A short-spacing intersection overflow control method considering dissipative overflow

Abstract

The present invention discloses an overflow control method for short-spacing intersections considering dissipable overflow, belonging to the technical field of traffic control. A traffic data collection system for short-spacing intersections is constructed by installing microwave radar detection equipment at intersections, and then the signal timing schemes, green-to-signal ratios, traffic capacities and phase differences of upstream and downstream intersections are calculated according to the collected traffic data. Then, the maximum number of vehicles entering the overflow control direction of the downstream intersection from the upstream intersection is calculated according to the number of vehicles passing when the green light is released in the overflow control direction of the upstream and downstream intersections and the maximum number of vehicles that can be accommodated in the short-spacing section. It is also judged whether the last vehicle entering the overflow control direction of the downstream intersection from the upstream intersection can enter the short-spacing section. Under the premise of ensuring that the traffic overflow can be dissipated, the green light and full red time of the upstream intersection entering the overflow control section of the downstream intersection are dynamically controlled, which is beneficial to avoiding the overflow of vehicles queuing at the intersection while comprehensively improving the traffic capacity between short-spacing intersections.

Description

Technical Field

[0001] The invention relates to the technical field of traffic control, and in particular to an overflow control method for short-spacing intersections taking dissipated overflow into consideration. Background Art

[0002] With the continuous development of urban economy and population growth, the number of vehicles has continued to increase. The growing traffic demand has brought difficulties to urban road traffic management under the premise of insufficient traffic supply. Especially during rush hour and in bad weather conditions, due to the short distance between some intersections, the accumulated traffic volume often exceeds the design capacity of the section, and it is easy for the downstream intersection to overflow to the upstream intersection, which is called intersection traffic overflow.

[0003] The current traffic control technology for intersection traffic overflow is to use traffic detectors to monitor the overflow status of the upstream intersection exit in real time. When vehicle queue overflow is detected, the upstream intersection immediately adopts traffic signal control methods, such as releasing the minimum green light time for the direction of traffic merging into the overflow section or directly adopting red light control measures to reduce the number of vehicles merging into the overflow section to prevent vehicles from overflowing to the upstream intersection and causing traffic locks at the intersection.

[0004] However, the above method does not consider whether the current traffic overflow phenomenon can be dissipated, especially the traffic overflow phenomenon often occurs at short-distance intersections. Once the overflow phenomenon is detected, the intersection will be controlled, which will inevitably have a great impact on the vehicle traffic at the short-distance intersection and seriously affect its traffic capacity. However, when the overflow phenomenon occurs, the upstream and downstream intersections are releasing green lights in the direction of the overflow section, and the overflow vehicles can enter the section between the intersections within the green light time, that is, the traffic overflow phenomenon can be dissipated. In the process of overflow vehicles entering the section from the intersection, the other conflicting directions of the upstream intersection are all red lights, so the overflow vehicles will not affect the traffic of vehicles in the intersecting direction.

[0005] Therefore, it is necessary to propose a control method for overflow at short-spacing intersections that takes into account dissipative overflow, so as to avoid overflow of queued vehicles at intersections and comprehensively improve the traffic capacity between short-spacing intersections. Summary of the invention

[0006] In order to make up for the shortcomings of the existing technical problems, the present invention proposes an overflow control method for short-spacing intersections taking into account dissipable overflow. The signal timing schemes, green-to-signal ratios, traffic capacity and phase difference of the upstream and downstream intersections are calculated through the data collected at the intersections, and the signal timing schemes required for the linkage overflow control of the upstream and downstream short-spacing intersections and the maximum number of vehicles entering the overflow control direction of the downstream intersection from the upstream intersection are obtained. On the premise of ensuring that the traffic overflow can be dissipated, the green light and full red time of the upstream intersection entering the overflow control section of the downstream intersection are dynamically controlled, which is beneficial to avoid the overflow of vehicles queuing at the intersection while comprehensively improving the traffic capacity between short-spacing intersections.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A short-spacing intersection overflow control method considering dissipative overflow includes the following steps:

[0009] (1) Constructing a traffic data collection system for short-distance intersections

[0010] The traffic data collection system includes a microwave radar detection device installed at the exit lane of the intersection, which detects the traffic flow and the number of vehicles in the queue at the entrance direction of the intersection, as well as the green light operation time corresponding to each vehicle passing through the intersection;

[0011] (2) Calculate the signal timing plan for short-distance intersections

[0012] Collect the traffic flow of the upstream and downstream intersections with short spacing in the past month, calculate the initial intersection signal cycle duration of the upstream and downstream intersections according to the average traffic flow of the upstream and downstream intersections in the past month, take the maximum value of the calculated initial intersection signal cycle duration as the final cycle duration of the upstream and downstream intersections, and then calculate the signal timing scheme, green-to-signal ratio, traffic capacity and phase difference of the upstream and downstream intersections according to the collected traffic data, and finally obtain the signal timing scheme required for the linkage overflow control of the upstream and downstream short spacing intersections;

[0013] (3) Establish a calculation method for dissipating vehicle queues at short-distance intersections

[0014] When traffic overflow occurs on a short-spacing section, the upstream and downstream intersections are releasing green lights in the direction of the overflow section, and the overflow vehicles enter the section between the intersections within the green light time, that is, the traffic overflow phenomenon can be dissipated; according to the number of vehicles passing when the upstream and downstream intersections are linked to the overflow control direction and the green light, the maximum number of vehicles that can be accommodated in the short-spacing section, and the average number of vehicles queuing in the short-spacing section, a calculation method for dissipating the vehicle queue at the short-spacing intersection is established, and the maximum number of vehicles entering the overflow control direction of the downstream intersection from the upstream intersection is calculated. When the number of vehicles entering the overflow control direction of the downstream intersection from the upstream intersection is less than or equal to the maximum number of vehicles, the vehicle queue in the overflow control direction of the downstream intersection can be dissipated;

[0015] (4) Determine overflow prevention and evacuation plans for vehicles at short-distance intersections

[0016] The microwave radar detection equipment at the upstream intersection is used to monitor in real time the vehicles that exit the stop line from the upstream intersection in the direction of the linkage overflow control, and the headway time between two adjacent vehicles that exit the stop line in the direction of the linkage overflow control of the upstream intersection is calculated in turn, and it is determined whether the headway time between two adjacent vehicles that exit the stop line is greater than the set threshold. If so, the green light release at the upstream intersection is terminated in time. Otherwise, the number of vehicles that exit the stop line is calculated in turn, and compared with the maximum number of vehicles that can pass in the direction of the linkage overflow control of the upstream intersection. When the number of vehicles that exit the stop line in the direction of the linkage overflow control of the upstream intersection reaches the maximum number of vehicles, the green light release at the upstream intersection is terminated in time; finally, it is determined whether the last vehicle that enters the overflow control direction of the downstream intersection from the upstream intersection can successfully enter the short-spacing section, and the green light and full red time of the upstream intersection entering the overflow control section of the downstream intersection are dynamically controlled on the premise of ensuring that the traffic overflow can be dissipated.

[0017] In the present invention, the microwave radar detection equipment is installed in the form of a crossbar at the position of the inlet road to be tested opposite to the outlet road, and the microwave radar detection equipment at the downstream intersection is used to obtain the corresponding one-month overflow control direction of the downstream intersection. T The number of queued vehicles in the time period is averaged to obtain the corresponding overflow control direction of the downstream intersection T Average number of vehicles in queue during the period Q 1 .

[0018] The phase difference in step (2) of the present invention refers to the time when the first vehicle at the upstream intersection is released by the green light drives at a certain speed to the end point D of the average vehicle queue of the short-distance section without stopping, and at a minimum headway time t s When following the queued vehicles at point D through the downstream intersection, there is a phase difference between the upstream and downstream intersections. At this time, the green light time at the downstream intersection will not cause idling.

[0019] The steps for calculating the maximum number of vehicles driving from the upstream intersection into the overflow control direction of the downstream intersection in step (3) of the present invention are as follows:

[0020] (1) Calculate the number of vehicles that can actually pass when the green light is released in the overflow control direction at the upstream and downstream intersections Q 2 , Q 3 ;

[0021] (10)

[0022] In the above formula, k 1 and k 2 They represent the coefficients of the number of vehicles that can pass when the overflow control direction is released with a green light at the upstream intersection A and the downstream intersection B, CAP AWS Indicates the capacity of the lane in the overflow control direction of the upstream intersection A. CAP BWS Indicates the traffic capacity of the lane in the overflow control direction of the downstream intersection B;

[0023] (2) Calculate the number of vehicles entering the overflow control direction of the downstream intersection when the upstream intersection overflow control direction is released green light ;

[0024] (11)

[0025] In the above formula, k 3 Indicates the proportional coefficient of vehicles moving from the overflow control direction of the upstream intersection to the overflow control direction of the downstream intersection, q 1 The traffic flow from the upstream overflow control direction to the downstream overflow control direction collected in the past month. q 1 + q 2 + q 3 Traffic flow in the overflow control direction of the upstream intersection collected in the past month;

[0026] (3) Calculate the maximum number of vehicles that can be accommodated by lanes between short-distance intersections Q 4 ;

[0027] (12)

[0028] In the above formula, L AB is the length of the short-spacing section, L Cis the average vehicle length, s is the average vehicle spacing;

[0029] (4) Conditions for the traffic overflow of the east through lane of the downstream intersection to dissipate:

[0030] (13)

[0031] In the above formula, Q 1 The average number of vehicles queuing in the east through lane between short-distance intersections;

[0032] (5) Calculate the maximum number of vehicles that enter the downstream intersection from the east straight direction at the upstream intersection ;

[0033] (14).

[0034] In step (4) of the present invention, the full red time is extended second by second on the premise that the overflow of the queued vehicles can be dissipated, until the overflowed vehicles enter the short-distance road section.

[0035] In step (4) of the present invention, in order to control vehicles entering the downstream intersection in the direction of the overflow control section, the upstream intersection ends the green light in advance based on the original green light time. When the green light time for the upstream intersection to go straight east is adjusted, in order to ensure that the signal cycle of the upstream intersection remains unchanged, the upstream intersection signal cycle time is subtracted from the adjusted green light time, all-red time and original yellow light time for the upstream intersection to go straight east, and the remaining time is allocated to other phase times according to the ratio between the original green-to-signal ratios of other phases.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention calculates the maximum number of vehicles entering the overflow control direction of the downstream intersection from the upstream intersection according to the number of vehicles passing when the green light is released in the overflow control direction of the upstream and downstream intersections and the maximum number of vehicles that can be accommodated in the short-distance section, and determines the overflow prevention and control and evacuation plan of the vehicle queue at the short-distance intersection accordingly. In this way, for the dissipable traffic overflow phenomenon in which the overflow vehicles can enter the section between the intersections within the green light time, the upstream intersection does not need to adopt the overflow prevention and control and evacuation plan; if the last vehicle entering the overflow control section of the downstream intersection from the east straight direction of the upstream intersection cannot enter the short-distance section smoothly, then the full red control will continue to be adopted when the east straight green light of the upstream intersection ends, which can ensure that the overflow vehicles will not affect the passage of vehicles in the intersecting direction while improving its traffic capacity.

[0038] 2. The present invention constructs a traffic data collection system for short-spacing intersections by adding microwave radar detection equipment to intersections, and then calculates the signal timing schemes, green-to-signal ratios, traffic capacities and phase differences of upstream and downstream intersections based on the collected traffic data, and then calculates the maximum number of vehicles that can pass through the overflow control direction of the downstream intersection from the upstream intersection based on the number of vehicles passing when the green light is released in the overflow control direction of the upstream and downstream intersections and the maximum number of vehicles that can be accommodated in the short-spacing section, and determines the overflow prevention, control and evacuation scheme for vehicle queues at short-spacing intersections; the overflow prevention, control and evacuation scheme for vehicle queues at short-spacing intersections is obtained based on objective data of intersections, which is more in line with actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the installation location of the short-spacing intersection traffic data collection system equipment of the present invention.

[0040] Figure 2 Schematic diagram of the optimal phase difference of the present invention.

[0041] Figure 3 It is a schematic diagram of a short-distance road section without traffic overflow according to the present invention.

[0042] Figure 4 It is a schematic diagram of the present invention showing that traffic overflow occurs on a short-distance road section and cannot be dissipated in time.

[0043] Figure 5 This is a schematic diagram of the invention showing that traffic overflow occurs on a short-distance road section but can be dissipated in time.

[0044] Figure 6 The present invention is a flow chart of the overflow prevention and control and evacuation scheme for vehicles at short-distance intersections. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] like Figure 1-6 As shown, the present invention discloses a short-spacing intersection overflow control method considering dissipative overflow, which is specifically as follows:

[0047] 1. Build a short-distance intersection traffic data collection system

[0048] like Figure 1 As shown, the present invention proposes a system for collecting traffic data at short-distance intersections. The system mainly includes a microwave radar detection device arranged at the exit lane of the intersection. The microwave radar detection device is installed in a crossbar manner at the exit lane opposite to the entrance lane to be tested, and the distance to the intersection is a ( aThe value range is 10 meters to 20 meters); Microwave radar longitudinal monitoring distance L D About 200 to 300 meters, of which the intersection length is 30 to 40 meters and the short-distance section length is L AB The microwave radar detection equipment can detect the traffic flow and the number of vehicles in the queue at the entrance of the intersection. The microwave radar detection equipment at the upstream intersection can monitor the traffic flow in real time, and the microwave radar detection equipment at the downstream intersection can monitor the number of vehicles in the queue at short intervals in real time. The system collects the traffic flow of each entrance lane of A and B at the upstream and downstream intersections within a month, and takes the average to obtain the traffic flow of each entrance lane of A and B at the upstream and downstream intersections within a certain period of time in a month. T Average hourly lane traffic flow (e.g. corresponding to peak travel times on weekdays when traffic overflow is more likely to occur) q i ,in T The traffic flows from the upstream intersection going straight from the east to the downstream intersection going straight, turning left, and turning right during the period are q 1 , q 2 , q 3 The microwave radar detection equipment at downstream intersection B is used to obtain the overflow control direction of the downstream intersection within one month. T The number of queued vehicles in the time period is averaged to obtain the corresponding overflow control direction of the downstream intersection T Average number of vehicles in queue during the period Q 1 In addition, the system can also record the green light operation time corresponding to each vehicle passing through the intersection.

[0049] 2. Calculate the signal timing plan for short-distance intersections

[0050] (1) Calculation T Initial cycle duration of upstream and downstream intersections A and B during the time period C A and C B .

[0051] After the average traffic flow of each entrance of the upstream and downstream intersections A and B is determined, the four-phase scheme of east-west straight, east-west left turn, north-south straight and north-south left turn is taken as an example to calculate T Initial cycle duration of upstream and downstream intersections A and B during the time period C A and C B .

[0052] ① Determine the traffic flow rate ratioy i .

[0053] (1)

[0054] In the above formula, y i Indicates the maximum lane flow rate ratio corresponding to the inlet flow direction contained in different phases of the intersection (for example, the east-west straight phase includes the east straight and west straight flow directions, and the maximum lane flow rate ratio between the east and west straight is taken). q i represents the average hourly lane traffic flow in the corresponding import direction, N i represents the corresponding number of import flow lanes, S i Represents the corresponding inlet lane saturation flow rate.

[0055] ②Calculate the cycle flow rate ratio Y .

[0056] (2)

[0057] ③Calculate the total loss time L .

[0058] (3)

[0059] In the above formula, l i Indicates the startup loss time of each phase, generally 3 seconds. r i Indicates the initial full red time of each phase. The initial value can be 0 or 1 second.

[0060] ④Determine the cycle length C .

[0061] (4)

[0062] (2) Calculation T Final cycle duration of upstream and downstream intersections A and B during the time period C A and C B .

[0063] When traffic overflow occurs on the road section between short-distance intersections and cannot be dissipated, in order to take overflow prevention and control measures in time, the upstream and downstream intersections need to use signal coordination to achieve linkage overflow control, so the cycle of the upstream and downstream intersections should be set to the same. The linkage overflow control direction of A and B at the upstream and downstream intersections is the direction of the lane that needs to be coordinated.

[0064] ①If CA > C B , then the cycle durations of the upstream and downstream intersections A and B are set to C A , the time extension of the downstream intersection B cycle is adjusted in the direction of the lane that needs to be coordinated at the downstream intersection.

[0065] ②If C B > C A , then the cycle durations of the upstream and downstream intersections A and B are set to C B , the extended time of the upstream intersection A cycle is adjusted in the direction of the lane that needs to be coordinated at the upstream intersection.

[0066] (3) Calculation T Green light duration of the phase corresponding to the direction of linkage overflow control at the upstream and downstream intersections during the time period g j , j Indicates upstream intersection A or downstream intersection B.

[0067] (5)

[0068] In the above formula, Q j is the maximum flow rate of a single lane in the phase corresponding to the direction of the upstream and downstream intersection linkage overflow control, C is the signal cycle length (based on the judgment of the previous step C A or C B ), S j is the corresponding saturation flow rate, X i The corresponding phase load level, in order to make the phase green light fully utilized and not overloaded, X j The acceptable value is 0.85.

[0069] (4) Calculation T Green signal ratio of the phase corresponding to the linkage overflow control direction of the upstream and downstream intersections during the time period λ j .

[0070] (6)

[0071] (5) Calculation T Lane capacity of the phase corresponding to the direction of linkage overflow control at the upstream and downstream intersections during the time period CAP j, that is, calculating the maximum number of vehicles that can theoretically pass through the upstream and downstream intersections in the direction of the linked overflow control within the green light time.

[0072] (7)

[0073] (6) Calculation T The optimal phase difference between the upstream and downstream intersections in the linkage overflow control direction during the time period.

[0074] The calculated phase difference is the difference between the green light start time of the phase corresponding to the linkage overflow control direction of the upstream and downstream intersections. Figure 2 As shown, L AB Indicates the length of the short-distance section; L 1 express T The average vehicle queue length at downstream intersection B during the time period; C Indicates the cycle duration of the upstream and downstream intersections, g A and g B Respectively represent the green light duration of the upstream intersection A and the downstream intersection B in the direction of linkage overflow control; Indicates the optimal phase difference between the upstream and downstream intersections; Point D indicates L 1 The line segments in the figure represent the running tracks of vehicles, where horizontal lines represent queued vehicles and oblique lines represent vehicles traveling at a certain speed. v (Usually 30 to 40 km / h) Drive to point D on the short-distance section without stopping, and at a minimum headway t s (Generally 2 to 3 seconds is taken, which refers to the minimum time difference for the front ends of the two vehicles in front and behind to pass through a certain section in turn) When following the queued vehicles at point D through the downstream intersection, the phase difference between the upstream and downstream intersections is the optimal phase difference. At this time, the green light time at the downstream intersection will not be idling.

[0075] ① Calculate the travel time of the first vehicle with a green light in the overflow control direction at the upstream intersection when it passes the stop line at the downstream intersection t 1 .

[0076] (8)

[0077] In the above formula, L AB Indicates the length of the short-distance section. L 3 represents the length of the upstream intersection, t qThis is the vehicle starting loss time, which is generally 3s.

[0078] ③ Calculate the optimal phase difference of the upstream and downstream intersection linkage overflow control direction .

[0079] (9)

[0080] In the above formula, t D It indicates the green light operation time of the downstream intersection corresponding to when the queued vehicles at point D pass through the downstream intersection, which can be specifically recorded by the downstream intersection traffic data collection system.

[0081] 3. Establish a calculation method for dissipating vehicle queues at short-distance intersections

[0082] Taking the upstream and downstream intersections A and B as an example, the traffic overflow situation at short-spacing intersections is analyzed. Figure 3 As shown in , if the traffic light for the east straight line at the upstream intersection is red, the last vehicle at the end of the east straight line green light can drive into the downstream intersection section, indicating that there is no traffic overflow at the downstream intersection during this period; Figure 4 As shown in the figure, if the traffic light for the upstream intersection is red for the east-going direction and green for the north-south direction, the vehicles at the downstream intersection will queue up at the upstream intersection, affecting the traffic of vehicles in the north-south direction of the upstream intersection. This indicates that traffic overflow that cannot be dissipated in time has occurred in the east-going direction of the downstream intersection during this period. Figure 5 As shown in the figure, if the upstream intersection has a green light for the east straight and a red light for the north-south direction, although the vehicles at the downstream intersection queue up to the upstream intersection, before the upstream intersection turns red for the east straight and green for the north-south direction, the last vehicle at the end of the east straight green light can enter the downstream intersection section, indicating that traffic overflow occurs in the downstream intersection in the east straight direction during this period but can be dissipated. Therefore, in order to ensure the traffic capacity of short-spacing intersections while preventing traffic overflow that cannot be dissipated in time, the above calculation is used T Based on the signal timing scheme for short-distance intersections during the period, taking the east through lane as an example, the calculation method for dissipating the queue of vehicles at short-distance intersections is established as follows:

[0083] (1) Calculate the number of vehicles that can actually pass through when the eastbound green light is on at the upstream and downstream intersections Q 2 , Q 3 .

[0084] (10)

[0085] In the above formula, k 1 and k2 They represent the coefficients of the number of vehicles that can pass when the green light is released for the eastward straight-going vehicles at the upstream intersection A and the downstream intersection B, respectively. They are generally between 0.8 and 1. CAP AWS It indicates the traffic capacity of the east through lane of the upstream intersection A. CAP BWS Indicates the traffic capacity of the east through lane of the downstream intersection B.

[0086] (2) Calculate the number of vehicles entering the downstream intersection in the eastward direction when the upstream intersection has a green light for eastward straight travel .

[0087] (11)

[0088] In the above formula, k 3 It indicates the ratio coefficient of vehicles going from the upstream intersection to the downstream intersection. q 1 , q 2 , q 3 The traffic flow in three directions, namely, going straight from the upstream intersection to the east entrance of the downstream intersection, turning left and turning right, was calculated from the traffic flow collected in the past month.

[0089] (3) Calculate the maximum number of vehicles that can be accommodated in the east-bound through lane between short-distance intersections Q 4 .

[0090] (12)

[0091] In the above formula, L AB is the length of the short-spacing section, L C is the average vehicle length, and s is the average vehicle spacing.

[0092] (4) Conditions for the traffic overflow of the east through lane of the downstream intersection to dissipate:

[0093] (13)

[0094] In the above formula, Q 1 It is the average number of vehicles queuing in the east through lane between short-distance intersections.

[0095] (5) Calculate the maximum number of vehicles that enter the downstream intersection from the east straight direction at the upstream intersection .

[0096] (14)

[0097] When the number of vehicles entering the downstream intersection from the east is less than or equal to When the traffic overflow is detected, the traffic overflow caused by the queue of vehicles in the east straight direction of the downstream intersection can be dissipated, and it is judged whether the last vehicle entering the east straight direction of the downstream intersection from the east straight direction of the upstream intersection can enter the short-spacing section. Under the premise of ensuring that the traffic overflow can be dissipated, the green light and all-red time of the upstream intersection in the overflow direction of the short-spacing section are dynamically controlled.

[0098] 4. Determine the overflow prevention and evacuation plan for vehicles at intersections

[0099] The queued vehicles in the process of traffic overflow dissipation are driving under congestion, so the last vehicle entering the overflow control section of the downstream intersection from the upstream intersection may not be able to enter the safe distance of the section. Therefore, continuing with the east straight lane as an example, it is necessary to determine whether the last vehicle entering the overflow control section of the downstream intersection from the east straight direction of the upstream intersection can enter the section, and dynamically control the green light and full red time of the upstream intersection entering the overflow control section of the downstream intersection on the premise of ensuring that the traffic overflow can be dissipated. The overflow prevention and control and evacuation plan for short-distance intersection vehicles is as follows: Figure 6 shown.

[0100] (1) First, the microwave radar detection equipment at the upstream intersection monitors the vehicles that leave the stop line from the upstream intersection in the east straight direction in real time, and calculates the headway time between two adjacent vehicles that leave the stop line from the upstream intersection in the east straight direction, that is, the time difference between the headways of the two adjacent vehicles passing the stop line.

[0101] (2) Determine whether vehicles can continuously and uninterruptedly pass the stop line of the intersection when the green light for eastbound straight driving is given at the upstream intersection. That is, determine whether the headway between two adjacent vehicles that have left the stop line is greater than a certain threshold (which can be set to 3 seconds and can be adjusted according to actual conditions).

[0102] ① When the headway between two adjacent vehicles leaving the stop line is not greater than the threshold, it is considered that the vehicles pass the stop line of the intersection continuously and uninterruptedly. The number of vehicles leaving the stop line is counted in sequence, and the difference between the number of vehicles leaving the stop line and the maximum number of vehicles is determined. If the number of vehicles leaving the stop line is about to reach the maximum number of vehicles, determine the last vehicle from the upstream intersection to the overflow control section of the downstream intersection, and end the green light release time for the upstream intersection to go straight east in advance. Otherwise, continue to release the green light time for the upstream intersection to go straight east.

[0103] ② When the headway between two adjacent vehicles leaving the stop line is greater than the threshold, it is considered that the vehicles are not leaving the stop line continuously and uninterruptedly. Even if the number of vehicles leaving the stop line has not reached the maximum number of vehicles, the green light release time for the east straight-travel at the upstream intersection can be ended to avoid the green light at the upstream intersection being vacant. At this time, the last vehicle from the upstream intersection entering the overflow control section of the downstream intersection is also determined.

[0104] (3) The overflow prevention and control and evacuation plan for vehicles at short-spacing intersections is determined based on whether the last vehicle driving from the upstream intersection in the east straight direction to the overflow control section of the downstream intersection can successfully enter the short-spacing section when the east straight green light at the upstream intersection ends.

[0105] ① If, at the end of the green light for the east straight at the upstream intersection, the last vehicle driving from the east straight direction of the upstream intersection into the overflow control section of the downstream intersection can smoothly enter the short-distance section, then there is no need to adopt overflow prevention and evacuation plans at the upstream intersection.

[0106] ② If, at the end of the green light for east straight driving at the upstream intersection, the last vehicle driving from the upstream intersection east straight driving direction into the overflow control section of the downstream intersection cannot enter the short-spacing section smoothly, then at the end of the green light for east straight driving at the upstream intersection, full red control will continue to be adopted, that is, red light control will be adopted in all directions of the intersection for vehicle clearance. The time of full red control adopted in the prior art is fixed and unchanged. When the intersection is congested and locked, the full red control duration is relatively long. When the full red time ends depends on the time when the intersection congestion is released, which is within a long time range and cannot be calculated, which is not conducive to traffic passage at the intersection. The present invention is based on the premise that the overflow of queued vehicles can be dissipated, and the full red time is extended second by second until the overflow vehicles enter the short-spacing section and end. The duration is generally within 1 to 6 seconds.

[0107] (4) The green light for the east straight at the upstream intersection will end in advance based on the original green light time because it is necessary to control the vehicles entering the overflow control section of the downstream intersection. When the green light time for the east straight at the upstream intersection is adjusted, in order to ensure that the signal cycle of the upstream intersection remains unchanged, the upstream intersection signal cycle time is subtracted from the adjusted green light time, full red time and original yellow light time of the east straight at the upstream intersection. The remaining time is then calculated according to the original green signal ratio of other phases. λ j The ratio between them is assigned to other phase times.

[0108] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A short-spacing intersection overflow control method considering dissipative overflow, characterized in that: The following steps are involved: (1) Build a traffic data collection system at short-distance intersections to detect vehicle passing data; (2) Collect the traffic flow of the short-spacing upstream and downstream intersections for the past month, calculate the initial intersection signal cycle duration of the upstream and downstream intersections respectively, take the maximum value of the calculated initial intersection signal cycle duration as the final cycle duration of the upstream and downstream intersections, and then determine the signal timing scheme required for the linkage overflow control of the upstream and downstream short-spacing intersections based on the collected traffic data; (3) Based on the number of vehicles passing through the green light in the overflow control direction of the upstream and downstream intersections, the maximum number of vehicles that can be accommodated in the short-distance section, and the average number of vehicles queuing in the short-distance section, a calculation method for dissipating the vehicle queue at the short-distance intersection is established to calculate the maximum number of vehicles entering the overflow control direction from the upstream intersection to the downstream intersection; (4) Using microwave radar detection equipment at the upstream intersection to monitor vehicles coming from the upstream intersection in the direction of overflow control in real time, determine the headway between two adjacent vehicles and the number of vehicles leaving the stop line, and based on this, determine the overflow prevention and control and evacuation plan for vehicles queuing at short-distance intersections; The overflow prevention and control and evacuation plan for vehicles at short-distance intersections is as follows: Determine whether the headway between two adjacent vehicles that have exited the stop line is greater than the set threshold. If so, end the green light release in time. Otherwise, calculate the number of vehicles that have exited the stop line in turn and compare it with the maximum number of vehicles that can pass in the direction of the upstream intersection linkage overflow control. When the number of vehicles that have exited the stop line in the direction of the upstream intersection linkage overflow control reaches the maximum number of vehicles, end the green light release at the upstream intersection in time. Finally, determine whether the last vehicle that enters the downstream intersection in the overflow control direction from the upstream intersection can enter the short-spacing section smoothly. Under the premise of ensuring that the traffic overflow can be dissipated, dynamically control the green light and full red time of the upstream intersection entering the overflow control section of the downstream intersection.

2. The short-spacing intersection overflow control method considering dissipative overflow according to claim 1 is characterized in that: The traffic data collection system includes a microwave radar detection device arranged at the exit lane of the intersection. The microwave radar detection device is installed in a horizontal bar manner at the exit lane opposite to the entrance lane to be tested. The microwave radar detection device at the downstream intersection obtains the vehicle passing data, the vehicle flow rate and the number of queued vehicles in the entrance direction of the intersection, and the green light operation time corresponding to each vehicle passing through the intersection.

3. The short-spacing intersection overflow control method considering dissipative overflow according to claim 1, characterized in that: The process of determining the signal timing scheme required for the linkage overflow control at short-distance upstream and downstream intersections: The traffic flow of short-spacing upstream and downstream intersections in the past month is collected, and the initial intersection signal cycle duration of the upstream and downstream intersections is calculated according to the average traffic flow of the upstream and downstream intersections in the past month. The maximum value of the calculated initial upstream and downstream intersection signal cycle duration is taken as the final cycle duration of the upstream and downstream intersections. The signal timing scheme, green-to-signal ratio, traffic capacity and phase difference of the upstream and downstream intersections are calculated based on the collected traffic data, and finally the signal timing scheme required for the linkage overflow control of the upstream and downstream short-spacing intersections is obtained.

4. The short-spacing intersection overflow control method considering dissipative overflow according to claim 3 is characterized in that: The phase difference in step (2) refers to the time when the first vehicle at the upstream intersection is released by the green light drives at a certain speed to the end of the average vehicle queue D on the short-distance section without stopping, and at a minimum headway time t s When following the queued vehicles at point D through the downstream intersection, there is a phase difference between the upstream and downstream intersections. At this time, the green light time at the downstream intersection will not cause idling.

5. The short-spacing intersection overflow control method considering dissipative overflow according to claim 1, characterized in that: The calculation steps for the maximum number of vehicles entering the overflow control direction from the upstream intersection to the downstream intersection in step (3) are as follows: (1) Calculate the number of vehicles that can actually pass when the green light is released in the overflow control direction at the upstream and downstream intersections Q 2. Q 3; （10） In the above formula, k 1 and k 2 respectively represent the coefficients of the number of vehicles that can pass when the overflow control direction is released with a green light at the upstream intersection A and the downstream intersection B, CAP AWS Indicates the capacity of the lane in the overflow control direction of the upstream intersection A. CAP BWS Indicates the traffic capacity of the lane in the overflow control direction of the downstream intersection B; (2) Calculate the number of vehicles entering the overflow control direction of the downstream intersection when the upstream intersection overflow control direction is released green light ; （11） In the above formula, k 3 represents the proportional coefficient of vehicles driving from the overflow control direction of the upstream intersection to the overflow control direction of the downstream intersection, q 1 is the traffic flow from the upstream intersection overflow control direction to the downstream overflow control direction collected in the past month, q 1+ q 2+ q 3 is the traffic flow in the overflow control direction of the upstream intersection collected in the past month; (3) Calculate the maximum number of vehicles that can be accommodated by lanes between short-distance intersections ; （12） In the above formula, L AB is the length of the short-span section, L C is the average vehicle length, s is the average vehicle spacing; (4) Conditions for the traffic overflow of the east through lane of the downstream intersection to dissipate: （13） In the above formula, Q 1 is the average number of vehicles queuing in the east through lane of the section between short-distance intersections; (5) Calculate the maximum number of vehicles that enter the downstream intersection from the east straight direction at the upstream intersection ; （14）。 6. The short-spacing intersection overflow control method considering dissipative overflow according to claim 1, characterized in that: The full red time is based on the premise that the overflow of queued vehicles can be dissipated. The full red time will be extended second by second until the overflowing vehicles enter the short-distance road section.

7. The short-spacing intersection overflow control method considering dissipative overflow according to claim 1, characterized in that: In step (4), in order to control the vehicles entering the downstream intersection in the direction of the overflow control section, the upstream intersection ends the green light in advance based on the original green light time. When the green light time of the upstream intersection is adjusted, in order to ensure that the signal cycle of the upstream intersection remains unchanged, the upstream intersection signal cycle time is subtracted from the adjusted green light time, all-red time and original yellow light time of the upstream intersection east straight, and the remaining time is allocated to other phase times according to the ratio between the original green-to-signal ratios of other phases.

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