A signalized intersection straight-ahead waiting area length design method and system

Abstract

This invention discloses a method and system for designing the length of the straight-ahead waiting area at a signalized intersection. The method includes: collecting relevant traffic data; calculating the maximum number of vehicles queuing for straight-ahead traffic behind the stop line at a red light at the intersection based on the fundamental relationships between the three traffic flow parameters and the Green Shield linear relationship between speed and density when traffic flow density is moderate; finally, converting this number of vehicles into the average queue length of straight-ahead vehicles in meters, calculating the maximum queue length, and removing the length of the lane-changing prohibition line at the approach lane, which is the length of the straight-ahead waiting area. This invention can largely solve the problem of wasted urban traffic resources and provides a targeted method to improve traffic congestion at intersections, while also rapidly improving living efficiency and social transportation development.

Description

Technical Field

[0001] This invention relates to the field of road traffic design, specifically to a method and system for designing the length of a straight-ahead waiting area. Background Technology

[0002] To adapt to the development of production and transportation activities, it is essential to continuously improve the traffic capacity of urban road intersections to alleviate congestion. Considering the scarcity of urban land resources, expanding existing roads is difficult, and modifying the channelization design of urban intersections requires significant costs for upgrading related supporting facilities. Therefore, optimizing intersection design is the main direction for improving the traffic capacity of road intersections. At urban road intersections, the through traffic flow is the largest; adjusting the through lanes will greatly improve the intersection's traffic capacity. Making full use of idle space resources and setting up through waiting areas can improve intersection operational efficiency and alleviate urban intersection congestion.

[0003] Currently, many scholars both domestically and internationally have conducted research on optimizing waiting areas to improve intersection capacity. However, most studies focus on verifying the increased traffic efficiency after setting up straight-ahead waiting areas, lacking research on the length of straight-ahead waiting areas at intersections. Furthermore, the regulations regarding the waiting length of straight-ahead waiting areas at highway intersections are not specific enough and cannot be directly applied. Therefore, it is necessary to propose a method for calculating the length of straight-ahead waiting areas at signalized intersections, which can rationally allocate traffic flow, effectively improve traffic congestion at intersections, and thus improve living efficiency and promote social traffic development. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method and system for designing the length of the straight-ahead waiting area at a signalized intersection, which analyzes the red light duration and uses the Green Shields linear relationship model and the maximum queue length to calculate the vehicle queue length within the red light duration of the straight-ahead waiting area.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention proposes a method for designing the length of the straight-ahead waiting area at a signalized intersection, specifically including the following steps:

[0007] S1. Collect traffic data;

[0008] S2. Establish a Green Shields linear relationship model for the straight lanes at the stop line of the intersection;

[0009] S3. Based on the fundamental relationships between the three traffic flow parameters, and the Green Shields linear relationship model between speed and density when the traffic flow density is moderate, calculate the maximum flow rate Q of the through lane at the stop line of the intersection. m ;

[0010] S4, combined with the maximum flow rate Q of the straight lane at the stop line of the intersection. m Calculate the maximum number N of vehicles N in the straight lane at the stop line of the intersection when the light is red. m And, in combination with the actual situation of the intersection signal timing, calculate the queue length L of straight-through vehicles within the red light interval;

[0011] S5. Remove the length of the lane change prohibition line at the entrance lane and calculate the length S of the straight-ahead waiting area at the intersection.

[0012] Furthermore, in step S1, the collected traffic data includes: vehicle speed of vehicles in the straight lane at the intersection entrance, red light duration t, average vehicle length l1 of vehicles in the straight lane at the intersection, and length X of the lane line prohibiting lane changes at the intersection entrance.

[0013] Furthermore, in step S2, the model establishment includes: calculating the congestion density K of the straight-ahead lane at the intersection by considering the average vehicle length l1 of vehicles in the straight-ahead lane at the intersection and the safe distance l2 between two adjacent vehicles when stopped at a red light. j , will K j Substituting these values ​​into the Green Shields linear relationship model completes the modeling; K j The specific formula for the linear relationship model with Green Shields is as follows:

[0014]

[0015]

[0016] Where V is the speed of vehicles in the straight lane at the stop line of the intersection; V f Let K be the speed at which vehicles travel smoothly when the traffic density in the straight lane at the stop line of the intersection approaches 0; and let H be the density of vehicles in the straight lane at the stop line of the intersection. d阻 It refers to the blocking headway of vehicles in the straight lane at the stop line of an intersection, that is, the headway between two adjacent vehicles that stop in the straight-going curved lane during a red light.

[0017] Furthermore, in step S3, the maximum flow rate Q of the straight-ahead lane at the stop line of the intersection... m The calculation process is as follows:

[0018] S301. Obtain the Green Shields linear relationship model between velocity and density:

[0019]

[0020] S302. Taking the first derivative with respect to the density, we get:

[0021]

[0022] S303, when the first derivative is 0, we get At this point, Q has a maximum value, then:

[0023]

[0024] Furthermore, in step S4, the maximum number of straight-going vehicles N at a red light... m The formula for calculating the queue length L of vehicles going straight during red light intervals is as follows:

[0025]

[0026]

[0027] Furthermore, in step S5, the formula for calculating the length S of the straight-ahead waiting area at the intersection is as follows:

[0028] S = LX = 250tV f -l2-X.

[0029] Furthermore, this invention also proposes a system for designing the length of the straight-ahead waiting area at a signalized intersection, comprising:

[0030] The data acquisition module is used to collect data including vehicle speed, red light duration t, average vehicle length l1 of vehicles in the straight lane at the intersection entrance, and length X of the lane change prohibition line at the intersection entrance.

[0031] The waiting area length calculation module is used to establish a Green Shields linear relationship model for the straight-ahead lanes at the intersection stop line, and to calculate the maximum flow rate Q of the straight-ahead lanes at the intersection stop line. m ; Calculate the maximum number N of vehicles N in the straight lane at the stop line of an intersection when the light is red. m Based on the actual signal timing at the intersection, the queue length L of straight-ahead vehicles during the red light interval is calculated; finally, the length S of the straight-ahead waiting area at the intersection is calculated.

[0032] Furthermore, in the waiting area length calculation module, the Green Shields linear relationship model for the straight lanes at the intersection stop line is established, and the specific formula of the model is as follows:

[0033]

[0034]

[0035] Among them, K j l1 is the congestion density of the straight-ahead lane at the stop line of the intersection; l2 is the average vehicle length of vehicles in the straight-ahead lane at the intersection; l3 is the safe distance between two adjacent vehicles when stopped at a red light; V is the speed of vehicles in the straight-ahead lane at the stop line of the intersection; V fLet K be the speed at which vehicles travel smoothly when the traffic density in the straight lane at the stop line of the intersection approaches 0; K is the density of vehicles in the straight lane at the stop line of the intersection. It refers to the blocking headway of vehicles in the straight lane at the stop line of an intersection, that is, the headway between two adjacent vehicles stopped in the straight lane during a red light.

[0036] Furthermore, based on the Green Shields linear relationship model of the straight lane at the intersection stop line in the aforementioned waiting area length calculation module, Q m N m The specific calculation formulas for L and S are as follows:

[0037] (1)Q m The calculation process is as follows:

[0038] Step 1: Obtain the Green Shields linear relationship model between velocity and density:

[0039]

[0040] Step 2: Taking the first derivative with respect to the density, we get:

[0041]

[0042] Step 3, when the first derivative is 0, we obtain At this point, Q has a maximum value, then:

[0043]

[0044] (2)N m The calculation process is as follows:

[0045]

[0046] (3) The calculation process for L is as follows:

[0047]

[0048] (4) The calculation process for S is as follows:

[0049] S = LX = 250tV f -l2-X.

[0050] The present invention adopts the above technical solution, and its significant technical effects compared with the prior art are as follows:

[0051] This invention provides road designers with a method for designing the length of straight-ahead waiting areas based on the Green Shields linear relationship model, filling the current gap in the design of straight-ahead waiting area lengths in China and improving the road service level of intersections. This invention can alleviate congestion of buses at intersections. Based on a thorough analysis and investigation of the construction of intersection facilities, this invention comprehensively considers the traffic density during peak hours and sets sufficient lengths for vehicles. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the straight-line waiting area of ​​the present invention.

[0053] Figure 2 This is a schematic diagram of the data measurement location for this invention.

[0054] Figure 3 The vehicle speed is 85% of the speed measured in this invention example.

[0055] Figure 4 Detailed diagram of the length of the straight-ahead waiting area at the intersection. Detailed Implementation

[0056] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0057] To achieve the above objectives, the present invention provides a method for designing the length of the straight-ahead waiting area at an intersection, comprising the following steps:

[0058] S1. Collect traffic data at the critical speed collection points for vehicles in the intersection's straight-ahead waiting area and the offset straight-ahead lane. Specific locations are as follows: Figure 1 , Figure 2 As shown, the collected data includes: 85% speed of vehicles in the straight lane at the intersection, red light duration t, average vehicle length l1 of vehicles in the straight lane at the intersection, and length X of the lane change prohibition line at the intersection entrance.

[0059] A survey point was set up at the stop line of the intersection. First, the duration of red light for vehicles within one red light cycle was surveyed and recorded. Then, at the survey point, the peak hour traffic volume of large, medium, and small vehicles passing through the offset straight lane was continuously surveyed at 3-minute intervals. All vehicles were classified into large, medium, and small vehicles and surveyed separately. The traffic volumes of large, medium, and small vehicles were statistically analyzed and converted into equivalent passenger car traffic volumes. The average vehicle length at the intersection was then calculated using the following conversion method: Q = ∑Q i E i Where Q is the converted equivalent car traffic volume, E i For conversion factors of vehicle class i, Q i Traffic volume for vehicle type i.

[0060] S2. Establish a Green Shields linear relationship model for the straight lanes at the stop line of the intersection.

[0061] Select intersections with high traffic flow density and determine the headway for blocking vehicles based on traffic flow micro-parameters. The congestion density K of the straight lane at the stop line of the intersection was calculated. j When traffic flow density is moderate, the relationship between speed and density is a Green Shield linear relationship. Therefore, the Green Shield linear model formula for the straight-ahead lane at the stop line of the intersection is:

[0062]

[0063] in, V represents the speed of vehicles in the straight-ahead lane at the stop line of the intersection, in kilometers per hour; f K represents the average speed when the traffic density in the straight-ahead lane at the stop line of an intersection approaches zero, allowing vehicles to move freely without obstruction. It is the unobstructed speed of vehicles in the straight-ahead lane at the stop line of an intersection, measured in kilometers per hour. j The congestion density of the straight-ahead lane at the stop line of the intersection is expressed in vehicles per kilometer; K is the vehicle density of the straight-ahead lane at the stop line of the intersection, expressed in vehicles per kilometer. l1 represents the blocking headway of vehicles in the straight-ahead lane at the intersection stop line, i.e., the headway between two adjacent vehicles stopped in the straight-ahead lane during a red light, in meters per vehicle; l2 represents the average vehicle length in the straight-ahead lane at the intersection stop line, in meters; l3 represents the safe distance between two adjacent vehicles when stopped at a red light, in meters. The optimal safe distance between vehicles when stopped at a red light is 1-2 meters. In this embodiment, to maximize the length of the straight-ahead waiting area, a safe distance of 2 meters is selected.

[0064] S3. Based on the fundamental relationships among the three traffic flow parameters—that traffic volume equals the product of speed and traffic density—and the Green Shield linear relationship between speed and density when traffic density is moderate, calculate the maximum flow rate Q of the through lane at the stop line of the intersection. m The specific calculation process is as follows:

[0065] Step 1: Obtain the Green Shields linear relationship model between velocity and density:

[0066]

[0067] Step 2: Taking the first derivative with respect to the density, we get:

[0068]

[0069] Step 3, when the first derivative is 0, we obtain At this point, Q has a maximum value, then:

[0070]

[0071] In the formula, Q m Unit: vehicles / hour.

[0072] S4, combined with the maximum flow rate Q of the straight lane at the stop line of the intersection. m Calculate the maximum number of straight-ahead vehicles N when the light is red. m Based on the actual signal timing at the intersection, the queue length L of vehicles going straight during the red light interval is calculated using the following formula:

[0073]

[0074]

[0075] In the formula, N m The unit of is vehicle; t is the red light duration, in seconds; the unit of L is meter.

[0076] S5. Remove the length of the lane change prohibition line at the entrance lane and calculate the length S of the straight-ahead waiting area at the intersection, using the following formula:

[0077] S = LX = 250tV f -l2-X;

[0078] In the formula, S is the length of the straight-ahead waiting area at the intersection, in meters; X is the length of the lane change prohibition line at the intersection entrance, in meters.

[0079] Taking the intersection of Chengde South Road and Mingyuan Road in Qingjiangpu District, Huai'an City as an example, this intersection has a traffic island. Chengde Road in the north-south direction is a two-way five-lane road, and Meicheng Road in the east-west direction is a two-way six-lane road. The intersection's approach lanes have four lanes: one dedicated left-turn lane, two through lanes, and one right-turn lane. The intersection has lane markings prohibiting lane changes at the approach lanes, but no through-traffic waiting area is provided. The steps for determining the length of the through-traffic waiting area are as follows:

[0080] 1. Record the red light duration of the straight lane at the red light duration survey point, and measure the red light duration t to be 38 seconds;

[0081] 2. Measure the length X of the no-lane-changing line at the intersection entrance, and find that the length X of the no-lane-changing line at the intersection entrance is 95 meters;

[0082] 3. Using a radar speedometer, measure the 85% speed of vehicles in the straight lane as they pass the stop line at the 85% speed survey point. The measured data is as follows: Figure 3 As shown, 85% of the vehicle speed V fAssuming a speed of 28 km / h, substituting this into the formula, the length S of the straight-ahead waiting area at this intersection is 0.012 km, meaning the straight-ahead waiting area is 12 meters. A detailed diagram of the straight-ahead waiting area length S at the intersection is shown below. Figure 4 As shown.

[0083] This invention also proposes a system for designing the length of the straight-ahead waiting area at a signalized intersection, including a data acquisition module, a waiting area length calculation module, and a computer program that can run on a processor. It should be noted that each module in the above system corresponds to a specific step of the method provided in this invention embodiment, possessing the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in this invention embodiment.

[0084] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for designing the length of the straight-ahead waiting area at a signalized intersection, characterized in that, Includes the following steps: S1. Collect traffic data; the collected traffic data includes: vehicle speed in the straight lane at the intersection entrance, and red light duration. Average vehicle length of vehicles in the straight lane at an intersection The length of the lane line that prohibits lane changes at the intersection entrance lane ; S2. Establish a Green Shields linear relationship model for the straight-ahead lanes at the stop line of the intersection; specifically: pass Safe distance between two adjacent vehicles when stopped at a red light Calculate the congestion density of the straight lane at the stop line of the intersection. ,Will By substituting these values ​​into the Green Shields linear relationship model, the modeling can be completed. The specific formula for the linear relationship model with Green Shields is as follows: ； ； in, The speed of vehicles in the straight lane at the stop line of the intersection; The smooth-moving speed of vehicles when the traffic density in the straight lane at the stop line of an intersection approaches 0. The density of vehicles in the straight lane at the stop line of the intersection; It refers to the blocking headway of vehicles in the straight lane at the stop line of an intersection, that is, the headway between two adjacent vehicles stopped in the straight lane during a red light; S3. Based on the fundamental relationships between the three traffic flow parameters, and the Green Shields linear relationship model between speed and density when the traffic flow density is moderate, the maximum flow rate of the straight lane at the stop line of the intersection is obtained. Specifically: S301. Obtain the Green Shields linear relationship model between velocity and density: ； S302. Taking the first derivative with respect to the density, we get: ； S303, when the first derivative is 0, we get If Q has a maximum value at this point, then: ； S4, derived from step S3 The maximum number of vehicles in the straight lane at the stop line of the intersection when the light is red is obtained. By combining the intersection signal timing, the queue length of vehicles going straight during the red light interval is obtained. ; S5. Remove the length of the lane change prohibition line at the entrance lane to obtain the length of the straight-ahead waiting area at the intersection. .

2. The method for designing the length of the straight-ahead waiting area at a signalized intersection according to claim 1, characterized in that, In step S4, the maximum number of vehicles in the straight lane at the stop line of the intersection during a red light. The length of the queue of vehicles going straight during the red light interval. The calculation formula is as follows: ； 。 3. The method for designing the length of the straight-ahead waiting area at a signalized intersection according to claim 2, characterized in that, In step S5, the length of the straight-ahead waiting area at the intersection The calculation formula is as follows: 。 4. A system applied to the method for designing the length of the straight-ahead waiting area at a signalized intersection as described in claim 1, characterized in that, include: The data acquisition module is used to collect data including vehicle speed and red light duration in the straight-ahead lane at the intersection entrance. Average vehicle length of vehicles in the straight lane at intersection The length of the lane markings that prohibit lane changes at intersection approach lanes Data; The waiting area length calculation module is used to establish a Green Shields linear relationship model for the straight-ahead lanes at the intersection stop line, and to calculate the maximum traffic flow of the straight-ahead lanes at the intersection stop line. ; Calculate the maximum number of vehicles in the straight lane at the stop line of an intersection when the light is red. Based on the actual signal timing at the intersection, the queue length of vehicles going straight during the red light interval is calculated. Finally, the length of the straight-ahead waiting area at the intersection was calculated. .

5. The system for designing the length of the straight-ahead waiting area at a signalized intersection according to claim 4, characterized in that, In the waiting area length calculation module, the Green Shields linear relationship model for the straight lanes at the intersection stop line is established. The specific formula of the model is as follows: ； ； in, The congestion density of the straight lane at the stop line of the intersection; The average length of vehicles in the straight lane at the intersection. The safe distance between two adjacent vehicles when stopped at a red light; The speed of vehicles in the straight lane at the stop line of the intersection; The smooth-moving speed of vehicles when the traffic density in the straight lane at the stop line of an intersection approaches 0. The density of vehicles in the straight lane at the stop line of the intersection; It refers to the blocking headway of vehicles in the straight lane at the stop line of an intersection, that is, the headway between two adjacent vehicles stopped in the straight lane during a red light.

6. The system for designing the length of the straight-ahead waiting area at a signalized intersection according to claim 5, characterized in that, Based on the Green Shields linear relationship model of the straight lane at the intersection stop line in the waiting area length calculation module. , , , The specific calculation formula is as follows: (1) The calculation process is as follows: Step 1: Obtain the Green Shields linear relationship model between velocity and density: ； Step 2: Taking the first derivative with respect to the density, we get: ； Step 3, when the first derivative is 0, we obtain If Q has a maximum value at this point, then: ； (2) The calculation process is as follows: ； (3) The calculation process is as follows: ； (4) The calculation process is as follows: 。

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