Variable speed limit determination method and device based on expressway traffic flow

Abstract

The invention provides a variable speed limit determination method and device based on expressway traffic flow, and the method comprises the steps: obtaining the road traffic state information and traffic flow parameter data of a target road section in an expressway in a current speed limit change period, and obtaining the variable speed limit of the target road section based on the traffic flow parameter data; determining a free flow vehicle speed value and a critical density value of the target road section; determining a target vehicle speed value of the target road section based on the road traffic state information, the free flow speed value and the critical density value; based on the traffic flow parameter data and the traffic setting parameters, the target road section is divided into a plurality of speed limit areas, and based on the real-time vehicle speed distribution data and the target vehicle speed value, the current speed limit value of each speed limit area in the current speed limit change period is determined. By means of the method, step-by-step smooth adjustment of the vehicle running speed from the upstream to the bottleneck is achieved, traffic shock waves are effectively restrained, the congestion forming probability in the expressway is reduced, and the stability and safety of expressway traffic operation are improved.

Description

Technical Field

[0001] This application relates to the fields of traffic engineering and intelligent transportation systems, and in particular to a method and apparatus for determining variable speed limits based on highway traffic flow. Background Technology

[0002] In highway traffic management, variable speed limit (VSL) has become an important means to improve road operation efficiency and safety. However, existing variable speed limit control methods are generally based on threshold triggering of local section speed or occupancy, lacking the ability to detect upstream traffic disturbances in advance and unable to block traffic shock waves from propagating downstream, thus easily causing congestion at bottlenecks and increasing traffic pressure on highways.

[0003] In addition, many speed limits in existing methods are set based on experience and lack scientific rigor. They are difficult to keep traffic flow stable near the design capacity under high demand. Speed ​​limit changes are often abrupt and lack reasonable speed transition zones, which can easily cause vehicles to decelerate suddenly or even create new shock waves, exacerbating traffic fluctuations and reducing the stability and safety of highway traffic. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method and apparatus for determining variable speed limits based on highway traffic flow. By collecting road traffic state information and traffic flow parameter data of a target road segment in real time, the method determines the free-flow speed value and critical density value of the target road segment, and further determines the free-flow speed value and critical density value. Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and the current speed limit value of each speed limit zone is determined. This achieves a smooth, step-by-step adjustment of vehicle speed from upstream to the bottleneck, effectively suppressing traffic shock waves, maintaining stable traffic flow near the design capacity, thereby reducing the probability of congestion on the highway and improving the stability and safety of highway traffic operation.

[0005] This application provides a method for determining variable speed limits based on highway traffic flow, the method comprising: Obtain road traffic status information and traffic flow parameter data of the target road segment in the current speed limit change cycle, and determine the free flow speed value and critical density value of the target road segment based on the traffic flow parameter data. Based on the road traffic state information, the free-flow velocity value, and the critical density value, the target vehicle speed value corresponding to the target road segment is determined; Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones. Based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value, the current speed limit value corresponding to the current speed limit change cycle for each speed limit zone is determined.

[0006] Furthermore, determining the free-flow vehicle speed and critical density value corresponding to the target road segment based on the traffic flow parameter data includes: Based on the traffic flow parameter data, a traffic flow parameter model corresponding to the target road segment in the current speed limit change cycle is constructed; wherein, the traffic flow parameter data includes real-time traffic flow distribution data, real-time vehicle speed distribution data, and real-time density distribution data; Based on the traffic flow parameter model, the free-flow section, critical density section and congested section in the target road segment are determined, and the free-flow speed value and critical density value corresponding to the target road segment are determined respectively.

[0007] Furthermore, determining the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free-flow velocity value, and the critical density value includes: Based on the road traffic status information and the free-flow velocity value, the target traffic flow value corresponding to the target road segment is determined; Based on the road traffic state information and the critical density value, a control density coefficient is determined; Based on the target traffic flow value and the control density coefficient, the target vehicle speed value corresponding to the target road segment is determined.

[0008] Furthermore, determining the target traffic flow value corresponding to the target road segment based on the road traffic state information and the free-flow velocity value includes: The product of the free-flow velocity value and the critical density value is determined as the traffic flow threshold corresponding to the target road segment; Determine the capacity reduction factor corresponding to the road traffic status information, and determine the target traffic flow value corresponding to the target road segment by multiplying the capacity reduction factor by the traffic flow threshold.

[0009] Furthermore, based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed-limited zones, including: Based on the real-time traffic flow distribution data and real-time density distribution data in the traffic flow parameter data, the traffic shock wave velocity value corresponding to each preset area in the target road segment is determined; Based on the traffic setting parameters corresponding to the target road segment and the traffic shock wave velocity value, the target road segment is divided into multiple speed limit zones; wherein, the speed limit zone includes at least one upstream disturbance absorption zone, at least one speed transition zone and at least one bottleneck control zone.

[0010] Furthermore, determining the current speed limit value for each speed limit zone corresponding to the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value includes: Based on the real-time vehicle speed distribution data in the traffic flow parameter data, the upstream real-time vehicle speed value and the upstream vehicle speed change corresponding to the target road segment are determined, and the difference between the upstream real-time vehicle speed value and the upstream vehicle speed change is determined as the first current speed limit value corresponding to the upstream disturbance absorption zone. Based on the target vehicle speed value and the first current speed limit value, determine the second current speed limit value corresponding to the speed transition zone; The target vehicle speed value is determined as the third current speed limit value corresponding to the bottleneck control area.

[0011] Furthermore, after determining the current speed limit value corresponding to the current speed limit change cycle for each speed limit zone, the method further includes: Based on the historical speed limit value corresponding to each speed limit zone in the historical speed limit change cycle, the current speed limit value is smoothed to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

[0012] This application embodiment also provides a variable speed limit determination device based on highway traffic flow, the variable speed limit determination device comprising: The traffic data processing module is used to acquire road traffic status information and traffic flow parameter data of the target road segment in the current speed limit change cycle, and to determine the free flow speed value and critical density value of the target road segment based on the traffic flow parameter data. The target vehicle speed determination module is used to determine the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free flow velocity value, and the critical density value. The speed limit zone control module is used to divide the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, and to determine the current speed limit value of each speed limit zone in the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value.

[0013] Furthermore, when the traffic data processing module determines the free-flow vehicle speed and critical density value corresponding to the target road segment based on the traffic flow parameter data, the traffic data processing module is used to: Based on the traffic flow parameter data, a traffic flow parameter model corresponding to the target road segment in the current speed limit change cycle is constructed; wherein, the traffic flow parameter data includes real-time traffic flow distribution data, real-time vehicle speed distribution data, and real-time density distribution data; Based on the traffic flow parameter model, the free-flow section, critical density section and congested section in the target road segment are determined, and the free-flow speed value and critical density value corresponding to the target road segment are determined respectively.

[0014] Furthermore, when the target vehicle speed determination module determines the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free-flow velocity value, and the critical density value, the target vehicle speed determination module is used to: Based on the road traffic status information and the free-flow velocity value, the target traffic flow value corresponding to the target road segment is determined; Based on the road traffic state information and the critical density value, a control density coefficient is determined; Based on the target traffic flow value and the control density coefficient, the target vehicle speed value corresponding to the target road segment is determined.

[0015] Furthermore, when the target vehicle speed determination module determines the target traffic flow value corresponding to the target road segment based on the road traffic state information and the free-flow velocity value, the target vehicle speed determination module is used to: The product of the free-flow velocity value and the critical density value is determined as the traffic flow threshold corresponding to the target road segment; Determine the capacity reduction factor corresponding to the road traffic status information, and determine the target traffic flow value corresponding to the target road segment by multiplying the capacity reduction factor by the traffic flow threshold.

[0016] Furthermore, when the speed limit zone control module divides the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the speed limit zone control module is used to: Based on the real-time traffic flow distribution data and real-time density distribution data in the traffic flow parameter data, the traffic shock wave velocity value corresponding to each preset area in the target road segment is determined; Based on the traffic setting parameters corresponding to the target road segment and the traffic shock wave velocity value, the target road segment is divided into multiple speed limit zones; wherein, the speed limit zone includes at least one upstream disturbance absorption zone, at least one speed transition zone and at least one bottleneck control zone.

[0017] Furthermore, when the speed limit zone control module determines the current speed limit value for each speed limit zone corresponding to the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value, the speed limit zone control module is used to: Based on the real-time vehicle speed distribution data in the traffic flow parameter data, the upstream real-time vehicle speed value and the upstream vehicle speed change corresponding to the target road segment are determined, and the difference between the upstream real-time vehicle speed value and the upstream vehicle speed change is determined as the first current speed limit value corresponding to the upstream disturbance absorption zone. Based on the target vehicle speed value and the first current speed limit value, determine the second current speed limit value corresponding to the speed transition zone; The target vehicle speed value is determined as the third current speed limit value corresponding to the bottleneck control area.

[0018] Furthermore, the variable speed limit determination device also includes a speed limit smoothing processing module, which is used for: Based on the historical speed limit value corresponding to each speed limit zone in the historical speed limit change cycle, the current speed limit value is smoothed to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

[0019] This application also provides an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, the steps of the variable speed limit determination method based on highway traffic flow described above are performed.

[0020] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the variable speed limit determination method based on highway traffic flow described above.

[0021] The present application provides a method and apparatus for determining variable speed limits based on highway traffic flow. The method includes: acquiring road traffic state information and traffic flow parameter data corresponding to a target road segment in the current speed limit change cycle; determining the free-flow speed value and critical density value corresponding to the target road segment based on the traffic flow parameter data; determining the target speed value corresponding to the target road segment based on the road traffic state information, the free-flow speed value, and the critical density value; dividing the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment; and determining the current speed limit value of each speed limit zone corresponding to the current speed limit change cycle based on the real-time speed distribution data in the traffic flow parameter data and the target speed value.

[0022] Compared with existing threshold triggering methods based on local cross-sectional speed or occupancy, this method determines the free-flow speed and critical density of a target road segment by real-time collection of road traffic status information and traffic flow parameter data. Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and the current speed limit value of each zone is determined. This enables a smooth, step-by-step adjustment of vehicle speed from upstream to the bottleneck, effectively suppressing traffic shock waves and maintaining stable traffic flow near the design capacity. Consequently, it reduces the probability of congestion on highways and improves the stability and safety of highway traffic operations.

[0023] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 One of the flowcharts for a variable speed limit determination method based on highway traffic flow provided in an embodiment of this application; Figure 2 A second flowchart illustrating a variable speed limit determination method based on highway traffic flow, provided as an embodiment of this application; Figure 3 One of the structural schematic diagrams of a variable speed limit determination device based on highway traffic flow provided in the embodiments of this application; Figure 4 A second schematic diagram of a variable speed limit determination device based on highway traffic flow provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0027] Research has found that in highway traffic management, variable speed limit (VSL) has become an important means to improve road operation efficiency and safety. However, existing variable speed limit control methods are generally based on threshold triggering of local section speed or occupancy, lacking the ability to detect upstream traffic disturbances in advance and unable to block traffic shock waves from propagating downstream, thus easily causing congestion at bottlenecks and increasing traffic pressure on highways.

[0028] In addition, many speed limits in existing methods are set based on experience and lack scientific rigor. They are difficult to keep traffic flow stable near the design capacity under high demand. Speed ​​limit changes are often abrupt and lack reasonable speed transition zones, which can easily cause vehicles to decelerate suddenly or even create new shock waves, exacerbating traffic fluctuations and reducing the stability and safety of highway traffic.

[0029] Based on this, this application provides a variable speed limit determination method based on highway traffic flow. By collecting real-time road traffic state information and traffic flow parameter data of the target road segment in the highway, the free-flow vehicle speed value and critical density value of the target road segment are determined. Then, based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and the current speed limit value of each speed limit zone is determined. This achieves a smooth adjustment of vehicle speed from upstream to the bottleneck, effectively suppressing traffic shock waves, maintaining stable traffic flow near the design capacity, thereby reducing the probability of congestion on the highway and improving the stability and safety of highway traffic operation.

[0030] Please see Figure 1 , Figure 1 This is one of the flowcharts for a variable speed limit determination method based on highway traffic flow, provided as an embodiment of this application. Figure 1 As shown in the embodiments of this application, the variable speed limit determination method based on highway traffic flow includes: S101. Obtain road traffic status information and traffic flow parameter data corresponding to the target road segment in the current speed limit change cycle, and determine the free-flow vehicle speed value and critical density value corresponding to the target road segment based on the traffic flow parameter data.

[0031] It should be noted that the target road segment is a section of a highway where speed limit control is desired to be implemented using the variable speed limit determination method based on highway traffic flow provided in this application embodiment.

[0032] In this embodiment of the application, the road traffic status information includes, but is not limited to, overall traffic status, accident status, construction status, and weather status; the traffic flow parameter data includes, but is not limited to, real-time traffic flow distribution data, real-time vehicle speed distribution data, and real-time density distribution data.

[0033] Here, the free-flow speed value represents the average speed of vehicles when the traffic flow is in a free-flow state. At this time, vehicles are not affected by the driving state of the vehicles in front and can travel at their own desired speed. It is a characteristic parameter of the free-flow segment in the basic traffic flow diagram. The critical density value represents the critical threshold for the traffic flow to transition from a free-flow state to a congested state. When the road vehicle density is less than the critical density value, it is a free flow (the flow rate increases linearly with the increase of density). When the road vehicle density is greater than the critical density value, it is a congested flow (the flow rate decreases with the increase of density).

[0034] In this step, the detectors preset on the target road segment are used to collect road traffic status information and traffic flow parameter data in real time for the target road segment on the highway during the current speed limit change cycle.

[0035] For example, one microwave traffic detector (sampling period of 5 minutes, i.e., speed limit change period of 5 minutes) is set up at each of K25+500, K26+500, K27+500, K28+500, and K29+500 to collect real-time traffic flow distribution data, real-time vehicle speed distribution data, real-time density distribution data, and road occupancy data; a weather sensor is set up at K26+000 to collect data such as rainfall and visibility; and an event detector is set up at K28+000 to identify abnormal events such as traffic accidents and road construction.

[0036] In one possible implementation of this application, in specific implementation, step S101, based on the traffic flow parameter data, determining the free-flow vehicle speed value and critical density value corresponding to the target road segment may include: S1011. Based on the traffic flow parameter data, construct a traffic flow parameter model for the target road segment corresponding to the current speed limit change cycle.

[0037] In this embodiment, the traffic flow parameter model uses the Fundamental Diagram (FD model) in traffic engineering as its core framework. The core logic is to describe the inherent relationship between the three traffic flow parameters: flow rate (Q, unit: pcu / h), density (K, unit: pcu / km), and vehicle speed (V, unit: km / h) through mathematical relationships. The model strictly follows the three-segment structure of the FD model (free flow segment, maximum flow segment near critical density, and congestion segment). The core correlation formula of the model is shown below.

[0038] .

[0039] in, This represents real-time traffic distribution data; This represents real-time vehicle speed distribution data; This represents real-time density distribution data.

[0040] Here, the traffic flow parameter model is generally in the form of a three-segment structure, including: free flow segment, critical density segment (the segment with the maximum flow near the critical density) and congestion segment.

[0041] Here, the density of the free flow section is less than the critical density value of the free flow section (the critical density value of the free flow section is usually taken as 0.6 to 0.8 times the critical density value); the density of the critical density section (the section with the maximum flow near the critical density) is greater than or equal to the critical density value of the free flow section and less than or equal to the critical density value; the density of the congested section is greater than the critical density value.

[0042] In this step, during implementation, firstly, by drawing "flow-density" scatter plots and "vehicle speed-density" scatter plots, and combining them with the characteristics of traffic flow theory, the density thresholds of the three-segment flow pattern are determined, and the core interval is divided. Then, corresponding mathematical models are constructed for the free-flow segment, the critical density segment, and the congested segment. Finally, the constructed mathematical models are integrated to obtain the traffic flow parameter model of the target road segment corresponding to the current speed limit change cycle.

[0043] S1012. Based on the traffic flow parameter model, determine the free-flow section, critical density section and congested section in the target road segment, and determine the free-flow speed value and critical density value corresponding to the target road segment respectively.

[0044] In this step, based on the "flow-density" scatter plot and "vehicle speed-density" scatter plot corresponding to the traffic flow parameter model, the peak point of the flow is found in the "flow-density" scatter plot. This peak point is the maximum traffic flow (i.e., the traffic flow threshold). In the "flow-density" scatter plot, the density corresponding to the maximum traffic flow is the critical density value. If there are multiple cross-sectional flows close to the maximum traffic flow, the average of the densities of these cross-sections is taken as the critical density value.

[0045] Furthermore, based on the critical density value, the free-flow section, critical density section, and congested section in the target road segment are determined, and the stable driving speed of vehicles in the free-flow section is determined as the free-flow speed value corresponding to the target road segment.

[0046] S102. Based on the road traffic state information, the free-flow velocity value, and the critical density value, determine the target vehicle speed value corresponding to the target road segment.

[0047] In the embodiments of this application, the target speed value represents the optimal operating speed that vehicles should reach before the bottleneck on the target road segment. Its core function is to keep the traffic flow near the optimal traffic volume, taking into account both traffic efficiency and safety. It is the final convergence value of the three-level speed limit control.

[0048] In one possible implementation of this application, step S102 may include: S1021. Based on the road traffic status information and the free-flow velocity value, determine the target traffic flow value corresponding to the target road segment.

[0049] Here, the target traffic flow value refers to the optimal traffic flow of the target road segment under the current actual traffic conditions, taking into account both traffic efficiency and safety. It is the "optimal control target" that dynamically adapts to the actual working conditions.

[0050] In one possible implementation of this application, step S1021 may include: S10211. The product between the free-flow velocity value and the critical density value is determined as the traffic flow threshold corresponding to the target road segment.

[0051] Here, the traffic flow threshold refers to the maximum traffic flow that a target road segment can safely carry under ideal traffic conditions (e.g., no severe weather, no accidents and / or construction, and no traffic disturbance). It is the theoretical upper limit of the road's capacity and is also known as the "maximum traffic flow".

[0052] In this embodiment of the application, the traffic flow threshold is determined by the following formula.

[0053]

[0054] in, Indicates the traffic flow threshold; Indicates the free-flow velocity value; This represents the critical density value.

[0055] S10212. Determine the capacity reduction coefficient corresponding to the road traffic status information, and determine the product between the capacity reduction coefficient and the traffic flow threshold as the target traffic flow value corresponding to the target road segment.

[0056] Here, the capacity reduction factor is dynamically adjusted according to the road traffic conditions to correct the maximum traffic flow, so that the target traffic flow value can adapt to different road traffic conditions (for example, severe weather, construction, etc. will reduce road traffic capacity, so the capacity reduction factor needs to be reduced). For example, the value range of the capacity reduction factor can be set from 0.3 to 1.0, and different road traffic conditions correspond to different reduction ratios.

[0057] In this embodiment of the application, the target traffic flow value is determined by the following formula.

[0058] .

[0059] in, Indicates the target traffic flow value; Indicates the capacity reduction factor; This indicates the traffic flow threshold.

[0060] S1022. Based on the road traffic state information and the critical density value, determine the control density coefficient.

[0061] Here, the control density coefficient represents the coefficient used to adjust the critical density value so that the critical density value is adapted to the safe operation requirements under different traffic conditions. The control density coefficient is determined by the following formula.

[0062] .

[0063] in, Indicates the control density coefficient; The coefficients represent the road traffic status information. This represents the critical density value.

[0064] S1023. Based on the target traffic flow value and the control density coefficient, determine the target vehicle speed value corresponding to the target road segment.

[0065] In this embodiment of the application, the target vehicle speed value is determined by the following formula.

[0066] .

[0067] in, Indicates the target vehicle speed value; Indicates the target traffic flow value; This represents the control density coefficient.

[0068] S103. Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value, the current speed limit value corresponding to the current speed limit change cycle for each speed limit zone is determined.

[0069] Here, the traffic setting parameters include, but are not limited to, traffic demand information and detector location information.

[0070] In this embodiment of the application, in order to avoid new traffic shock waves caused by sudden changes in speed limits, this embodiment of the application sets up a three-level speed limit zone along the traffic flow direction to achieve a smooth speed transition. That is, the speed limit zone includes at least one upstream disturbance absorption zone (first-level speed limit zone), at least one speed transition zone (second-level speed limit zone), and at least one bottleneck control zone (third-level speed limit zone).

[0071] In one possible implementation of this application, in specific implementation, step S103, which involves dividing the target road segment into multiple speed-limited zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, may include: S1031. Based on the real-time traffic flow distribution data and real-time density distribution data in the traffic flow parameter data, determine the traffic shock wave velocity value corresponding to each preset area in the target road segment.

[0072] Here, the traffic shock wave velocity value reflects the propagation speed and direction of traffic disturbance.

[0073] Based on traffic flow shock wave theory, the traffic shock wave velocity value describes the ratio of the flow difference to the density difference between two adjacent cross sections, directly reflecting the propagation characteristics of traffic disturbances (such as congestion and sudden speed changes). The larger the absolute value of the traffic shock wave velocity value, the faster the shock wave propagates. The speed limit zone length needs to be extended accordingly to fully absorb the disturbance and prevent the shock wave from spreading to the downstream bottleneck section.

[0074] In this embodiment of the application, the traffic shock wave velocity value is determined by the following formula.

[0075] .

[0076] in, This indicates the speed of the traffic shock wave. and This represents the single-lane traffic flow at two adjacent detection sections in the real-time traffic distribution data; and This represents the single-lane density of two adjacent detection sections in the real-time density distribution data.

[0077] S1032. Based on the traffic setting parameters corresponding to the target road segment and the traffic shock wave speed value, the target road segment is divided into multiple speed limit zones.

[0078] In this step, during implementation, firstly, based on the detector location information, the start and end references of the three-level speed limit zones are determined; then, based on traffic demand information and traffic shock wave velocity values, the length of each level of speed limit zone is calculated; finally, combined with the detector location, the specific mileage range of each level of speed limit zone is determined, and the mileage range is adaptively adjusted to divide the target road segment into multiple speed limit zones.

[0079] In this embodiment, the upstream disturbance absorption zone (primary speed limit zone) absorbs upstream traffic disturbances in advance, reduces speed fluctuations, and blocks the shock wave from propagating downstream. It is located downstream of the free flow section and upstream of the secondary zone, and needs to cover the initial impact range of the upstream shock wave propagation.

[0080] The speed transition zone (secondary speed limit zone) is located downstream of the primary speed limit zone and is used to smoothly transition the vehicle speed from the upstream state to near the target speed in order to avoid speed jumps.

[0081] The bottleneck control zone (level 3 speed limit zone) is located immediately upstream of the bottleneck (e.g., 0.5 to 1 km from the bottleneck starting point). The length of the zone must ensure that the vehicle speed fully converges to the target speed value, ensuring that the traffic flow in front of the bottleneck is stable and operates close to the theoretical capacity.

[0082] In one possible implementation of this application, in specific implementation, the step S103 of determining the current speed limit value for each speed limit zone corresponding to the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value may include: S1033. Based on the real-time vehicle speed distribution data in the traffic flow parameter data, determine the upstream real-time vehicle speed value and the upstream vehicle speed change corresponding to the target road segment, and determine the difference between the upstream real-time vehicle speed value and the upstream vehicle speed change as the first current speed limit value corresponding to the upstream disturbance absorption zone.

[0083] Here, the upstream real-time vehicle speed value refers to the average driving speed of vehicles in the upstream undisturbed zone of the target road segment during the current speed limit change cycle, which is a core parameter reflecting the original operating state of the upstream traffic flow; the upstream vehicle speed change refers to the speed reduction range set in the upstream undisturbed zone to absorb slight disturbances in the upstream traffic flow and achieve a smooth speed transition.

[0084] In this embodiment of the application, the first current speed limit value corresponding to the upstream disturbance absorption zone is determined by the following formula.

[0085] .

[0086] in, This indicates the first current speed limit value corresponding to the upstream disturbance absorption zone; This indicates the real-time vehicle speed value upstream; This indicates the change in upstream vehicle speed.

[0087] S1034. Based on the target vehicle speed value and the first current speed limit value, determine the second current speed limit value corresponding to the speed transition zone.

[0088] In this embodiment of the application, the second current speed limit value corresponding to the speed transition zone is determined by the following formula.

[0089] .

[0090] in, This indicates the second current speed limit value corresponding to the speed transition zone; This indicates the first current speed limit value corresponding to the upstream disturbance absorption zone; This indicates the target vehicle speed value.

[0091] S1035. The target vehicle speed value is determined as the third current speed limit value corresponding to the bottleneck control area.

[0092] Here, the bottleneck control zone (level 3 speed limit zone) is the final control link of the level 3 speed limit system. Its core function is to guide the traffic flow to converge stably to the optimal operating state before entering the bottleneck section, and ensure that the traffic flow passes through the bottleneck safely with an efficiency close to the theoretical capacity. Therefore, the target speed value is directly determined as the third current speed limit value of this area.

[0093] Optional, please refer to Figure 2 , Figure 2 This is a second flowchart illustrating a variable speed limit determination method based on highway traffic flow, provided as an embodiment of this application. Figure 2 As shown in the figure, the method provided in this application embodiment, in addition to steps S101 to S103, also includes step S104. Specifically, step S104 is used to explain the method of performing data smoothing after determining the current speed limit value corresponding to the current speed limit change cycle for each speed limit zone, so as to prevent the speed limit value jump from causing the vehicle to decelerate suddenly, and to ensure the continuous change of the speed limit value, thereby reducing new speed disturbances.

[0094] S104. Based on the historical speed limit value corresponding to each speed limit zone in the historical speed limit change cycle, the current speed limit value is smoothed to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

[0095] In this embodiment, the current speed limit value of each speed limit zone is smoothed using the following formula to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

[0096] .

[0097] in, Indicates the first The target speed limit value corresponding to the current speed limit change cycle for each speed limit zone; Indicates the first The historical speed limit value corresponding to the historical speed limit change cycle for each speed limit zone; Indicates the first The current speed limit value corresponding to the current speed limit change cycle for each speed limit zone; represents the preset smoothing coefficient (for example, it can be selected in the range of 0.7 to 0.9).

[0098] Furthermore, after determining the target speed limit value for each speed limit zone during the current speed limit change cycle, the target speed limit value is displayed on the roadside speed limit signs for each speed limit zone.

[0099] Thus, the method provided in this application, based on traffic flow theory, derives the optimal speed limit to maintain traffic flow in its optimal operating state; it introduces a traffic state determination mechanism to adapt to various scenarios such as accidents, construction, and severe weather; the three-level speed limit zone design achieves gradual speed transitions, reducing disturbances and accident risks caused by speed limit jumps; the upstream speed feedback mechanism can absorb traffic shock waves in advance, reducing the probability of congestion and suppressing "hidden bottlenecks"; and the traffic flow is smoothly guided to the optimal speed before the bottleneck, allowing the flow rate to approach the theoretical capacity and improving road traffic efficiency.

[0100] The variable speed limit determination method based on highway traffic flow provided in this application determines the free-flow vehicle speed and critical density value of the target road segment by real-time collection of road traffic state information and traffic flow parameter data of the target road segment. Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and the current speed limit value of each speed limit zone is determined. This achieves a smooth, step-by-step adjustment of vehicle speed from upstream to the bottleneck, effectively suppressing traffic shock waves and maintaining stable traffic flow near the design capacity. This reduces the probability of congestion on the highway and improves the stability and safety of highway traffic operation.

[0101] Please see Figure 3 , Figure 4 , Figure 3 This is one of the structural schematic diagrams of a variable speed limit determination device based on highway traffic flow provided in an embodiment of this application. Figure 4 This is a second schematic diagram of a variable speed limit determination device based on highway traffic flow, provided as an embodiment of this application. Figure 3 As shown, the variable speed limit determining device 300 includes: Traffic data processing module 310 is used to acquire road traffic status information and traffic flow parameter data of the target road segment in the current speed limit change cycle, and to determine the free flow speed value and critical density value of the target road segment based on the traffic flow parameter data. The target vehicle speed determination module 320 is used to determine the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free flow velocity value, and the critical density value. The speed limit zone control module 330 is used to divide the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, and to determine the current speed limit value of each speed limit zone in the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value.

[0102] Furthermore, when the traffic data processing module 310 determines the free-flow vehicle speed and critical density value corresponding to the target road segment based on the traffic flow parameter data, the traffic data processing module 310 is used to: Based on the traffic flow parameter data, a traffic flow parameter model corresponding to the target road segment in the current speed limit change cycle is constructed; wherein, the traffic flow parameter data includes real-time traffic flow distribution data, real-time vehicle speed distribution data, and real-time density distribution data; Based on the traffic flow parameter model, the free-flow section, critical density section and congested section in the target road segment are determined, and the free-flow speed value and critical density value corresponding to the target road segment are determined respectively.

[0103] Furthermore, when the target vehicle speed determination module 320 determines the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free-flow velocity value, and the critical density value, the target vehicle speed determination module 320 is used to: Based on the road traffic status information and the free-flow velocity value, the target traffic flow value corresponding to the target road segment is determined; Based on the road traffic state information and the critical density value, a control density coefficient is determined; Based on the target traffic flow value and the control density coefficient, the target vehicle speed value corresponding to the target road segment is determined.

[0104] Furthermore, when the target vehicle speed determination module 320 determines the target traffic flow value corresponding to the target road segment based on the road traffic state information and the free-flow velocity value, the target vehicle speed determination module 320 is used to: The product of the free-flow velocity value and the critical density value is determined as the traffic flow threshold corresponding to the target road segment; Determine the capacity reduction factor corresponding to the road traffic status information, and determine the target traffic flow value corresponding to the target road segment by multiplying the capacity reduction factor by the traffic flow threshold.

[0105] Furthermore, when the speed limit zone control module 330 divides the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the speed limit zone control module 330 is used to: Based on the real-time traffic flow distribution data and real-time density distribution data in the traffic flow parameter data, the traffic shock wave velocity value corresponding to each preset area in the target road segment is determined; Based on the traffic setting parameters corresponding to the target road segment and the traffic shock wave velocity value, the target road segment is divided into multiple speed limit zones; wherein, the speed limit zone includes at least one upstream disturbance absorption zone, at least one speed transition zone and at least one bottleneck control zone.

[0106] Furthermore, when the speed limit zone control module 330 determines the current speed limit value for each speed limit zone corresponding to the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value, the speed limit zone control module 330 is used to: Based on the real-time vehicle speed distribution data in the traffic flow parameter data, the upstream real-time vehicle speed value and the upstream vehicle speed change corresponding to the target road segment are determined, and the difference between the upstream real-time vehicle speed value and the upstream vehicle speed change is determined as the first current speed limit value corresponding to the upstream disturbance absorption zone. Based on the target vehicle speed value and the first current speed limit value, determine the second current speed limit value corresponding to the speed transition zone; The target vehicle speed value is determined as the third current speed limit value corresponding to the bottleneck control area.

[0107] Furthermore, such as Figure 4 As shown, the variable speed limiting determination device 300 further includes a speed limiting smoothing processing module 340, which is used for: Based on the historical speed limit value corresponding to each speed limit zone in the historical speed limit change cycle, the current speed limit value is smoothed to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

[0108] The variable speed limit determination device based on highway traffic flow provided in this application embodiment determines the free-flow vehicle speed and critical density value of the target road segment by real-time collection of road traffic state information and traffic flow parameter data of the target road segment. Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, and the current speed limit value of each speed limit zone is determined. This achieves a smooth, step-by-step adjustment of vehicle speed from upstream to the bottleneck, effectively suppressing traffic shock waves and maintaining stable traffic flow near the design capacity. This reduces the probability of congestion on the highway and improves the stability and safety of highway traffic operation.

[0109] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 5 As shown, the electronic device 500 includes a processor 510, a memory 520, and a bus 530.

[0110] The memory 520 stores machine-readable instructions executable by the processor 510. When the electronic device 500 is running, the processor 510 and the memory 520 communicate via the bus 530. When the machine-readable instructions are executed by the processor 510, they can perform the operations described above. Figure 1 as well as Figure 2 The steps of the variable speed limit determination method based on highway traffic flow in the method embodiment shown are specifically implemented in the method embodiment and will not be repeated here.

[0111] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can perform the above-described actions. Figure 1 as well as Figure 2 The steps of the variable speed limit determination method based on highway traffic flow in the method embodiment shown are specifically implemented in the method embodiment and will not be repeated here.

[0112] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0113] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0114] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0115] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0116] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0117] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining variable speed limits based on highway traffic flow, characterized in that, The method includes: Obtain road traffic status information and traffic flow parameter data of the target road segment in the current speed limit change cycle, and determine the free flow speed value and critical density value of the target road segment based on the traffic flow parameter data. Based on the road traffic state information, the free-flow velocity value, and the critical density value, the target vehicle speed value corresponding to the target road segment is determined; Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones. Based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value, the current speed limit value corresponding to the current speed limit change cycle for each speed limit zone is determined.

2. The method according to claim 1, characterized in that, The step of determining the free-flow vehicle speed and critical density value corresponding to the target road segment based on the traffic flow parameter data includes: Based on the traffic flow parameter data, a traffic flow parameter model corresponding to the target road segment in the current speed limit change cycle is constructed; wherein, the traffic flow parameter data includes real-time traffic flow distribution data, real-time vehicle speed distribution data, and real-time density distribution data; Based on the traffic flow parameter model, the free-flow section, critical density section and congested section in the target road segment are determined, and the free-flow speed value and critical density value corresponding to the target road segment are determined respectively.

3. The method according to claim 1, characterized in that, Determining the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free-flow velocity value, and the critical density value includes: Based on the road traffic status information and the free-flow velocity value, the target traffic flow value corresponding to the target road segment is determined; Based on the road traffic state information and the critical density value, a control density coefficient is determined; Based on the target traffic flow value and the control density coefficient, the target vehicle speed value corresponding to the target road segment is determined.

4. The method according to claim 3, characterized in that, The step of determining the target traffic flow value corresponding to the target road segment based on the road traffic state information and the free-flow velocity value includes: The product of the free-flow velocity value and the critical density value is determined as the traffic flow threshold corresponding to the target road segment; Determine the capacity reduction factor corresponding to the road traffic status information, and determine the target traffic flow value corresponding to the target road segment by multiplying the capacity reduction factor by the traffic flow threshold.

5. The method according to claim 1, characterized in that, Based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, the target road segment is divided into multiple speed limit zones, including: Based on the real-time traffic flow distribution data and real-time density distribution data in the traffic flow parameter data, the traffic shock wave velocity value corresponding to each preset area in the target road segment is determined; Based on the traffic setting parameters corresponding to the target road segment and the traffic shock wave velocity value, the target road segment is divided into multiple speed limit zones; wherein, the speed limit zone includes at least one upstream disturbance absorption zone, at least one speed transition zone and at least one bottleneck control zone.

6. The method according to claim 5, characterized in that, The step of determining the current speed limit value for each speed limit zone in the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value includes: Based on the real-time vehicle speed distribution data in the traffic flow parameter data, the upstream real-time vehicle speed value and the upstream vehicle speed change corresponding to the target road segment are determined, and the difference between the upstream real-time vehicle speed value and the upstream vehicle speed change is determined as the first current speed limit value corresponding to the upstream disturbance absorption zone. Based on the target vehicle speed value and the first current speed limit value, determine the second current speed limit value corresponding to the speed transition zone; The target vehicle speed value is determined as the third current speed limit value corresponding to the bottleneck control area.

7. The method according to claim 1, characterized in that, After determining the current speed limit value for each speed limit zone corresponding to the current speed limit change cycle, the method further includes: Based on the historical speed limit value corresponding to each speed limit zone in the historical speed limit change cycle, the current speed limit value is smoothed to determine the target speed limit value corresponding to each speed limit zone in the current speed limit change cycle.

8. A variable speed limit determination device based on highway traffic flow, characterized in that, The variable speed limit determination device includes: The traffic data processing module is used to acquire road traffic status information and traffic flow parameter data of the target road segment in the current speed limit change cycle, and to determine the free flow speed value and critical density value of the target road segment based on the traffic flow parameter data. The target vehicle speed determination module is used to determine the target vehicle speed value corresponding to the target road segment based on the road traffic state information, the free flow velocity value, and the critical density value. The speed limit zone control module is used to divide the target road segment into multiple speed limit zones based on the traffic flow parameter data and the traffic setting parameters corresponding to the target road segment, and to determine the current speed limit value of each speed limit zone in the current speed limit change cycle based on the real-time vehicle speed distribution data in the traffic flow parameter data and the target vehicle speed value.

9. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. The machine-readable instructions are executed by the processor to perform the steps of the variable speed limit determination method based on highway traffic flow as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the variable speed limit determination method based on highway traffic flow as described in any one of claims 1 to 7.

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