Conflict elimination method for weaving area of exit ramp and intersection connecting section

Abstract

The application provides a conflict elimination model and method for a weaving area of a quick exit ramp and a connection road section of an intersection. According to the optimization theory and the rolling horizon control principle, the conflict elimination model adopts a linear programming expression form, and takes the maximum average driving speed of all vehicles as an optimization target. Constraint conditions are set in the light of traffic safety and efficiency, including vehicle weaving decision constraints, safety distance constraints and vehicle dynamics constraints. The weaving vehicle is separated in time and space, the passing right of the vehicle in the area is orderly controlled, the purpose of zero conflict of the vehicle driving is achieved in the model control range, and the traffic passing efficiency of the road section is improved to a certain extent.

Description

Technical Field

[0001] This invention relates to the field of transportation technology, and in particular to a conflict elimination model and method for the weaving zone of a fast exit ramp and an intersection connecting road section. Background Technology

[0002] The vehicle weaving area between urban expressway exit ramps and adjacent intersections is a bottleneck area prone to urban traffic problems. To alleviate this issue and improve the traffic efficiency of this section of road, a vehicle trajectory control method based on connected vehicle technology is proposed. Existing methods mainly focus on real-time updates and dynamic control of intersection signals, or on the organizational optimization design of this connecting area. In terms of connected vehicle technology, they mainly adopt general control algorithms and strategies, focusing on the overall control of a single traffic flow. They cannot guarantee the complete elimination of traffic conflicts within the control range, and no targeted control optimization methods have been found. Furthermore, no invention patents of this type have been retrieved.

[0003] A literature review of existing technologies revealed the following main methods for traffic optimization control in expressway exit ramp areas:

[0004] 1. Signal Control-Based Methods. This approach involves redesigning and adjusting the signal control schemes of adjacent intersections by considering the traffic impact of expressway exit ramps, or adding additional signal control devices at the exit ramp exit point. Signal coordination is achieved through the installation of detection devices, thereby increasing the traffic capacity of road sections and reducing traffic conflicts caused by vehicle weaving. This is described in the invention patents “Dynamic Signal Control Technology for Intersections Connecting Expressway Exit Ramps and Local Roads” (CN201811178625.1), “A Signal Light Linkage Control System and Method for Urban Expressway Exit Ramps and Adjacent Intersections” (CN201010289988.X), and “A Joint Control Method for Expressway Exit Ramps and Connecting Intersections” (CN202111558852.9).

[0005] 2. Methods based on road traffic organization optimization. This involves modifying and designing the overall traffic organization structure of the exit ramp system, designing a completely new lane layout system to address vehicle weaving bottlenecks, or reorganizing and optimizing the signs, markings, or roadside traffic information devices in the connecting sections between exit ramps and adjacent intersections to better guide vehicles. This is described in the invention patents "A Ramp System Connecting Elevated Expressways and Ground Roads" (CN201620699303.1) and "An Optimization Organization Method for the Connecting Section of an Expressway Exit Ramp and an Adjacent At-Grade Intersection" (CN201810915087.3).

[0006] 3. Control methods based on connected vehicle equipment and information technology. This involves applying intelligent technologies such as information transmission and data collaboration to onboard units or roadside facilities to process real-time traffic flow data and generate instructions, providing traffic flow decisions to control orderly lane changes in bottleneck areas and improve road capacity. The invention patent "A Traffic Control Algorithm Optimization Algorithm for Improving Traffic Efficiency in Different Traffic Bottlenecks" (CN201610542723.3) uses ramp control and variable speed limit control to achieve optimal vehicle control. The invention patent "Intelligent Vehicle Lane Changing Guidance Method and System for Multi-Lane Expressway Exit Ramp Diversion Area" (CN202110066741.X) involves an intelligent vehicle lane changing guidance method and system for multi-lane expressway exit ramp diversion areas. The guidance system uses real-time traffic flow data from traffic information collection equipment to maximize the satisfaction of vehicle lane changing needs.

[0007] Methods 1 and 2 address traffic issues at the connection points between expressway exit ramps and adjacent intersections from the perspectives of traffic signal control, road organization optimization, and collaborative strategy control. They have relatively mature design and application systems and are superior in terms of overall strategy optimization.

[0008] Method 3 utilizes intelligent technologies such as connected vehicle information interaction, data processing, and decision generation to alleviate vehicle conflicts at expressway exit ramps and adjacent intersections by controlling vehicle trajectories, thereby improving road capacity. However, existing methods primarily focus on overall traffic flow, employing control strategies such as upstream flow restrictions, road speed limits, and traditional lane-changing models. Their practical effectiveness is easily affected by variations in road organization, real-time traffic flow, and driver habits. Therefore, they can only alleviate traffic conflicts in most scenarios and cannot achieve zero-conflict vehicle movement within the control area. Furthermore, previous methods tend to overemphasize surrounding road traffic factors, neglecting specific optimization for key scenarios and failing to propose efficient control methods for major bottleneck sections. They often require extensive system computation and data collection, thus reducing control effectiveness.

[0009] Existing control methods cannot completely eliminate the weaving conflict between expressway exit ramps and adjacent intersections within the control range, and lack a more scientific and reasonable control method to improve traffic efficiency in the weaving area of ​​this connection section while ensuring inherent safety. Summary of the Invention

[0010] The purpose of this invention is to propose a model and method for eliminating weaving conflicts at the exit ramp connection section of expressways. By pre-setting weaving areas and weaving rules, vehicles that need to change lanes are ordered to change lanes in an orderly manner within the area. By maximizing efficiency, vehicles can maintain maximum speed while ensuring safe lane changing and weaving, ensuring that each vehicle passes through the intersection safely and efficiently within the control range and control time.

[0011] To achieve the above objectives, this invention proposes a conflict elimination model for the weaving area of ​​the connecting road section between a fast exit ramp and an intersection. The conflict elimination model takes maximizing the average driving speed of all vehicles as its optimization objective.

[0012] The objective function is:

[0013] ;

[0014] In the formula, This refers to the unit time interval during system operation. Total system uptime; This refers to the total number of vehicles; This is the lane number for reversible lanes, with a value range of [value range missing]. ; This refers to the vehicle number on a single lane, with a value range of [value range missing]. ; The number is The lane number is The total longitudinal distance traveled by the vehicles within the total time;

[0015] The conflict elimination model also includes vehicle weaving decision constraints, safe distance constraints, and vehicle dynamics constraints.

[0016] Furthermore, the control range of the conflict elimination model is determined based on the position of the vehicle furthest from the intersection stop line in the opposite direction under the initial conditions and the position of the vehicle furthest from the intersection stop line in the forward direction after the running time ends, satisfying the following formula:

[0017] ;

[0018] In the formula, The number is Lane number The vehicle's initial coordinates; The number is Lane number The final coordinates of the vehicle at the end of the model run; .

[0019] Furthermore, the vehicle dynamics constraints include vehicle speed limits, vehicle acceleration limits, and vehicle acceleration rate of change limits.

[0020] Furthermore, the safety distance constraints include: safety limits on the distance between the front ends of vehicles and limits on the time interval between the front ends of vehicles passing through the same cross section.

[0021] Furthermore, the vehicle weaving decision constraints include inward weaving lane change restrictions, outward weaving lane change restrictions, and vehicle queue overflow and signal control constraints.

[0022] Furthermore, the inward lane-changing restriction requires the vehicle to meet the following formula:

[0023] ;

[0024] ;

[0025] In the formula, The longitudinal length of a single interlacing control area; The number is Lane number The vehicle in The coordinates of the time point; This indicates the number of times vehicles need to change lanes during this traffic jam; The number is Lane number Vehicle flow direction; The number is The flow of traffic in the entrance lanes; This is the lane number for reversible lanes, with a value range of [value range missing]. .

[0026] Furthermore, the vehicle outward lane-changing restriction requires the vehicle to meet the following formula:

[0027] ;

[0028] .

[0029] Furthermore, vehicle queuing overflow and signal control constraints require vehicles to satisfy the following formula:

[0030] ;

[0031] ;

[0032] ;

[0033] In the formula, M represents a very large infinity; Represent a binary variable, This indicates that the vehicles are in a queue. This indicates that the vehicle is not in the queue.

[0034] The intersection signal control scheme ensures that when the signal phase of a lane within the control area is during the red light period, the vehicle position must comply with basic traffic regulations. That is, vehicles that can cross the intersection within the constraint area need to accelerate through the intersection, while vehicles that cannot cross the intersection in time must gradually reduce their speed until they stop before the stop line. Vehicles should meet the following formula S3:

[0035] ;

[0036] ;

[0037] In the formula, These represent the start and end times of the green light for the straight-ahead phase, respectively. Indicates the effective green light time for the straight-ahead phase; Indicates the signal period number. It is a set of integers; This represents a binary variable.

[0038] This invention also proposes a conflict elimination method for the weaving zone of a fast exit ramp and an intersection connecting road section, using a conflict elimination model and including the following steps:

[0039] S1: Input various parameters into the conflict elimination model to maximize the average speed of all vehicles;

[0040] S2: Based on constraints, the vehicle's speed, acceleration, rate of change of acceleration, safe distance, and lane-changing rules are limited in real time; in the event of vehicle queue overflow, the vehicle's position coordinates are limited in conjunction with the traffic light control conditions.

[0041] S3: Evaluate the solutions that meet the constraints.

[0042] In S3, the proportion of post-intrusion time, average driving speed, and average vehicle delay are used as evaluation indicators, and the implementation scheme is evaluated by comparing it with the VISSIM simulation control scheme.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] 1. The elimination model and elimination method of the present invention will determine whether the flow direction of all vehicles entering the control range matches the function of the lane they are in, and perform lane changing operations according to the constraints. Through the pre-set weaving area and weaving rules, the vehicles that need to change lanes will be orderly carried out in the area, separating the lane changing vehicles in time and space. By maximizing the efficiency target, the vehicles can maintain the maximum driving speed as much as possible while ensuring safe lane changing and weaving, and ensure that each vehicle passes through the intersection safely and efficiently within the control range and control time.

[0045] 2. The elimination model and method of this invention are both guided by traffic safety and efficiency, and are designed with efficient and practical constraints. The control method remains flexible and lightweight while achieving the goals of vehicle safety and improving traffic operation. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the research object and geometric parameters of this invention.

[0047] Figure 2 These are the geometric and signal control parameters in Embodiment 1 of the present invention.

[0048] Figure 3 This is the vehicle speed trajectory diagram obtained in Embodiment 1 of the present invention.

[0049] Figure 4 This is the vehicle position trajectory diagram obtained in Embodiment 1 of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0051] This invention proposes a conflict elimination model for the weaving zone of fast exit ramps and intersection connecting road sections. The research object is as follows: Figure 1 As shown, with the goal of maximizing the average driving speed of all vehicles, considering vehicle weaving decision constraints, safety distance constraints, and vehicle dynamics constraints, the passage rights of weaving vehicles in the driving area are allocated in time and space. Vehicles exiting the exit ramp and ground vehicles are unified in the overall framework, aiming to ensure zero conflict during the weaving and lane changing process, while simultaneously optimizing and improving the overall vehicle driving efficiency.

[0052] The optimization model is based on the principle of rolling time-domain control and uses a linear expression. Its objective function is given by Formula 1, which is expressed as:

[0053] ;

[0054] In Formula 1, This refers to the unit time interval during system operation. Total system uptime; This refers to the total number of vehicles; This is the lane number for reversible lanes, with a value range of [value range missing]. ; This refers to the vehicle number on a single lane, with a value range of [value range missing]. ;; The number is The lane number is The total longitudinal distance traveled by the vehicles within the total time; ;

[0055] The control range of the optimization model is determined based on the position of the vehicle furthest from the intersection stop line in the opposite direction under the initial conditions and the position of the vehicle furthest from the intersection stop line in the forward direction after the running time ends, that is, it satisfies the requirements of Formula 2, which is expressed as:

[0056] ;

[0057] In Formula 2, The number is Lane number The vehicle's initial coordinates; The number is Lane number The final coordinates of the vehicle at the end of the model run; The meanings of the parameters are the same as those described above.

[0058] Vehicle constraints must meet the following three conditions:

[0059] First, there is a vehicle speed limit. Vehicles traveling on normal roads must comply with the speed thresholds set by the road. The speed of a vehicle at any given moment should not exceed a certain range, as expressed in equation (3).

[0060] ;

[0061] Second, there is a limit to vehicle acceleration. Based on the actual performance of the vehicle, there are limits to its acceleration and deceleration. The acceleration of the vehicle at any given moment should not exceed a certain range, as expressed in equation (4).

[0062]

[0063] Third, the vehicle acceleration change rate limit. Based on the driving habits, comfort level and vehicle performance of real road drivers, the vehicle acceleration change rate at every moment should not exceed a certain range, expressed as Equation (5).

[0064] ;

[0065] Safety constraints must satisfy the following two conditions:

[0066] First, the distance between the front ends of vehicles should be kept within a safe range to avoid collisions, as given by equation (6):

[0067]

[0068] Second, the front ends of vehicles should pass through the same cross section at a certain time interval, as given by equation (7):

[0069] ;

[0070] The vehicle weaving decision control constraint requires that the following two constraints be met:

[0071] When a vehicle needs to weave inwards to change lanes, the vehicle should meet the requirements of formula (8):

[0072] ;

[0073] ;

[0074] When a vehicle needs to weave outwards to change lanes, the vehicle should meet the requirements of formula (9):

[0075] ;

[0076] ;

[0077] Vehicle queue overflow and signal control constraints must satisfy the following two conditions:

[0078] Formulas 10 and 11 are used to address special cases of vehicle queuing on roads. Vehicles should meet the requirements of formulas (10)-(11):

[0079] ;

[0080] ;

[0081] ;

[0082] The intersection signal control scheme ensures that when the signal phase of the lane within the control range is during the red light period, the vehicle position must comply with the basic traffic regulations. That is, vehicles that can pass through the intersection within the constraint range need to accelerate through the intersection, while vehicles that cannot pass through the intersection in time must gradually reduce their speed before the stop line until they stop. The vehicles should meet the requirements of formula (12).

[0083] ;

[0084] ;

[0085] To further illustrate the effects of the present invention, this application provides an example 1.

[0086] Example 1:

[0087] The scene geometry and signal control conditions in Embodiment 1 of this invention are as follows: Figure 2As shown, the expressway exit ramp has 2 lanes, the surface road has 4 lanes, the middle 2 lanes connect to the ramp lanes, and the entrance lane has no channelization measures.

[0088] Using the method in this invention, the vehicle speed trajectory is controlled with the goal of maximizing the average speed of all vehicles, and the effect is compared with that of a vehicle weaving scenario built using VISSIM simulation software. The design input parameters are: The unit time interval for system operation is taken as 0.5s; The total system runtime is set to 60 seconds. The total number of lanes is 4. Total number of vehicles, take 12veh; The longitudinal length of the lane that cannot be changed before the stop line is taken as 50m; The longitudinal length of the reversible lane on the ground road is taken as 100m; The longitudinal length of a single interlacing area is taken as 20m; The maximum speed limit for this section of road is 16 m / s. The minimum speed for the road section is set to 0 m / s. The maximum acceleration of the road segment is taken as 2 m / s². 2 ; The minimum acceleration of the road segment is taken as -4 m / s². 2 ; The rate of change of acceleration limited by the road segment is taken as 1 m / s². 3 ; The minimum headway constraint is set at 5m. The minimum headway constraint is set to 1.5s. The intersection signal cycle is set to 60 seconds. The duration of the all-red state is 2 seconds. The start time of the green light for the straight-ahead phase is set to 0; The time when the green light ends for the straight-ahead phase is taken as 40. The initial coordinates of the vehicles should be entered in order of vehicle number, and the values ​​are -34.2, -61.1, -82.3, -17.9, -41.4, -68.2, -17.9, -41.4, -68.2, -7.4, -29.7, -40.2, -9.8, -21.5, -43.5. The initial vehicle speed should be entered in order of vehicle number, and can be set to 14 m / s, 12.3 m / s, 10.4 m / s, 10.2 m / s, 11 m / s, 9.7 m / s, 14 m / s, 15 m / s, 9.2 m / s, 11.2 m / s, 13.4 m / s, or 10.8 m / s.

[0089] See Table 1 for details:

[0090] Table 1. Parameter representation of Example 1

[0091]

[0092] The specific process is briefly described below:

[0093] Step 1: Substitute the above input parameters into the linear programming optimization model established in this invention. To enable the model involved in the invention's method to be solvable, the classic Big M linear method is used, where M represents an infinitely large number and e represents an infinitely small number. , , , Both represent a binary variable that can only take the integer values ​​0 or 1.

[0094]

[0095] ;

[0096] ;

[0097] ;

[0098] ;

[0099] ;

[0100] ;

[0101] ;

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] Step 2: The above model is a linear programming model, which can be solved using a linear optimization solver (CPLEX). The resulting vehicle acceleration and velocity trajectory are as follows: Figure 3 As shown, the vehicle position trajectories are respectively as follows: Figure 4 As shown.

[0107] Step 3: Design Scheme Evaluation. The post-intrusion time (PET) ratio, average vehicle speed, and average vehicle delay were used as evaluation indicators, and compared with a VISSIM simulation control scheme. The PET ratio was set at a standard threshold of 1.5 seconds. In the control scheme, all vehicles performed lane-changing and weaving behaviors according to a predetermined path, and the system lacked a clear optimization guide. The evaluation results are shown in Table 2. The method of this invention maintains a zero PET ratio, achieving zero conflict within the control range. Compared with the control scheme, safety is improved by 22.4%, average speed is improved by 15.1%, and average vehicle delay is reduced by 17.8%. This indicates that the method of this invention can improve the traffic efficiency of the expressway merging area and reduce travel delay while ensuring the elimination of vehicle weaving conflicts.

[0108] Table 2 Optimization Results and Comparison of the Invention Method

[0109] Group Method of the present invention VISSIM Simulation Control Method Post-intrusion time percentage (%) 0.0 22.4 Average vehicle speed (m / s) 12.41 10.78 Average delay per train (s) 15.05 18.30

[0110] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for eliminating conflicts in the weaving zone of a fast exit ramp and an intersection connecting road section, characterized in that, Based on the conflict elimination model of the weaving area of ​​the fast exit ramp and the intersection connecting road section, the conflict elimination model takes the maximum average driving speed of all vehicles as the optimization objective. The objective function is: ； In the formula, This refers to the unit time interval during system operation. Total system uptime; This refers to the total number of vehicles; This is the lane number for reversible lanes, with a value range of [value range missing]. ; This refers to the vehicle number on a single lane, with a value range of [value range missing]. ; The number is The lane number is The total longitudinal distance traveled by the vehicles within the total time; The conflict elimination model also includes vehicle weaving decision constraints, safe distance constraints, and vehicle dynamics constraints; The vehicle weaving decision constraints include restrictions on inward weaving lane changes, restrictions on outward weaving lane changes, and constraints on vehicle queue overflow and signal control. The inward lane-changing restriction for vehicles requires vehicles to meet the following formula: ； ； In the formula, The longitudinal length of a single interlacing control area; The number is Lane number The vehicle in The coordinates of the time point; This indicates the number of times vehicles need to change lanes during this traffic jam; The number is Lane number Vehicle flow direction; The number is The flow of traffic in the entrance lanes; This is the lane number for reversible lanes, with a value range of [value range missing]. ; The vehicle outward lane-changing restriction requires the vehicle to meet the following formula: ； ； Vehicle queue overflow and signal control constraints require vehicles to satisfy the following formula: ； ； ； In the formula, M represents a very large infinity; Represent a binary variable, This indicates that the vehicles are in a queue. This indicates that the vehicle is not in the queue; The intersection signal control scheme ensures that when the signal phase of a lane within the control area is during the red light period, the vehicle position must comply with basic traffic regulations. That is, vehicles that can cross the intersection within the constraint area need to accelerate through the intersection, while vehicles that cannot cross the intersection in time must gradually reduce their speed until they stop before the stop line. Vehicles should meet the following formula S3: ； ； In the formula, These represent the start and end times of the green light for the straight-ahead phase, respectively. Indicates the effective green light time for the straight-ahead phase; Indicates the signal period number. It is a set of integers; Represent a binary variable; The method for eliminating conflicts in the weaving zone between the express exit ramp and the intersection connection section includes the following steps: S1: Input various parameters into the conflict elimination model to maximize the average speed of all vehicles; S2: Based on constraints, the vehicle's speed, acceleration, rate of change of acceleration, safe distance, and lane-changing rules are limited in real time; in the event of vehicle queue overflow, the vehicle's position coordinates are limited in conjunction with the traffic light control conditions. S3: Evaluate the solutions that meet the constraints.

2. The method for eliminating conflicts in the weaving area between a rapid exit ramp and an intersection connecting road section according to claim 1, characterized in that, The control range of the conflict elimination model is determined based on the position of the vehicle furthest from the intersection stop line in the opposite direction under the initial conditions and the position of the vehicle furthest from the intersection stop line in the forward direction after the running time ends, satisfying the following formula: ； In the formula, The number is Lane number The vehicle's initial coordinates; The number is Lane number The final coordinates of the vehicle at the end of the model run; .

3. The method for eliminating conflicts in the weaving area between a rapid exit ramp and an intersection connecting road section according to claim 1, characterized in that, The vehicle dynamics constraints include vehicle speed limits, vehicle acceleration limits, and vehicle acceleration rate of change limits.

4. The method for eliminating conflicts in the weaving area between a rapid exit ramp and an intersection connecting road section according to claim 1, characterized in that, The safety distance constraints include: safety limits on the distance between the front ends of vehicles and restrictions on maintaining a certain time interval between the front ends of vehicles passing through the same cross section.

5. The method for eliminating conflicts in the weaving area of ​​a fast exit ramp and an intersection connecting road section according to claim 1, characterized in that, In S1, the model's input parameters include: The unit time interval of system operation Total system uptime Total number of lanes Total number of vehicles The longitudinal length of the lane that cannot be changed before the stop line, Longitudinal length of reversible lanes on ground roads The longitudinal length of a single interlacing region Maximum speed of vehicles on the road section Minimum speed on the road section Maximum acceleration of the road section Minimum acceleration of road segment The rate of change of acceleration restricted by the road section Minimum headway constraint Minimum headway constraint Intersection signal cycle, All-Red Time The start time of the green light for the straight-ahead phase The end time of the green light for the straight-ahead phase. The initial coordinates of the vehicle should be entered in order of vehicle number. Initial vehicle speed, enter in order of vehicle number; In S3, the proportion of post-intrusion time, average driving speed, and average vehicle delay are used as evaluation indicators, and the implementation scheme is evaluated by comparing it with the VISSIM simulation control scheme.

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