Road safety reliability evaluation method based on operation linear parameters

Abstract

The invention provides a highway safety reliability evaluation method based on operation linear parameters, and aims to solve the technical problem that reliability evaluation is lacked in the field of highway safety. The method mainly comprises the following steps: constructing an operation circular curve radius calculation model, an operation superelevation calculation model and a curve parking sight distance calculation model according to a driving track of a vehicle; constructing a specification conformity performance function and a vehicle transverse stability performance function; the running distance and the running speed serve as random variables, and the standard conformity reliability and the transverse stability reliability are calculated; and evaluating the road safety according to whether the standard conformity reliability and the transverse stability reliability meet a target reliability requirement or not. According to the method, the safety of different road sections in different weather scenes and when the road alignment design value meets the standard value but is close to the limit value can be better evaluated, the safety evaluation can be more intuitively and truly carried out, and the defects of an existing road safety evaluation method are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of highway safety evaluation, and in particular to a highway safety reliability evaluation method based on operating line parameters. Background Art

[0002] With the rapid growth of my country's national economy, highway construction has made great progress. With the continuous increase in highway mileage, the current highway safety situation is becoming more and more serious, and the requirements for quality and safety are becoming more stringent. Highway safety evaluation is a systematic evaluation procedure for highway driving safety, with the purpose of highway driving safety and reducing traffic accidents. my country has also paid more and more attention to highway safety evaluation. In 2014, the Ministry of Transport issued the "Highway Engineering Technical Standard" (JTG B01-2014), which listed the traffic safety evaluation of secondary and above trunk roads as a normative work; in 2015, the Ministry of Transport revised the recommended "Highway Project Safety Evaluation Guide" (JTG / T B05-2004) into the mandatory "Highway Project Safety Evaluation Specification" (JTG B05-2015), requiring highway safety status evaluation to be carried out throughout the entire process of engineering feasibility study, preliminary design, construction drawing design, delivery and post-evaluation. In 2015, the "Technical Guidelines for the Implementation of Highway Safety Life Protection Projects (Trial)" jointly edited by the Highway Research Institute of the Ministry of Transport and the Guizhou Provincial Department of Transport was released, and the work of highway safety life protection projects began to be promoted. The issue of highway safety evaluation has attracted great attention from domestic and foreign experts and has achieved certain research results. In domestic and foreign research, the commonly used highway safety evaluation methods include: (1) conformity evaluation method; (2) system analysis method; (3) safety service level evaluation method; (4) statistical analysis method.

[0003] Running alignment parameters are important parameters that describe the geometric characteristics of traffic routes such as highways. They have a significant impact on the operating safety, stability and passenger comfort of vehicles. Highway safety is closely related to highway conditions, especially alignment conditions. In the current road design, fixed-value design parameters are usually used. Designers mostly consider whether the design meets the design specifications, and insufficiently consider the impact of random variable parameters such as weather on driving safety in alignment design. Carrying out highway geometric alignment evaluation work is helpful to evaluate the quality of design alignment, thereby significantly improving the level of highway safety. Domestic and foreign researchers mainly use accident rate, driver load, vehicle lane deviation, lateral acceleration, running speed, etc. as media, and use a variety of mathematical models to analyze the impact of route geometric design alignment parameters on highway safety. For example, a variety of regression analysis models are used to establish the relationship curves between plane alignment, longitudinal alignment, cross-section design parameters, sight distance, etc. and accident rate, driver load, vehicle lane deviation, lateral acceleration, running speed, etc., and then evaluate the safety of highway alignment.

[0004] The application of reliability theory in highway safety has not been widely carried out. At present, reliability theory is mainly used in structural engineering. There is a lack of research on the impact mechanism between reliability evaluation and highway safety. Therefore, in view of the current research status, there are still many areas that need to be enriched, improved and improved in the research on highway safety reliability evaluation.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] In view of this, the present application provides a highway safety reliability evaluation method based on operating line parameters to make up for the shortcomings of existing highway safety evaluation methods. The method can evaluate the highway safety of different highway grades and different sections under different weather scenarios, and quantify the safety of highway design indicators. It provides a safety basis and an objective evaluation method for designers to refine the highway traffic safety under different conditions. It has reference significance and practical value for improving the safety of vehicles driving on highways and for highway linear safety evaluation and design optimization, and can be applied in highway construction and planning.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] (1) The lateral offset value, travel distance and road design line parameters of the vehicle on the road at different times are collected, and the radius of the running circle curve is calculated by the following formula:

[0009]

[0010] In the formula, R d is the design circular curve radius, w is the lane width; d y is the lateral offset distance; d is the driving distance; R1 is the radius of the inner lane circular curve;

[0011] The operating superelevation is calculated by the following formula:

[0012] i v =i h ·cosα,

[0013] In the formula, i h is the design superelevation; α is the deviation angle between the vehicle's driving direction and the tangent direction of the road centerline during lane change;

[0014] (2) Based on the radius of the running circle and the running superelevation, the curved parking sight distance is calculated by the following formula:

[0015]

[0016] Where v is the instantaneous speed of the target vehicle when braking; T is the reaction time; g is the acceleration of gravity; f is the friction coefficient of the road surface; R v i is the radius of the running circle curve; v To run superelevation;

[0017] (3) The following specification compliance function is constructed based on the operating line parameters, and the reliability of specification compliance is calculated using the driving distance and driving speed as random variables:

[0018] Function of compliance of circular curve radius specification: Z = R v -R min ;

[0019] The function function of the compliance of the standard for the parking sight distance of the running curve is: Z = SSD-SSD w ;

[0020] In the above formula, R min It is the minimum radius limit value of circular curve corresponding to different design speeds and different maximum superelevations in JTG D20-2017; SSD is the stopping sight distance value corresponding to different design speeds in JTG D20-2017;

[0021] (4) Based on the radius of the running circle and the running superelevation, the following vehicle lateral stability function is constructed, and the lateral stability reliability is calculated with the driving distance and driving speed as random variables:

[0022]

[0023]

[0024] In the formula, is the lateral friction coefficient that the road can provide, which is a random variable; μ is the lateral force coefficient;

[0025] (5) Compare the compliance reliability and lateral stability reliability to see whether they meet the target reliability requirements to evaluate highway safety.

[0026] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0027] 1. It is proposed to use safety reliability evaluation as a new quantitative indicator of highway safety, which has reference significance and practical value for improving vehicle driving safety on highways and for highway linear safety evaluation and design optimization.

[0028] 2. This application is based on the specification compliance function, which can evaluate the safety of highways in different sections and provide a theoretical basis for the safe driving of vehicles in different sections.

[0029] 3. This application is based on the lateral stability function. By providing the lateral friction coefficient of the road under different weather scenarios, it can further evaluate the safety of road sections under different weather scenarios, respond to the negative impact of natural disasters on road traffic, and improve the stability and reliability of road traffic.

[0030] 4. The target reliability of this application is taken as different values ​​according to the highway grade. By comparing whether the specification compliance reliability and lateral stability reliability meet the target reliability requirements, the highway safety under different highway grade conditions can be directly and objectively evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of highway safety reliability evaluation based on operating linear parameters in one embodiment of the present application.

[0032] Figure 2 This is a relationship diagram between the radius of the running circular curve, the design radius and the lane change length in one embodiment of the present application.

[0033] Figure 3 This is a relationship diagram between operating superelevation and lane change length in one embodiment of the present application.

[0034] Figure 4 This is a comparison diagram of the curved parking sight distance and the designed parking sight distance when the design speed is 80 km / h in one embodiment of the present application.

[0035] Figure 5 This is a relationship diagram between the probability of failure of compliance with the operating circular curve radius specification and the designed circular curve radius in one embodiment of the present application.

[0036] Figure 6 This is a relationship diagram between the probability of failure of compliance with parking sight distance standards and the designed circular curve radius in one embodiment of the present application.

[0037] Figure 7 This is a graph showing the relationship between the probability of failure of compliance with the parking sight distance specification and the operating speed in one embodiment of the present application.

[0038] Figure 8 This is a failure probability diagram when the design speed is 80 km / h in one embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0040] Example:

[0041] This embodiment provides a highway safety reliability evaluation method based on operating line parameters, such as Figure 1 As shown, it mainly includes the following steps:

[0042] (1) The vehicle's driving trajectory is calculated based on the lateral offset value, driving distance and road design linear parameters of the vehicle at different times. Analyzing the lateral offset process of the vehicle helps determine the vehicle's driving trajectory. The point where the vehicle starts to lateral offset is P1, and the point where the vehicle ends the lateral offset and starts to drive along the lane is P2. The lateral offset distance is d y The distance traveled by the vehicle is represented by d.

[0043] The driving trajectory of the vehicle in the process of lateral deviation is approximately regarded as a circular curve, and the lane changing trajectory of the vehicle in normal driving is used as the trajectory for calculating the operating linear parameters. The basic assumptions and related definitions involved in the driving trajectory of the lane changing process are defined as follows: 1) Lane changing trajectory: the vehicle driving trajectory that deviates laterally to the adjacent lane due to the influence of external factors or internal factors during normal driving of a passenger car; 2) After the lateral deviation, the vehicle's driving direction remains consistent with the highway linear direction; 3) The lane changing trajectory is approximately regarded as a circular curve.

[0044] When driving on a curved road section, the driving trajectory of a passenger car changing lanes from lane 1 to lane 2 and then to lane 1 is the unfavorable trajectory line, and the circular curve radius corresponding to the unfavorable trajectory line is the operating circular curve radius.

[0045] The lateral offset value, travel distance and road design linear parameters of the vehicle on the road at different times are collected, and the radius of the running circle curve is calculated by the following formula:

[0046]

[0047] In the formula, R d is the design radius of the circular curve, w is the lane width; d y is the lateral offset distance; d is the driving distance; R1 is the circular curve radius of the inner lane.

[0048] In this example, let d = vt, where v is the vehicle speed, m / s; t is the lane change time, s. Under normal vehicle driving conditions, the lateral offset value is equal to the lane width value of 3.75m. Assume that the original vehicle driving trajectory coincides with the center line of the inner lane. Assume that the maximum lateral offset value is the lane width, that is, d y = 3.75m, and the lane-changing distance d corresponding to different lane-changing times is calculated based on the running speed of 80km / h. The calculation results of the circular curve radius in this example are as follows Figure 2 shown.

[0049] The point where the deviation angle between the driving direction of the passenger car and the tangent direction of the road line is the largest during the driving process is taken as the unfavorable position point for calculating the operating superelevation. The operating superelevation is: the superelevation value corresponding to the tangent of the driving direction when the target vehicle changes lanes on a curved road section and the deviation angle between the driving direction of the passenger car and the tangent direction of the road line is the largest.

[0050] The operating superelevation is calculated by the following formula:

[0051] i v =i h ·cosα,

[0052] In the formula, i h is the design superelevation; α is the deviation angle between the vehicle's driving direction and the tangent direction of the road centerline during lane change;

[0053] In this example, when the design superelevation is 8%, the relationship between the running superelevation and the design circular curve radius and the lane change length is as follows: Figure 3 shown.

[0054] (2) The calculation model of the parking sight distance for curved roads is obtained by modifying the calculation model of the parking sight distance for horizontal straight lines. The parking sight distance for curved roads is calculated by the following formula:

[0055]

[0056] Where v is the instantaneous speed of the target vehicle when braking, in m / s; T is the reaction time, in s; g is the acceleration of gravity, with a value of 9.8; f is the friction coefficient of the road surface; R v is the radius of the circular curve, in meters; i v To run superelevation;

[0057] In this example, based on the radius of the running circle and the running superelevation, the calculation results of the curved parking sight distance are as follows: Figure 4 shown.

[0058] (3) Based on the operating line parameters, the following compliance function functions are constructed, including: the compliance function function of the circular curve radius and the compliance function function of the curved parking sight distance. The compliance reliability is calculated using the driving distance and driving speed as random variables.

[0059] Taking into account the uncertainty of vehicle speed and lane-changing time, based on the circular curve radius and the minimum radius limit value of the circular curve specified in the specification, the circular curve radius specification compliance function is: Z = R v -R min ;

[0060] Taking the parking sight distance specified in the specification as the threshold, the standard compliance function of the parking sight distance for running curves is: Z = SSD-SSD w ;

[0061] In the above formula, R min It is the minimum radius limit value of circular curve corresponding to different design speeds and different maximum superelevations in the Highway Alignment Design Specifications (JTG D20-2017); i max =8%, the minimum circular curve radius corresponding to the design speed of 120km / h is 650m, the minimum circular curve radius corresponding to the design speed of 100km / h is 400m, and the minimum circular curve radius corresponding to the design speed of 80km / h is 250m; SSD is the stopping sight distance value corresponding to different design speeds in the "Highway Route Design Specifications" (JTG D20-2017), the stopping sight distance value corresponding to the design speed of 120km / h is 210m, the stopping sight distance value corresponding to the design speed of 100km / h is 160m, and the stopping sight distance value corresponding to the design speed of 80km / h is 110m.

[0062] It is worth noting that the Highway Route Design Specifications (JTG D20-2017) clearly defines the limit values ​​of highway technical indicators under different design speeds. If Z < 0, it is invalid and in an unsafe state.

[0063] Compare whether the reliability of compliance with the specification meets the target reliability requirements to evaluate the safety of the highway. The target reliability is taken as different values ​​according to the highway grade, with the target reliability of expressways being 95% and that of first-class highways being 90%.

[0064] In the functional function of this example, the random variables are lane change time and running speed. Assuming that the lane change time conforms to the normal distribution, the mean of the vehicle lane change time is 5.75s, the standard deviation is 1.91s, the mean of the turning speed is 85.958km / h, and the standard deviation of the turning speed is 3.612km / h. The Monte Carlo simulation method is used for reliability analysis to calculate the failure probability of the vehicle on the curved road section.

[0065] In this example, according to the Highway Engineering Technical Standard (JTGB01-2014), when the design superelevation is 8%, the minimum circular curve radius limit corresponding to the design speed of 80km / h is 250m. Set the estimated number of sampling times to 10 6 Second, random numbers are generated according to the random variable distribution model of lane change time and running speed, and the function value of the running circle curve radius is calculated. Finally, the simulation test results are statistically analyzed to obtain the failure probability, such as Figure 5 shown.

[0066] According to the Highway Route Design Specifications (JTG D20-2017), the minimum radius of a circular curve corresponding to a design speed of 80 km / h is generally 400 m, with a failure probability of 7.25%. The reliability is lower than the target reliability of 95% for expressways, but higher than the target reliability of 90% for first-class highways.

[0067] In this example, the function of the compliance of the parking sight distance specification is difficult to express as a clear analytical expression, so the Monte Carlo simulation method is used for reliability analysis. Similarly, the estimated number of sampling is set to 10 6 The random number is generated according to the random variable distribution model of lane change time and running speed, and the failure risk of the vehicle's parking sight distance on the curved road section is calculated. Under different design speeds, when the design circular curve radius is 700m to 2000m, the corresponding failure probability of the running curve parking sight distance specification compliance is as follows: Figure 6 As shown, it can be seen that the failure probability is almost unaffected by the design circle curve radius.

[0068] In this example, the estimated number of sampling is set to 10 6 times, random numbers are generated according to the random variable distribution model of lane change time. To discuss the impact of operating speed, it is assumed that the standard deviation of different operating speed means is 4 km / h. Taking the design circular curve radius of 1000m as an example, based on different design speeds, the failure probability of compliance with the operating stopping sight distance specification under different operating speed distributions is calculated as follows: Figure 7 shown.

[0069] (4) Based on the radius of the running circle and the running superelevation, the following vehicle lateral stability function is constructed, and the lateral stability reliability is calculated with the driving distance and driving speed as random variables:

[0070]

[0071]

[0072] In the formula, is the lateral friction coefficient that the road can provide, which is a random variable; μ is the lateral force coefficient;

[0073] It is worth noting that in order to prevent lateral slippage during driving, the lateral force coefficient μ should be smaller than the lateral friction coefficient that the road can provide. Should satisfy If Z < 0, it fails and is in an unsafe state.

[0074] Compare whether the lateral stability reliability meets the target reliability requirements to evaluate highway safety.

[0075] In this example, according to the design linear parameters of expressways and first-class highways, the lane width w and the design superelevation i are h , lateral offset value d y As deterministic variables, they are taken as 3.75m, 8%, and 3.75m respectively.

[0076] It is worth noting that the road friction coefficient follows a normal distribution, and when the road is dry, the friction coefficient is not affected by the running speed, with a mean of 0.8852 and a standard deviation of 0.0949. The change in the friction coefficient depends on the influencing factors under different road conditions, and the friction coefficient influencing factor ranges from 0.2 to 1. According to the principle of stress decomposition, the friction coefficient is divided into a lateral friction coefficient and a longitudinal friction coefficient, and the ratio of the maximum lateral friction coefficient to the maximum longitudinal friction coefficient is 1:0.925, so the lateral friction coefficient can be calculated based on the friction coefficient and this ratio.

[0077] In this example, the estimated number of samples is 10 6 times, according to the lateral friction coefficient The normal distribution model of random variables such as running speed v and lane change time t generates random numbers, and finally the simulation test results are statistically analyzed to obtain the failure probability. Python coding is used to calculate the failure probability of vehicle lateral stability.

[0078] Python key code examples:

[0079]

[0080]

[0081] In this example, the friction coefficient influencing factors of different road surfaces are taken. When the design speed is 80km / h, the probability of vehicle lateral stability failure under different design circular curve radii and different road conditions is as follows: Figure 8 shown.

[0082] The embodiments described above are only used to explain the present invention and are not intended to limit the scope of implementation of the present invention. For those skilled in the art, other implementation methods can certainly be easily made by replacement or modification based on the technical contents disclosed in this specification. Therefore, all changes and improvements made on the principles of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A highway safety reliability evaluation method based on operating line parameters, characterized in that: The steps include: (1) The lateral offset value, travel distance and road design line parameters of the vehicle on the road at different times are collected, and the radius of the running circle curve is calculated by the following formula: In the formula, R d is the design circular curve radius, w is the lane width; d y is the lateral offset distance; d is the driving distance; R1 is the radius of the inner lane circular curve; The operating superelevation is calculated by the following formula: i v =i h ·cosα, In the formula, i h is the design superelevation; α is the deviation angle between the driving direction and the tangent direction of the road centerline during the vehicle lane change process; (2) Based on the radius of the running circle and the running superelevation, the curved parking sight distance is calculated by the following formula: Where v is the instantaneous speed of the target vehicle when braking; T is the reaction time; g is the acceleration of gravity; f is the friction coefficient of the road surface; R v i is the radius of the running circle curve; v To run superelevation; (3) The following specification compliance function is constructed based on the operating line parameters, and the reliability of specification compliance is calculated using the driving distance and driving speed as random variables: Function of compliance of circular curve radius specification: Z = R v -R min ; The function function of the compliance of the standard for the parking sight distance of the running curve is: Z = SSD-SSD w ; In the formula, R min It is the minimum radius limit value of circular curve corresponding to different design speeds and different maximum superelevations in JTG D20-2017; SSD is the stopping sight distance value corresponding to different design speeds in JTG D20-2017; (4) Based on the radius of the running circle and the running superelevation, the following vehicle lateral stability function is constructed, and the lateral stability reliability is calculated with the driving distance and driving speed as random variables: In the formula, is the lateral friction coefficient that the road can provide, which is a random variable; μ is the lateral force coefficient; (5) Compare the compliance reliability and lateral stability reliability to see whether they meet the target reliability requirements to evaluate highway safety.

2. The highway safety reliability evaluation method according to claim 1, characterized in that: In step (5), the target reliability is set to different values ​​according to the highway grade. The target reliability of the expressway is set to 95%, and the target reliability of the first-class highway is set to 90%.

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