A highway multi-region lane-divided variable speed limit control method and system

Abstract

The application relates to a highway multi-region and multi-lane variable speed limit control method and system. The method comprises the following steps: firstly, acquiring traffic flow data; secondly, determining the opening and closing of speed limit regions of each lane and the speed limit values of each lane according to the current traffic flow data, wherein the speed limit regions of each lane are pre-divided, the speed limit regions include always-open speed limit regions and buffer speed limit regions, and the speed limit regions are located before bottleneck regions of the highway; finally, determining the current vehicle lane changing direction, guiding the vehicle to change lanes in advance, and re-acquiring the traffic flow data according to the current speed limit region opening and closing and the speed limit value difference of different lanes, wherein the speed limit value difference of different lanes is determined by the current speed limit value. Compared with the prior art, the application has the advantages of improving the accuracy of the highway multi-region and multi-lane variable speed limit control and the adaptability to different traffic conditions, relieving the highway traffic congestion, and providing more effective traffic control measures.

Description

Technical Field

[0001] This invention relates to the field of intelligent traffic control and management technology, and in particular to a method and system for multi-zone lane-specific variable speed limit control on highways. Background Technology

[0002] A highway is a road system used for high-speed transportation, typically connecting different cities and serving as a vital link in regional transportation. Highways are designed to provide high-speed, safe, and efficient transportation to meet long-distance and high-capacity traffic demands. Highway speed limits are primarily implemented through fixed speed limits, variable speed limits, and lane-specific speed limits. Fixed speed limits are indicated by fixed speed limit signs set by road management agencies to show drivers the maximum permissible speed on that section of the highway. Variable speed limits are implemented on some highways based on factors such as traffic flow, visibility, weather conditions, and accidents to improve traffic safety and mobility. Lane-specific speed limits are different for different lanes on some highways. Regardless of the speed limit method used, drivers must abide by the speed limits on the road.

[0003] Existing variable speed limit methods do not differentiate between lanes on multi-lane highways. All lanes have the same and synchronized speed limit, and the control area is singular. This fails to account for situations where increased traffic demand leads to congestion and subsequent speed limit failure in some sections. In reality, highways have fast and slow lanes, and traffic conditions vary between lanes at the same time. Lane changes also alter traffic conditions, causing variable speed limits in a single area to malfunction. Therefore, improving the accuracy and adaptability of multi-area, multi-lane variable speed limit control on highways to adapt to different traffic conditions, thereby improving highway efficiency and alleviating congestion, is a problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology, namely, the low accuracy and adaptability to different traffic conditions of multi-zone, multi-lane variable speed limit control on highways, and to provide a method and system for multi-zone, multi-lane variable speed limit control on highways.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] According to a first aspect of the present invention, a method for multi-zone lane-specific variable speed limit control on highways is provided, comprising the following steps:

[0007] S1, acquire traffic flow data;

[0008] S2, based on the current traffic flow data, determine the opening and closing status of the speed limit zone for each lane and the speed limit value for each lane. The speed limit zone for each lane is pre-divided, and the speed limit zone includes a normally open speed limit zone and a buffer speed limit zone, and is located before the bottleneck area of ​​the highway.

[0009] S3, based on the current opening and closing status of the speed limit zone and the speed limit difference between different lanes, determines the current lane-changing direction of the vehicle, guides the vehicle to change lanes in advance, and returns to S1. The speed limit difference between different lanes is determined by the current speed limit.

[0010] As a preferred technical solution, the opening and closing status of the speed limit zone is represented by the lane line changes. The process of representing the lane line changes includes using light strip technology to visualize the dynamic changes of dashed and solid lines. Dashed lines indicate that vehicles are allowed to change lanes from the lane on the dashed line side, and solid lines indicate that vehicles are prohibited from changing lanes from the lane on the solid line side.

[0011] As a preferred technical solution, the speed limit difference between different lanes is related to the lane-changing attraction rate, which is determined by comparing the speed difference and density difference between different lanes, and the speed difference and density difference are determined by the traffic flow data.

[0012] As a preferred technical solution, the lane-changing attraction rate is the minimum value between the velocity difference and the density difference.

[0013] As a preferred technical solution, the difference in speed limits between the different lanes is less than or equal to 30 km / h.

[0014] As a preferred technical solution, the speed limit value of the normally open speed limiting region is greater than the speed limit value of the buffer speed limiting region.

[0015] As a preferred technical solution, the speed limit value of each lane is determined by processing traffic flow data and the opening and closing status of the speed limit zone of each lane using a predictive control method.

[0016] As a preferred technical solution, the process of determining the opening and closing status of the speed limit zone for each lane includes: determining whether the current speed limit is invalid; if not, opening the normally open speed limit zone and closing the buffer speed limit zone; otherwise, opening both the normally open speed limit zone and the buffer speed limit zone simultaneously.

[0017] As a preferred technical solution, the result of determining whether the current speed limit is invalid is determined by comparing the actual traffic density of each lane and each road segment with the critical traffic density. When the actual traffic density is less than or equal to the critical traffic density, the speed limit is not invalid; otherwise, the speed limit is invalid.

[0018] As a second aspect of the present invention, a multi-zone lane-specific variable speed limit control system for highways is provided, comprising a traffic flow detection unit, a control unit, and a variable information display unit connected in sequence by signals. The lanes include cross-sections for dividing speed limit zones into sections, and both the traffic flow detection unit and the variable information display unit are installed at these cross-sections.

[0019] The traffic flow detection unit is used to acquire traffic flow data at intervals and send the traffic flow data to the control unit;

[0020] The control unit is used to receive and determine the opening and closing status of the speed limit zone for each lane and the speed limit value for each lane based on the current traffic flow data. Based on the current opening and closing status of the speed limit zone and the difference in speed limit values ​​between different lanes, it determines the current lane-changing direction of the vehicle and guides the vehicle to change lanes in advance. The speed limit zones for each lane are pre-divided. The speed limit zones include normally open speed limit zones and buffer speed limit zones, and are located before the bottleneck area of ​​the highway. The difference in speed limit values ​​between different lanes is determined by the current speed limit value.

[0021] The variable information display unit is used to display the speed limit value and speed limit area that change at intervals.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention attracts vehicles to change lanes before entering the bottleneck area of ​​a highway by using the speed limit difference between different lanes. It takes into account the lateral traffic flow of the highway and guides vehicles to control their speed and change lanes in advance by combining the current opening and closing status of the speed limit area. This achieves control of the longitudinal traffic flow. Lane allocation is achieved through variable speed limits. It takes into account both the lateral and longitudinal traffic flow of the highway and directly integrates the variable speed limit area and the lane change control area. This speed limit control method is more in line with the actual road conditions. It can effectively improve the accuracy of variable speed limit control in multiple areas and multiple lanes of the highway and the adaptability to different traffic conditions. It can achieve precise control of vehicle speed within the speed limit area, effectively reduce the number of vehicles flowing into the bottleneck area, alleviate highway traffic congestion, and provide more effective traffic management measures.

[0024] 2. When setting lane-specific speed limit zones, this invention indicates the opening and closing of the speed limit zone by changing the lane lines. The lane lines will dynamically change from dashed to solid lines as the speed limit value changes, restricting vehicles to only changing lanes from the dashed line side to the solid line side. The invention also uses light strip technology to achieve visualization, which can distinguish multiple speed limit zones longitudinally and improve the accuracy of lane change prompts for vehicles.

[0025] 3. This invention considers multiple zones in the division of variable speed limit zones, setting up a normally open speed limit zone and a buffer speed limit zone. The speed limit value of the normally open speed limit zone is always greater than that of the buffer speed limit zone, which helps to reduce the speed difference between the upstream and the speed limit zone, improves traffic safety on congested sections of highways, and makes the setting of the two speed limit zones simpler and more convenient.

[0026] 4. This invention introduces the concept of lane-changing attraction rate in lane-specific variable speed limits. The lane-changing attraction rate is closely related to the difference in speed limits between different lanes. Since vehicle lane-changing behavior is affected by various factors, in actual road conditions, drivers tend to switch from lanes with poorer driving conditions to lanes with better driving conditions, such as switching from a low-speed-limit lane to a high-speed-limit lane. Therefore, the lane-changing attraction rate is calculated by comprehensively using the speed difference and density difference between lanes, thereby guiding the direction and time of lane changes. This provides a theoretical basis for controlling lateral traffic flow, reduces the speed difference between adjacent areas, reduces the number of vehicles forced to change lanes, further improves the traffic efficiency in high-speed power bottleneck areas, enhances driving safety, and reduces the risk of accidents. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the method in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the system structure in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of a highway scene in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of a variable information indicator panel in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the lane line change process in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the decision-making process for obtaining speed limit values ​​using predictive control in an embodiment of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0034] Example

[0035] This embodiment provides a method and system for multi-zone lane-specific variable speed limit control on highways.

[0036] like Figure 1As shown, the method flow provided in this embodiment includes:

[0037] Step S1: Obtain traffic flow data, including vehicle driving data such as flow rate, speed, and density for each lane and road segment;

[0038] Step S2: Based on the current traffic flow data, determine the opening and closing status of the speed limit zone for each lane and the speed limit value for each lane. The speed limit zone for each lane is pre-divided, including the normally open speed limit zone and the buffer speed limit zone, and is located before the bottleneck area of ​​the highway.

[0039] Step S3: Based on the current opening and closing status of the speed limit zone and the speed limit difference between different lanes, determine the current lane-changing direction of the vehicle, guide the vehicle to change lanes in advance, and return to S1. The speed limit difference between different lanes is determined by the current speed limit.

[0040] The above method can be achieved through, for example Figure 2 The system implementation is shown. Figure 2 The system shown includes a traffic flow detection unit, a control unit, and a variable information display unit connected in sequence by signals. The traffic flow detection unit uses a commonly used traffic flow detection device, and the variable information display unit uses a variable information display panel. Figure 3 As shown, the lanes before the bottleneck area of ​​the highway have been pre-divided into multiple speed limit zones by various cross-sections, and traffic flow detection devices and variable message signs are installed at the corresponding cross-sections. Laterally, the highway is divided into lanes; longitudinally, each lane can be divided into two speed limit zones: a normally open speed limit zone and a buffer speed limit zone. The speed limit in the normally open speed limit zone is higher than that in the buffer speed limit zone. The speed limit in the buffer speed limit zone is maintained at a fixed difference from the speed limit in the normally open speed limit zone in the speed control strategy. The primary function of this buffer speed limit zone is safety, reducing the speed difference between the upstream area and the speed limit zone.

[0041] The traffic flow detection device is used to acquire traffic flow data at intervals, and step S1 can be implemented through the traffic flow detection device. Specifically:

[0042] Step S1: The traffic flow detection device collects traffic flow data at regular intervals, i.e., road traffic condition information of each road segment, and transmits the information to the control unit. The collected traffic flow data includes vehicle driving data such as flow rate, speed, and density of each lane and road segment, i.e., the number of vehicles, average speed of each road segment, and actual traffic density of each lane and road segment.

[0043] The control unit receives and, based on current traffic flow data, determines the opening / closing status of speed limit zones for each lane and the speed limit value for each lane. Based on the current speed limit zone opening / closing status and the difference in speed limits between different lanes, it determines the current lane-changing direction and guides vehicles to change lanes in advance. The difference in speed limits between different lanes is determined by the current speed limit value. For example... Figure 4 As shown, the variable message sign is used to display the speed limit value and speed limit zone with varying intervals. The opening and closing status of the speed limit zone is indicated by changes in lane markings. Steps S2 and S3 can be implemented through the control unit and the variable message sign. Specifically:

[0044] In step S2, the control unit determines the current traffic status of the road segment (whether it is congested) based on the received information, calculates how many speed limit zones need to be opened and the speed limit values ​​of each lane, and the number of zones to be opened is represented by the lane line settings.

[0045] Determine the current traffic status of the road segment (whether it is congested), that is, determine whether the current speed limit is invalid. The result of this determination can be determined by formula (1), that is, by comparing the actual traffic density of each lane and each road segment with the critical traffic density. When the actual traffic density is less than or equal to the critical traffic density, the speed limit is not invalid and the speed of the vehicles on the road segment is equal to the speed limit value. Otherwise, the speed limit is invalid and the speed of the vehicles on the road segment is equal to the congestion wave speed.

[0046]

[0047] If the speed limit is not invalid, the variable speed limit will only be applied in the normally open speed limit area, and the buffer speed limit area will be closed; if the speed limit is invalid, the speed limit buffer area will be opened for auxiliary speed limiting, and the lane line settings on the variable information sign will also change accordingly.

[0048] Variable message signs can display speed limit information and lane markings for corresponding speed-limited zones. Lane marking changes are correlated with the opening and closing status of the speed-limited zones. Light strip technology is used to visualize the dynamic changes between dashed and solid lines. Dashed lines indicate that vehicles are permitted to change lanes from the lane on the dashed line side, while solid lines indicate that vehicles are prohibited from changing lanes from the lane on the solid line side. Vehicles can only change lanes from the dashed line side to the solid line side. The changes are as follows: Figure 5 As shown. Figure 5 (a) This shows the lane markings on a regular road section. Subsequently, with the opening of the permanently open variable speed limit zone, the lane markings changed accordingly. Figure 5 (b) The situation is as follows. As traffic congestion worsens, buffer speed zones are also opened, such as... Figure 5 As shown in (c), the dynamic change of dashed and solid lines provides a new control method for multi-zone speed limit control strategies. Vehicles can only change lanes from the lane containing the dashed line to the lane containing the solid line, thus restricting the direction of lane changing.

[0049] Step S3: Based on the current opening / closing status of the speed limit zone and the speed limit value, update the data displayed on the variable message sign at the corresponding section. The control center can obtain the speed limit difference between different lanes based on the updated speed limit value, and determine the current lane-changing direction of the vehicle based on the current opening / closing status of the speed limit zone and the speed limit difference between different lanes. This prompts drivers on the road segment, guiding vehicles to change lanes in advance, and then returns to step S1 to continue lane-specific variable speed limit control. The speed limit value is determined by processing traffic flow data and the opening / closing status of the speed limit zone for each lane using a predictive control method. The decision-making process includes:

[0050] Assume the current speed limit for this road section is V. max Set the lower limit of dynamic variable speed control to V. min , where V max 100km / h can be taken, V min A speed of 40 km / h is acceptable.

[0051] Within adjacent control cycles, ΔV1 = 20 km / h. The lane-specific variable speed limit pre-control decision-making process for closing the buffer speed limit zone and only opening the normally open speed limit zone is as follows: Figure 6 As shown; the variable speed limit commands include "Keep the default speed limit", "Reduce the speed limit by 20 km / h", and "Increase the speed limit by 20 km / h".

[0052] If the speed limit is invalid, the speed limit in the two-lane buffer speed limit zone will be the variable speed limit in the normally open speed limit zone plus 20 km / h. That is, the maximum difference in speed limits between adjacent longitudinal speed limit zones is 20 km / h. Meanwhile, from a traffic safety perspective, the difference in speed limits between lanes should not exceed ΔV2 = 30 km / h. That is, the maximum difference in speed limits between adjacent lateral lanes is 30 km / h.

[0053] In the method provided in this embodiment, the speed limit difference between different lanes is related to the lane-change attraction rate. The concept of lane-change attraction rate is introduced to consider the lateral traffic flow on highways. Vehicle lane-changing behavior is influenced by various factors. In actual road conditions, drivers tend to change lanes with better driving conditions from lanes with poorer conditions, such as changing from a lower speed limit lane to a higher speed limit lane. Speed ​​and density differences are obtained from traffic flow data collected at intervals. The lane-change attraction rate can be calculated by comprehensively utilizing the speed and density differences between different lanes. Finally, the minimum value between the speed and density differences is selected as the lane-change attraction rate, i.e., A. i，j，j+1 (t) can be calculated using equations (2) to (4).

[0054]

[0055]

[0056]

[0057] Where P is the density weighting coefficient, usually with a value of 1. If the vehicle is in several specific highway locations, such as upstream of entrance and exit ramps, or at locations where the number of lanes decreases, the value of P needs to be recalibrated; μ is a model parameter reflecting the vehicle's aggressiveness during lane changes; w represents the time required for a lane change, usually with a value of 3 seconds; ρ i，j (t) represents the density of cell (i, j) at time t, v f Represents the free-flow velocity; ρ i，j+1 (t) represents the density of cell (i, j+1) at time t, where i represents the cell index, j represents the lane index, and v i，j (t) represents the velocity of cell (i, j) at time t; This represents the lane-changing attraction rate calculated based on density; This represents the lane-change attraction rate calculated based on speed. The lane-change attraction rate is negatively correlated with the lane-change duration. From a conservative perspective, the final calculated lane-change attraction rate is the minimum value. That is, in the control method provided in this embodiment, for the sake of conservatism and to ensure relatively stable traffic flow before the bottleneck area, and also from a safety perspective, the number of lane changes is selected to be relatively small.

[0058] In summary, the multi-zone lane-specific variable speed limit control method and system for highways provided in this embodiment introduces the lane-change attraction rate to characterize the speed limit difference between different lanes, thus considering the lateral traffic flow of highways. Simultaneously, it considers speed limit failure by adding a buffer speed limit zone to the existing open speed limit zone, and utilizes dynamic lane markings to reflect changes in the opening and closing status of different speed limit zones, thereby considering the longitudinal traffic flow of highways. Based on the aforementioned factors, it determines the lane-changing direction of vehicles and guides them to change lanes in advance. This method and system can control the speed of vehicles within the speed limit zone, reduce the speed difference between adjacent zones, reduce the number of vehicles flowing into bottleneck areas and the number of vehicles forced to change lanes, alleviate highway traffic congestion, improve driving safety, enrich the selection of variable speed limit control strategies, and expand traditional variable speed limit control methods. It has practical engineering application value in improving traffic efficiency in highway bottleneck areas and reducing accident risks.

[0059] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for multi-zone lane-specific variable speed limit control on highways, characterized in that, Includes the following steps: S1, acquire traffic flow data; S2, based on the current traffic flow data, determine the opening and closing status of the speed limit zone for each lane and the speed limit value for each lane. The speed limit zone for each lane is pre-divided, and the speed limit zone includes a normally open speed limit zone and a buffer speed limit zone, and is located before the bottleneck area of ​​the highway. S3, based on the current opening and closing status of the speed limit zone and the speed limit difference between different lanes, determines the current lane-changing direction of the vehicle, guides the vehicle to change lanes in advance, and returns to S1. The speed limit difference between different lanes is determined by the current speed limit.

2. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The opening and closing status of the speed limit zone is indicated by changes in lane lines. The process of indicating changes in lane lines includes using light strip technology to visualize the dynamic changes of dashed and solid lines. Dashed lines indicate that vehicles are allowed to change lanes from the lane on the side of the dashed line, while solid lines indicate that vehicles are prohibited from changing lanes from the lane on the side of the solid line.

3. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The speed limit difference between different lanes is related to the lane-changing attraction rate, which is determined by comparing the speed difference and density difference between different lanes, and the speed difference and density difference are determined by the traffic flow data.

4. The variable speed limit control method for multi-zone lane division on highways according to claim 3, characterized in that, The lane-changing attraction rate is the minimum value between the velocity difference and the density difference.

5. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The difference in speed limits between the different lanes is less than or equal to 30 km / h.

6. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The speed limit value of the normally open speed limit area is greater than the speed limit value of the buffer speed limit area.

7. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The speed limit for each lane is determined by processing traffic flow data and the opening / closing status of the speed limit zone for each lane using predictive control methods.

8. The variable speed limit control method for multi-zone lane division on highways according to claim 1, characterized in that, The process of determining the opening and closing status of the speed limit zone for each lane includes: determining whether the current speed limit is invalid; if not, opening the normally open speed limit zone and closing the buffer speed limit zone; otherwise, opening both the normally open speed limit zone and the buffer speed limit zone simultaneously.

9. The variable speed limit control method for multi-zone lane division on highways according to claim 8, characterized in that, The determination of whether the current speed limit is invalid is made by comparing the actual traffic density of each lane and each road segment with the critical traffic density. When the actual traffic density is less than or equal to the critical traffic density, the speed limit is not invalid; otherwise, the speed limit is invalid.

10. A multi-zone lane-specific variable speed limit control system for highways, characterized in that, The system includes a traffic flow detection unit, a control unit, and a variable message display unit connected in sequence by signals. The lane includes a cross-section for dividing the lanes into speed limit zones. Both the traffic flow detection unit and the variable message display unit are installed at this cross-section. The traffic flow detection unit is used to acquire traffic flow data at intervals and send the traffic flow data to the control unit; The control unit is used to receive and determine the opening and closing status of the speed limit zone for each lane and the speed limit value for each lane based on the current traffic flow data. Based on the current opening and closing status of the speed limit zone and the difference in speed limit values ​​between different lanes, it determines the current lane-changing direction of the vehicle and guides the vehicle to change lanes in advance. The speed limit zones for each lane are pre-divided. The speed limit zones include normally open speed limit zones and buffer speed limit zones, and are located before the bottleneck area of ​​the highway. The difference in speed limit values ​​between different lanes is determined by the current speed limit value. The variable information display unit is used to display the speed limit value and speed limit area that change at intervals.

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