Expressway reconstruction and expansion separation overpass left entry guide change ramp and speed control method

Abstract

The present application relates to a kind of expressway reconstruction and expansion separation type overpass left entry guide change ramp and speed control method, belong to intelligent transportation field.The method is combined with traffic guide change organization scheme by entry ramp control, speed guidance, collision warning and other active control strategies, ensure that the vehicle speed on ramp at left entry merging area is close to the vehicle on the inner lane of main line, which is beneficial to ensure driving order, reduce the speed dispersion of merging area and improve traffic safety level.The present application can be applied to the left entry guide change point of separation type overpass during the reconstruction and expansion period of expressway, ordinary highway and urban road, for fine intelligent management and control of the left entry guide change point of separation type overpass during the reconstruction and expansion period of expressway.

Description

Technical Field

[0001] This invention belongs to the field of intelligent transportation and relates to a method for converting left-entry ramps and speed control in the reconstruction and expansion of grade-separated interchanges on highways. Background Technology

[0002] At interchanges, except for mainline branching and merging points, entrances and exits should be located on the right side of the mainline lanes. This means that entrance and exit ramps generally use right-out and right-in routes, not left-out and left-in routes. However, during highway reconstruction and expansion, due to the influence of new construction on both sides, some existing roads form interchanges with intersecting highways, while new roads form grade-separated interchanges with intersecting highways. This means the new roads and intersecting highways are not connected, creating a point for grade-separated interchange relocation during highway reconstruction and expansion. During the construction and operation phases of the new road, the entrance ramps normally merge right-in onto the existing road.

[0003] During the old road reconstruction phase, traffic from the entrance ramps merged into the new road via left-hand entry at the S-shaped switching point. This meant the entrance ramps directly merged into the inner fast lane of the main line, posing a serious safety hazard compared to the previous right-hand entry (where the entrance ramp merged into the outer slow lane of the main line). Due to acceleration conditions and lane changes, traffic merging from the entrance ramps generally struggled to quickly reach the fast lane speeds. Furthermore, vehicles with poor acceleration, such as large trucks, also participated. If left-hand entry was used, the fast-moving vehicles on the inner lane would interweave with the slower-moving vehicles from the entrance ramps, creating a high risk of collisions and other traffic accidents. In particular, the left-hand entry at the S-shaped switching point during the reconstruction and expansion phase was problematic. The S-shaped switching alignment at the traffic diversion point had poor conditions, with vehicle trajectories consisting of two opposing circular curves. Combined with the elevation difference between the old and new roads, the road environment was extremely complex, making it difficult for drivers to quickly accelerate to the required speed to merge into the main line, thus posing a significant safety risk.

[0004] Therefore, in response to concerns about left-entry ramps at grade-separated interchanges during highway reconstruction and expansion, there is an urgent need for a method for controlling the speed of left-entry ramps at grade-separated interchanges during highway reconstruction and expansion to ensure vehicle driving safety at these ramps. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for controlling the speed of left-entry ramps at grade-separated interchanges in highway reconstruction and expansion. This method overcomes the problems of high vehicle speed dispersion in the merging area, prominent risks and hidden dangers of vehicles merging into the main line from the left on the ramps, and limited acceleration conditions for vehicles during S-shaped switching at left-entry ramps formed during the reconstruction and expansion of highway hub interchanges under the new construction mode on both sides. This method ensures that the vehicle speed on the ramp at the left-entry merging area is close to that of the vehicles on the inner lane of the main line, improves the driving safety level of left-entry ramps, and achieves refined management and control of left-entry ramps at grade-separated interchanges in highway reconstruction and expansion.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for converting left-entry ramps and controlling speeds at grade-separated interchanges in highway reconstruction and expansion projects, specifically including the following steps:

[0008] S1: Ramp control, used to dynamically adjust the merging traffic flow at the entrance ramp;

[0009] The control cycles are numbered chronologically. Control algorithm utilizes cycle Traffic data acquired by the detector determines the cycle. The control parameters specifically include the following steps:

[0010] S11: Calculate three initial ramp regulation rates based on the mainline average speed, the mainline allowable traffic flow, and the ramp allowable queue length, respectively; then determine the actual ramp regulation rate based on the relationship between the three initial ramp regulation rates.

[0011] S12: Calculate the green light duration and red light duration of the ramp traffic lights;

[0012] S13: Divide the green light duration and red light duration of the ramp traffic lights into equal parts. N The copies are numbered in chronological order. ;use Green light red light, Green light red light,…, Green light The intermittent red light release method inputs the results into the ramp control facility and executes the ramp control strategy. The method of displaying the red light only after all the green lights have ended is not used here because ramp control needs to balance the traffic flow to ensure that vehicles on the ramp can travel at the prescribed speed.

[0013] S14: When each green light display is about to end, use detector III installed on the old road entrance ramp to obtain the vehicle type of the vehicle immediately approaching the entrance ramp;

[0014] S15: If the green light time exceeds the maximum value. If the green light turns red, the process returns to step S14; otherwise, proceed to step S16.

[0015] S16: If the sum of the green light duration and the red light duration of the ramp traffic lights in the current cycle exceeds the control cycle duration, then the control for this cycle ends.

[0016] S17: Determine whether to end ramp control. If yes, turn off ramp control; otherwise, proceed to step S11.

[0017] S2: Speed ​​guidance, used to adjust the speed of vehicles on the entrance ramp to ensure safe and smooth vehicle traffic;

[0018] Speed ​​guidance is achieved through control algorithms for multiple sets of speed guidance facilities I installed on the old road entrance ramps and multiple sets of speed guidance facilities II installed at the S-shaped transition points of the ramps. Among them, the control algorithm of speed guidance facility I adjusts the speed limit value according to the traffic light status and the length of the vehicle queue to ensure that drivers can safely decelerate and stop. The control algorithm of speed guidance facility II suggests drivers to accelerate step by step according to the speed of vehicles in the inner fast lane of the main line to ensure that the speed of vehicles on the ramps and vehicles on the main line remains close when vehicles merge into the main line from the left.

[0019] S3: Collision Warning, which includes the following steps:

[0020] S31: Use detector VI, which is set up in the merging area of ​​the new road, to obtain traffic data such as the position and speed of vehicles on the left-entry merging ramp and the vehicles in front and behind the inner fast lane;

[0021] S32: If all conditions for disabling collision warnings are met, then collision warnings are disabled; otherwise, collision warnings are enabled.

[0022] S33: Input the collision warning command into the information dissemination facility II located on the ramp at the left merging nose of the new road, and execute the collision warning strategy.

[0023] Furthermore, in step S11, the initial ramp adjustment rate is calculated based on the average speed of the main line, specifically including the following steps:

[0024] S1101: Using historical traffic flow data at the S-shaped switching point of the entrance ramp, a three-parameter relationship function of flow rate-density-speed is established, as shown in equation (1). Based on this, the allowable flow rate is determined according to the acceptable driving speed. The three-parameter relationship function of flow rate-density-speed can be in the form of equations (2) to (4).

[0025] (1)

[0026] (2)

[0027] (3)

[0028] (4)

[0029] in, For period Initial ramp adjustment rate for mainline average speed correction / (pcu / h); For period Average speed on the ramp (km / h); , , , , , For function parameters;

[0030] S1102: The average speed of the inner fast lane of the main line is obtained by using detector V set up upstream of the new main line, and then input into equation (1) to calculate the initial ramp adjustment rate. To ensure safe left-entry merging, the merging speed of vehicles on the entrance ramp in the main line merging area should be as similar as possible to the speed of the inner fast lane of the main line. If the flow of traffic on the entrance ramp is too large, vehicles will not be able to accelerate to the prescribed speed at the S-shaped transition point. Therefore, it is necessary to control the flow of traffic on the entrance ramp to ensure the acceleration conditions of vehicles on the ramp.

[0031] Furthermore, in step S11, the initial ramp regulation rate is calculated based on the allowable flow rate of the main line, specifically including the following steps:

[0032] S1111: Using historical traffic flow data from the mainline merging zone, a three-parameter relationship function of flow rate, density, and speed is established to determine the capacity of the mainline merging zone;

[0033] S1112: Use detector V, which is set up upstream of the main line of the new road, to obtain the main line flow rate upstream of the merging zone. Calculate the allowable flow rate of the entrance ramp based on the traffic capacity of the main line merging zone, i.e., the initial ramp regulation rate, as shown in equation (5).

[0034] (5)

[0035] in, For period The initial ramp regulation rate (pcu / h) that allows for traffic flow correction on the main line; Main line merging zone capacity / (pcu / h); For period upstream mainline flow rate in the merging zone / (pcu / h).

[0036] Furthermore, in step S11, the initial ramp regulation rate is calculated based on the allowable queue length of the ramp, specifically including: using detector III set on the old road entrance ramp to obtain the vehicle queue length and flow rate of the entrance ramp, and calculating the initial ramp regulation rate based on the allowable queue length of the entrance ramp, as shown in equation (6).

[0037] (6)

[0038] in, For period Initial ramp adjustment rate (pcu / h) for ramp queue length correction. For period Entrance ramp flow rate (pcu / h); To control the cycle duration in seconds; For period Queue length at entrance ramps / pcu; The permissible queue length for the entrance ramp is per pcu.

[0039] Furthermore, in step S11, the formula for determining the actual ramp adjustment rate is:

[0040] (7)

[0041] in, For period Actual ramp regulation rate / (pcu / h).

[0042] Furthermore, in step S12, the green light duration and red light duration of the ramp traffic lights are calculated, as shown in equations (8) and (9).

[0043] (8)

[0044] (9)

[0045] in, The saturation flow rate of the entrance ramp is expressed as (pcu / h). For period Green light duration of ramp traffic lights (in seconds); For period Red light duration of ramp traffic lights / seconds.

[0046] Furthermore, step S14 specifically includes: for vehicles with poor acceleration performance, such as large trucks, the green light duration of the ramp traffic lights can be extended. See equation (10); otherwise proceed to step S16; the alignment conditions at the S-shaped switching point are poor, and the truck may not be able to quickly reach the specified driving speed after stopping and then accelerating, so trucks should be stopped as much as possible;

[0047] (10)

[0048] in, Extend the green light time per unit of ramp traffic lights by / s; For detector III to acquire vehicle Distance to the stop line of the ramp signal light / m; For detector III to acquire vehicle Travel speed (m / s); The safety interval time is expressed in seconds.

[0049] Furthermore, in step S2, the control algorithm for speed guidance facility I specifically includes the following steps:

[0050] S201: When there is no queue at the entrance ramp of the old road and the ramp traffic lights are not in use, the speed limit value of each sub-speed guidance facility shall be taken as the design speed of the corresponding location.

[0051] S202: When a queue forms at the entrance ramp of the old road, the speed limit value of the sub-speed guidance facility closest to the end of the queue upstream is determined using the following formula (11), and a step-by-step deceleration method is adopted to ensure that vehicles arriving from upstream can safely decelerate and stop when they reach the end of the queue.

[0052] (11)

[0053] in, Minimum parking distance / m; Obtain the average vehicle speed (m / s) for detector III; Driver's reaction time in seconds; Acceleration due to gravity / (m / s²) 2 ); The longitudinal friction coefficient;

[0054] S203: When the ramp traffic light is green, the speed limit value of the sub-speed guidance facility from the traffic light to the head of the queue is taken as the design speed of the corresponding position; when the ramp traffic light is red, the speed limit value of the sub-speed guidance facility from the traffic light to the head of the queue is still determined in step S202.

[0055] Furthermore, in step S2, the control algorithm for speed guidance facility II specifically includes: numbering the multiple sets of speed guidance facilities II as follows: Each sub-speed guidance facility issues a recommended speed; sub-speed guidance facilities The recommended speed value is the same as the average speed of the inner fast lane of the main line obtained by detector V located upstream of the main line of the new road, and the sub-speed guidance facility The recommended speed is the design speed for the corresponding location. Other sub-facilities adopt a step-by-step acceleration method, but cannot exceed the design speed for the corresponding location. By guiding drivers to accelerate step by step, it is ensured that the merging speed of vehicles on the ramp is the same as the speed of the inner fast lane of the main line, reducing the speed dispersion in the merging area and improving driving safety.

[0056] Furthermore, step S32 specifically includes: if all of the following conditions for disabling collision warnings are met, then the collision warning is disabled; otherwise, the collision warning is enabled.

[0057] (12)

[0058] (13)

[0059] (14)

[0060] (15)

[0061] (16)

[0062] in, Obtain the speed of a single vehicle in (m / s) for detector VI; The free-flow velocity in the confluence zone is expressed as (m / s). For speed safety reduction factor; , , These represent the longitudinal positions (in meters) of vehicles on the merging ramp and vehicles in front and behind on the inner fast lane. , , The speeds of vehicles on the merging ramp and in front and behind the vehicles on the inner fast lane are respectively (m / s). , , These are the lengths (m) of vehicles on the merging ramp and the vehicles in front and behind the inner fast lane, respectively. Safety distance / m; Minimum headway / m; The lane change duration is expressed in seconds.

[0063] The beneficial effects of this invention are as follows: This invention can be applied to the left-entry diversion points of grade-separated interchanges during the reconstruction and expansion of highways, ordinary roads, and urban roads. It is used for the refined and intelligent management of left-entry diversion points of grade-separated interchanges during the reconstruction and expansion of highways. By combining active control strategies such as entrance ramp control, speed guidance, and collision warning with traffic diversion organization schemes, it ensures that the vehicle speed on the ramp at the left-entry merging area is close to that of the vehicles on the inner lane of the main line, which helps to ensure traffic order, reduce speed dispersion in the merging area, and improve traffic safety.

[0064] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0065] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0066] Figure 1 This is a facility layout diagram of the left-entry ramp and speed control method for highway reconstruction and expansion of grade-separated interchanges according to the present invention.

[0067] Figure 2 This is a flowchart illustrating the ramp control process of the left-entry ramp and speed control method for highway reconstruction and expansion grade-separated interchanges according to the present invention. Detailed Implementation

[0068] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0069] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0070] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0071] Please see Figures 1-2 To address the problems existing in the left-entry guidance point relocation of grade-separated interchanges during reconstruction and expansion, this invention provides a control method combining ramp control, speed guidance, and collision warning. The outer facilities are arranged as follows: Figure 1 As shown.

[0072] Depend on Figure 1(a) It can be seen that during the construction phase of the new road: a stop line and traffic lights are installed at the merging nose of the old road to control the entrance ramp signal; at the same time, information display facility 1 is installed at the merging nose of the old road to display messages such as "follow the traffic light instructions" and "be careful of merging" to remind drivers to pay attention to the traffic light instructions and improve the safety of ramp control; detector 1 is installed upstream of the main line of the old road, detector 2 is installed in the merging area of ​​the old road, and detector 3 is installed on the entrance ramp to obtain traffic flow data such as lane-level flow, density, speed, occupancy, and vehicle queuing, as well as vehicle-level driving data such as speed, position, driving trajectory, and vehicle type; multiple sets of speed guidance facilities 1 are installed on the entrance ramp to control the vehicle speed on the entrance ramp and ensure that vehicles can safely slow down and stop when they see a red light.

[0073] Depend on Figure 1 (b) It is known that during the old road reconstruction phase: Information display facility 2 is installed on the ramp at the merging nose of the new road left-entry lane, and information display facility 3 is installed on the main line to display information such as "collision warning," "caution: oncoming vehicles from the side," and "caution: left-entry merging," improving the safety of vehicles merging into the main line from the ramp; detector 5 is installed upstream of the new road main line, detector 6 is installed in the new road merging area, and detector 4 is installed at the S-shaped transition point of the ramp to obtain traffic flow data such as lane-level flow rate, density, speed, and occupancy, as well as vehicle-level speed, position, and trajectory data at the corresponding locations; multiple sets of speed guidance facilities 2 are installed at the S-shaped transition point of the ramp to guide the driving speed of vehicles on the ramp, ensuring that they merge into the main line at an appropriate speed. Traffic lights, stop lines, information display facility 1, detector 3, and speed guidance facility 1 are reused to avoid redundant construction and waste of resources. The signal control facilities are still located at the merging nose of the old road because the left-entry merging from the new road needs to ensure that vehicles on the ramp enter the main line at high speed. If the signal control facilities are located at the merging nose of the new road, due to the S-shaped switching alignment conditions, vehicles may not have enough time to slow down and stop before the signal light or to accelerate and enter the main line after the signal light. This could easily lead to dangerous driving behaviors such as sudden deceleration and sudden acceleration on the sharp bends and steep slopes of the S-shaped switching section, posing certain safety hazards.

[0074] Depend on Figure 1 (c) It can be seen that during the operation phase after the completion of the renovation and expansion project, traffic lights, parking lines, information release facilities 1 and 3, detectors 1, 2, 3, 5, speed guidance facilities 1, etc. are reused. Most of these facilities can be used during both the construction and operation phases, which is in line with the green design concept of "combining permanent and temporary facilities".

[0075] The control strategies during the construction and operation phases of new roads are relatively simple. This embodiment focuses on the control strategies during the reconstruction phase of existing roads, as follows:

[0076] (1) Ramp control is used to dynamically adjust the merging traffic flow at the entrance ramps. When the mainline traffic flow is high, the merging traffic flow at the ramps is reduced to avoid congestion and paralysis in the mainline merging area. When the mainline traffic flow is low, the vehicles in the inner fast lane of the mainline travel at higher speeds. By reducing the merging traffic flow at the ramps, the vehicle speeds on the ramps are increased, ensuring the safety of vehicles merging into the mainline merging area. Considering the poor acceleration performance of large trucks, if a large truck is detected as an approaching vehicle at the end of the green light at the ramp, the green light duration can be appropriately extended to reduce the number of times large trucks stop.

[0077] (2) Speed ​​guidance is used to adjust the speed of vehicles on the entrance ramp to ensure safe and smooth vehicle traffic. Speed ​​guidance facility 1 adjusts the speed limit value according to the traffic light status and the length of the vehicle queue to ensure that drivers can safely decelerate and stop. Speed ​​guidance facility 2 suggests drivers to accelerate step by step according to the speed of vehicles in the inner fast lane of the main line to ensure that the speed of vehicles on the ramp and vehicles on the main line remain close when vehicles merge into the main line from the left.

[0078] (3) Collision warning: Through intelligent road studs, external broadcasts, variable information signs and other sound, light, color and shape information release facilities, remind drivers of vehicles on the main line and ramps at the left entry merging point that a collision may occur, and that they should increase their driving attention to reduce the accident risk of vehicles merging.

[0079] like Figure 2 As shown, the specific control strategy for the old road reconstruction phase is as follows:

[0080] (1) Ramp control

[0081] The control cycles are numbered chronologically. Control algorithm utilizes cycle Traffic data acquired by the detector determines the cycle. The control parameters are as follows. The specific control process is as follows:

[0082] Step 1: Calculate the initial ramp adjustment rate based on the average speed of the main line.

[0083] Step 1.1: Using historical traffic flow data at the S-shaped transition point of the entrance ramp, establish a three-parameter relationship function of flow rate-density-speed, as shown in equation (1). Based on this, determine the allowable flow rate according to the acceptable driving speed. The three-parameter relationship function of flow rate-density-speed can be in the form of equations (2) to (4).

[0084] (1)

[0085] (2)

[0086] (3)

[0087] (4)

[0088] in, For period Initial ramp adjustment rate for mainline average speed correction / (pcu / h); For period Average speed on the ramp (km / h); , , , , , These are function parameters.

[0089] Step 1.2: Use detector 5 to obtain the average speed of the inner fast lane of the main line, and input it into formula (1) to calculate the initial ramp adjustment rate. In order to ensure the safety of left-entry merging, the merging speed of vehicles on the entrance ramp in the main line merging area should be as similar as possible to the speed of the inner fast lane of the main line. If the flow of the entrance ramp is too large, the vehicles will not be able to accelerate to the specified speed at the S-shaped switching point. Therefore, it is necessary to control the flow of the entrance ramp to ensure the acceleration conditions of the ramp vehicles.

[0090] Step 2: Calculate the initial ramp adjustment rate based on the allowable flow rate of the main line.

[0091] Step 2.1: Using historical traffic flow data from the mainline merging zone, establish a three-parameter relationship function of flow rate, density, and speed to determine the capacity of the mainline merging zone.

[0092] Step 2.2: Use detector 5 to obtain the upstream mainline flow in the merging zone, and calculate the allowable inflow flow of the entrance ramp based on the mainline merging zone capacity, i.e., the initial ramp regulation rate, as shown in equation (5).

[0093] (5)

[0094] In the formula: For period The initial ramp regulation rate (pcu / h) that allows for traffic flow correction on the main line; Main line merging zone capacity / (pcu / h); For period upstream mainline flow rate in the merging zone / (pcu / h).

[0095] Step 3: Calculate the initial ramp adjustment rate based on the allowable queue length of the ramp.

[0096] The vehicle queue length and flow rate at the entrance ramp are obtained using detector 3. The initial ramp adjustment rate is calculated based on the allowable queue length at the entrance ramp, as shown in equation (6).

[0097] (6)

[0098] in, For period Initial ramp adjustment rate (pcu / h) for ramp queue length correction. For period Entrance ramp flow rate (pcu / h); To control the cycle duration in seconds; For period Queue length at entrance ramps / pcu; The permissible queue length for the entrance ramp is per pcu.

[0099] Step 4: Combine the three preliminary ramp adjustment rate relationships to determine the actual ramp adjustment rate, as shown in equation (7).

[0100] (7)

[0101] in, For period Actual ramp regulation rate / (pcu / h).

[0102] Step 5: Calculate the green light duration and red light duration of the ramp traffic lights, see formulas (8) and (9).

[0103] (8)

[0104] (9)

[0105] in, The saturation flow rate of the entrance ramp is expressed as (pcu / h). For period Green light duration of ramp traffic lights (in seconds); For period Red light duration of ramp traffic lights / seconds.

[0106] Step 6: Divide the green light duration and red light duration of the ramp traffic lights into equal parts. N The copies are numbered in chronological order. .use Green light red light, Green light red light,…, Green light The intermittent red light release method inputs the results into the ramp control facilities, and the ramp control strategy is executed. The method of displaying the red light only after all green lights have ended is not used here because ramp control needs to balance traffic flow to ensure that vehicles on the ramps can travel at the prescribed speeds.

[0107] Step 7: As each green light is about to end, use detector 3 to identify the vehicle type of the vehicle immediately following the entrance ramp. If the vehicle is a large truck or other vehicle with poor acceleration, the green light duration at the ramp can be extended. See equation (10); otherwise proceed to step 9. The alignment conditions at the S-shaped transition point are poor, and large trucks may not be able to quickly reach the prescribed speed after stopping and then accelerating. Therefore, large trucks should be kept away from stopping as much as possible.

[0108] (10)

[0109] in, Extend the green light time per unit of ramp traffic lights by / s; For detector 3 to acquire vehicles Distance to the stop line of the ramp signal light / m; For detector 3 to acquire vehicles Travel speed (m / s); The safety interval time is expressed in seconds.

[0110] Step 8: If the green light time exceeds the maximum value. If the green light turns red, the process ends and returns to step 7; otherwise, proceed to step 9.

[0111] Step 9: If the sum of the green light duration and red light duration of the ramp traffic lights in the current cycle exceeds the control cycle duration, then end the control for this cycle.

[0112] Step 10: Determine whether to end ramp control. If yes, turn off ramp control; otherwise, proceed to step 1.

[0113] (2) Speed ​​guidance

[0114] Multiple speed guidance facilities 1, numbered from downstream to upstream, are respectively... The multiple sets of speed guidance facilities 2 are numbered as follows: The difference between the speed limits of two adjacent sub-facilities shall not exceed 20 km / h, and the speed limit shall be an integer multiple of 10 km / h. Specific controls are as follows:

[0115] ① Speed ​​guidance facility 1 control

[0116] Step 1: When there is no queue at the entrance ramp and the ramp traffic lights are not in use, the speed limit value of each sub-facilities shall be taken as the design speed of the corresponding location.

[0117] Step 2: When a queue forms at the entrance ramp, the speed limit value of the sub-facility closest to the end of the queue upstream is determined using the following formula (11), and a step-by-step deceleration method is adopted to ensure that vehicles arriving from upstream can safely decelerate and stop when they reach the end of the queue.

[0118] Step 3: When the ramp traffic light is green, the speed limit value of the sub-facilities from the traffic light to the head of the queue is taken as the design speed of the corresponding location; when the ramp traffic light is red, the speed limit value of the sub-facilities from the traffic light to the head of the queue is still determined in the manner of Step 2.

[0119] (11)

[0120] in, Minimum parking distance / m; Obtain the average vehicle speed (m / s) for detector 3; Driver's reaction time in seconds; Acceleration due to gravity / (m / s²) 2 ); is the longitudinal friction coefficient.

[0121] ② Speed ​​guidance facility 2 control

[0122] The speed at which each sub-facility issues recommendations, sub-facility The recommended speed value is the same as the average speed of the inner fast lane of the main line obtained by detector 5, sub-facilities The recommended speed is the design speed for the corresponding location. Other sub-facilities adopt a step-by-step acceleration method, but cannot exceed the design speed for the corresponding location. By guiding drivers to accelerate step by step, it ensures that the merging speed of vehicles on the ramp is the same as the speed of the inner fast lane of the main line, reducing speed dispersion in the merging area and improving driving safety.

[0123] (3) Collision warning

[0124] Collision warning uses sound, light, color, and visual information to alert the driver to a potential collision risk approaching from the front and to increase their attention. The specific control procedure is as follows:

[0125] Step 1: Use detector 6 to obtain traffic data such as the position and speed of vehicles on the left-entry merging ramp and the vehicles in front and behind on the inner fast lane.

[0126] Step 2: If all of the following conditions for disabling collision warnings are met, then the collision warnings will not be enabled; otherwise, the collision warnings will be enabled.

[0127] (12)

[0128] (13)

[0129] (14)

[0130] (15)

[0131] (16)

[0132] in, For detector 6, obtain the speed of a single vehicle in m / s. The free-flow velocity in the confluence zone is expressed as (m / s). For speed safety reduction factor; , , These represent the longitudinal positions (in meters) of vehicles on the merging ramp and vehicles in front and behind on the inner fast lane. , , The speeds of vehicles on the merging ramp and in front and behind the vehicles on the inner fast lane are respectively (m / s). , , These are the lengths (m) of vehicles on the merging ramp and the vehicles in front and behind the inner fast lane, respectively. Safety distance / m; Minimum headway / m; The lane change duration is expressed in seconds.

[0133] Step 3: Input the collision warning command into information dissemination facility 2 and execute the collision warning strategy.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for converting a left-entry ramp to a speed control ramp in a grade-separated interchange during highway reconstruction and expansion, characterized in that... The method specifically includes the following steps: S1: Ramp control, used to dynamically adjust the merging traffic flow at the entrance ramp; The control cycle is numbered in chronological order as , the control algorithm uses the traffic data obtained by the detector in cycle to determine the control parameters of cycle , specifically including the following steps: S11: Calculate three initial ramp regulation rates based on the mainline average speed, the mainline allowable traffic flow, and the ramp allowable queue length; then determine the actual ramp regulation rate based on the relationship between the three initial ramp regulation rates. S12: Calculate the green light duration and red light duration of the ramp traffic lights; S13: Divide the green light duration and red light duration of the ramp traffic lights into equal parts. N The copies are numbered in chronological order. ;use Green light red light, Green light red light,…, Green light The intermittent red light release method inputs the results into the ramp control facilities and executes the ramp control strategy; S14: When each green light display is about to end, use detector III installed on the old road entrance ramp to obtain the vehicle type of the vehicle immediately approaching the entrance ramp; S15: If the green light time exceeds the maximum value. If the green light turns red, the process returns to step S14; otherwise, proceed to step S16. S16: If the sum of the green light duration and the red light duration of the ramp traffic lights in the current cycle exceeds the control cycle duration, then the control for this cycle ends. S17: Determine whether to end ramp control. If yes, turn off ramp control; otherwise, proceed to step S11. S2: Speed ​​guidance, used to adjust the speed of vehicles on the entrance ramp to ensure safe and smooth vehicle traffic; Speed ​​guidance is achieved through the control algorithms of multiple sets of speed guidance facilities I installed on the old road entrance ramp and multiple sets of speed guidance facilities II installed at the S-shaped switching point of the ramp; among them, the control algorithm of speed guidance facility I adjusts the speed limit value according to the traffic light status and the length of the vehicle queue; the control algorithm of speed guidance facility II suggests drivers to accelerate step by step according to the speed of vehicles in the inner fast lane of the main line. The control algorithm for speed guidance facility I specifically includes the following steps: S201: When there is no queue at the entrance ramp of the old road and the ramp traffic lights are not in use, the speed limit value of each sub-speed guidance facility shall be taken as the design speed of the corresponding location. S202: When a queue forms at the entrance ramp of the old road, the speed limit value of the sub-speed guidance facility closest to the end of the queue upstream is determined using the following formula (11), and a step-by-step deceleration method is adopted to ensure that vehicles arriving from upstream can safely decelerate and stop when they reach the end of the queue. （11） in, Minimum parking distance; To obtain the average speed of the vehicle for detector III; This refers to the driver's reaction time. It is the acceleration due to gravity; The longitudinal friction coefficient; S203: When the ramp traffic light is green, the speed limit value of the sub-speed guidance facility from the traffic light to the head of the queue is taken as the design speed of the corresponding position; when the ramp traffic light is red, the speed limit value of the sub-speed guidance facility from the traffic light to the head of the queue is still determined in step S202. S3: Collision Warning, which includes the following steps: S31: Use detector VI, which is set up in the merging area of ​​the new road, to obtain traffic data of vehicles on the merging ramp at the left-entry merging point and vehicles in front and behind the inner fast lane. S32: If all conditions for disabling collision warnings are met, then collision warnings are disabled; otherwise, collision warnings are enabled. S33: Input the collision warning command into the information dissemination facility II located on the ramp at the left merging nose of the new road, and execute the collision warning strategy.

2. The method according to claim 1, wherein In step S11, the initial ramp adjustment rate is calculated based on the average speed of the main line, which specifically includes the following steps: S1101: Using historical traffic flow data at the S-shaped switching point of the entrance ramp, a three-parameter relationship function of flow rate-density-speed is established, as shown in equation (1). Based on this, the allowable flow rate is determined according to the acceptable driving speed. The three-parameter relationship function of flow rate-density-speed adopts the functional form of equations (2) to (4). （1） （2） （3） （4） in, For period Initial ramp adjustment rate for mainline average speed correction; For period Average speed on the ramp; , , , , , For function parameters; S1102: The average speed of the inner fast lane of the main line is obtained by using detector V set up upstream of the new main line, and then input into equation (1) to calculate the initial ramp adjustment rate. To ensure safe left-entry merging, vehicles merging at the main line merging zone should have the same speed as those in the inner fast lane of the main line. If the flow of traffic on the entrance ramp is too high, vehicles will not be able to accelerate to the prescribed speed at the S-shaped transition point. Therefore, it is necessary to control the flow of traffic on the entrance ramp to ensure the acceleration conditions of vehicles on the ramp.

3. The method according to claim 2, wherein, In step S11, the initial ramp regulation rate is calculated based on the allowable flow rate of the main line, which specifically includes the following steps: S1111: Using historical traffic flow data from the mainline merging zone, a three-parameter relationship function of flow rate, density, and speed is established to determine the capacity of the mainline merging zone; S1112: Use detector V, which is set up upstream of the main line of the new road, to obtain the main line flow rate upstream of the merging zone. Calculate the allowable flow rate of the entrance ramp based on the traffic capacity of the main line merging zone, i.e., the initial ramp regulation rate, as shown in equation (5). （5） wherein, is the period the initial ramp metering rate that the mainline can allow for the discharge flow modification; is the mainline merging area capacity; is the period is the mainline flow upstream of the merging area.

4. The method of claim 3, wherein the method further comprises: determining a speed of the vehicle; and determining whether the vehicle is in the first lane or the second lane based on the determined speed of the vehicle. In step S11, the initial ramp regulation rate is calculated based on the allowable queue length of the ramp. Specifically, this includes: using detector III installed on the old road entrance ramp to obtain the vehicle queue length and flow rate of the entrance ramp, and calculating the initial ramp regulation rate based on the allowable queue length of the entrance ramp, as shown in equation (6). （6） in, For period The initial ramp adjustment rate that allows for queue length correction; For period Entrance ramp traffic flow; To control the cycle duration in seconds; For period Queue length at entrance ramps; The permissible queue length for the entrance ramp.

5. The method of claim 4, wherein the method further comprises: In step S11, the formula for determining the actual ramp adjustment rate is: （7） in, For period Actual ramp adjustment rate.

6. The method for converting left-entry ramps and speed control in grade-separated interchanges for highway reconstruction and expansion according to claim 5, characterized in that, In step S12, the green light duration and red light duration of the ramp traffic lights are calculated, as shown in equations (8) and (9). （8） （9） wherein, is the on-ramp saturation flow rate; is the period is the on-ramp signal light green time; is the period is the on-ramp signal light red time.

7. The method of claim 6, wherein the method further comprises: Step S14 specifically includes: If it is a large truck, extend the green light duration of the ramp traffic lights. See equation (10); otherwise proceed to step S16; the alignment conditions at the S-shaped switching point are poor, and the truck cannot quickly reach the specified driving speed after stopping and then accelerating, so avoid stopping the truck. （10） in, Extend the green light time for ramp traffic lights; For detector III to acquire vehicle Distance to the stop line of the ramp signal light / m; For detector III to acquire vehicle Driving speed; This is the safe interval time.

8. The method of claim 1, wherein the method further comprises: In step S2, the control algorithm for speed guidance facility II specifically includes: numbering the multiple sets of speed guidance facilities II as follows: Each sub-speed guidance facility issues a recommended speed; sub-speed guidance facilities The recommended speed value is the same as the average speed of the inner fast lane of the main line obtained by detector V located upstream of the main line of the new road, and the sub-speed guidance facility The recommended speed is the design speed for the corresponding location. The remaining sub-facilities adopt a step-by-step acceleration method, but cannot exceed the design speed for the corresponding location.

9. The method of claim 1, wherein the method further comprises: determining a speed of the vehicle; and determining a distance between the vehicle and the vehicle in front of the vehicle. Step S32 specifically includes: If all of the following conditions for disabling collision warnings are met, then the collision warnings are disabled; otherwise, the collision warnings are enabled. （12） （13） （14） （15） （16） in, For detector VI, obtain the speed of a single vehicle; The free-flow velocity in the confluence region; Speed ​​safety reduction factor; , , These represent the longitudinal positions of vehicles on the merging ramp and vehicles in front of and behind on the inner fast lane, respectively. , , These represent the speeds of vehicles on the merging ramp and the speeds of vehicles in front of and behind the inner fast lane, respectively. , , These are the lengths of vehicles on the merging ramp and the vehicles in front of and behind the inner fast lane, respectively. To maintain a safe distance; Minimum headway; This refers to the lane change duration.

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