A method for evaluating excessive traffic flow on urban roads

Abstract

The present invention discloses a method for evaluating the over-limit of urban road traffic flow in the field of urban traffic management, including the following steps: defining large and medium-sized civilian, commercial, and public building sites with vehicle access on both sides of urban roads as key sites, and calculating the vehicle merging reduction coefficient e of the key sites i ; combining the vehicle merging reduction coefficient e i and the lane passing factors to calculate the total passing capacity C of multi-lane roads s ; obtaining the actual traffic flow T of the lane within the collection period flow ; calculating the traffic flow over-limit warning value Ewr, and evaluating the passing capacity of the road section according to the traffic flow over-limit warning value Ewr, and further evaluating the saturation of the road section. The present invention can deduce the reduction coefficient of the passing capacity of the vehicles entering the road from the exits of key sites along urban roads, provide data support for the evaluation and alarm of traffic flow over-limit, and realize the accurate calculation of road passing capacity.

Description

Technical Field

[0001] The invention relates to the field of urban traffic management, in particular to an urban road traffic flow over-limit assessment method. Background Art

[0002] Effective monitoring and early warning of urban road traffic flow directly affects the traffic service capacity of the entire area. If the traffic volume exceeds the actual maximum capacity during the road cycle, it will cause traffic congestion due to excessive saturation flow. In particular, the influx of vehicles at key locations along the road directly affects the road's traffic capacity, which in turn leads to a decline in the road section service level and makes it difficult to ensure the efficiency of lane use. The current assessment of road traffic flow does not take into account the impact of the influx of vehicles at key locations on the road's traffic capacity, resulting in the calculated road capacity being higher than the actual situation, which misleads decision makers and is not conducive to the implementation of road planning. Summary of the invention

[0003] The purpose of the present invention is to provide a method for evaluating excessive traffic flow on urban roads to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for evaluating excessive traffic flow on urban roads comprises the following steps:

[0006] Define large and medium-sized civil, commercial and public buildings on both sides of urban roads with vehicles entering and exiting as key places, and calculate the vehicle inflow reduction coefficient e of key places i ;

[0007] Combined with the vehicle import reduction factor e i and lane traffic factors to calculate the total capacity C of multi-lane roads S ;

[0008] Get the actual traffic flow T of the lane during the collection period flow ;

[0009] Calculate the road traffic flow over-limit warning value Ewr,

[0010] The lane section saturation is evaluated based on the road traffic flow excessive warning value Ewr.

[0011] Furthermore, the vehicle import reduction factor e i The calculation formula is:

[0012]

[0013] Among them, A inflowT represents the average hourly traffic volume entering the road at key locations; inflow Indicates the time required for a vehicle to merge into the road, with a value of 3 to 5 seconds; T lane_flow P represents the average hourly traffic volume of the road lane; road It represents the location coefficient of the key place, and MT represents the average travel time of vehicles passing through the road, in seconds.

[0014] Furthermore, the vehicle merging reduction coefficient gradually decreases as the number of lanes increases, that is, the impact of vehicles merging along the way on the traffic capacity on the inner side of the road gradually decreases. After obtaining the single-lane traffic capacity, multiply it by the corresponding number of lanes and combine it with the lane reduction coefficient to obtain the total traffic capacity of the multi-lane road. The total traffic capacity of the multi-lane road C S The calculation formula is:

[0015]

[0016] Among them, C P represents the single lane capacity, which can be calculated according to the method disclosed in the prior art and will not be described here; split represents the green signal ratio, that is, the ratio of the effective green light time and cycle time; n represents the specific number of lanes; m represents the maximum number of lanes; k n It represents the reduction coefficient of each lane. Usually, the lane close to the center line or the central dividing strip is the first lane, and its capacity is 1. The second lane has a capacity of 0.85-0.95 of the first lane. The third lane has a capacity of 0.65-0.85 of the first lane. The fourth lane has a capacity of 0.5-0.6 of the first lane. a0 represents the road classification coefficient of the motor vehicle lane. The main urban road takes 0.85, the secondary road (highway below level 2) takes 0.9, and the branch road takes 0.95.

[0017] Furthermore, the location coefficient P of the key place road It is expressed as the ratio of the distance from the location of the key place to the starting point of the road to the total length of the road. The starting point of the road is determined as the starting intersection when the motor vehicle is traveling. For example, if the motor vehicle travels from intersection 1 to intersection 2, then intersection 1 is the starting point of the road and intersection 2 is the end point of the road. When the total length of the route is 1000 meters, if the location of the key place is 400 meters away from the starting point of the road, then the location coefficient P road That is 400 / 1000=0.4.

[0018] Furthermore, after defining key places, in order to facilitate the rapid evaluation of urban traffic flow, a key place resource library can be established, and the name information, location information, corresponding road starting point information, end point information and location coefficient of all key places on both sides of urban roads can be counted by using big data technology combined with map resources. The location information of key places, the location information of the road starting point and the end point can be expressed in longitude and latitude. When evaluating any urban road, the key place data on both sides of the urban road can be directly called from the key place resource library.

[0019] Furthermore, the actual traffic flow T flow The data is collected by video surveillance devices installed on the road. For example, radar video vehicle detectors, video traffic detectors, etc., using visual vehicle detection, high-precision data analysis and large-area detection, combined with the high-precision map road channelization design of the urban traffic brain, can achieve accurate statistics of lane traffic in each lane. The actual traffic flow in the lane cycle T flow The calculation formula is:

[0020]

[0021] T flow Indicates the total traffic flow statistics of each lane of the road during the cycle; flow lane Indicates the traffic flow statistics within a single lane cycle.

[0022] Beneficial effects: The present invention regards the vehicle merging at key locations as an important factor affecting the road lane capacity, and involves it in the evaluation and calculation of the lane capacity, which can improve the accuracy of the evaluation results and provide strong data support for the planning of urban road traffic. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the principle of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The following is described in conjunction with specific embodiments:

[0026] The length from the intersection of Donghai Avenue and Caoshan Road in Bengbu City to the intersection of Donghai Avenue and Xuehai Road is about 1 kilometer from east to west. At 300 meters from east to west is the exit of Donghai Avenue of University Science and Technology Park. During peak hours, vehicles from the park merge into the main road, causing the road's traffic capacity to be severely reduced. However, the conventional traffic capacity calculation formula does not include the vehicle influx factors from key locations along the way into the calculation scope.

[0027] Without considering the vehicle inflow reduction factor, the data collected from the intersection of Donghai Avenue and Caoshan Road to the intersection of Donghai Avenue and Xuehai Road are shown in the following table:

[0028]

[0029]

[0030] Without considering the reduction factor of vehicle merging, we first calculate the total capacity of multi-lane roads by combining the data in Table 1:

[0031] The traffic flow data of the road section during the peak period is collected by monitoring equipment such as radar video vehicle detectors and video vehicle flow detectors, and the average flow rate T in the lane collection cycle is obtained. flow =1280(pcu / h).

[0032] Therefore, the road traffic flow over-limit warning value can be obtained

[0033] The present invention adopts a method for evaluating the over-limit of urban road traffic flow, such as Figure 1 As shown, the method is as follows:

[0034] University science and technology parks are parks that gather a large number of high-tech industries, with a large number of people and vehicles entering and leaving, and are key places in the definition. In fact, according to the definition of key places, key places mainly include medical institutions, civil service institutions, comprehensive shopping malls, catering places, exhibition places, tourist places, cultural and entertainment places, sports venues, hotels, stations and docks, residential communities, etc.

[0035] Since the university science and technology park is 300 meters away from the starting point of the road, the location coefficient P road is 0.3. Through monitoring and statistics, we can obtain the average hourly traffic volume A of key places entering the road. inflow , the average hourly traffic volume of the road lanes T lane_flow and the average travel time MT of vehicles passing through the road. Select the time T when the vehicle merges into the road inflow , taking the middle value of 4 seconds. Combining the above data, the vehicle inflow reduction factor e of key places can be calculated i , we get the following table:

[0036]

[0037] Taking into account the reduction factor for vehicle merging, the total capacity of multi-lane roads is calculated based on the data in the following table:

[0038]

[0039]

[0040] The total traffic capacity of multi-lane roads is C s =1462(pcu / h).

[0041] Calculate the warning value of excessive traffic flow on the road

[0042] Evaluate the lane section saturation based on the correspondence table between section saturation and service level.

[0043] Service Level A B C D E F Saturation Less than 0.4 0.4-0.6 0.6-0.75 0.75-0.85 0.85-0.95 Greater than 0.95

[0044] Therefore, according to the existing evaluation method, when the calculation result of the vehicle merging reduction coefficient is not considered, the road section is in a D light congestion state. According to the evaluation method provided by the present invention, when the vehicle merging reduction coefficient is considered, the road capacity is calculated more accurately, and the road service level is E moderate congestion state, which improves the calculation accuracy of the road section service level and is more in line with the actual road traffic conditions.

[0045] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0046] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A method for evaluating excessive traffic flow on urban roads, characterized in that: The methods include the following: Define large and medium-sized civil, commercial and public buildings on both sides of urban roads with vehicles entering and exiting as key places, and calculate the vehicle inflow reduction coefficient for key places ; Vehicle inflow reduction factor for the above-mentioned key locations The calculation formula is: in, It indicates the average hourly traffic volume merging into the road at key locations; Indicates the time required for the vehicle to merge into the road, with a value of 3 to 5 seconds; It indicates the average hourly traffic volume of the road lane; Indicates the location coefficient of key places. It is expressed as the ratio of the distance from the location of the key place to the starting point of the road to the total length of the road, where the starting point of the road is determined as the starting intersection when the motor vehicle is traveling; MT represents the average driving time of the vehicle through the road; Combined vehicle import reduction factor Calculate the total capacity of multi-lane roads based on lane traffic factors ;Total capacity of multi-lane roads The calculation formula is: in, represents the single lane capacity; split represents the green-to-signal ratio; n represents the actual number of lanes; m represents the maximum number of lanes; Indicates the reduction factor of each lane; The road classification coefficient representing the motorway; Get the actual traffic flow of the lane during the collection period ; Calculate the warning value of excessive traffic flow on the road , ; According to the road traffic flow over-limit warning value Evaluate the road segment saturation of the lane.

2. The method for evaluating excessive traffic flow on urban roads according to claim 1, characterized in that: It also includes the establishment of a key place resource library to count the name information, location information, corresponding road starting point information, end point information and location coefficients of all key places on both sides of urban roads.

3. The method for evaluating excessive traffic flow on urban roads according to claim 1, characterized in that: Actual traffic volume of the lane The data is collected and acquired using video surveillance devices installed on the road.

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