Variable speed limit and ramp control linkage method and system for confluence area in ice and snow weather

Abstract

The invention relates to a variable speed limit and ramp control linkage method and system for a confluence area in ice and snow weather, and belongs to the field of intelligent traffic. The method comprises the following steps: S1, collecting data: detecting and obtaining ice and snow weather road surface state data in real time through a road surface state detector, detecting and obtaining traffic flow data in real time through a traffic flow detector, and uploading the traffic flow data to a central controller; s2, linkage strategy optimization and decision making: a central controller optimizes a variable speed limit and ramp control linkage strategy of the confluence area in ice and snow weather based on real-time detection data, and performs decision issuing; and S3, linkage strategy issuing: the central controller issues a linkage strategy decision result control instruction to the variable speed limit sign, the variable information sign and the ramp signal lamp. According to the method, the problem that variable speed limit and ramp control are insufficiently considered in a special ice and snow weather environment is solved, coupling linkage control of variable speed limit and ramp control in ice and snow weather is achieved, and the traffic safety level of a road confluence area in ice and snow weather is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of intelligent transportation, and relates to a variable speed limit and ramp control linkage method and system for a merging area in ice and snow weather.

[0002] With the continuous improvement of highway and urban expressway networks, the merging area, as the intersection hub of mainline traffic and ramp traffic, has become a sensitive node with the most intense traffic flow conflict and frequent accidents. In winter ice and snow weather, the road adhesion coefficient is greatly reduced, and the vehicle braking performance is severely attenuated, resulting in more severe challenges to traffic safety and operating efficiency in the merging area.

[0003] At present, the traffic management strategies for adverse weather mainly include variable speed limit (VSL) control and ramp metering (RM), but in actual application, the existing technical system still has the following limitations: (1) The existing variable speed limit system mainly relies on macroscopic traffic flow theory or preset weather response plans. The control parameters (such as speed limit threshold) are usually based on the average traffic volume of the entire section or simple weather classification triggering, and the mainline vehicles are passively speed-limited through variable information signs along the line. This strategy lacks consideration of the specific physical constraints of the merging area, especially in the ice and snow low adhesion environment, ignoring the fact that vehicles from the ramp may not be able to accelerate to the desired speed limit value of the mainline within a limited distance due to insufficient friction on the acceleration lane, thereby causing a sharp speed difference between the mainline and the incoming flow, inducing rear-end and side collision accidents.

[0004] (2) The existing ramp control system mainly focuses on preventing the mainline density from exceeding the critical capacity. However, the feedback model and key parameters (such as capacity and saturation flow) are usually calibrated based on dry road conditions. In ice and snow weather, drivers will actively increase the following distance to ensure safety, resulting in a significant decrease in actual road capacity. If the control logic in the conventional environment is still used, it will lead to traffic overload in the merging area, disrupting the original traffic flow balance.

[0005] (3) In the existing technology, variable speed limit and ramp control are usually operated as two independent subsystems in parallel, lacking deep coupling. Variable speed limit does not consider the actual acceleration capability constraints of ramp vehicles when adjusting the mainline speed; while ramp control does not associate the dynamic safety distance demand after the mainline speed limit in real time when regulating the incoming flow. This "information island" type of management mode makes the system unable to provide the optimal traffic coordination scheme in the high-risk ice and snow environment.

[0006] Therefore, how to combine the physical characteristics of the road surface in the ice and snow weather, and construct a speed limit and ramp linkage control system that can comprehensively consider the main line driving safety, ramp acceleration constraint and dynamic following demand has become a key technical problem to be solved in the current intelligent transportation field. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a variable speed limit and ramp control linkage method and system in a merging area in ice and snow weather, which overcomes the problem of insufficient consideration of variable speed limit and ramp control in special ice and snow weather environment, and realizes the coordination of variable speed limit and ramp control in a merging area in ice and snow weather through coupling linkage, thereby improving the safety level of the merging area.

[0008] To achieve the above purpose, the present application provides the following technical solutions: A variable speed limit and ramp control linkage method in a merging area in ice and snow weather, specifically comprising the following steps: S1: collecting data: acquiring real-time ice and snow weather road surface state data through a road surface state detector, and acquiring real-time traffic flow data through a traffic flow detector, and uploading to a central controller; S2: linkage strategy optimization and decision: the central controller optimizes the linkage strategy of variable speed limit and ramp control in a merging area in ice and snow weather based on real-time detection data, and makes a decision; S3: linkage strategy issuing: the central controller issues the linkage strategy decision result control instruction to a variable speed limit sign, a variable information sign and a ramp signal lamp.

[0009] Further, in step S1, the road surface state detector is deployed on the main line x upstream of the merging nose end, the end point of the merging area acceleration lane x downstream, and the acceleration lane, to detect real-time ice and snow weather road surface state data such as road surface friction coefficient, ice thickness, water depth, visibility and snowfall at the corresponding positions; The traffic flow detector is deployed on the main line x upstream of the merging nose end, the end point of the merging area acceleration lane x downstream, and the ramp upstream of the merging nose end y to detect real-time traffic flow data such as speed, flow and density at the corresponding positions.

[0010] Further, in step S3, the variable speed limit sign is deployed on the main line x upstream of the merging nose end and the end point of the merging area acceleration lane x downstream; The variable information sign is deployed on the main line x upstream of the merging nose end and the end point of the merging area acceleration lane x downstream; The ramp signal lamp is arranged at the start position of the acceleration lane.

[0011] Further, in step S2 or S3, the central controller is arranged at the merging area.

[0012] Further, in step S2, the ramp control linkage strategy of the variable speed limit of the merging area comprises a variable speed limit strategy decision, specifically comprising: (1) determining the variable speed limit value downstream of the merging area; The variable speed limit value of the merging area downstream is released by the variable speed limit sign II, which is determined by factors such as the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall at the location.

[0013]

[0014] wherein, is the variable speed limit value of the merging area downstream released by the variable speed limit sign II; is the variable speed limit value calculation function of the variable speed limit sign II downstream of the merging area; respectively, the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall obtained by the road surface state detector II downstream of the merging area; Further determine the safe following distance downstream of the merging area in ice and snow weather:

[0015] wherein, is the safe following distance downstream of the merging area in ice and snow weather; is the reaction time; is the acceleration of gravity; is the stopping safety distance; (2) determining the variable speed limit value upstream of the merging area; The variable speed limit value upstream of the merging area is released by the variable speed limit sign I, which is determined by factors such as the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall at the location, the speed value that the vehicle on the ramp can reach on the acceleration lane, and the variable speed limit value released by the variable speed limit sign II downstream of the merging area.

[0016] The speed value that the vehicle on the ramp can reach on the acceleration lane is determined by factors such as the length of the acceleration lane, the road surface friction coefficient, and the maximum acceleration that the vehicle can reach.

[0017]

[0018]

[0019]

[0020] wherein, is the speed limit value of the variable speed limit sign Ⅰ upstream of the merging area; is the speed limit value of the variable speed limit sign Ⅰ upstream of the merging area considering the road surface state data in icy and snowy weather; is the speed value that a vehicle on the ramp can reach on the acceleration lane; is the speed limit value calculation function of the variable speed limit sign Ⅰ upstream of the merging area; respectively are the road friction coefficient, ice thickness, water depth, visibility and snowfall obtained by the road surface state detector Ⅰ upstream of the merging area; is the length of the acceleration lane; is the maximum acceleration that a vehicle can reach; further determines the safe following distance upstream of the merging area in icy and snowy weather:

[0021] wherein, is the safe following distance upstream of the merging area in icy and snowy weather.

[0022] Further, in step S2, the variable speed limit of the merging area and the ramp control linkage strategy further include ramp control decision, specifically including: (1) calculating the allowable traffic flow downstream of the merging area: The allowable traffic flow downstream of the merging area is determined by the speed limit value of the variable speed limit sign Ⅱ downstream of the merging area, the safe following distance upstream of the merging area, etc.

[0023]

[0024] wherein, is the allowable traffic flow downstream of the merging area in icy and snowy weather; (2) calculating the allowable ramp release flow: The allowable ramp release flow cannot exceed the allowable traffic flow downstream of the merging area minus the traffic flow obtained by the detector upstream of the merging area.

[0025]

[0026] wherein, is the allowable ramp release flow; is the traffic flow obtained by the traffic flow detector Ⅰ upstream of the merging area.

[0027] Further, in step S3, the variable speed limit sign Ⅰ upstream of the merging area releases the speed limit value , and the variable speed limit sign Ⅱ downstream of the merging area releases the speed limit value ; The variable information sign Ⅰ upstream of the merging area releases the recommended safe following distance value in icy and snowy weather , downstream of the merging area, the variable information sign II releases the ice and snow weather recommended safe following distance value ; The ramp signal lamp controls through red, green and yellow light colors, and ensures that the flow entering the expressway from the ramp is not more than .

[0028] The present application has the advantages that the present application can be applied to the merging area of urban expressway and expressway, the ice and snow weather road surface state and the speed value of the vehicle on the ramp in the acceleration lane under the control of the ramp are considered in the variable speed limit control, the main line variable speed limit and the allowed traffic flow under the safe following distance are considered in the ramp control, so as to regulate the ramp inflow, the variable speed limit and the ramp control of the merging area under the ice and snow weather are coupled and linked to realize the cooperation, and the safety level of the merging area is improved. The specific embodiments are as follows: (1) The coupling and linking mechanism overcomes the limitation of the traditional technology that the variable speed limit and the ramp control are "isolated running". The system no longer depends on single speed limit or flow control, but realizes the deep cooperation of the two, so as to improve the overall safety level of the merging area under extreme weather.

[0029] (2) When setting the upstream speed limit value of the main line, the actual maximum speed of the ramp inflow vehicle under the ice and snow road surface (low adhesion) and the acceleration lane length limit is fully considered. This design avoids the sharp speed difference between the main line flow and the ramp inflow, effectively inducing the risk of rear-end and side collision accidents.

[0030] (3) The ramp control no longer blindly applies the model of dry road surface, but dynamically associates the dynamic safe following distance under the ice and snow weather and the main line speed limit value to calculate the allowed traffic capacity. By accurately calculating the allowed ramp release flow, it is ensured that the inflow does not exceed the actual carrying capacity downstream of the merging area, and the traffic flow stability is prevented from being broken due to the overload of ice and snow weather.

[0031] (4) The system can realize real-time sensing of multi-dimensional weather data including road surface friction coefficient, ice thickness, water depth, visibility and snowfall through the deployment of road surface state detectors and traffic flow detectors. This enables the control strategy to be dynamically optimized with weather changes, rather than relying on rigid preset strategies.

[0032] (5) The system and method can be widely applied to the merging area node of urban expressway and expressway. Through the unified decision and issuance of the central controller to the variable speed limit sign, information sign and ramp signal lamp, the traffic running environment of the sensitive node of the merging area can be significantly improved.

[0033] Additional advantages, objects, and features of the application will be apparent to those skilled in the art upon examination of the following detailed description, it being understood that each of the foregoing general statements are true of the particular embodiments of the application and that such statements are not intended to serve as limitations upon the scope of the application. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the drawings, in which: Figure 1 Facility deployment diagram of the variable speed limit and ramp control linkage system in the confluence area under ice and snow weather; Figure 2 Flowchart of the variable speed limit and ramp control linkage method in the confluence area under ice and snow weather. DETAILED DESCRIPTION

[0035] The embodiments of the present application will be described in detail below with reference to specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied in other different embodiments, and various modifications or changes can be made to the details in the present specification based on different views and applications without departing from the spirit of the present application. It should be noted that the diagrams provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0036] The drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0037] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and should not be understood as a limitation on the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] Example 1: Please refer toFigure 1 The embodiment provides a variable speed limit and ramp control linkage system in a merging area under ice and snow weather, which comprises: A road surface state detector 1 is arranged 200 m away from the upstream of the merging nose end of the main line, a road surface state detector 2 is arranged 200 m away from the downstream of the merging area acceleration lane end, and a road surface state detector 3 is arranged in the acceleration lane. The road surface state detector detects the ice and snow weather road surface state data such as the road surface friction coefficient, the ice thickness, the water depth, the visibility and the snowfall amount of the corresponding position in real time.

[0039] A variable speed limit sign 1 is arranged 200 m away from the upstream of the merging nose end of the main line, and a variable speed limit sign 2 is arranged 200 m away from the downstream of the merging area acceleration lane end. The variable speed limit sign publishes the speed limit value of the corresponding position under ice and snow weather.

[0040] A variable information sign 1 is arranged 200 m away from the upstream of the merging nose end of the main line, and a variable information sign 2 is arranged 200 m away from the downstream of the merging area acceleration lane end. The variable information sign publishes the prompt information of the corresponding position under ice and snow weather.

[0041] A traffic flow detector 1 is arranged 200 m away from the upstream of the merging nose end of the main line, a traffic flow detector 2 is arranged 200 m away from the downstream of the merging area acceleration lane end, and a traffic flow detector 3 is arranged 100 m away from the upstream of the ramp of the merging nose end. The traffic flow detector detects the traffic flow data such as the speed, the flow and the density of the corresponding position in real time.

[0042] A ramp signal lamp is arranged at the position of the start of the acceleration lane, and a ramp stop line is marked, which is used for publishing the ramp control strategy information.

[0043] One set of central controllers is arranged in the merging area, receives the detector data, determines the implementation scheme of the variable speed limit and ramp control linkage strategy through a control algorithm, and issues the scheme to the ramp signal lamp and the variable speed limit sign.

[0044] Embodiment 2: Please refer to Figure 2 The embodiment provides a variable speed limit and ramp control linkage method in a merging area under ice and snow weather, which comprises: S1, data collection. Real-time detection is performed by a road surface state detector to obtain ice and snow weather road surface state data, real-time detection is performed by a traffic flow detector to obtain traffic flow data, and the data is uploaded to a central controller.

[0045] S2, linkage strategy optimization and decision. The central controller optimizes the variable speed limit and ramp control linkage strategy in the merging area under ice and snow weather based on the real-time detection data, and makes a decision.

[0046] S21, variable speed limit strategy decision.

[0047] (1) Determination of the variable speed limit value downstream of the merging area.

[0048] The speed limit value published by the variable speed limit sign 2 downstream of the merging area is determined by the road surface friction coefficient, the ice thickness, the water depth, the visibility, the snowfall, and other factors at this location.

[0049]

[0050] In the formula: is the speed limit value published by the variable speed limit sign 2; is the speed limit value calculation function of the variable speed limit sign 2; is the road surface friction coefficient obtained by the road surface state detector 2; is the ice thickness obtained by the road surface state detector 2; is the water depth obtained by the road surface state detector 2; is the visibility obtained by the road surface state detector 2; is the snowfall obtained by the road surface state detector 2.

[0051] Further determine the safe following distance downstream of the merging area in icy and snowy weather:

[0052] In the formula: is the safe following distance downstream of the merging area in icy and snowy weather; is the reaction time; is the acceleration of gravity; is the stopping safety distance.

[0053] (2) Variable speed limit value determination upstream of the merging area.

[0054] The speed limit value published by the variable speed limit sign 1 upstream of the merging area is determined by the road surface friction coefficient, the ice thickness, the water depth, the visibility, the snowfall, and other factors at this location. The speed value that the vehicle from the ramp can reach on the acceleration lane, the speed limit value published by the variable speed limit sign 2 downstream of the merging area, and other factors are also considered.

[0055] The speed value that the vehicle from the ramp can reach on the acceleration lane is determined by the acceleration lane length, the road surface friction coefficient, the maximum acceleration that the vehicle can reach, and other factors, controlled by the ramp signal light.

[0056]

[0057]

[0058]

[0059] In the formula: is the speed limit value published by the variable speed limit sign 1; Ice and snow weather road surface state data for variable speed limit sign 1 speed limit value; For the speed value that the vehicle on the ramp can reach on the acceleration lane; For the variable speed limit sign 1 speed limit value calculation function; For the road surface friction coefficient obtained by the road surface state detector 1; For the ice thickness obtained by the road surface state detector 1; For the water depth obtained by the road surface state detector 1; For the visibility obtained by the road surface state detector 1; For the snowfall obtained by the road surface state detector 1; For the acceleration lane length; For the maximum acceleration that the vehicle can reach.

[0060] Further determine the safe following distance upstream of the merging area in ice and snow weather:

[0061] In the formula: Safe following distance upstream of the merging area in ice and snow weather.

[0062] S22, ramp control decision.

[0063] (1) Merging area downstream allowable traffic flow calculation.

[0064] The allowable traffic flow downstream of the merging area is determined by the speed limit value issued by the variable speed limit sign 2 downstream of the merging area, the safe following distance upstream of the merging area, etc.

[0065]

[0066] In the formula: The allowable traffic flow downstream of the merging area in ice and snow weather.

[0067] (2) Ramp allowable release flow calculation.

[0068] The ramp allowable release flow cannot exceed the allowable traffic flow downstream of the merging area minus the traffic flow obtained by the detector upstream of the merging area.

[0069]

[0070] In the formula: Ramp allowable release flow; Traffic flow obtained by traffic flow detector 1.

[0071] S3, linkage strategy issuance The central controller issues linkage strategy decision control instructions to variable speed limit signs, variable information signs, and ramp signal lights.

[0072] Variable speed limit sign 1 posts speed limit value Variable speed limit sign 2 posts speed limit value .

[0073] Variable information sign 1 posts safe following distance value in icy weather Variable information sign 2 posts safe following distance value in icy weather .

[0074] Ramp signal light controls by red, green and yellow light color, ensures that the flow from ramp into highway does not exceed .

[0075] Finally, it is pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, and they should all be covered in the scope of the claims of the present application.

Claims

1. A method for linking variable speed limits in merging areas with ramp control in icy and snowy weather, characterized in that, The method specifically includes the following steps: S1: Data collection: Real-time detection of road surface condition data in icy and snowy weather is achieved through road surface condition detectors, and real-time detection of traffic flow data is achieved through traffic flow detectors, and the data is uploaded to the central controller. S2: Linkage Strategy Optimization and Decision-Making: Based on real-time detection data, the central controller optimizes the linkage strategy between variable speed limit in merging areas and ramp control under icy and snowy weather, and issues decisions accordingly. S3: Linkage Strategy Issuance: The central controller issues the linkage strategy decision result control command to the variable speed limit sign, variable information sign and ramp signal light.

2. The method for linking variable speed limit in merging areas and ramp control in icy and snowy weather as described in claim 1, characterized in that, In step S1, the road condition detector is deployed on the mainline upstream of the merging nose. x meters, downstream of the end of the merging acceleration lane x The system monitors the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall in real time at the meter and acceleration lanes. The traffic flow detector is deployed on the mainline upstream of the merging nose. x meters, downstream of the end of the merging acceleration lane x meters and the upstream ramp at the merging nose y At a distance of meters, the speed, flow rate, and density at the corresponding location are detected in real time.

3. The method for linking variable speed limits and ramp control in merging areas under icy and snowy weather as described in claim 1, characterized in that, In step S3, the variable speed limit sign is deployed on the mainline upstream of the merging nose. x downstream of the merging zone acceleration lane end x meters; The variable information flag is deployed on the upstream mainline of the merging nose. x downstream of the merging zone acceleration lane end x meters; The ramp traffic lights are located at the start of the acceleration lane.

4. The method for linking variable speed limit in merging areas and ramp control in icy and snowy weather as described in claim 1, characterized in that, In step S2 or S3, the central controller is deployed in the merging zone.

5. The method for linking variable speed limit in merging areas and ramp control in icy and snowy weather as described in claim 3, characterized in that, In step S2, the linkage strategy between the merging zone variable speed limit and ramp control includes variable speed limit strategy decision-making, specifically including: (1) Determine the variable speed limit value downstream of the merging zone; in, Speed ​​limit values ​​will be issued for the downstream variable speed limit sign II in the merging zone; A function for calculating the speed limit value of the downstream variable speed limit sign II in the merging zone; The data are obtained from the road surface condition detector II downstream of the merging zone, including the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall. Further determine the safe following distance downstream of the confluence zone under icy and snowy weather conditions: in, To ensure a safe following distance downstream of the merging zone in icy and snowy weather; Reaction time; It is the acceleration due to gravity; To maintain a safe parking distance; (2) Determine the variable speed limit value upstream of the merging zone; in, The speed limit value is issued for the variable speed limit sign I upstream of the merging zone; The speed limit value for variable speed limit sign I upstream of the merging zone takes into account road surface condition data during icy and snowy weather. This represents the speed that vehicles entering the highway from the ramp can reach in the acceleration lane. A function for calculating the speed limit value of variable speed limit sign I upstream of the merging zone; The data are obtained from the road surface condition detector I upstream of the merging zone, including the road surface friction coefficient, ice thickness, water depth, visibility, and snowfall. To increase lane length; This allows the vehicle to achieve its maximum acceleration. Further determine the safe following distance upstream of the confluence zone under icy and snowy weather conditions: in, To ensure a safe following distance upstream of the merging zone in icy and snowy weather.

6. The method for linking variable speed limit in merging areas and ramp control in icy and snowy weather as described in claim 5, characterized in that, In step S2, the linkage strategy between the variable speed limit in the merging zone and the ramp control also includes ramp control decisions, specifically including: (1) Calculate the allowable flow rate downstream of the merging zone: in, The permitted traffic flow downstream of the confluence zone during icy and snowy weather; (2) Calculate the allowable traffic flow of the ramp: in, Allowed traffic flow for ramps; Traffic flow obtained by traffic flow detector I upstream of the merging zone.

7. The method for linking variable speed limit in merging areas and ramp control in icy and snowy weather as described in claim 6, characterized in that, In step S3, the variable speed limit sign I upstream of the merging zone displays the speed limit value. The downstream variable speed limit sign II of the merging zone displays the speed limit value. ; Upstream of the merging zone, variable message sign I provides recommendations for safe following distance during icy and snowy weather. Downstream of the confluence area, variable message sign II provides recommendations for safe following distance during icy and snowy weather. ; The ramp traffic lights are controlled by red, green, and yellow lights to ensure that the flow of traffic entering the highway from the ramps does not exceed [a certain limit]. .

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