent the area in the region that safe class is k, n_kRepresent the number of the grid that safe class is k；

5.9) for more intuitively presenting safety evaluation result, according to corresponding relation, color value corresponding for each level code is assigned to each grid, constructs color code matrix.