Double-lane road local section single-lane alternate traffic signal dynamic timing method

Abstract

The invention discloses a double-lane road local road section single-lane alternate traffic signal dynamic timing method. The method comprises the following steps: determining a local road section traffic influence range of an event; collecting traffic flow data, and analyzing traffic flow characteristics; calculating a delay-based small vehicle equivalent quantity, and calculating a large vehicle adverse impact factor; constructing a signal dynamic timing method for alternate passage of road sections affected by double-lane road events; according to the method, a signal timing optimization model based on dynamic traffic flow characteristics is constructed, traffic flow data, including actual passing time, vehicle model proportion, actual arrival traffic volume and the like, of an event influence road section are collected in real time according to a special scene of an alternate passing road section of a double-lane road, and a signal period and a phase timing scheme are dynamically adjusted. The method can quickly adapt to the traffic fluctuation of the alternate passage road section, reduces the vehicle delay under manual command, improves the vehicle passage efficiency, and enhances the flexibility and dynamic adaptability of the signal timing of the alternate passage road section of the double-lane road.

Description

Technical Field

[0001] The invention relates to the technical field of dynamic timing of traffic signals, and in particular to a dynamic timing method for alternating traffic signals of single lanes on a local section of a two-lane highway. Background Art

[0002] As an important transportation infrastructure connecting urban and rural areas, two-lane highways often face serious traffic obstacles under specific geographical environments and natural conditions. In actual projects, there are many high-risk scenarios that lead to a significant decrease in road capacity. For example, when a unilateral landslide occurs in a road cutting section or a landslide occurs on the excavation side of a semi-filled and semi-excavated section, due to the large amount of landslide, it is impossible to reinforce and remove the landslide body in a short period of time, which directly affects the normal traffic of the road; secondly, a unilateral landslide or water damage may occur in the embankment section or the semi-filled and semi-excavated section, and the road needs to be occupied for construction, and the construction scope is wide and the repair time is long, which will also cause serious restrictions on the traffic capacity of the section. In these typical scenarios, especially in remote and rural areas, most of the road networks in the region are national and provincial roads, with a large proportion of bends, and narrow sections of roads often present two characteristics: one is that the narrow section is long, and the other is that the narrow section is short but the sight distance is limited. Therefore, it is necessary to ensure the traffic efficiency and traffic safety of the road through traffic control.

[0003] At present, the traffic control method for one-way sections of two-lane highways mainly relies on traditional manual command, which is to set up traffic controllers at both ends of narrow sections to direct traffic according to the on-site situation. This has obvious shortcomings. On the one hand, the traditional manual control method is mostly based on experience to release traffic alternately, which is quite arbitrary and difficult to achieve scientific and efficient traffic flow organization, resulting in a long average delay time for vehicles and low overall traffic efficiency. On the other hand, this method requires a lot of human resources, which is not only costly, but also prone to safety hazards. In addition, manual control is difficult to respond to the dynamically changing traffic flow characteristics in a timely manner, and lacks the ability to adapt to the differences between different types of vehicles (such as trucks and cars), which further limits the traffic efficiency of typical scene sections of two-lane highways.

[0004] Existing traffic signal timing schemes, especially the stop line method used in traditional intersections to calculate traffic capacity, are difficult to adapt to the one-way traffic scenarios of two-lane highways with long or short-distance parallax. On the one hand, alternating traffic on a two-lane highway usually requires a long clearing time (yellow light time). In some extreme cases, the clearing time may even exceed 50% of the entire cycle, significantly reducing the traffic capacity. On the other hand, the alternating traffic section has the typical single-lane convoy driving characteristics, with narrow roads and poor road conditions, which are significantly different from the operating speed and traffic status of normal sections. In addition, there are large differences in the traffic performance of different types of vehicles in the alternating traffic section (such as the start time, passing time, speed, etc. of large and small vehicles), and the degree of influence on the saturated flow of different entrances is also different, which requires that the traffic control scheme must be accurately calibrated according to the actual traffic status. At the same time, the traffic volume characteristics of two-lane highways at different times are quite different, and the signal timing scheme also needs to consider real-time performance and have dynamic adaptability.

[0005] The patent number CN201910603409.5, "A method for optimizing signal timing at intersections with construction zones", proposes a signal timing optimization model for intersections with construction zones. The model is based on the classic following model and introduces multiple parameters such as speed difference to calculate the saturated flow rate of the island construction zone, the release rate state change moment of each entrance lane, the phase clearing time, etc., and finally establishes the objective function and finds the optimal solution as the signal timing in the case of a construction zone. However, this patent is mainly aimed at intersections with island construction zones, and the core of the optimization lies in the intersection signal control of the entrance and exit lanes. In typical two-lane scenarios, there is usually no complex multi-entry or exit signal interaction, but it is necessary to optimize the dynamic signal control of alternating release in a single direction. At the same time, the calculation of saturated flow rate and clearing time is based on fixed geometric parameters and traffic flow characteristics, and lacks the ability to dynamically adjust real-time traffic conditions.

[0006] The patent number CN202110461029.6, "Construction Area Traffic Control and Induction Method Based on Dynamic Traffic Flow Short-term Forecasting", uses a neural network model to construct a short-term traffic flow prediction model for key points of spatiotemporal convergence of traffic flow. By acquiring traffic information during the construction period in real time, analyzing the road service level load, and formulating a diversion plan to alleviate road congestion during the construction period. However, it focuses on solving the overall traffic control of the road network around the construction area, focusing on the flow distribution and induction problems of the road network around the construction area, rather than the specific signal control of alternating single lanes, and the model is highly complex and has poor applicability.

[0007] The patent number CN109935092A, "Single-lane two-way traffic adaptive signal light control system", proposes an adaptive signal light control system suitable for single-lane two-way traffic in construction areas. The vehicle detectors sense the queue length and arrival of vehicles at both ends in real time, and use adaptive algorithms to dynamically adjust the release time of the signal light. However, this patent is mainly aimed at short-distance single-lane two-way traffic control in construction areas, and does not consider the situation where the narrow road section is long or the sight distance is limited. At the same time, the differences in vehicle types (such as large vehicles and small vehicles) and dynamic traffic flow characteristics (such as passing speed) are not sufficiently considered.

[0008] The paper "Signal Control Method and Simulation Research for Two-Way Two-Lane Construction Zone" proposes a strategy to add signal control to address the problem of bottlenecks and reduced traffic capacity in closed sections of two-way two-lane highway construction. On the one hand, the patent uses Vissim simulation software to adjust different parameters, and the signal control model is based on preset parameter settings, lacking the ability to dynamically adjust real-time traffic conditions. In addition, the paper assumes that the average speed through the construction zone is the same and the saturated flow rate of different entrances is the same. However, in real scenarios, the passing speeds of different vehicle models vary greatly, and the saturated flow rates are different in different disaster scenarios.

[0009] At present, the research on traffic strategies for two-lane highway sections under the influence of disaster events and road construction still has the following shortcomings:

[0010] (1) Currently, the main method for maintaining traffic flow in one direction on two-lane highways is manual control. This method is arbitrary and slow to respond, resulting in long average vehicle delays and low overall traffic efficiency. In addition, existing technologies or models are mainly based on signal optimization or flow control models for multi-lane, urban roads or highway construction areas. Their effectiveness and applicability under two-lane conditions have rarely been verified, and the applicability of the models is limited.

[0011] (2) Most current signal timing models calculate saturated flow rate based on the stop line method, assuming that vehicles continue to accelerate after crossing the stop line. However, in the typical scenario of the present invention, vehicles in the alternating traffic section show obvious single-lane convoy driving characteristics, and due to the poor driving conditions of the section, the speed difference of vehicles when passing the alternating traffic section is large. The existing model is difficult to apply to one-way traffic scenarios with longer distances.

[0012] (3) Many models use complex traffic flow prediction methods (such as neural networks and genetic algorithms) and rely on large amounts of historical data and real-time data processing, which increases the difficulty of applying strategies in emergency situations, especially on two-lane roads in mountainous areas with limited data or high real-time requirements, which makes it difficult to meet the needs of rapid response. At the same time, there is a lack of comprehensive consideration of factors such as the start time, passing speed, and traffic volume differences of different vehicle types (such as trucks and cars), making it difficult to meet the changing traffic needs in typical scenarios of two-lane roads.

[0013] Therefore, in order to solve the problem of alternating traffic in narrow sections of two-lane highways in disaster events, construction, planned control or other special scenarios, a scientific and efficient signal timing method is urgently needed to dynamically adapt to actual traffic conditions, improve traffic efficiency and ensure traffic safety. In response to this demand, the present invention aims to propose a dynamic timing method for alternating traffic signals of single lanes in a local section of a two-lane highway, which can realize the dynamic organization of traffic flow in narrow sections of two-lane highways through reasonable data collection and scientific timing models, and solve the shortcomings of the existing technology. Summary of the invention

[0014] In view of the problems existing in the prior art of two-lane highway section traffic strategy under typical scenarios, such as low manual control efficiency, inapplicability of existing signal timing models, and insufficient dynamic adaptability, the present invention proposes a signal dynamic timing method specifically suitable for single-lane alternating traffic in local sections of two-lane highways. Traffic flow data is collected in real time through system-deployed data acquisition, and the differences in saturation flow rates of different entrance lanes, start-up time, passing speed and delay between large and small vehicles are comprehensively considered. The alternating traffic signal timing scheme is dynamically calculated to optimize the traffic flow in local sections of two-lane highways under the influence of events, and realize safe and efficient alternating traffic of vehicles.

[0015] In order to solve the above technical problems, the present invention provides a technical solution: a method for dynamic timing of single-lane alternating traffic signals in a local section of a two-lane highway, comprising the following steps:

[0016] (1) Obtain the event attribute characteristics of the local road section affected by the event and the basic information of the road section where the event occurred, and determine the traffic impact range of the local road section of the event;

[0017] (2) Deploy traffic flow collection equipment to collect traffic flow data of alternating traffic on local sections of roads under the influence of the event, and analyze the traffic flow characteristics of the alternating traffic sections;

[0018] (3) Using measured traffic flow data, considering the impact of different vehicle types on traffic delays, calculating the equivalent volume of small vehicles based on delays, and constructing a small vehicle equivalent volume prediction model to calculate the adverse impact factor of large vehicles;

[0019] (4) Observe the actual travel time of the fleet on the alternating traffic section, correct the saturated flow of different entrances, and construct a dynamic signal timing method for alternating traffic on the section affected by events on two-lane highways.

[0020] Preferably, the step (1) specifically comprises:

[0021] (1.1) Obtaining event attribute features: Obtain the event type, location, duration, and length of the road section occupied by the event through on-site traffic surveys;

[0022] (1.2) Collect basic information about the road section where the incident occurred: Obtain the number of lanes, lane width, road design speed, and road design capacity of the road section where the incident occurred through on-site traffic surveys.

[0023] (1.3) Determine the traffic impact range L of the alternate traffic section of the event d .

[0024] Preferably, in step (1.3), L d The method for determining , specifically comprises the following steps:

[0025] (1.3.1) According to the provisions of the Highway Maintenance Safety Operation Regulations (JTG H30-2015), during construction, maintenance personnel must be deployed upstream and downstream of L1 outside the work area, and warning signs must be set up on both sides of the road section affected by the incident. The distance between the signs is determined in accordance with the Highway Maintenance Safety Operation Regulations (JTG H30-2015);

[0026] (1.3.2) The additional length L2 is determined based on the actual staff placement needs, road visibility conditions, safety and other factors of the alternate traffic section to ensure the operating space for staff and the safety and smoothness of traffic flow;

[0027] (1.3.3) Determine the traffic impact range of the alternate traffic section under the influence of the event as Ld:

[0028] Ld=L0+2L1+2L2.

[0029] Preferably, in step (1.3.2), the method for determining L2 specifically includes the following contents:

[0030] (1.3.2.1) According to the operational needs of the staff and the requirements for equipment placement, a temporary work area is designated in the available area of ​​the alternate traffic section. The length of the temporary work area is L S ;

[0031] (1.3.2.2) To ensure that drivers can clearly see the work area and warning signs before entering the alternating traffic section, the sight distance should meet the following formula:

[0032]

[0033] Where, L v is the minimum sight distance in m, V is the design speed in km / h, T r is the driver's reaction time, generally 2.5s; the additional length of the curved road section is 15-30m;

[0034] (1.3.2.3) The additional length of a two-lane highway section with alternating single lane traffic is calculated using the following formula:

[0035] L2=L S +L V ;

[0036] Preferably, the step (2) specifically includes:

[0037] (2.1) Deployment of traffic flow collection equipment: Deploy MetroCount traffic flow detectors at free flow sections and control sections of different entrances outside the traffic impact range of the alternate traffic section; deploy drones over the midstream sections affected by the incident;

[0038] (2.2) Traffic flow detectors installed at different entrances of the road section affected by the incident are used to collect traffic characteristic parameters including vehicle entry or exit time, vehicle type information, and speed at different entrances;

[0039] (2.3) According to the time difference between the free flow section and the controlled section of different entrance channels, the arrival traffic volume is statistically determined;

[0040] (2.4) The video data of the road section affected by the incident is collected by deploying drones in the middle of the road section affected by the incident, and the traffic flow characteristic parameters such as passing speed, acceleration, and start time are extracted using video analysis tools.

[0041] Preferably, the step (3) specifically comprises:

[0042] (3.1) Based on the collected traffic flow data, the SUMO simulation software is used to construct a simulation scenario of the impact of the two-lane highway event. The total delay when the traffic flow is composed of all small cars is collected, and the average delay value of small cars is calculated:

[0043]

[0044] In the formula, i=1, 2, representing different inlet channels, i=1 represents the upstream inlet channel, and i=2 represents the downstream inlet channel; d i,0 is the average delay of each small car at different entrance lanes, Q i,0 is the total traffic volume (vehicles / hour) when all the entrance lanes are small cars, D i,0 The total delay when all the entrance lanes are small cars;

[0045] (3.2) Based on the total delay collected when large vehicles are mixed in, the average delay when trucks are mixed in is calculated:

[0046]

[0047] Where, d i,t is the average delay of large vehicles mixed into different entrance lanes, Q i,t is the total flow of large vehicles at different entrances, in vehicles / hour, D i,t The total delay caused by the mixing of large vehicles from different import lanes;

[0048] (3.3) Calculate the large vehicle mixing rate:

[0049]

[0050] In the formula, p i,H is the mixing rate of large vehicles at different import lanes, Q i,t is the total flow of large vehicles at different entrances, in vehicles / hour; Qi is the total flow of large vehicles at different entrances, in vehicles / hour;

[0051] (3.4) Considering the impact of large vehicles on the delay of two-lane highways, the small vehicle equivalent D_SVE based on the delay is calculated:

[0052]

[0053] (3.5) Based on the calculated value of D_SVE, a relationship model between the small vehicle equivalent quantity D_SVE and the large vehicle mixing rate and total flow is established;

[0054]

[0055] In the formula, α i is the coefficient of large vehicle mixing rate at different import lanes, β i is the coefficient of total flow rate at different inlets;

[0056] (3.6) The prediction model of the equivalent quantity of small vehicles considering the delay of large vehicles is as follows:

[0057]

[0058] (3.7) The method for calculating the adverse impact factor of large vehicles on the section of a two-lane highway affected by an event is:

[0059]

[0060] In the formula, p i,H is the mixing rate of large vehicles at different entrances, D_SVE iis the small car equivalent value D_SVE of different import lanes;

[0061] Preferably, the step (4) specifically comprises:

[0062] (4.1) Calculate the phase clearing time of the section affected by the event on a two-lane highway;

[0063]

[0064] Where, L d is the length of the traffic impact zone of the two-lane highway incident, p i,H is the mixing rate of large vehicles at different import lanes, v i,H is the average passing speed of large vehicles at different entrances, v i,C is the average passing speed of small vehicles at different entrance lanes;

[0065] (4.2) Considering the differences in the starting time and passing through the event section of large and small vehicles, the total loss time W per signal cycle of the event-affected section of the two-lane highway is calculated;

[0066]

[0067] Where, t T is the starting time of large vehicles; t C is the start time of the small car, t i,AR The full red duration of each phase of the road section affected by events at different entrances;

[0068] (4.3) The time when the last vehicle of the convoy enters and leaves the alternating traffic section is collected by the cross-section traffic detector for 10-15 cycles, and the actual travel time of the convoy on the alternating traffic section is obtained. The 85% percentile value is used as the actual travel time Tc of the alternating traffic section; the saturated flow of different entrances of the alternating traffic section is corrected by the actual travel time Tc, and the maximum value of the saturated flow of different entrances after correction is taken as the final result; the calculation formula is as follows:

[0069]

[0070] Where N i,c is the total number of convoys at each import lane, T i,c The actual observed convoy travel time at each entrance;

[0071] (4.4) Considering the impact of large vehicle delays, the adverse impact factor of large vehicles is used to correct the arrival flow of different entrances, and the sum of the maximum flow ratios of each signal phase is calculated;

[0072]

[0073] In the formula, q i,cis the actual traffic volume of small cars on different import lanes, q i,t is the actual traffic volume of large vehicles on different import lanes, f i,HV is the adverse impact factor of large vehicles, C i,s is the corrected saturation flow rate of different inlet channels;

[0074] (4.5) Calculate the optimal signal period for the section of a two-lane highway affected by an event:

[0075]

[0076] Where W is the total loss time per cycle, and Y is the sum of the maximum flow ratios of each signal phase;

[0077] (4.6) Calculate the green light display time g for each phase i,e '.

[0078] (4.7) Calculate the red light display time of each phase:

[0079] R i,e =Tg i,e '

[0080] In summary, we get the signal cycle duration T and the green light duration g of each phase. i,e and display red light duration R i,e , together forming the signal timing plan for the section of a two-lane highway affected by the incident.

[0081] Preferably, the step (4.6) displays the green light time g i,e The calculation method of ' includes:

[0082] (4.6.1) Calculate the total effective green time:

[0083] G e =T-2W

[0084] (4.6.2) Calculate the effective green light time of each phase:

[0085]

[0086] (4.6.3) Calculate the green light time of each phase:

[0087] g i,e '=g i,e +t T +t C

[0088] In the formula, G e is the total effective green time per cycle, g i,e is the effective green light time of each phase, g i,e' is the green light display time of each phase, Y is the sum of the maximum flow ratios of all signal phases that make up the cycle, and y i is the maximum flow ratio of phase i.

[0089] The advantages of the present invention compared with the prior art are:

[0090] 1. The present invention constructs a signal timing optimization model based on dynamic traffic flow characteristics, collects traffic flow data of the event-affected section in real time for the special scenario of the alternating traffic section of a two-lane highway, including actual travel time, vehicle type ratio, and actual arrival traffic volume, and dynamically adjusts the signal cycle and phase timing scheme. The method can quickly adapt to traffic fluctuations in the alternating traffic section, reduce vehicle delays under manual command, improve vehicle traffic efficiency, and enhance the flexibility and dynamic adaptability of signal timing in the alternating traffic section of a two-lane highway.

[0091] 2. The present invention takes into account the distance between sign settings, the operating requirements of staff, the additional length of equipment placement, and the minimum sight distance, and determines the traffic impact range of the alternating traffic section. It also uses drones and cross-sectional sensors to comprehensively collect traffic flow characteristics of the alternating traffic section, uses observation data to accurately correct the saturated flow of the entrance road of the alternating traffic section, and calculates the phase clearing time in combination with dynamic traffic flow characteristics, so that the signal timing is more in line with actual needs. Through dynamic signal control, the traffic control problem of alternating traffic under complex conditions such as limited visibility or long sections is effectively solved.

[0092] 3. Aiming at the significant impact of large vehicles on traffic delays on alternating traffic sections of two-lane highways, the present invention proposes a small vehicle equivalent prediction model based on delays, and introduces the adverse impact factors of large vehicles to dynamically correct the signal timing scheme, which can effectively reduce the impact of large vehicle delays on the overall traffic efficiency and improve the overall traffic flow conditions of the alternating traffic sections during the event.

[0093] 4. The present invention uses real-time traffic data collection technology, combined with a dynamic signal timing optimization model, to quickly respond to the impact of events on alternate traffic sections without relying on a large amount of historical data. This technology is particularly suitable for disaster scenarios on two-lane highways with sparse data and significant traffic flow fluctuations, providing efficient and reliable technical support for complex and changeable road section traffic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 The invention provides a dynamic timing method for single lane alternating traffic signals on a local section of a two-lane highway.

[0095] Figure 2 This is a schematic diagram of alternating single-lane traffic on a local section of road affected by a two-lane incident.

[0096] Figure 3This is a schematic diagram of the layout of data collection equipment for the dynamic timing scheme of single-lane alternating traffic signals on a partial section of a two-lane highway.

[0097] Figure 4 Traffic volume statistics of different entrances to the Sichuan-Tibet G318 road section affected by the disaster event;

[0098] Figure 5 This is a splicing diagram of the Sichuan-Tibet G318 road sections affected by the disaster;

[0099] Figure 6 This is a schematic diagram of the one-way alternating traffic signal timing for the section of a two-lane highway affected by an incident. DETAILED DESCRIPTION

[0100] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0101] Example:

[0102] The embodiment of the present invention provides a method for dynamically timing a single lane alternating traffic signal on a local section of a two-lane highway, such as Figure 1 As shown, the modeling method includes the following steps:

[0103] Step (1) obtaining the event attribute characteristics of the local road section affected by the event and the basic information of the road section where the event occurred, and determining the traffic impact range of the local road section of the event;

[0104] (1.1) Obtaining event attribute characteristics: Obtain the disaster event type, location, duration, and length of the road section occupied by the disaster event L0 through on-site traffic survey;

[0105] The road network of the Tibet Autonomous Region is mainly composed of national highways, provincial highways and county highways. Due to the limitations of the geographical environment and economic development level, the development of road facilities is relatively lagging. At the same time, affected by the topographic and geological conditions, geological disasters frequently occur in the Tibet Autonomous Region, including landslides, water damage, mudslides, rockfalls, etc. Therefore, the road network of the Tibet Autonomous Region, where two-lane roads account for a large proportion and disaster events frequently occur, is selected as the object, and the specific example is the Sichuan-Tibet Highway G318 line Basu-Bomi section, a disaster-affected point, as an example for analysis. Furthermore, the on-site investigation found that the attributes of the disaster events are shown in Table 1.

[0106] Table 1 Attribute characteristics of disaster events detected by on-site investigation

[0107] Disaster event type Occurrence location Duration of disaster event Disaster event section length L0 Large landslide Near Mingdong, No. 1 Niutagou, G318, Sichuan-Tibet Highway 4 months 1230m

[0108] (1.2) Collect basic information of the road section where the incident occurred: The number of lanes, lane width, road design speed, and road design capacity of the road section where the incident occurred were obtained through on-site traffic surveys. Furthermore, the on-site investigation revealed that a large-scale landslide geological disaster occurred on the Basu-Bomi section of Sichuan-Tibet Highway G318. The basic information of the road section where the incident occurred is shown in Table 2:

[0109] Table 2 Basic information of the road section where the incident occurred

[0110] Number of lanes Lane Width Number of occupied lanes Road design speed (km / h) Designed road capacity (vehicles / hour / lane) 2 3.75m 1 40 1000

[0111] (1.3) Determining the traffic impact range Ld of the disaster event includes the following steps:

[0112] (1.3.1) Determine the sign setting distance L1:

[0113] According to the Highway Maintenance Safety Operation Regulations (JTGH30-2015), the road construction maintenance area consists of four sections: warning area → upstream transition area → work area → downstream transition area. Figure 2 shown.

[0114] Secondly, the investigation shows that in this embodiment, one person is posted at 5m upstream and downstream of the disaster event area, and cones are used to temporarily close the two-lane road, and a speed limit of 20km / h is set on both sides of the disaster event impact area, so L1 = 5m;

[0115] (1.3.2) Based on the actual staff placement needs, road visibility conditions, safety and other factors of the alternate traffic section, the additional length L2 of the work area of ​​the alternate traffic section is determined:

[0116] (1.3.2.1) According to the on-site investigation, according to the operation requirements and equipment placement requirements of the workers in the construction and renovation of the No. 1 open tunnel of G318 Basu-Bomi Niutagou, a temporary work area is demarcated in the available area of ​​the alternate traffic section, and the length of the temporary work area is Ls = 55m;

[0117] (1.3.2.2) To ensure that drivers can clearly see the work area and warning signs before entering the alternate traffic section, the minimum sight distance on the G318 Basu-Bomi alternate traffic section is:

[0118]

[0119] (1.3.2.3) Finally, the traffic impact range of the disaster event is determined to be L d :

[0120] L d =L0+2L1+2L2=1230+2*5+2*(55+28)=1406m.

[0121] Step (2) deploying traffic flow collection equipment to collect traffic flow data of alternating traffic on a local road section under the influence of the event, and analyzing traffic flow characteristics of the alternating traffic section;

[0122] (2.1) Deployment of traffic flow collection equipment: Deploy MetroCount traffic flow detectors in the free flow sections and control sections of different entrances outside the traffic impact range of the alternate traffic section; deploy drones over the midstream sections affected by the disaster event;

[0123] (2.2) Traffic flow detectors installed at different entrances of the road section affected by the incident are used to collect traffic characteristic parameters including vehicle entry or exit time, vehicle type information, and speed at different entrances;

[0124] (2.3) According to the time difference between the free flow section and the controlled section of different entrance channels, the arrival traffic volume is statistically determined;

[0125] First, referring to the vehicle dimensions in the Highway Engineering Technical Standard (JTGBO1-2014), vehicles with a total length of 6m or more are considered large vehicles, and vehicles with a total length of less than 6m are considered small vehicles; the vehicle classification standards are shown in Table 3;

[0126] Table 3 Classification standards for different vehicle models

[0127] Model Vehicle classification standards Small car Total length of vehicle ≥6m Large car Total length of vehicle: 6m

[0128] Secondly, using the traffic flow data collected by MetroCount, the number of vehicles passing through the two sections of the Basu free flow end (1# traffic flow sensor) and the Basu control end (2# traffic flow sensor) in each time period was extracted from the data. The actual arrival traffic volume information of the Basu entrance at each time interval was obtained as follows: Figure 4 As shown; similarly, according to the number of vehicles in the two sections of the Bomi free flow end (3# traffic flow sensor) and the Bomi control end (4# traffic flow sensor), the actual arrival traffic volume information of the Bomi entrance at each time interval is obtained.

[0129] (2.4) Video data of the road section affected by the disaster is collected by deploying drones in the middle of the road section affected by the disaster, and video analysis tools are used to extract traffic flow characteristic parameters such as passing speed, acceleration, and start time;

[0130] First, since the road section affected by the disaster event is long and a single drone flight cannot fully cover it, a segmented overlapping photography method is used to collect data on the entire road section affected by the disaster event. The drone takes segmented photos along the flight path of the road section affected by the disaster event to ensure that there is an appropriate overlapping area between adjacent photos. In the collected photos, significant landmarks or structural features of the road section affected by the disaster event, such as curbs, markers or construction equipment, are marked as splicing reference points. Image processing software is used to splice overlapping photos according to key feature points to form a continuous image of the road section affected by the disaster event. The spliced ​​Niutagou No. 1 Mingdong disaster section is shown in the figure below. Figure 5 shown.

[0131] Then, the video trajectory extraction software DataFromSky was used to automatically identify and track the movement trajectory of the vehicles. The average speed of large vehicles in the disaster-affected area was 10 km / h, and the acceleration of large vehicles was 1.0 m / s2; the average speed of small vehicles was about 15 km / h, and the acceleration of small vehicles was 2.0 m / s 2 .

[0132] Next, using two frames of photos taken by the drone at the same location, the displacement of large and small vehicles between the static and start frames was converted into actual distances using the scale of the photos of the spliced ​​disaster event shadow section. Combined with the timestamps of the photos, the start delay of large vehicles was calculated to be 6 seconds and that of small vehicles to be 3 seconds.

[0133] Finally, according to the collected data, the statistics show that the peak traffic volume of the eastbound entrance road (Bomi-Basu) is 95 (vehicles / hour / lane), and the peak traffic volume of the eastbound entrance road (Bomi-Basu) is 131 (vehicles / hour / lane); the peak traffic volume of the westbound entrance road (Basu-Bomi) is 175 (vehicles / hour / lane), and the peak traffic volume of the westbound entrance road is 215 (vehicles / hour / lane). The truck mixing rate of the westbound entrance road (Basu-Bomi) is 43%, and the truck mixing rate of the eastbound entrance road (Bomi-Basu) is 0.31%.

[0134] In summary, the characteristic parameters of the road sections affected by the disaster event are shown in Table 4.

[0135] Table 4 Basic characteristic parameters of the sections affected by disaster events on two-lane highways

[0136]

[0137]

[0138] Step (3) using measured traffic flow data, considering the impact of different vehicle types on traffic delays, calculating the equivalent of small vehicles based on delays, building a small vehicle equivalent prediction model, and calculating the adverse impact factor of large vehicles;

[0139] (3.1) Based on the collected traffic flow data, the SUMO simulation software is used to construct a simulation scenario of the impact of disaster events on a two-lane highway. The total delay when the traffic flow is composed of all small cars is collected, and the average delay value of each small car is calculated:

[0140]

[0141] In the formula, i=1, 2, representing different inlet channels, i=1 represents inlet channel 1, i=2 represents inlet channel 2; d i,0 is the average delay of each small car at different entrance lanes, Q i,0 is the total traffic volume (vehicles / hour) when all the entrance lanes are small cars, D i,0 Total delay when all the entrance lanes are small cars.

[0142] (3.2) Based on the total delay collected when large trucks are mixed in, the average delay for each truck mixed in scenario is calculated:

[0143]

[0144] Where, d i,t is the average delay of large vehicles mixed into different entrance lanes, Q i,t is the total flow of large vehicles at different entrances (vehicles / hour), D i,t The total delay caused by the mixing of large vehicles from different import lanes.

[0145] (3.3) Calculate the large vehicle mixing rate:

[0146]

[0147] In the formula, p i,H is the mixing rate of large vehicles at different import lanes, Q i,t is the total flow of large vehicles at different import lanes (vehicles / hour), Qi is the total flow of large vehicles at different import lanes (vehicles / hour).

[0148] (3.4) Considering the impact of large vehicles on the delay of two-lane highways, the small vehicle equivalent D_SVE based on the delay is calculated:

[0149]

[0150] (3.5) Studies have shown that vehicle delay is proportional to the relative number of large vehicles in traffic flow, so a linear relationship is assumed. Based on the calculated value of D_SVE, a relationship model between the small vehicle equivalent D_SVE and the large vehicle mixing rate and total flow is established;

[0151]

[0152] In the formula, α i is the coefficient of large vehicle mixing rate at different import lanes, β i is the coefficient of total flow rate at different inlets.

[0153] (3.6) The prediction model of the equivalent quantity of small vehicles considering the delay of large vehicles is as follows:

[0154]

[0155] The best fitting result (R2≥0.85) is selected as the final value of the fitting parameters. The best fitting parameters of this embodiment are α=-0.32204, β=0.02763, R2=0.893. Therefore, the prediction model of the equivalent quantity of small vehicles considering the delay of large vehicles is:

[0156]

[0157] (3.7) Based on the small car equivalent prediction model, calculate the adverse impact factor of large vehicles on the section affected by the disaster event on the two-lane highway;

[0158]

[0159] In the formula, p i,H is the mixing rate of large vehicles at different entrances, D_SVE i is the small car equivalent value D_SVE at different import lanes.

[0160] Based on the small car equivalent prediction model, the calculation method of the adverse impact factor of large vehicles on the road section affected by the disaster event in this embodiment is:

[0161]

[0162] Step (4) observes the actual travel time of the fleet in the alternating traffic section, corrects the saturated flow of different entrance roads, and constructs a signal timing optimization model for alternating traffic on sections of two-lane highways affected by disaster events.

[0163] Based on the Webster signal timing method, truck delays are taken into account, the arrival flow is adjusted by adjusting the coefficient of the adverse impact factor of large vehicles, and combined with the actual situation of single-lane traffic control, a signal control method suitable for one-way alternating traffic on partially closed sections of two-way two-lane highways caused by disasters, road construction, etc. is proposed. The schematic diagram of signal control for one-way alternating traffic on partially closed sections of two-lane highways is shown in the figure below. Figure 6As shown in the figure, when the green light is on in phase 1, the red light is on in phase 2, and vehicles in phase 1 can pass; when the red light is on in phase 1, the last vehicle passing the stop line in phase 1 is allowed to pass, and phase 2 continues to keep the red light. Therefore, there is no yellow light time on the disaster-affected section of a two-lane highway, and the green light interval is the start time plus the time it takes for the last vehicle to pass through the traffic affected area of ​​the disaster, that is, the phase clearing time.

[0164] (4.1) Calculate the phase clearing time of the road section affected by the disaster event on a two-lane highway:

[0165] Phase clearing time of Bomi-Basu entrance:

[0166]

[0167] Phase clearing time of Basu-Bomi entrance:

[0168]

[0169] (4.2) Considering the differences in the starting time of large and small vehicles and the sections through which disaster events occur, the total loss time W per signal cycle of the section affected by the disaster event on the two-lane highway is calculated:

[0170] W=max{Σ(t T +t C +t i,AR )}=max{354.08,367.07}=367.07s

[0171] Where, t T is the starting time of large vehicles; t C is the start time of the small car, t i,AR The full red duration of each phase of the road section affected by disaster events at different entrances;

[0172] (4.3) For long-distance alternating traffic sections, the saturated flow calculated based on the passing time of a single vehicle cannot directly reflect the traffic capacity. Starting from the traffic capacity per unit time of the fleet (i.e., the fleet traffic rate), the saturated flow calculation method based on the stop line is improved:

[0173] First, the time when the first vehicle of the convoy entered and the last vehicle left the G318 Basu-Bomi alternating section was collected according to the cross-section traffic detector for 10 cycles, and the actual travel time of the observed alternating section was obtained, and the 85% percentile value was used as the actual travel time Tp of the alternating section. The actual travel time of the Basu-Bomi entrance road is 18 minutes, and the actual travel time of the Bomi-Basu entrance road is 13 minutes.

[0174] Then, the saturated flow rates of different entrances of the alternating traffic section are corrected according to the actual travel time Tp.

[0175] The corrected saturation flow rate of the Bomi-Basu inlet is:

[0176]

[0177] The corrected saturation flow rate of the Basu-Bomi inlet is:

[0178]

[0179] In summary, the corrected saturation flow of the alternating traffic section of Sichuan-Tibet G318 is:

[0180]

[0181] Where N i,c is the total number of convoys at each import lane, T i,c It is the actual observed convoy travel time of each entrance.

[0182] (4.4) Considering the impact of large vehicle delays, the arrival flow of different entrances is corrected using the adverse impact factor of large vehicles, and the sum of the maximum flow ratios of each signal phase is calculated;

[0183]

[0184] In the formula, q i,c is the actual traffic volume of small cars on different import lanes, q i,t is the actual traffic volume of large vehicles on different import lanes, f i,HV is the adverse impact factor of large vehicles, C i,s is the corrected saturation flow rate at different inlet ports.

[0185] (4.5) Calculate the optimal signal period for the section of a two-lane highway affected by a disaster event.

[0186]

[0187] Where W is the total loss time per cycle, and Y is the sum of the maximum flow ratios of each signal phase.

[0188] (4.6) Calculate the green light display time g for each phase i,e ';

[0189] First, calculate the total effective green time per cycle:

[0190] G e =T-2W=1585.65-2×367.07=851.49(s)

[0191] Then, calculate the effective green time of each phase:

[0192] ① Effective green light time of each phase of Bomi-Basu entrance road:

[0193]

[0194] ②Effective green light time of each phase of Basu-Bomi entrance:

[0195]

[0196] Next, calculate the green light display time of each phase:

[0197] ① The green light display time of each phase of the Bomi-Basu entrance road:

[0198] g 1,e '=g 1,e +t T +t C =241.30+6+3=250.31(s)

[0199] ② The green light display time of each phase of the Basu-Bomi entrance road:

[0200] g 2,e '=g 2,e +t T +t C =610.19+6+3=619.19(s)

[0201] (4.7) Calculate the red light display time for each phase

[0202] ① The red light display time of each phase of the Bomi-Basu entrance road:

[0203] R 1,e =Tg 1,e '=1585.65-250.31=1335.35(s)

[0204] ② Red light display time of each phase of Basu-Bomi entrance road:

[0205] R 2,e =Tg 2,e '=1585.65-619.19=966.46(s)

[0206] In summary, according to the alternating traffic signal timing optimization model for the section affected by disaster events on the two-lane highway proposed in the present invention, the traffic flow characteristic parameters extracted from the measured data are used to calculate the optimal signal cycle duration of a disaster-affected point on the Basu-Bomi section of the Sichuan-Tibet Highway G318, which is 26.4 minutes. The signal timing scheme is shown in Table 5.

[0207] Table 5G318 Signal timing plan for a section affected by a disaster

[0208]

[0209] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A method for dynamic timing of single lane alternating traffic signals on a local section of a two-lane highway, characterized in that: The following steps are involved: (1) Obtain the event attribute characteristics of the local road section affected by the event and the basic information of the road section where the event occurred, and determine the traffic impact range of the local road section of the event; (2) Deploy traffic flow collection equipment to collect traffic flow data of alternating traffic on local sections of roads under the influence of the event, and analyze the traffic flow characteristics of the alternating traffic sections; (3) Using measured traffic flow data, considering the impact of different vehicle types on traffic delays, calculating the equivalent volume of small vehicles based on delays, and constructing a small vehicle equivalent volume prediction model to calculate the adverse impact factor of large vehicles; (4) Observe the actual travel time of the fleet on the alternating traffic section, correct the saturated flow of different entrances, and construct a dynamic signal timing method for alternating traffic on the section affected by events on two-lane highways.

2. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 1, characterized in that: The step (1) specifically comprises: (1.1) Obtaining event attribute features: Obtain the event type, location, duration, and length of the road section occupied by the event through on-site traffic surveys; (1.2) Collect basic information about the road section where the incident occurred: Obtain the number of lanes, lane width, road design speed, and road design capacity of the road section where the incident occurred through on-site traffic surveys. (1.3) Determine the traffic impact range L of the alternate traffic section of the event d .

3. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 2, characterized in that: In step (1.3), L d The method for determining , specifically comprises the following steps: (1.3.1) According to the provisions of the Highway Maintenance Safety Operation Regulations (JTG H30-2015), during construction, maintenance personnel must be deployed upstream and downstream of L1 outside the work area, and warning signs must be set up on both sides of the road section affected by the incident. The distance between the signs is determined in accordance with the Highway Maintenance Safety Operation Regulations (JTG H30-2015); (1.3.2) The additional length L2 is determined based on the actual staff placement needs, road visibility conditions, safety and other factors of the alternate traffic section to ensure the operating space for staff and the safety and smoothness of traffic flow; (1.3.3) Determine the traffic impact range of the alternate traffic section under the influence of the event as Ld: Ld=L0+2L1+2L2.

4. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 3, characterized in that: In step (1.3.2), the method for determining L2 specifically includes the following: (1.3.2.1) According to the operational needs of the staff and the requirements for equipment placement, a temporary work area is designated in the available area of ​​the alternate traffic section. The length of the temporary work area is L S ; (1.3.2.2) To ensure that drivers can clearly see the work area and warning signs before entering the alternating traffic section, the sight distance should meet the following formula: Where, L v is the minimum sight distance in m, V is the design speed in km / h, T r is the driver's reaction time, generally 2.5s; the additional length of the curved road section is 15-30m; (1.3.2.3) The additional length of a two-lane highway section with alternating single lane traffic is calculated using the following formula: L2=L S +L V。 5. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 1, characterized in that: The step (2) specifically comprises: (2.1) Deployment of traffic flow collection equipment: Deploy MetroCount traffic flow detectors at free flow sections and control sections of different entrances outside the traffic impact range of the alternate traffic section; deploy drones over the midstream sections affected by the incident; (2.2) Traffic flow detectors installed at different entrances of the road section affected by the incident are used to collect traffic characteristic parameters including vehicle entry or exit time, vehicle type information, and speed at different entrances; (2.3) According to the time difference between the free flow section and the controlled section of different entrance channels, the arrival traffic volume is statistically determined; (2.4) Video data of the road section affected by the event is collected by deploying drones in the middle of the road section affected by the event, and video analysis tools are used to extract traffic flow characteristic parameters such as passing speed, acceleration, and start time.

6. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 1, characterized in that: The step (3) specifically comprises: (3.1) Based on the collected traffic flow data, the SUMO simulation software is used to construct a simulation scenario of the impact of the two-lane highway event. The total delay when the traffic flow is composed of all small cars is collected, and the average delay value of small cars is calculated: In the formula, i=1, 2, representing different inlet channels, i=1 represents the upstream inlet channel, and i=2 represents the downstream inlet channel; d i,0 is the average delay of each small car at different entrance lanes, Q i,0 is the total traffic volume (vehicles / hour) when all the entrance lanes are small cars, D i,0 The total delay when all the entrance lanes are small cars; (3.2) Based on the total delay collected when large vehicles are mixed in, the average delay when trucks are mixed in is calculated: Where, d i,t is the average delay of large vehicles mixed into different entrance lanes, Q i,t is the total flow of large vehicles at different entrances, in vehicles / hour, D i,t The total delay caused by the mixing of large vehicles from different import lanes; (3.3) Calculate the large vehicle mixing rate: In the formula, p i,H is the mixing rate of large vehicles at different import lanes, Q i,t is the total flow of large vehicles at different entrances, in vehicles / hour; Qi is the total flow of large vehicles at different entrances, in vehicles / hour; (3.4) Considering the impact of large vehicles on the delay of two-lane highways, the small vehicle equivalent DSVE based on the delay is calculated: (3.5) Based on the calculated value of D_SVE, a relationship model between the small vehicle equivalent quantity D_SVE and the large vehicle mixing rate and total flow is established; In the formula, α i is the coefficient of large vehicle mixing rate at different import lanes, β i is the coefficient of total flow rate at different inlets; (3.6) The prediction model of the equivalent quantity of small vehicles considering the delay of large vehicles is as follows: (3.7) The method for calculating the adverse impact factor of large vehicles on the section of a two-lane highway affected by an event is: In the formula, p i,H is the mixing rate of large vehicles at different entrances, D_SVE i is the small car equivalent value D_SVE at different import lanes.

7. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 1, characterized in that: The step (4) specifically comprises: (4.1) Calculate the phase clearing time of the section affected by the event on a two-lane highway; Where, L d is the length of the traffic impact zone of the two-lane highway incident, p i,H is the mixing rate of large vehicles at different import lanes, v i,H is the average passing speed of large vehicles at different entrances, v i,C is the average passing speed of small vehicles at different entrance lanes; (4.2) Considering the differences in the starting time and passing through the event section of large and small vehicles, the total loss time W per signal cycle of the event-affected section of the two-lane highway is calculated; Where, t T is the starting time of large vehicles; t C is the start time of the small car, t i,AR The full red duration of each phase of the road section affected by events at different entrances; (4.3) The time when the last vehicle of the convoy enters and leaves the alternating traffic section is collected by the cross-section traffic detector for 10-15 cycles, and the actual travel time of the convoy on the alternating traffic section is obtained. The 85% percentile value is used as the actual travel time Tc of the alternating traffic section; the saturated flow of different entrances of the alternating traffic section is corrected by the actual travel time Tc, and the maximum value of the saturated flow of different entrances after correction is taken as the final result; the calculation formula is as follows: Where N i,c is the total number of convoys at each import lane, T i,c The actual observed convoy travel time at each entrance; (4.4) Considering the impact of large vehicle delays, the adverse impact factor of large vehicles is used to correct the arrival flow of different entrances, and the sum of the maximum flow ratios of each signal phase is calculated; In the formula, q i,c is the actual traffic volume of small cars on different import lanes, q i,t is the actual traffic volume of large vehicles on different import lanes, f i,HV is the adverse impact factor of large vehicles, C i,s is the corrected saturation flow rate of different inlet channels; (4.5) Calculate the optimal signal period for the section of a two-lane highway affected by an event: Where W is the total loss time per cycle, and Y is the sum of the maximum flow ratios of each signal phase; (4.6) Calculate the green light display time g for each phase i,e ′; (4.7) Calculate the red light display time of each phase: R i,e =T-g i,e ′ In summary, we get the signal cycle duration T and the green light duration g of each phase. i,e and display red light duration R i,e , together forming the signal timing plan for the section of a two-lane highway affected by the incident.

8. The method for dynamic timing of single lane alternating traffic signals in a local section of a two-lane highway according to claim 7, characterized in that: The step (4.6) shows the green light time g i,e The calculation method of ′ specifically includes: (4.6.1) Calculate the total effective green time: G e =T-2W (4.6.2) Calculate the effective green light time of each phase: (4.6.3) Calculate the green light time of each phase: g i,e ′=g i,e +t T +t C In the formula, G e is the total effective green time per cycle, g i,e is the effective green light time of each phase, g i,e ' is the green light display time of each phase, Y is the sum of the maximum flow ratios of all signal phases that make up the cycle, and y i is the maximum flow ratio of phase i.

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