Traffic signal real-time mode control method

Abstract

The traffic signal real-time mode control method comprises the steps of (1) identifying a mode instruction and a switching type thereof, (2) calculating a configuration mode time difference and a switching transition period thereof according to the mode instruction, and (3) running the switching transition period before executing a new period. According to the method, the optimization of the signal mode conversion mode is realized, the signal mode conversion time is shortened, the mode conversion zero-time redundancy waiting and seamless smooth switching are realized, the response time of the signal along with the change of the traffic condition is reduced, the paradox of'causing congestion for smooth response 'is solved, and the real-time performance of the signal system is improved. Even if the mode switching is carried out by taking a time difference period remainder as waiting, the signal efficiency can be improved by more than 50%, the redundancy waiting can be reduced by more than 50%, and the traffic flow accumulation and congestion caused by the mode switching can be well reduced.

Description

Technical Field

[0001] This invention relates to the field of traffic signal control technology. Specifically, it relates to a real-time mode control method for traffic signals. Background Technology

[0002] Currently, traffic signal patterns include ratio-based patterns and green wave patterns. Recently, several specialized green wave patterns with different effects have been proposed, such as two-dimensional green wave, congestion-relief green wave, dual congestion-relief green wave, and hybrid green wave. All green wave patterns are designed based on the ratio-based pattern, with the green wave time difference distribution at each intersection adjusted. The transition between patterns requires completing the corresponding time difference and simultaneously clearing the intersection with a full red light in the relevant area. The larger the area, the longer the clearing time. This operation is time-consuming and causes waiting; even a one-minute red light can cause hundreds of vehicles to accumulate and wait to enter the controlled area, leading to traffic congestion at intersections within the area and reducing the effectiveness of the originally good new pattern. This leads to an industry paradox and dilemma: "The response made to ensure smooth traffic flow actually exacerbates congestion." Therefore, achieving smooth transitions and reducing the time spent on pattern transitions and unnecessary waiting is of great practical significance. Summary of the Invention

[0003] The purpose of this invention is to reduce the time spent on mode transitions and unnecessary waiting in between, and to improve traffic and control efficiency. By designing new signal algorithms, computer control technology, and intelligent technologies such as the Internet, this invention provides a method that can achieve smooth transition between signal modes.

[0004] This invention proposes a solution to achieve the above objectives, specifically as follows: A real-time mode control method for road traffic signal networks, characterized by the following steps: S1 Startup: Configure the original ratio mode and the length of each road segment and traffic time in the road network; S2 calculates and configures the new mode and its transition period according to the mode command: 1) The signal mode to be operated according to the mode command, referred to as the command mode, and the currently operating signal mode, referred to as the current mode, determine the transition category; the transition category includes wave activation, restoration, or wave-wave. Wave activation means that the command mode is a green wave and the current mode is the default ratio mode. Restoration means that the command mode is the default ratio and the current mode is a green wave. Wave-wave means that the command mode is a green wave and the currently operating mode is also a green wave. 2) Calculate and configure the transition period of the new mode according to the transition category: (2.1) Determine the intersection position of the starting point of the time difference between the two modes involved in the transition period category. (2.2) Calculate and configure the time difference and cycle residual of each intersection in the transition period of the new mode: the cycle residual of the time difference of the intersection = the time difference of the intersection divided by the cycle duration of the signal mode and take the remainder (i.e., the intersection time difference % cycle duration). (2.3) Configure the transition period corresponding to each cycle residual: cycle residual = transition period duration = main flow duration + secondary flow duration. S3 execution: Before the new cycle begins, the transition period is completed, and then the ratio mode is run. The road segment refers to the road between adjacent intersections; The traffic time includes travel time and the time required for a congested convoy to start; travel time refers to the time required for a vehicle to travel the entire road segment at the prescribed speed; convoy start time refers to the time required for the first vehicle in the convoy to move to the end of the convoy; congestion refers to a situation where the length of the convoy is equal to the length of the road segment, i.e., the road segment is completely blocked; the prescribed speed is determined by the designed green wave propagation speed; the designed green wave propagation speed is determined by the traffic time used to calculate the time difference at the intersection, and must not exceed the legally limited speed limit on the road; The green wave refers to the periodic, wave-by-wave directional propagation of green lights at intersections in a certain direction within a road network, with each green light turning on sequentially upstream and downstream in that direction. This direction is a defined direction, formed by configuring the intersection time differences according to the following rules: Each intersection is configured with a time difference greater than the time difference of its upstream adjacent intersection by the traffic time difference of the adjacent road segment. This defined direction, i.e., the directional propagation direction, is called the green wave flow direction. The time difference at the upstream intersection of the green wave flow direction is set to 0. Thus, the intersection time difference refers to the lag time of the green light turn-on time at an intersection in the same signal period and phase timing road network relative to a defined intersection. This lag time is equal to the sum of the traffic times of each road segment in the passageway connecting the intersection and the defined intersection. This defined intersection is called the green wave time difference starting point intersection, located at the upstream intersection of the green wave flow direction. The signal period leads the period of equal green wave waves.

[0005] According to the real-time mode control method of the present invention: step S1 further includes: S11 The traffic time refers to the driving time or the convoy start time: the driving time is equal to the travel time at the legal speed of the road segment, and the convoy start time is equal to the convoy start coefficient * congestion coefficient * road segment length, wherein the congestion coefficient is a number less than or equal to 1, and equal to 1 indicates congestion;

[0006] According to the real-time mode control method of the present invention, the feature is that S1 further includes: S14-2 the aforementioned driving time minus the braking time at the legal speed;

[0007] According to the real-time mode control method of the present invention, its characteristic is that S222) further includes: S21 When the transition category is wave activation, configure the wave activation transition period: calculate the time difference of each intersection and the wave activation transition period for configuring the new mode transition period: (S21.1) determine the starting point intersection positions of the two signal modes involved in the transition category according to the following rules: if the signal mode is a ratio mode, any intersection can be considered as the time starting point, and the intersection of the green wave mode time difference starting point is selected as its starting point intersection; if the signal mode is a green wave, its starting point is determined by the specific green wave mode. The formula determines that: the starting point for calculating the time difference of a guiding green wave is at the intersection of its channel flow direction; the starting point for calculating the time difference of a congestion-relief green wave is at the intersection of its channel flow direction. The channel flow direction is the same as the guiding green wave direction and opposite to the congestion-relief flow direction. Two intersecting green waves are called two-dimensional green waves, including all two-dimensional guiding, congestion-relief, and mixed guiding / congestion-relief green waves. Their starting point intersections are all at a corner of the area, called corner intersections, which are the intersections of the two channel flow directions in the area. If the green wave mode is a two-dimensional guiding green wave, the intersection of the two guiding flow direction starting points in the area is set as the corner intersection for calculating the green wave time difference. If the green wave mode is a two-dimensional guiding green wave, the intersection of the two guiding flow direction starting points in the area is set as the corner intersection for calculating the green wave time difference. The formula is a two-dimensional traffic congestion relief green wave. The intersection of the two traffic congestion relief flow endpoints in the area is set as the starting point angle intersection for calculating the green wave time difference. If the green wave mode is a mixed traffic congestion relief and guidance green wave, the intersection of the guidance flow endpoint and the traffic congestion flow endpoint in the area is set as the starting point angle intersection for calculating the green wave time difference. Let one of the two intersecting green wave channels be the main flow direction and the other be the secondary flow direction. The starting point for the main flow direction green wave time difference is the starting point intersection of the main flow direction green wave in each channel, and the starting point for the secondary flow direction green wave time difference is the starting point intersection of the green wave time difference in all main channels, forming the secondary flow direction green wave starting point intersection within the secondary flow channel. (S21.2) According to the following wave start rules, calculate the time difference and cycle residual difference of each intersection in the configuration command mode: add the traffic time of each segment in the corresponding main and secondary green wave channel segments between each intersection and the green wave start point intersection to obtain the time difference of each intersection, and divide the intersection time difference by the cycle and take the remainder to obtain the cycle residual difference; that is the cycle residual difference of the new mode intersection in the wave start category, which is used to make the new mode wave start transition period; (S21.3) Configure the new mode wave start transition period: make the cycle residual difference of each intersection in the new mode into the corresponding signal cycle, that is, the wave start transition period;

[0008] According to the real-time mode control method of the present invention, its feature is that S222 further includes: S22 When the transition category is restoration, configure the restoration transition period: calculate the time difference of each intersection and the restoration transition period for configuring the new mode transition period: (S22.1) determine the intersection positions of the starting points of the two modes involved in the transition period according to the above signal mode time difference starting point rule; (S22.2) calculate the intersection time difference cycle residual difference of the current mode according to the above wave start rule; calculate its cycle compensation according to the following restoration rule: the cycle compensation is equal to the cycle duration of the green wave mode minus the cycle residual difference of the intersection, that is, cycle compensation = cycle duration - its cycle residual difference; the intersection cycle compensation is used as the intersection time difference and cycle residual difference of the new mode transition period of the restoration category to create the new mode restoration transition period; (S22.3) Configure the new mode restoration transition period: each intersection makes its new mode cycle compensation into its corresponding signal cycle, that is, restoration transition period;

[0009] According to the real-time mode control method of the present invention, its feature is that S222) further includes: S23 When the transition category is wave-wave: calculate the time difference of each intersection and the wave-wave transition period during the transition period of the new mode: (S23.1) determine the starting point intersection position of each of the two signal modes involved in the transition category according to the above signal mode time difference starting point rule; (S23.2) calculate the time difference of each intersection and its cycle residual difference during the transition period of the new mode according to the following wave-wave rule: (1) calculate the intersection time difference cycle residual difference and its cycle compensation of the current mode according to the above wave-wave starting rule and restoration rule: intersection cycle compensation = cycle duration - intersection cycle (2) Calculate the time difference and periodic residual difference of each intersection in the configuration instruction mode according to the above-mentioned wave start rule; (3) Add the intersection time difference periodic residual difference of the current mode to the intersection time difference periodic compensation obtained above, and the resulting value is called the intersection time difference of the new mode transition period of the wave type. Divide it by the period and take the remainder, and the resulting value is called the wave period residual difference; use the wave period residual difference of the intersection as the new mode intersection periodic residual difference of the wave type to make the new mode wave transition period; (S23.3) Configure the new mode wave transition period, and each intersection constructs its new mode wave period residual difference into its corresponding signal period, which is called the wave transition period;

[0010] According to the real-time mode control method of the present invention: the configuration transition period in S2 further includes: S24 configuration transition period, each intersection starts to configure its own transition period according to the mode instruction at the start or in the second half of the current cycle, and directly makes the excessively small time difference into an equal-length red light time or allocates it into the green light time of the half cycle.

[0011] Note 1: The road network nodes of the network are intersections formed by the convergence of multiple road segments, which are controlled by the corresponding traffic light signal network system; Note: 1) Road segment refers to the road between two adjacent intersections, 2) Channel refers to multiple connected road segments and intersections, and the channel that runs through both ends of the road network is called a straight road.

[0012] Note 2: The road network scope and characteristics include how many intersections the entire signal system controls, how they are distributed, the length of each road segment, and the travel time, etc.; the travel time includes the start time of the congested convoy and the travel time. The start time of the congested convoy refers to the time taken for the first vehicle in the convoy to move to the last vehicle in the convoy during congestion, and the travel time refers to the time taken for a vehicle to pass through the road segment at the prescribed speed; the road network of M x N intersections, M columns of straight roads, and N rows of straight roads is denoted as {M, N) or {(0, 0), (M-1, N-1)}, where (,) represents the intersection coordinates; the set of road segments is denoted as {M, N-1){==}, representing the total number of columns M, each column of straight roads includes N-1 road segments, and the m-th column of straight roads... The set of road segment times is denoted as m{==}, where == represents the time taken for (N-1) column road segments; the set of row road segments is denoted as {N, M-1}{==}, representing the total number of rows N, with each straight road row containing M-1 road segments. The set of time taken for the straight road segments in the nth row is denoted as n{==}, where == represents the time taken for (M-1) road segments; the total number of road segments is N*(M-1)+M*(N-1). When there are fewer or more than 4 intersections in the area, the total number of road segments is less than or more than N*(M-1)+M*(N-1); the numerical values ​​of the elements in the set represent the length of the corresponding road segment, the time taken for congested convoys to start, or the travel time, corrections, etc.; parallel and opposite road segments are not required to be absolutely parallel or of equal length.

[0013] Note 3: The aforementioned traffic flow channel intersection green wave time difference refers to the sum of the time taken for each road segment in the intersection channel time set between an intersection and its channel green wave starting point. Green waves are for traffic relief, and their time is the start time of congested vehicle convoys; their channel green wave starting point intersection is the end intersection of the traffic flow direction. Green waves, on the other hand, are for guidance, and their time is the travel time; their channel green wave starting point intersection is the beginning intersection of the traffic flow direction. The resulting traffic flow channel intersection green wave time difference is also called the intersection channel time difference. Together with the aforementioned intersection channel time, their set is denoted as d#{*}. The information is derived from the road network segment {M, N-1}{==} or row segment {N, M-1}{==} set and added to the starting intersection 0. d represents the vehicle flow direction, which can be southeast, west, or north, etc. # represents the intersection coordinates (i, j), i.e., d(i, j){*}. The positions of d and 0 within the curly braces indicate the direction of traffic flow guidance or congestion relief. For example, north (6, 2){==, 0} indicates that the road segment between intersection i=6, j=2 on the road network with the traffic flow direction towards the north and the starting point of the traffic flow direction, i.e., the northernmost intersection (6, 4), is congested. The sum of the starting times of the congestion convoy is a subset. If 0 is on the left, i.e., North (6, 2) {0, ==} represents the sum of the travel times of the road segment between intersection i=6, j=2 on the northbound road network and the starting point of the traffic flow, i.e., the southernmost intersection (6, 0). When the passage runs through the road network, # represents the straight road number, such as West 1 {0, ==}, which represents the sum of the starting times of the congestion convoy formed by all intersections j=1 on the westbound road network. The westernmost intersection is the starting intersection, and the starting time of the congestion convoy in its segment is... The time taken is 0, while South 4{0, ==} represents the set of times taken for the congested convoy to start in the southbound i=4 channel. The southernmost intersection is the starting intersection, and its congested convoy start time is 0. If West 1{ ==, 0} represents the subset of the total travel time of all intersections j=1 on the road network guiding the flow to the west. The easternmost intersection is the starting intersection, and its road segment travel time is 0. South 4{ ==, 0} represents the subset of the travel time of the southbound i=4 channel, and the northernmost intersection is the starting intersection, and its travel time is 0.

[0014] The advantages of this invention are as follows: it shortens the signal mode switching time, optimizes the signal mode switching method, achieves zero time redundancy waiting for mode switching, improves the real-time performance of the signal system, reduces the response time of signals as traffic conditions change, and improves traffic control efficiency. Even compared to using the time difference cycle remainder for mode switching, this invention improves signal efficiency by 50%, reduces redundant waiting by 50%, makes signal mode switching smoother, and effectively avoids congestion caused by mode switching. Attached Figure Description

[0015] Figure 1 Schematic diagram of two-dimensional instruction guidance mode under hybrid dual-different combination mode on road network; Figure 2A diagram showing the time difference between the road network signaling system and the hybrid mode, as well as the distribution of its signal and mode-switching time differences. Figure 3 Schematic diagram of the real-time activation timing of the hybrid dual-group green wave road network: 0->60 seconds; Figure 4 Schematic diagram of the real-time restoration progress of the road network using hybrid dual-group green wave: 360 -> 420 seconds; Figure 5 Schematic diagram of the real-time wave mode switching progress of the hybrid dual-group green wave road network: 360->495 seconds; Figure 6 Flowchart of real-time traffic signal mode switching control method;

[0016] The number index in the attached diagram: Figure 1 1-Road network, 2-Intersection, 3-Southbound 7-channel northbound traffic green wave, 4-Eastbound 5-channel westbound traffic green wave, 5-Channels for northbound traffic awaiting guidance, 6-Channels for eastbound traffic awaiting traffic clearing, 7-Channels for northbound traffic awaiting guidance, 8-Eastbound 5-channel eastbound traffic green wave.

[0017] Figure 2 1--Network intersection node coding identifier starting point (0,0) is the lower left corner intersection of the road network; 2--{(0,0), (6,4)} is the road network symbol; 3--Intersection; 4--Traffic light; 5-Traffic convoy; 6--Intersection signal controller; 7--Internet; 8--Central control system; 9--Two-dimensional origin symbol Q and small octagon node and its coordinates (6,0); 10--Intersection spacing - the start time / travel time of congested convoy is recorded as #-# / #: unit: meters-seconds / second; 11--Main green wave flow direction arrow points left-west, number 6, recorded as z6; 12--Number 4 secondary green wave flow direction, recorded as f4, arrow points up-north; the lower left corner z1 is leaving. Number 1 represents the main green wave; additionally, the length of the arrows indicating the main and secondary green wave flow directions represents the estimated duration, such as f6 representing approximately 18 seconds, f4 approximately 43 seconds, z10 45 seconds, 13 - guiding northbound traffic in each lane, 14 - congested eastbound traffic in each lane; the green wave distribution in the diagram is at 360 seconds; the numbers in square brackets represent the time difference of the green wave for traffic flow to alleviate congestion at intersections, arranged horizontally and vertically corresponding to the corresponding intersections of the main and secondary green wave lanes; in the following diagrams, hollow arrows generally represent green waves and their flow directions, horizontally westward for the main flow direction, and vertically northward for the secondary flow direction; the numbers marked in square brackets above the left of each intersection in lane 1 represent the green wave time difference of each intersection in the main flow direction lane in the dual guidance mode of the mode instruction; the numbers in the following diagrams are generally the same as those in this diagram.

[0018] Figure 31. The number # in the parentheses above the left of the intersection represents the cycle residual of the intersection. 2. The small ellipse marked at the intersection indicates its initial green wave transition period. A horizontal line indicates the first half of the green wave for east-west traffic, and a vertical line indicates the second half for north-south traffic. The dashed ellipse indicates that the transition has been completed. Correspondingly, the # number represents the duration of the green wave signal at the intersection. #25 indicates that the intersection (1,1) has been running its westward green wave for 25 seconds, where 25 is the current signal time <= 60 (time increment) - 35 (transition period). 3. The dashed hollow arrow here shows that the completed green wave transition period precedes the initial green wave leader. Figure 3-6 First, the solid ellipse at intersection (3,0) is generated, where -# indicates that the transition period is not yet complete. For example, -8 here means that the first westward green wave cycle will begin in 8 seconds. 5- The dashed hollow arrow here shows the advanced green wave formed during the incomplete transition period. Figure 3-3 The green waves that form in advance are collectively referred to as quasi-green waves or derived green waves. 6 - Here, the solid line hollow arrow shows the initial westward green wave front.

[0019] Figure 4 1. The numbers # / # in the square brackets represent the cycle difference and cycle compensation at the intersection to the lower right. 2. The ellipse represents the running signal: horizontal indicates east-west green light, vertical indicates north-south green light. The # number represents the signal duration at that intersection. # Signal Time = Time Increment 60 - Remaining Green Wave Time 80 = -20. This negative number indicates that the green wave signal at that intersection still needs 20 seconds to complete its cycle before starting its recovery transition. 3. Signal Time # greater than or equal to 0 indicates the time the recovery transition signal has been running. 4. Further signal time # greater than the recovery transition duration indicates that the signal has been running for the default ratio mode time. The / negative number indicates that the recovery transition duration value is subtracted from the last half-cycle of the green wave at that location. The dashed ellipse indicates that the recovery transition at that intersection has completed. This diagram shows the signal running for 360 seconds in the congestion guidance mode. Figure 2The signal distribution shown is as follows: After receiving the restoration command halfway through the cycle and starting operation 360 seconds later, the signal distribution runs for 60 to 420 seconds. At the origin intersection (6,0), there is no time difference and no need for restoration; the original cycle of 60 seconds is completed. At other intersections, such as the East 1st Passage intersection (5,0), the restoration transition period is long = cycle difference 63. At 420 seconds, the second half of the green wave cycle (27 seconds) and the restoration transition period (63 seconds) are completed, including the first half of the cycle (32 seconds). After the east-west green light turns into the north-south green light, it runs for 1 second. As indicated by the vertical elliptical marker, the current required restoration time = restoration transition period length 63 - its already run time 33 = 63 - (time increment 60 - remaining green wave time 27) = 30 seconds. The signal distribution continues until the full cycle reaches 63 seconds. After completion, it will be synchronized with the original intersection in terms of time and flow direction; the restoration transition period of intersection (3,1) is 10 seconds long. After 420 seconds, it will complete its green wave cycle of 60 seconds with 20 seconds remaining, which is -20 seconds. The 20-second difference in the second half of the green wave cycle means that its restoration cycle of 10 seconds cannot be started. The current required restoration time = restoration transition period 10 - its running time (-20) = 10 - (time increment 60 - green wave remaining time 80) = 30 seconds, which will be synchronized with the original intersection in terms of time and flow direction; the restoration cycle of intersection (2,0) is 85 seconds long. By directly subtracting the 5-second cycle difference from its cycle, it will be synchronized with the original intersection as indicated by the vertical ellipse mark on its dashed line. After 420 seconds, it has run the original cycle of 60 seconds;

[0020] Figure 5 : 1- The # number in parentheses represents the green wave time difference of the main eastward channel of the new dual-guidance mode at this intersection. The secondary flow to the north remains unchanged, so the time difference between the corresponding flow directions at the intersections remains unchanged and is not marked separately. 2- The # / # number in parentheses represents the green wave time difference cycle residual difference / cycle compensation of the intersection under the new dual-guidance mode at the upper right intersection. The number # marked in the ellipse indicates the running time of the new mode at this intersection. The dashed ellipse indicates that the transition period of this wave has been completed, and the solid ellipse indicates that the transition period of this wave is about to start or is in progress. The "-" in the number -# indicates the remaining seconds of the direct transition period that has not yet been completed. 3- The hollow arrow indicates the direction of the formed green wave. This is the leading edge of the new green wave. 4- The dashed hollow arrow indicates the direction of the derived green wave. It is at the solid ellipse where the transition period has not been completed. 5- The dashed hollow arrow also indicates the direction of the leading green wave. It is at the dashed ellipse where the transition period has been completed, but the leading edge of the new green wave has not yet arrived. At the intersection of East 1st Passage (0,0), the transition period of the new dual-guidance mode origin is equal to the cycle remainder (0+44) = 44. After completing the 135-second interval following the 360-second interval at 495 seconds, the remaining green wave cycle time is 46 seconds and the transition period is 44 seconds, as indicated by the vertical ellipse marked by the dotted line. After becoming the origin of the new mode, it runs for another 135-46-44 = 45 seconds, with the eastward green wave indicated by the eastward-flowing arrow. That is, the current new green wave signal running time = time increment 135 - current green wave remaining time 46 - transition period (44+0) = 45 seconds; At the intersection (1,0), the transition period of the new dual-guidance mode is... =67+10=77, 495 seconds. During the 135 seconds added after 360 seconds, the remaining time of the second half of the green wave cycle is 23 seconds and the transition period of 77 seconds is completed. As shown by the vertical ellipse mark on the dashed line, the new mode eastward main green wave runs for 35 seconds as shown by the eastward arrow mark. The transition period of the new mode intersection wave at intersection (5,0) is long = cycle remainder (63+48)=21. During the 135 seconds added after 360 seconds, the remaining time of the current green wave cycle is 27 seconds and the transition period of 21 seconds is shown by the vertical ellipse mark on the dashed line. After that, the new double-guide cycle runs for 87 seconds as shown by the northward arrow mark. The transition period for the new dual-guided intersection (1, 4) of the East 4th Passage is 25 + 52 = 77. After completing the transition in 360 seconds, the remaining 135 seconds of the green wave second half cycle is 20 seconds. 70 seconds of the 77-second transition period are still 7 seconds short of completion. The vertical ellipse and -7 / 77 mark should be displayed. The transition period for the new dual-guided intersection (4, 4) is 3 + 82 = 85. After completing the transition in 360 seconds, the remaining 135 seconds of the green wave second half cycle is 42 seconds. 48 seconds of the 85-second transition period are still 37 seconds short of completion. That is, 135 - 87 - 85 = -37. The vertical ellipse and -37 / 85 mark should be displayed. Detailed Implementation

[0021] Three embodiments of the real-time mode conversion of the present invention are described in detail with reference to the accompanying drawings: Create a method for road networks such as Figure 2 intersections Figure 2-3 Traffic flow at various intersections, such as Figure 2-5 The installed straight-ahead and left-turn two-phase signal lights Figure 2-4 And intersection signal controllers, such as Figure 2-6 Or add sensors, or use communication networks such as Figure 2 -7 is controlled by a central control system, such as Figure 2 -8 control, its real-time mode control operation function is as follows: Figure 3 Qibo Configuration Figure 4 Restore configuration Figure 5 Bobo configuration diagram and execution real-time mode control method flow are as follows: Figure 6 ;

[0022] like Figure 2 The road network features include the starting coordinates of the intersection at the lower left corner node. Figure 2-1 (0, 0), Figure 2-2 {(0,0),(6,4)}, or road network {7,5}, has a total of 35 intersections, 7 north-south thoroughfares, and 5 east-west thoroughfares. The time set for straight road segments is {7,4}{==}, consisting of 28 north-south road segments. The time set for straight road segments is {5,6}{==}, consisting of 30 east-west road segments. #-# / # indicates the length of each road segment - time taken for the congested convoy to start / time taken. Figure 2-1 0, Unit: m-s / s, Congested convoy start-up time = convoy start-up coefficient * congestion coefficient |=1 * road segment length, or * separation coefficient. This is the formula for calculating the convoy start-up time for controllable separation. Where congestion coefficient |=1 indicates that the congestion coefficient is equal to 1. The congestion coefficient ranges from less than or equal to 1, indicating congestion. The separation coefficient ranges from greater than or equal to 1, indicating current congestion relief. The convoy start-up coefficient, calculated experimentally, ranges from 0.14 to 0.22, with the midpoint of 0.18. Calculations are based on a congestion coefficient of 1, with the convoy length equal to the road segment length. The separation coefficient is set to 1 for current separation, ignoring the influence of intersection width. Therefore, the convoy start-up time for each road segment is calculated as follows: =Length of each road segment x 0.18. Travel time is calculated based on the assumed legal speed of 45 km / h. For example, the distance from intersection (5,0) to (6,0) is 150 meters, and the congested traffic jam takes 27 seconds to start and 12 seconds to travel. The distance from intersection (5,2) to (5,3) is 125 meters, and the travel time is 23 seconds / 10 seconds. The time set for each road segment of each eastbound passage includes: from East 1 to East 5, the values ​​are {23 / 10, 18 / 8, 27 / 12, 23 / 10, 18 / 8, 27 / 12}. The time set for each road segment of each southbound passage includes: from South 1 to East 5, the values ​​are {27 / 12, 18 / 8, 23 / 10, 27 / 12}.

[0023] like Figure 2 This displays the time difference distribution of the main and secondary traffic flows in a road network under the current "congestion guidance" hybrid mode and the new "dual guidance" mode, as well as the signal distribution of the current congestion guidance mode at 360 seconds. The origin of the time difference in the current congestion guidance mode, which is also the starting point of the secondary traffic flow green wave, is intersection (6, 0). Figure 2 -9, the main green wave flows westward to alleviate congestion, while congested traffic flows eastward, so all z# are... Figure 2-1 1. The secondary green wave is all f# in the north. Figure 2-12. The direction of traffic flow is also north. The set of starting points for the main green wave is column 6 {(6,0), (6,1), (6,2), (6,3), (6,4)}. The sum of the starting times of congested convoys at intersections in the main green wave direction includes: East 1 {*} to East 5 {*}, all with values ​​of {140, 113, 95, 68, 45, 27, 0}. The rightmost 0 is the starting time of the congested convoys at the starting point of the main green wave in this row, and the other 6 values ​​are the corresponding values ​​in the straight line {5, 6} {==}. The sum of the driving times for traffic flow guidance at intersections in the secondary direction includes: South 6 {*} == {0, 12, 20, 30, 42}. The leftmost 0 is the driving time at the starting point of the secondary green wave in this column, and the other 4 values ​​are the corresponding values ​​in column {7, 4} {==}. The origin of the time difference in the new dual-flow model, i.e., the starting point of the secondary flow green wave, is the intersection (0, 0). Figure 2-1 The main green wave flows east, guiding traffic flow eastward; the secondary green wave flows northward for all vehicles. Figure 2-1 2. The direction of traffic flow is also north. The starting point set of the main green wave is column 0{(0,0),(0,1),(0,2),(0,3),(0,4)}. The sum of the travel times at the main green wave intersection includes: East 1{*} to East 5{*}, all of which are... {0, 10, 18, 30, 40, 48, 60}, where the leftmost 0 is the driving time of the main green wave starting point added to this row, and the other 6 values ​​are the corresponding values ​​in the straight road {5, 6}{==}; the sum of the driving time of the secondary flow intersection guidance includes: North 0{*}=={0, 12, 20, 30, 42}, where the leftmost 0 is the driving time of the secondary flow green wave starting point added to this column, and the other 4 values ​​are the corresponding values ​​in the column {7, 4}{==};

[0024] like Figure 6Taking the two-dimensional green wave real-time mode control method as an example, its features include the following steps: S1 Configure the default ratio signal mode: (1) The main direction of the signal at all intersections of the road network is north, the cycle duration is 90 seconds, the green time ratio is 1, each direction is 45 seconds, the green time ratio of the straight-left phase is 2, the straight phase is 30 seconds, and the left phase is 15 seconds; (2) And obtain the traffic time of each intersection in the quadrilateral road network area composed of 7x5 intersections, with 7 columns and 5 rows of channels: the start time of the congested convoy / the driving time, where the start time of the congested convoy = convoy start coefficient * congestion coefficient * road segment length * separation coefficient, where the congestion coefficient range is less than or equal to 1, and equal to 1 indicates congestion, the separation coefficient range is greater than or equal to 1, and equal to 1 indicates congestion according to the current situation, the convoy start coefficient is calculated and obtained from the experiment with a value range of 0.14 to 0.22, the middle value is 0.18, according to the congestion Congestion calculation with coefficient = 1, vehicle length equal to road segment length, and separation coefficient set to 1 for current separation, ignoring the impact of intersection width. Therefore, the start time of congested vehicle convoys on each road segment = road segment length x 0.18, with the travel time calculated based on an assumed legal speed of 45 km / h. For example, if the distance from intersection (5,0) to (6,0) is 150 meters, the start time of the congested vehicle convoy is 27 seconds / travel time is 12 seconds. The distance from intersection (5,2) to (5,3) is... 125 meters, taking 23 seconds / 10 seconds; thus, the time set configurations for each section of the eastbound corridor include: from East 1 to East 5, the values ​​are {23 / 10, 18 / 8, 27 / 12, 23 / 10, 18 / 8, 27 / 12}, and the time set configurations for each section of the southbound corridor include: from South 1 to East 5, the values ​​are {27 / 12, 18 / 8, 23 / 10, 27 / 12}.

[0025] Specific embodiment 1, such as Figure 3 This displays the progress of the real-time wave activation configuration of the road network initiation and diversion mode after 60 seconds of operation. The real-time mode control operation is as follows: S2 calculates and configures the new mode and its transition period according to the mode command: 1) The road network starts the default ratio mode. The command mode is a mixed congestion relief and guidance green wave. It is necessary to calculate and configure the wave start transition period: 2) Configure the transition period according to the command: The command mode is a congestion relief and guidance green wave. Configure the congestion relief and guidance mixed green wave start transition period: (S21.1) Because of the wave start, the default ratio mode is that its starting point intersection is arbitrary. The command mode is a congestion relief and guidance green wave. Its regional vehicle mixed green wave double heterogeneous group origin intersection: intersection (6,0). Then the main and secondary flow directions are obtained: the main flow is eastward congestion-the secondary flow is northward guidance. The corresponding main green wave flow is westward-the secondary green wave flow is northward. The intersection where the end of the congestion flow direction and the beginning of the guidance flow direction meet is: intersection (6,0) is the origin of the mixed mode. The set of intersections of the starting point of the main green wave channel {(6,0), (6,1), (6,2)}. (6,3), (6,4)); (S21.2) Calculate the time difference and cycle residual of each intersection: (1) Calculate the green wave time difference of the main direction: the sum of the time taken by each intersection in this area for all road segments between the starting point of the green wave time difference of its main direction channel and the intersection where it is located: if the main direction is congested, sum the time taken by each road segment to start the congested convoy; (2) Calculate the sum of the time taken by each road segment between the starting point of the green wave of each main direction channel and the starting point of the green wave of the corner intersection as the starting point of the green wave of the secondary direction channel, corresponding to the time taken by the main direction. If the main direction is congested, then the secondary direction is guidance. Sum the time taken by each road segment; (3) the green wave time difference of the main direction channel intersection of each intersection plus the green wave time difference of the secondary direction channel of its main direction channel relative to the origin of the mixed green wave; specific calculation results: The set of main green wave time differences at intersections of each access road (East 1 to East 5) values ​​are {136, 113, 95, 68, 45, 27, 0}, and the set of secondary green wave time differences at intersections of access road North 6 (North 6) values ​​are {0, 12, 20, 30, 42}. Set of time differences for mixed green wave guidance and dredging: East 5{*}={136+42,113+42,95+42,68+42,45+42,27+42,0+42, East 4{*)={136+30,113+30,95+30,68+30,45+30,27+30,0+30}, East 3{*}={136+20,113+20,95+20,68+20,45+20,27+20,0+20}, East 2{*}={136+12,113+12,95+12,68+12,45+12,27+12,0+12, East1{*)={136+0,113+0,95+0,68+0,45+0,27+0,0+0); Specifically, at intersections, for example, The third intersection of East 4th Passage is intersection (2, 3), and its mixed green wave time difference =

[95] +

[30] = 125. The first intersection of East 5th Passage is intersection (0, 4) in the upper left corner of the area, and its mixed green wave time difference... =

[136] +

[42] =178; The calculation results of the periodic residual difference for the time difference at each intersection are as follows: Intersection time difference / period duration (90 seconds) remainder: East 5 {*} = {88, 65, 47, 20, 87, 69, 42}, East 4{*}={76, 53, 35, 8, 75, 57, 30} East 3{*}={66, 43, 25, 88, 65, 47, 20}, East2{*}={58, 35, 17, 80, 57, 39, 12}, East1{*}={46, 23, 5, 68, 45, 27, 0}; (S21.3) Configure the signal start-up transition period: If the cycle residual difference of intersection (2,0) is 5 and the cycle residual difference of intersection (3,3) is 8, and the values ​​are too small, a red light prohibition cycle is made. For other intersections, the cycle residual difference is directly used as the duration segmentation to construct the signal cycle east-west travel time + north-south travel time, denoted as #+#, to obtain the signal start-up transition period for each intersection: East 5{*}={44+44,33+32,24+23,10+10,44+43,35+34,21+21}; East 4{*}={38+38,27+26,18+17,8,38+37,29+28,15+15}, East 3{*}={33+33,22+21,13+12,44+44,33+32,24+23,10+10}, East 2{*}={27+27,18+17,9+8,40+40,29+28,20+19,6+6}, East1{*}={23+23,12+11,5,34+34,23+22,24+23,0}; After the S3 operation completes the transition period for a red light or no signal, it runs in ratio mode: if there is a transition period value > 0, and there is a red light or no signal, it decrements by 1 and waits for the next second until the value = 0, then it starts executing ratio mode.

[0026] Specific embodiment 2, such as Figure 4 This displays the progress of the real-time restoration of the road network after 360 seconds of operation in the current traffic diversion mode. The real-time mode control operation is as follows: S2 calculates and configures the new mode and its transition period according to the mode instructions: 1) The road network is currently operating in a mixed traffic diversion green wave mode, the instruction mode is restored to the default ratio mode, and the transition period category is restored. 2) Calculate and configure the cycle difference and restore the transition period for each intersection: (S22.1) Determine the starting point intersection position between modes according to the mode rules: the starting point intersection for the current traffic diversion guidance mode is (6, 0), and the default ratio mode is synchronized with this starting point. (S22.2) Calculate the periodic residual difference and its periodic compensation for the intersection time difference obtained from the previous congestion guidance mode: Periodic duration - its periodic residual difference. The periodic compensation configuration results for each intersection are as follows: East 5 {*} = {2, 25, 43, 70, 3, 21, 48}. East 4{*}={14, 37, 55, 82, 15, 33, 60}, East 3{*}={24, 47, 65, 2, 25, 43, 70}, East2{*}={32, 55, 73, 10, 33, 51, 78}, East1{*}={44, 67, 85, 22, 45, 63, 90}; (S22.3) Configuration of restoration transition period: The cycle residual difference of intersection (3,1) is 10, the cycle residual difference of intersection (3,2) is 2, the cycle residual difference of intersection (0,3) is 14, the cycle residual difference of intersection (4,3) is 15, and the cycle residual difference of intersection (0,4) is 2. If these values ​​are too small, they will be converted into red light prohibition cycles. For the other intersections, the cycle residual difference will be used as the duration segmentation to construct the signal cycle east-west travel time + north-south travel time, denoted as #+#. The restoration transition period for each intersection is as follows: East 5{*}={2, 13+12, 22+21, 35+35, 3, 11+10, 24+24}, East 4{*}={14, 19+18, 28+27, 41+41, 15, 17+16, 30+30} East 3{*}={12+12,24+23,33+32,2,13+12,22+21,35+35}, East 2{*}={16+16,28+27,37+36,10,17+16,26+25,39+39}, East 1{*}={22+22,34+33,43+42,11+11,23+22,32+31,45+45}, After the S3 operation completes the transition period for a red light or no signal recovery, it runs in ratio mode: if there is a transition period value > 0, and there is a red light or no signal, it decrements by 1, waits for the next second, and continues until the value = 0, then it starts executing ratio mode.

[0027] Specific embodiment 3, such as Figure 5 The display shows the progress of the real-time wave configuration from the current traffic diversion mode running for 360 seconds to the dual-guide mode running for 135 seconds. The real-time mode control operation is as follows: S2 calculates and configures the new mode and its transition period according to the mode instructions: 1) The road network is currently operating in a mixed diversion green wave mode, the instruction mode is a dual guidance mode, and the transition period category is wave wave; 2) Calculate and configure the wave wave transition period for each intersection: (S22.1) Determine the starting point intersection position between modes according to the mode rules: The starting point intersection for the current diversion guidance mode is (6,0), its main flow is west of the green wave and the secondary flow is north; the starting point intersection for the dual guidance mode of the instruction mode is (0,0), its main flow is east of the green wave and the secondary flow is north; (S22.2) Calculate and configure the direct switching time difference and its cycle residual difference according to the rules of the dual guidance mode and the diversion mode: (1) Calculate the cycle residual difference of the intersection time difference obtained from the previous diversion guidance mode and its cycle compensation: cycle duration - its cycle residual difference: cycle duration - its cycle residual difference, the cycle compensation configuration results for each intersection are as follows: East 5{*}={2, 25, 43, 70, 3, 21, 48}, East 4{*}={14, 37, 55, 82, 15, 33, 60}, East 3{*}={24, 47, 65, 2, 25, 43, 70}, East2{*}={32, 55, 73, 10, 33, 51, 78}, East1{*}={44, 67, 85, 22, 45, 63, 90); (2) Calculate and configure the green wave time difference and cycle residual difference for each intersection based on the new dual-guided green wave model and its rules: The cycle residual difference for each intersection is as follows: East 5{*)={42, 52, 60, 72, 82, 0, 12}, East 4{*}={30, 40, 48, 60, 70, 78, 0}, East 3{*}={20, 30, 38, 50, 60, 68, 80}, East2{*}={12, 22, 30, 42, 52, 60, 72}, East1{*}={0, 10, 18, 30, 40, 48, 60}; (3) Calculate the mode switching time difference at each intersection based on the green wave category and its rules in the new mode: Add the time difference cycle residual of each intersection under the new mode dual guidance to the time difference cycle compensation of the current mode to obtain the direct switching time difference, and then divide by the cycle to obtain the direct switching cycle residual. The results are as follows: East 5{*}={44, 77, 13, 52, 85, 21, 60}, East 4{*}={44, 77, 13, 52, 85, 21, 60}, East 3{*}={44, 77, 13, 52, 85, 21, 60}, East2{*}={44, 77, 13, 52, 85, 21, 60}, East1{*}={44, 77, 13, 52, 85, 21, 60}; (S23.3) Configuration of transition period: If the period residual difference of column 2 {==}(2,x) is too small, a red light prohibition period is made. For the other intersections, the period residual difference is directly used as the duration segmentation to construct the signal period east-west travel time + north-south travel time, denoted as #+#. The restoration transition period of each intersection is as follows: East 5{*}={22+22,34+33,13,25+26,43+42,11+10,30+30}, East 4{*}={22+22,34+33,13,25+26,43+42,11+10,30+30}, East 3{*}={22+22,34+33,13,25+26,43+42,11+10,30+30}, East 2{*}={22+22,34+33,13,25+26,43+42,11+10,30+30}, East1{*}={22+22,34+33,13,25+26,43+42,11+10,30+30}; After the S3 operation completes the red light or no signal transition period, it runs in ratio mode: if there is a transition period value > 0, and there is a red light or no signal, it decrements by 1 and waits for the next second until the value = 0, then it starts executing ratio mode.

Claims

1. A method of real-time pattern control of traffic signals of a road network, characterized in that Including the following steps: S1 Startup: Configure the original ratio mode and the length of each road segment and traffic time in the road network; S2 calculates and configures the new mode and its transition period according to the mode command: 1) The signal mode to be operated according to the mode command, referred to as the command mode, and the current signal mode, referred to as the current mode, determine the transition category; the transition category includes wave activation, restoration, or wave-wave. Wave activation means that the command mode is a green wave and the current mode is the default ratio mode. Restoration means that the command mode is the default ratio and the current mode is a green wave. Wave-wave means that the command mode is a green wave and the current mode is also a green wave. 2) Calculate and configure the transition period of the new mode according to the transition category: (2.1) Determine the intersection position of the starting point of the time difference between the two modes involved in the transition category. (2.2) Calculate and configure the time difference and cycle residual of each intersection in the transition period of the new mode: the cycle residual of the intersection time difference = the intersection time difference divided by the signal mode cycle duration and take the remainder (i.e., the intersection time difference % cycle duration). (2.3) Configure the new mode transition period corresponding to the cycle residual of each intersection: cycle residual = transition period duration = main flow duration + secondary flow duration. S3 execution: Before the new cycle begins, the transition period is completed, and then the ratio mode is run. The road segment refers to the road between adjacent intersections; The traffic time includes travel time and the time required for a congested convoy to start; travel time refers to the time required for a vehicle to travel the entire road segment at the prescribed speed; convoy start time refers to the time required for the first vehicle in the convoy to move to the end of the convoy; congestion refers to a situation where the length of the convoy is equal to the length of the road segment, i.e., the road segment is completely blocked; the prescribed speed is determined by the designed green wave propagation speed; the designed green wave propagation speed is determined by the traffic time used to calculate the time difference at the intersection, and must not exceed the legally limited speed limit on the road; The green wave refers to the periodic, wave-by-wave directional propagation of green lights at intersections in a certain direction within a road network, with each green light turning on sequentially upstream and downstream in that direction. This direction is a defined direction, and the time difference between intersections in this defined direction is configured according to the following rules: each intersection is configured with a time difference greater than the time difference of its upstream adjacent intersection by the traffic time difference of the adjacent road segment. This defined direction, i.e., the directional propagation direction, is called the green wave flow direction. The time difference at the upstream intersection of the green wave flow direction is set to 0. Thus, the intersection time difference refers to the lag time of the green light turn-on time at an intersection in the same signal period and phase timing road network relative to a defined intersection. The configured lag time is equal to the sum of the traffic times of each road segment in the passageway connecting the intersection and the defined intersection. This defined intersection is called the starting point intersection for the green wave time difference, located at the upstream intersection of the green wave flow direction. The signal period leads the period of equal green wave waves.

2. The method according to claim 1, characterized in that: Step S1 further includes: The convoy start time in the traffic time mentioned in S11 is equal to the convoy start coefficient * congestion coefficient * road segment length, where the congestion coefficient is a number less than or equal to 1, and a value of 1 indicates congestion.

3. The method according to claim 2, characterized in that: Step S1 further includes: S12 refers to the driving time minus the braking time at the legal speed.

4. The method according to claim 3, characterized in that: Step S2, 2) further includes: S21 When the transition category is wave activation, configure the new mode wave activation transition period: Calculate the time difference at each intersection and the wave activation transition period for configuring the new mode transition period: (S21.1) Determine the intersection positions of the time difference starting points for the two signal modes involved in the transition category according to the following signal mode time difference starting point rules: If the signal mode is a ratio mode, any intersection can be considered as the time starting point, and the intersection with the time difference starting point of the involved green wave mode is selected as its starting point intersection; if the signal mode is a green wave, its starting point is determined by the specific green wave mode: guide the green wave time difference starting point road The starting point of the green wave time difference calculation is at the intersection where the green wave originates from its channel direction, and at the intersection where it ends from its channel direction. The channel direction is the same as the guiding green wave direction and opposite to the congestion relief green wave direction. Two intersecting green waves constitute a two-dimensional green wave, including all two-dimensional guiding, congestion relief, and mixed guiding / congestion relief green waves. Their starting intersections are all located at a corner of the area, called corner intersections, which are the intersections of the two channel directions within the area. If the green wave pattern is a two-dimensional guiding green wave, the intersection where the two guiding flow origins of the two directions intersect is set as the corner intersection for calculating the green wave time difference. If the green wave pattern is a two-dimensional congestion relief green wave, the intersection where the two guiding flow origins intersect is set as the corner intersection for calculating the green wave time difference. The intersection where the end points of the traffic flow converge are designated as the starting point corner intersections for calculating the green wave time difference; if the green wave mode is a mixed green wave for both traffic flow and traffic guidance, the intersection where the starting point of the guiding flow and the end point of the traffic flow converge in this area is designated as the starting point corner intersection for calculating the green wave time difference; let one of the two intersecting green wave channels be the main flow direction and the other be the secondary flow direction; the starting point for calculating the green wave time difference of the main flow direction is the starting point intersection of the green wave in each channel of the main flow direction, and the starting point for calculating the green wave time difference of the secondary flow direction is the starting point intersection of the green wave in the secondary flow direction channel formed by all the starting point intersections of the green wave time difference of the main channels, i.e., the corner intersection; (S21.2) According to the following wave-starting rules, calculate and configure the time difference and cycle residual difference of each intersection: add the traffic time of each segment in the corresponding main and secondary green wave channel segments between each intersection and the starting point of the signal mode time difference, and the value obtained is the intersection time difference of the new mode transition period of the wave-starting category; divide the intersection time difference by the cycle and take the remainder, and the cycle residual difference is obtained, which is the intersection cycle residual difference of the new mode transition period of the wave-starting category, which is used to create the new mode wave-starting transition period; (S21.3) Configure the new mode wave-starting transition period: make the cycle residual difference of each intersection of the new mode into the corresponding signal cycle, that is, the wave-starting transition period.

5. The method according to claims 1-4, characterized in that: Step S2, 2) further includes: S22 When the transition category is restoration, configure the restoration transition period: calculate the time difference and restoration transition period for each intersection in the new mode transition period: (S22.1) Determine the intersection positions of the time difference starting points for the two modes involved in the transition category according to the above signal mode time difference starting point rules; (S22.2) Calculate the current mode intersection time difference and its cycle residual difference according to the above wave start rules; calculate its cycle compensation according to the following restoration rules: the cycle compensation is equal to the cycle duration of the green wave mode minus the cycle residual difference of the intersection, that is, cycle compensation = cycle duration - its cycle residual difference; the intersection cycle compensation is used as the intersection time difference and cycle residual difference of the new mode transition period in the restoration category to create the new mode restoration transition period; (S22.3) Configure the new mode restoration transition period: each intersection uses its new mode cycle compensation to make its corresponding signal cycle, that is, the restoration transition period.

6. The method according to claim 5, characterized in that: Step S2, 2) further includes: S23 When the transition category is wave-wave, configure the wave-wave transition period: Calculate the time difference of each intersection and the wave-wave transition period for configuring the new mode transition period: (S23.1) Determine the intersection positions of the time difference starting points of the two signal modes involved in the transition category according to the above signal mode time difference starting point rules; (S23.2) Calculate the time difference of each intersection and its cycle residual difference for configuring the new mode transition period according to the following wave-wave rules: (1) Calculate the intersection time difference cycle residual difference and its cycle compensation according to the above wave-starting rules and restoration rules: Intersection cycle compensation = cycle duration - intersection cycle residual difference; (2) According to the above wave-starting rules Calculate the time difference and period residual of each intersection in the configuration instruction mode; (3) Add the time difference and period residual of the intersection in the instruction mode obtained above to the corresponding time difference and period compensation of the current mode, and the resulting value is called the intersection time difference of the new mode transition period of the wave type. Divide it by the signal mode period duration and take the remainder, and the resulting value is called the wave period residual; use the wave period residual of the intersection as the new mode intersection period residual of the wave type to make the new mode wave transition period; (S23.3) Configure the new mode wave transition period, and each intersection constructs its new mode wave period residual into its corresponding signal period, which is called the wave transition period.

7. The method according to claim 1, characterized in that: Step S2, configuring the transition period, also includes: S24 configuration transition period: Each intersection will configure its own transition period according to the mode instruction at the start or in the second half of the current cycle. If the time difference is too small, it will be directly made into a red light time of equal duration or allocated into the green light time of that half cycle.

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