Two-phase signal intersection pedestrian nested phase control method and determination method for inserting pedestrian nested phase

Abstract

The application provides a two-phase signal intersection pedestrian nested phase optimization model and a judgment method for inserting a pedestrian nested phase, solves the conflict between existing intersection pedestrians and turning vehicles, and specifically designs a control system for the information interaction of the intersection street-crossing pedestrians and the passing vehicles and the signal lights.In the signal light pedestrian nested phase setting condition, a total cost (including two parts of the conflict number and the delay) of the traffic participants is used as an optimization target, a pedestrian nested phase total cost model is provided, the motor vehicle avoidance pedestrian behavior in the human-vehicle interaction behavior is considered to be different in different cities and different intersections, and therefore, the suggestion value of whether to set the pedestrian nested phase is given under different traffic flow environments, the human-vehicle can pass through the intersection under the condition that the traffic operation cost is minimum, the efficiency and safety of the human-vehicle passing through the intersection are ensured, and the efficiency and safety of the human-vehicle passing through the intersection are ensured.

Description

Technical Field

[0001] This invention relates to the field of intelligent traffic system technology, and in particular to a method for pedestrian nested phase control at two-phase signal intersections and a method for determining the insertion of pedestrian nested phases. Background Technology

[0002] In recent years, China has advocated for motor vehicles to yield to pedestrians, altering the conditions of pedestrian-vehicle interaction. However, yielding to pedestrians remains largely self-organized, and the efficiency and safety of mixed-traffic intersections require improved pedestrian signal control methods. While requiring turning vehicles to yield to pedestrians at signalized intersections ensures pedestrian safety, it also significantly alters pedestrian-vehicle interaction patterns, impacting safety and efficiency during such interactions. In the core urban areas of developing countries, many intersections with high pedestrian and vehicle density frequently experience congestion caused by yielding to pedestrians. Signal control strategies for mixed-traffic flow include traditional traffic signal control (TWC), pedestrian-only phase control (EPP), and pedestrian advance signal control (LPI). However, the latter two primarily focus on improving pedestrian safety and have limited effectiveness in alleviating congestion caused by yielding to pedestrians. Setting up dedicated right-turn phases can alleviate conflicts between pedestrians and right-turning vehicles to some extent, but excessively long red light times during right turns significantly increase traffic delays.

[0003] Against this backdrop, it is evident that under the new conditions of human-vehicle interaction, in order to balance safety and efficiency and alleviate intersection congestion in different traffic environments, it is urgent to research and design a new signal control strategy for vehicles yielding to pedestrians, so as to reflect the important people-oriented requirements of my country's traffic environment. Summary of the Invention

[0004] The purpose of this invention is to take into account the differences in pedestrian yielding behavior of motor vehicles in different cities and at different intersections during human-vehicle interaction, and to provide suggested values ​​for whether to set pedestrian nested phases under different traffic flow environments. While ensuring traffic safety and efficiency, this invention enables people and motor vehicles to pass through intersections with the lowest possible traffic operating costs, thus ensuring the efficiency and safety of people and vehicles passing through intersections.

[0005] To achieve the above objectives, this invention proposes a pedestrian nested phase optimization model for two-phase signal intersections, which inserts several short red light periods into the pedestrian green light at the two-phase signal intersection; during the red light period, only vehicles can pass, and pedestrians do not have the right of way; during the green light period, both vehicles and pedestrians have the right of way, and vehicles yield to pedestrians.

[0006] The objective function of the pedestrian nested phase optimization model is to minimize the total cost of traffic safety and efficiency. ;

[0007] In the formula, It is the unit cost of safety. It is the unit cost of efficiency. This represents the number of pedestrian-vehicle conflicts at pedestrian-embedded phase intersections per hour. Total delay for pedestrians and vehicles at intersections with nested phase signals for pedestrians.

[0008] Furthermore, the constraints of the pedestrian nested phase optimization model include signal cycle constraints, vehicle green light time constraints, pedestrian nested green light time constraints, and pedestrian nested red light time constraints.

[0009] Furthermore, the signal period constraint is as follows: the signal period is the sum of the pedestrian red light time, the nested green light time for each pedestrian, and the nested red light time for each pedestrian, and the signal period satisfies a set minimum value. and maximum value scope:

[0010] ;

[0011] .

[0012] Furthermore, the green light time constraint for vehicles is as follows:

[0013] Green light time for vehicles It should be no less than the minimum green light time. :

[0014] ;

[0015] ;

[0016] Furthermore, the pedestrian nested green light time constraint is as follows:

[0017] The pedestrian nested green light time should be sufficient to ensure pedestrians can cross half of the crosswalk, guaranteeing pedestrian safety. This assumes that the pedestrian nested green light time is equal each time. The minimum value should be met. and maximum value scope:

[0018] ;

[0019] ;

[0020] .

[0021] Furthermore, the pedestrian nested red light time constraint is as follows:

[0022] The pedestrian nested red light time should be sufficient to ensure that N' vehicles turning left at the intersection can smoothly cross the pedestrian crossing. Assume that the pedestrian nested red light time is equal each time it is inserted, and that the pedestrian nested red light time... The minimum value should be met. and maximum value scope:

[0023] ;

[0024] ;

[0025] .

[0026] Furthermore, in order to calculate the number of pedestrian-vehicle conflicts at pedestrian-nested phase intersections per unit hour... It also includes the establishment of a pedestrian nested phase vehicle-pedestrian conflict number model:

[0027] In a traditional two-phase signalized intersection, right-turning vehicles are not affected by signal control, and their arrival rate is the actual arrival rate; left-turning vehicles and pedestrians are controlled by the signal and must wait for the green light, so their arrival rate is the arrival rate upon entering the intersection; each phase of the intersection has 6 conflict points between vehicles and pedestrians, including 4 right-turning vehicle / pedestrian conflict points and 2 left-turning vehicle / pedestrian conflict points; (g) ij Indicates the flow of vehicles in the direction of import lane i, g NS Indicating pedestrian flow in the north-south direction, g EW Representing east-west pedestrian flow, the distribution of pedestrian-vehicle conflict points at traditional two-phase signal intersections is obtained;

[0028] Phase 1 Left-turn vehicle and pedestrian conflict numbers Number of conflicts between right-turning vehicles and pedestrians :

[0029] ;

[0030] ;

[0031] Phase 2 and Phase 2 have the same distribution of pedestrian-vehicle conflict points. The same calculation method is used to obtain the total number of pedestrian-vehicle conflicts per hour at a traditional two-phase intersection:

[0032] ;

[0033] For pedestrian-embedded phase signal intersections, the number of pedestrian-vehicle conflicts is calculated as follows:

[0034] The conflict point distribution of phases 2, 4, and 6 at pedestrian nested phase signal intersections is the same as that of phase 1. Phases 3 and 5 eliminate pedestrian-vehicle conflicts due to the insertion of nested red light times. Therefore, the number of pedestrian-vehicle conflicts at pedestrian nested phase signal intersections per hour is obtained as follows:

[0035] .

[0036] Furthermore, in order to calculate the total delay of pedestrians and vehicles at intersections with nested phase signals for pedestrians... It also includes the establishment of a pedestrian nested phase delay model:

[0037] The pedestrian nested phase delay model includes the creation of cumulative vehicle curves and cumulative pedestrian curves embedded with two red light times:

[0038] Motor vehicle delay is defined as the area enclosed by the cumulative arrival and departure lines on the cumulative vehicle graph over a given period, assuming vehicle arrival and departure rates are constant.

[0039] ;

[0040] Regarding conflict delays, since the inserted pedestrian nested green light time eliminates the conflict between pedestrians and vehicles, the conflict delay during this period is 0.

[0041] Pedestrian delay under nested phase is signal control delay. The delay is defined as the area enclosed by the cumulative pedestrian arrival line and the cumulative vehicle departure line in the cumulative pedestrian curve within one period, treating pedestrian arrival rate and dissipation rate as constants.

[0042]

[0043] The final total delay for pedestrians and vehicles at the pedestrian nested phase signal intersection is:

[0044] .

[0045] This invention also proposes a method for determining the insertion of nested pedestrian phases, comprising the following steps:

[0046] Step 1: In practical engineering applications, first determine the unit cost ratio of conflict to delay and the number of pedestrian nested red light times;

[0047] Step 2: Initialize various parameters in the system, including the headway adjustment coefficient, pedestrian fluctuation coefficient before and after pedestrian nested phase, reduction coefficient for conflicts between pedestrians and right-turning motor vehicles, signal cycle duration, green light ratio, pedestrian-only duration, intersection pedestrian crossing width, lane width, number of lanes, average passenger load factor of cars, average passenger load factor of buses, proportion of left-turning vehicles, proportion of buses, and pedestrian importance coefficient.

[0048] Step 3: Input the traffic flow of vehicles turning left, going straight, and turning right at the intersection, as well as the pedestrian flow data with and without pedestrian nested phases set;

[0049] Step 4: Calculate the following before and after setting up the pedestrian nested phase: passenger delay in motor vehicles, average queue length at the intersection, motor vehicle throughput, pedestrian delay, total delay, and number of pedestrian-vehicle conflicts. Compare the total cost to traffic participants at the intersection before and after setting up the pedestrian nested phase.

[0050] Step 5: If the total cost of traffic participants after setting the pedestrian nested phase is less than or equal to the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed reasonable. If it is greater than the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed unreasonable.

[0051] Furthermore, in step one, the unit cost ratio of conflict to delay in different control areas is as follows: intersections with high pedestrian traffic in commercial areas: 9:24.7; intersections near residential areas and rest areas: 7:24.7; intersections in industrial areas and suburbs: 7:26.7.

[0052] The ratio of the number of pedestrian nested red light times in different control areas is: 1 for intersections with high pedestrian traffic such as commercial areas, and 2 for others.

[0053] Compared with the prior art, the advantages of the present invention are:

[0054] 1. This invention proposes a new pedestrian signal control method for traffic environments where vehicles yield to pedestrians. Taking into account the differences between different cities and intersections, this method can alleviate intersection congestion under pedestrian yielding conditions and improve the safety and efficiency of people and vehicles.

[0055] 2. This invention establishes a total cost model for the operation of intersections before and after setting up pedestrian nested phases. It describes the delay time and number of conflicts more accurately than the traditional model in the context of yielding to pedestrians. It innovatively introduces the unit cost ratio of conflict and delay to establish an optimization model, and provides the safety efficiency cost ratio, number of embedded phases and duration for various traffic flow demands under practical applications.

[0056] 3. In the context of intelligent information systems, the technical implementation of collecting real-time traffic flow data of pedestrians and motor vehicles enables timely updates of traffic flow data at intersections. By inputting data from different control areas into the model, it is possible to provide targeted guidance for the setting of pedestrian nested phases at signalized intersections in different types of areas such as commercial areas, residential areas, and industrial areas. Attached Figure Description

[0057] Figure 1 A nested phase diagram for pedestrians at a four-entry, two-phase signal controlled intersection.

[0058] Figure 2 This is a schematic diagram of a traditional two-phase vehicle-pedestrian conflict.

[0059] Figure 3 Schematic diagram of pedestrian-vehicle conflict in nested phases;

[0060] Figure 4 A cumulative vehicle curve chart embedding two red light periods;

[0061] Figure 5 Accumulated pedestrian curve with two red light periods embedded;

[0062] Figure 6. Flowchart for determining the conditions for nested phase setting of pedestrians at a two-phase signal controlled intersection.

[0063] Figure 7 Sensitivity analysis results;

[0064] Figure 8 Applicability analysis results. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0066] This invention proposes a pedestrian nested phase control method, specifically involving a control system for the interaction of pedestrians crossing the street, vehicles, and traffic lights at intersections. In the setting conditions for pedestrian nested phases, the total cost of traffic participants (including conflict numbers and delays) is used as the optimization objective. A total cost model for pedestrian nested phases is proposed, considering the differences in vehicle yielding behavior to pedestrians in different cities and intersections. This provides suggested values ​​for whether to set pedestrian nested phases under different traffic flow environments, ensuring both traffic safety and efficiency while allowing pedestrians and vehicles to pass through intersections with minimal traffic operating costs, thus guaranteeing both efficiency and safety for pedestrians and vehicles crossing intersections.

[0067] The technical effects of the present invention will be described below through specific solutions.

[0068] 1. Pedestrian nested phase

[0069] This invention proposes a pedestrian nested phase design, which inserts several short red light periods into the pedestrian green light. During these red light periods, only vehicles can pass, and pedestrians do not have the right-of-way. The vehicle conflict zone at a two-phase intersection caused by vehicles yielding to pedestrians is shown in the figure. For ease of study, the embedded short red light periods are called pedestrian nested red light periods, and the green light periods before and after the pedestrian nested red light periods are called pedestrian nested green light periods. Taking two embedded short red light periods as an example... Figure 1In the diagram, c and e represent the pedestrian nested red light time, and b, d, and f represent the pedestrian nested green light time. The specific number of nested passage times is determined by the actual intersection requirements. Taking intermittent passage twice as an example, the pedestrian nested phase is as follows: Figure 1 As shown.

[0070] 1.2 Pedestrian Nested Phase Optimization Model:

[0071] 1.2.1 Basic Assumptions

[0072] This technical solution makes the following assumptions:

[0073] (1) Two-phase signal control intersections under saturation or oversaturation conditions are not considered for the time being. For the research object in this paper, it is assumed that vehicle arrivals follow a Poisson distribution.

[0074] (2) The rate of vehicles yielding to pedestrians is 100%, without considering situations where vehicles violate traffic regulations.

[0075] (3) Pedestrians cross the street in groups in the form of queues. In the early stage of the green light, pedestrians disappear at a saturation rate, and in the later stage, they disappear at an arrival rate.

[0076] Objective function:

[0077] To facilitate model validation and comparison, this paper introduces safety cost and efficiency cost, representing the safety and efficiency performance of intersections before and after implementing nested phases using cost value. The objective function of the optimization model is to minimize the total cost of traffic safety and efficiency.

[0078]

[0079] In the formula: It is the unit cost of safety. It is the unit cost of efficiency.

[0080] 1.2.2 Constraints

[0081] (1) Signal period constraint

[0082] The signal cycle is the sum of the pedestrian red light time, the green light time for each pedestrian nested area, and the red light time for each pedestrian nested area, and the cycle must meet the set minimum value. and maximum value scope:

[0083] ;

[0084] ;

[0085] (2) Green light time constraints for vehicles

[0086] Green light time for vehicles It should be no less than the minimum green light time. :

[0087] ;

[0088] ;

[0089] (3) Pedestrian nested green light time constraints

[0090] The pedestrian nested green light time should be sufficient to ensure pedestrians can cross half of the crosswalk safely. This assumes that the green light time for each inserted pedestrian nested green light is equal. The minimum value should be met. and maximum value scope:

[0091] ;

[0092] ;

[0093] ;

[0094] (4) Pedestrian nested red light time constraints

[0095] The pedestrian nested red light time should be sufficient to ensure that N' vehicles turning left at the intersection can smoothly cross the pedestrian crossing. Assume that the pedestrian nested red light time is equal each time it is inserted, and that the pedestrian nested red light time... The minimum value should be met. and maximum value scope:

[0096] ;

[0097] ;

[0098] ;

[0099] 1.2.3 Pedestrian Nested Phase Vehicle-Pedestrian Conflict Count Model

[0100] In a traditional two-phase signalized intersection, right-turning vehicles are not affected by signal control, and their arrival rate is the actual arrival rate. Left-turning vehicles and pedestrians are controlled by the signal and must wait for the green light; their arrival rate is the arrival rate upon entering the intersection. Each phase of the intersection has 6 conflict points between vehicles and pedestrians, including 4 right-turning vehicle / pedestrian conflict points and 2 left-turning vehicle / pedestrian conflict points. (Using g...) ij Indicates the flow of vehicles in the direction of import lane i, g NS Indicating pedestrian flow in the north-south direction, g EW Representing east-west pedestrian flow, the distribution of pedestrian-vehicle conflict points at traditional two-phase signal intersections is obtained as follows: Figure 2 As shown:

[0101] Phase 1 Left-turn vehicle and pedestrian conflict numbers Number of conflicts between right-turning vehicles and pedestrians :

[0102] (1.14)

[0103] (1.15)

[0104] make Then the intersection per hour import Turning traffic and The number of pedestrian-vehicle conflicts at the entrance is:

[0105]

[0106] In the formula, Within a unit of hour import Total number of pedestrian-vehicle conflicts between turning traffic and pedestrians; Let S represent the green light duration for different phases. In a traditional two-phase signalized intersection, right-turning vehicles are not affected by signal control, and their arrival rate is the actual arrival rate; left-turning vehicles and pedestrians are controlled by the signal and must wait for the green light, so their arrival rate is the arrival rate upon entering the intersection. Each phase of the intersection has 6 conflict points between vehicles and pedestrians, including 4 right-turning vehicle / pedestrian conflict points and 2 left-turning vehicle / pedestrian conflict points. express Import channel directional traffic flow Indicates pedestrian flow in the north-south direction. Representing east-west pedestrian flow, the distribution of pedestrian-vehicle conflict points at traditional two-phase signal intersections is obtained as follows: Figure 2 As shown:

[0107] Based on the distribution map of pedestrian-vehicle conflict points, a distribution table of pedestrian-vehicle conflicts can be obtained:

[0108] Table of Phase One-Vehicle Conflict Distribution

[0109] <![CDATA[g 12 ]]> <![CDATA[g 21 ]]> <![CDATA[g 22 ]]> <![CDATA[g 32 ]]> <![CDATA[g 41 ]]> <![CDATA[g 42 ]]> <![CDATA[g EW1 ]]> R L R <![CDATA[g EW3 ]]> R R L

[0110] Note: Conflict between pedestrians and left-turning vehicles; Conflict between pedestrians and right-turning vehicles; For the reason Turning at intersection Traffic flow at the intersection.

[0111] Phase 2 and Phase 2 have the same distribution of pedestrian-vehicle conflict points. The same calculation method is used to obtain the total number of pedestrian-vehicle conflicts per hour at a traditional two-phase intersection:

[0112] (1.16)

[0113] For pedestrian-embedded phase signal intersections, taking two pedestrian-embedded red light times as an example, the distribution diagram of pedestrian-vehicle conflict points is as follows: Figure 3 As shown, the number of pedestrian-vehicle conflicts is calculated as follows:

[0114] The conflict point distribution of phases 2, 4, and 6 at pedestrian nested phase signal intersections is the same as that of phase 1. Phases 3 and 5 eliminate pedestrian-vehicle conflicts due to the insertion of nested red light times. Therefore, the number of pedestrian-vehicle conflicts at pedestrian nested phase signal intersections per hour is obtained as follows:

[0115] (1.17)

[0116] 1.2.4 Pedestrian Nested Phase Delay Model

[0117] Calculation of total delay for pedestrians and vehicles at pedestrian-embedded phase intersections:

[0118] (1) Motor vehicle delays

[0119] Regarding signal control delays, the cumulative delay curve for motor vehicles changes after setting up pedestrian nested phases, for example... Figure 4 As shown.

[0120] The uniform delay is the area of ​​the shaded region in the figure:

[0121] (1.27)

[0122] Regarding conflict delays, since the inserted pedestrian nested green light time eliminates the conflict between pedestrians and vehicles, the conflict delay during this period is 0, while the conflict delay for motor vehicles is calculated according to the formula.

[0123] (1) Pedestrian delay

[0124] Pedestrian delay under nested phases is signal control delay, and the delay is... Figure 5 Area of ​​the shaded region:

[0125] (1.28)

[0126] Combining the above formulas, the total delay for pedestrians and vehicles at pedestrian-nested phase signal intersections is obtained as follows:

[0127] (1.29)

[0128] Minimum value in the above formula and maximum value The settings are based on the U.S. Road Capacity Manual 2010 (HCM2010).

[0129] The parameters in the above formula and their explanations:

[0130]

[0131]

[0132]

[0133]

[0134] The following is in conjunction with the appendix Figure 6-8 Further explanation of the pedestrian nested phase determination process and specific implementation method of the present invention:

[0135] Step 1: In practical engineering applications, first determine the unit cost ratio of conflict to delay and the number of pedestrian nested red light times (tri);

[0136] Table 1. Unit cost ratio of conflict to delay

[0137] Control Area ratio Commercial areas and other densely populated intersections 9:24.7 Intersections near residential areas and rest areas 7:24.7 Intersection of industrial zone and suburbs 7:26.7

[0138] Table 2 Number of nested pedestrian red light times (tri)

[0139] Control Area ratio Commercial areas and other densely populated intersections 1 other 2

[0140] Step 2: Initialize various parameters in the system, including the headway adjustment coefficient, pedestrian fluctuation coefficient before and after pedestrian nested phase, reduction coefficient for conflicts between pedestrians and right-turning motor vehicles, signal cycle duration, green light ratio, pedestrian-only duration, intersection pedestrian crossing width, lane width, number of lanes, average passenger load factor of cars, average passenger load factor of buses, proportion of left-turning vehicles, proportion of buses, pedestrian importance coefficient, etc.

[0141] Step 3: Input the traffic flow of vehicles turning left, going straight, and turning right at the intersection, as well as the pedestrian flow data with and without pedestrian nested phases set;

[0142] Step 4: Calculate the following before and after setting up the pedestrian nested phase: passenger delay in motor vehicles, average queue length at the intersection (meters), motor vehicle throughput, pedestrian delay, total delay, and number of pedestrian-vehicle conflicts. Compare the total cost to traffic participants at the intersection before and after setting up the pedestrian nested phase.

[0143] Step 5: If the total cost of traffic participants after setting the pedestrian nested phase is less than or equal to the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed reasonable. If it is greater than the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed unreasonable.

[0144] To analyze the sensitivity of each parameter in the model proposed in this study, we analyzed each important parameter according to practical application requirements. In this numerical analysis, we discussed the changes in the total cost incurred by traffic participants after setting up pedestrian nested phases under different vehicle and pedestrian flow rates.

[0145] This study analyzes the changes brought about by the unit cost ratio of conflict and delay. First, it determines the cost ratio when both safety and efficiency are equally emphasized, adopting the value of 7 yuan determined by Wang Junhua et al. in their research on the conflict costs between motor vehicles and pedestrians in Shanghai as the benchmark conflict cost. The benchmark delay cost is 24.7 yuan per hour, calculated based on an 8-hour workday in Shanghai in 2020. The ratio is further adjusted based on the 7:24.7 unit cost ratio of conflict and delay, and the changes in the total cost for traffic participants after setting up pedestrian nested phases under different working conditions are discussed. This study analyzes three scenarios: prioritizing safety (unit cost ratio of conflict and delay 9:24.7), prioritizing both safety and efficiency (unit cost ratio of conflict and delay 7:24.7), and prioritizing efficiency (unit cost ratio of conflict and delay 7:26.7). An insertion of a t... ri (Figures a, b, c) and inserting two t ri (Figures d, e, f) Two conditions, such as Figure 7 As shown.

[0146] from Figure 7 The six figures show that under low vehicle traffic (100-300 pcu / h) and low pedestrian traffic (100-300 people / h) conditions, the cost increase is slightly less than 0%, indicating the applicability of pedestrian nested phases within this range, but the effect is not significant. This is because in scenarios with low pedestrian and vehicle traffic, the behavior of vehicles yielding to pedestrians is also reduced accordingly. Therefore, the use of pedestrian nested phases does not significantly affect pedestrian safety costs and motor vehicle efficiency costs.

[0147] Under high vehicle traffic (500-700 pcu / h) and low pedestrian traffic (100-500 people / h) conditions, the cost increment after setting up pedestrian nested phases significantly decreases, indicating that the conditions for implementation are met. With the same vehicle traffic volume, the cost increment after setting up pedestrian nested phases also shows a decreasing trend as pedestrian traffic decreases, reaching its minimum at a vehicle traffic volume of 600, further enhancing the suitability for implementation. When the vehicle traffic volume exceeds 700, the nested phase method proposed in this paper becomes inapplicable due to oversaturation.

[0148] For conditions with high pedestrian traffic, the cost increase is significant, making it unsuitable to implement nested pedestrian phases. This is because while nested pedestrian phases can alleviate vehicle queuing, nested red light times also cause a large number of pedestrians to wait to cross the street, resulting in a loss of pedestrian efficiency.

[0149] from Figure 7 From a, b, and c, we can see that when inserting a t...ri When the conflict-to-delay unit cost ratio is 7:24.7, the negative increment range is the largest. Under this condition, the flow range suitable for setting nested phases is the largest. The negative increment ranges for conflict-to-delay unit cost ratios of 9:24.7 and 7:26.7 are not significantly different. By comparing embedding one tri (Figures a, b, c) and two tri (Figures d, e, f), it can be seen that embedding two tris results in a larger positive increment range because two tris have a greater impact on the total pedestrian traffic delay.

[0150] Based on the analysis results of this study, in practical engineering applications, it is recommended that the unit cost ratio of conflict to delay be 9:24.7 in densely populated areas such as commercial districts, prioritizing pedestrian safety; 7:24.7 in residential areas and near rest areas, balancing safety and efficiency; and 7:26.7 in suburbs and industrial areas, prioritizing efficiency. It is also recommended that the number of inserted tri elements be 1 in densely populated areas such as commercial districts, and 2 in all other areas.

[0151] To verify the effectiveness of the pedestrian nested phase optimization model at intersections, this paper takes the Beijing West Road-Changde Road intersection in Shanghai as an example. Using vehicle and pedestrian flow as variables, online electronic maps are used to obtain the intersection's geometric shape and lane composition information. Pedestrian-vehicle interaction data is obtained based on video recordings of the pedestrian-vehicle interaction area. Other user-specified parameters are calculated according to the methods provided in HCM2010. The conflict-to-delay unit cost ratio is adopted as 7:24.7, balancing safety and efficiency, based on the analysis results above. By calculating and comparing the total operating costs before and after setting up the pedestrian nested phase at the existing intersection, the pedestrian signal control strategy with the lowest total cost is selected as the final signal control scheme for the case intersection. The optimized number of tri phases and the corresponding cycle duration and nested red light duration are shown below. Figure 8 As shown.

[0152] As shown in Figure g, the number of nested phases increases sequentially from high pedestrian / low vehicle traffic areas to low pedestrian / high vehicle traffic areas. Due to the constraint of nested phase duration, the maximum number of nested phases is two. It can be observed that nesting two phases is suitable for high vehicle traffic / low pedestrian traffic scenarios, but its applicability is relatively small. In this scenario, it is more beneficial for releasing densely packed vehicles than not setting nested phases, and more beneficial for dispersing sparse pedestrians than setting only one phase. The traffic flow range in the upper left area of ​​the figure is not suitable for setting nested phases, consistent with the cost increment trend mentioned above. Figure h shows the optimized cycle duration, which is not significantly different from the results calculated by the traditional Webster method. Due to the cycle constraint, the maximum optimized cycle is 120 seconds. The nested red light duration gradually increases with increasing vehicle traffic and decreasing pedestrian traffic, reaching its maximum at the boundary between suitable settings of one and two phases, and then tends to decrease.

[0153] Figure 8Figures a, b, and c illustrate the changes in cost increment after optimization. The white area in the figure shows a cost increment of 0 because the optimized result is the same as the original total cost without nested phases. Overall, the benefits are significant in scenarios with medium to high vehicle traffic and low pedestrian traffic, with safety benefits being broader and more pronounced than efficiency benefits.

[0154] Figure 8 The specific cost trends before and after optimization are shown. It can be seen that safety costs gradually increase with increasing vehicle and pedestrian traffic. Compared to safety costs, efficiency costs increase even faster with increasing vehicle traffic, especially when traffic volume exceeds 500 pcu / h. This indicates that high-volume traffic is more susceptible to congestion due to pedestrians than low- to medium-volume traffic, necessitating measures to improve intersection efficiency. Furthermore, efficiency costs are not significantly affected by increased pedestrian traffic in high-volume scenarios. This suggests that even with only a small number of pedestrians, strict pedestrian yielding can still significantly impact the overall efficiency of all traffic participants.

[0155] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for nested phase control of pedestrians at a two-phase signal intersection, characterized in that, The control system involving the interaction of pedestrians crossing the street and the information of vehicles and traffic lights at intersections adopts the total cost of traffic participants, including the number of conflicts and delays, as the optimization objective in the setting conditions of pedestrian nested phases of traffic lights. The total cost model of pedestrian nested phases is proposed, taking into account the differences in the behavior of motor vehicles yielding to pedestrians in different cities and different intersections, so as to give the recommended value of whether to set up pedestrian nested phases under different traffic flow environments. The pedestrian nested phase total cost model includes the following technical aspects: Insert several short red light periods into the pedestrian green light at a two-phase signal intersection; during the red light period, only vehicles can pass, and pedestrians do not have the right of way; during the green light period, both vehicles and pedestrians have the right of way, and vehicles yield to pedestrians. The objective function of the pedestrian nested phase optimization model is to minimize the total cost of traffic safety and efficiency. ； In the formula, It is the unit cost of safety. It is the unit cost of efficiency. This represents the number of pedestrian-vehicle conflicts at pedestrian-embedded phase intersections per hour. Total delay for pedestrians and vehicles at intersections with nested phase signals; To calculate the number of pedestrian-vehicle conflicts at pedestrian-nested phase intersections per hour It also includes the establishment of a pedestrian nested phase vehicle-pedestrian conflict number model: In a traditional two-phase signalized intersection, right-turning vehicles are not affected by signal control, and their arrival rate is the actual arrival rate; left-turning vehicles and pedestrians are controlled by the signal and must wait for the green light, so their arrival rate is the arrival rate upon entering the intersection; each phase of the intersection has 6 conflict points between vehicles and pedestrians, including 4 right-turning vehicle / pedestrian conflict points and 2 left-turning vehicle / pedestrian conflict points; (g) ij Indicates the flow of vehicles in the direction of import lane i, g NS Indicating pedestrian flow in the north-south direction, g EW Representing east-west pedestrian flow, the distribution of pedestrian-vehicle conflict points at traditional two-phase signal intersections is obtained; Phase 1 Left-turn vehicle and pedestrian conflict numbers Number of conflicts between right-turning vehicles and pedestrians : ； ； Phase 2 and Phase 2 have the same distribution of pedestrian-vehicle conflict points. The same calculation method is used to obtain the total number of pedestrian-vehicle conflicts per hour at a traditional two-phase intersection: ； For pedestrian-embedded phase signal intersections, the number of pedestrian-vehicle conflicts is calculated as follows: The conflict point distribution of phases 2, 4, and 6 at pedestrian-nested phase signal intersections is the same as that of phase 1. Phases 3 and 5 eliminate pedestrian-vehicle conflicts due to the insertion of nested red light times. Therefore, the number of pedestrian-vehicle conflicts at pedestrian-nested phase signal intersections per hour is obtained as follows: ； To calculate the total delay of pedestrians and vehicles at an intersection with nested pedestrian phase signals. It also includes the establishment of a pedestrian nested phase delay model: The pedestrian nested phase delay model includes the creation of cumulative vehicle curves and cumulative pedestrian curves embedded with two red light times: Motor vehicle delay is defined as the area enclosed by the cumulative arrival and departure lines on the cumulative vehicle graph over a given period, assuming vehicle arrival and departure rates are constant. ； Regarding conflict delays, since the inserted pedestrian nested green light time eliminates the conflict between pedestrians and vehicles, the conflict delay during this period is 0. Pedestrian delay under nested phase is signal control delay. The delay is defined as the area enclosed by the cumulative pedestrian arrival line and the cumulative vehicle departure line in the cumulative pedestrian curve within one period, treating pedestrian arrival rate and dissipation rate as constants. ； The final total delay for pedestrians and vehicles at the pedestrian nested phase signal intersection is: 。 2. The pedestrian nested phase control method for two-phase signal intersections according to claim 1, characterized in that, The constraints of the pedestrian nested phase optimization model include signal cycle constraints, vehicle green light time constraints, pedestrian nested green light time constraints, and pedestrian nested red light time constraints.

3. The pedestrian nested phase control method for two-phase signal intersections according to claim 2, characterized in that, The signal period constraint is as follows: the signal period is the sum of the pedestrian red light time, the nested green light time for each pedestrian, and the nested red light time for each pedestrian, and the signal period must satisfy a set minimum value. and maximum value scope: ； 。 4. The pedestrian nested phase control method for two-phase signal intersections according to claim 2, characterized in that, The green light time constraint for the vehicle is: Green light time for vehicles It should be no less than the minimum green light time. : ； 。 5. The pedestrian nested phase control method at a two-phase signal intersection according to claim 2, characterized in that, The pedestrian nested green light time constraint is as follows: The pedestrian nested green light time should be sufficient to ensure pedestrians can cross half of the crosswalk, guaranteeing pedestrian safety. This assumes that the pedestrian nested green light time is equal each time. The minimum value should be met. and maximum value scope: ； ； 。 6. The pedestrian nested phase control method for two-phase signal intersections according to claim 2, characterized in that, The pedestrian nested red light time constraint is as follows: The pedestrian nested red light time should be sufficient to ensure that N' vehicles turning left at the intersection can smoothly cross the pedestrian crossing. Assume that the pedestrian nested red light time is equal each time it is inserted, and that the pedestrian nested red light time... The minimum value should be met. and maximum value scope: ； ； 。 7. A method for determining whether nested pedestrian phases are inserted, used to determine whether the application of the two-phase signal intersection pedestrian nested phase control method as described in any one of claims 1-6 is reasonable, comprising the following steps: Step 1: In practical engineering applications, first determine the unit cost ratio of conflict to delay and the number of pedestrian nested red light times; Step 2: Initialize various parameters in the system, including the headway adjustment coefficient, pedestrian fluctuation coefficient before and after pedestrian nested phase, reduction coefficient for conflicts between pedestrians and right-turning motor vehicles, signal cycle duration, green light ratio, pedestrian-only duration, intersection pedestrian crossing width, lane width, number of lanes, average passenger load factor of cars, average passenger load factor of buses, proportion of left-turning vehicles, proportion of buses, and pedestrian importance coefficient. Step 3: Input the traffic flow of vehicles turning left, going straight, and turning right at the intersection, as well as the pedestrian flow data with and without pedestrian nested phases set; Step 4: Calculate the following before and after setting up the pedestrian nested phase: passenger delay in motor vehicles, average queue length at the intersection, motor vehicle throughput, pedestrian delay, total delay, and number of pedestrian-vehicle conflicts. Compare the total cost to traffic participants at the intersection before and after setting up the pedestrian nested phase. Step 5: If the total cost of traffic participants after setting the pedestrian nested phase is less than or equal to the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed reasonable. If it is greater than the total cost of traffic participants before setting the pedestrian nested phase, then the setting of the pedestrian nested phase at the intersection is deemed unreasonable.

8. The method for determining the nested phase of an inserted pedestrian according to claim 7, characterized in that, In step one, the unit cost ratio of conflict to delay in different control areas is as follows: intersections with high pedestrian traffic in commercial areas: 9:24.7; intersections near residential areas and rest areas: 7:24.7; intersections in industrial areas and suburbs: 7:26.

7. The ratio of the number of pedestrian nested red light times in different control areas is: 1 for densely populated intersections in commercial areas, and 2 for others.

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