CN110175799B - A method for generating flow restriction scheme of emergency material distribution path branch - Google Patents

Abstract

The invention discloses a method for generating a branch current limiting scheme of an emergency material distribution path, which comprises the steps of coding nodes and road sections of the distribution path, acquiring traffic state and flow information of each coded intermediate node and road section on the distribution path, acquiring attribute information of each coded road section on the distribution path, solving the current limiting time of each coded intermediate node and the transportation time of each coded road section, calculating the current limiting starting time of each coded intermediate node by taking the distribution starting time as a reference, generating the branch current limiting scheme of the distribution path and the like; the invention can rapidly make a set of traffic cooperative guarantee scheme, scientifically and reasonably select the branch for limiting the flow and control the flow limiting time, meets the time requirement of material distribution to the maximum extent, simultaneously minimizes the traffic influence generated by flow limiting, and has important reference value for emergency decision commanders.

Description

A method for generating flow restriction scheme of emergency material distribution path branch

technical field

The invention relates to the technical field of computer application and the field of transportation science and technology, in particular to a method for quickly generating a branch current-limiting traffic coordination scheme of a distribution path during emergency rescue material transportation.

Background technique

In recent years, unconventional emergencies such as earthquakes, floods, mudslides, wind and hail, accidents and disasters have occurred in various regions of our country, which have had a serious impact on people's normal life and caused heavy casualties and economic losses. In order to minimize the casualties of accidents and reduce the loss of public property, whether the demand for emergency supplies at the disaster site can be met in a short time after the disaster has become a crucial part. The key to post-disaster emergency rescue and disaster relief is to distribute emergency supplies to disaster-affected points to meet their needs.

The transportation time of the emergency material distribution path is significantly affected by the traffic flow density. The greater the traffic flow density, the longer the transportation time. Reducing the traffic flow density of the distribution path is an effective way to shorten the transportation time. The traffic flow density of the distribution route will be significantly affected by the inflow of branch traffic. The larger the inflow flow of the branch, the greater the traffic flow density of the distribution route. In order to shorten the delivery and transportation time, it is necessary to quickly formulate an effective branch traffic flow inflow restriction scheme. The distribution route branch traffic flow restriction scheme involved in the present invention refers to a scheme of time-limiting the inflow of the branch traffic flow of the distribution route under the current road traffic conditions, so that the transportation time of the distribution route is as short as possible. At the same time, the restricted branch road traffic volume is kept as low as possible.

At present, in the research on the vehicle routing problem of emergency materials distribution, based on the time window constraints of emergency materials at the disaster site, a mathematical model is established and solved by applying soft and hard time window penalties to the transportation time, and the theoretical optimal distribution path can be obtained. However, in the actual post-disaster traffic network, the traffic conditions of the distribution routes are complex and changeable, and the traffic volume will be too large, so that the actual distribution time may not be able to achieve the optimal effect obtained by the theoretical solution, thus failing to meet the emergency The time goal of rescue; therefore, quickly formulate a set of traffic coordination security plans, scientifically and rationally select the flow-limiting branch and control the flow-limiting time, so as to meet the time requirements of material distribution to the greatest extent, and at the same time minimize the traffic impact caused by the flow-limiting. , which has important reference value for emergency decision-making commanders.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for generating a branch current limiting scheme of an emergency material distribution path. Under the condition of minimally affecting urban traffic, a time limit scheme for each branch on the emergency material distribution path to merge into the traffic flow is given, which is an emergency Management or command personnel provide decision-making reference.

The technical solution adopted in the present invention is: a method for generating a current limiting scheme for an emergency material distribution path branch, comprising the following specific steps: a method for generating a current limiting scheme for an emergency material distribution path branch, which is characterized by comprising the following steps:

Step 1: Encode the nodes and sections of the delivery route;

Taking the starting point of the delivery route as the starting node and the end point of the delivery route as the end node, starting from the starting node, searching along the delivery route to the end node, and sequentially retrieving the intersection or ramp entrance that intersects the delivery route and has traffic flow as the intermediate node , the nodes are coded as Pi, _i =1,2,3,...,end, the road between the nodes Pi and Pi ₊₁ is coded as RS _i as a road segment, _i =1,2,3,...,end- 1; wherein, i=1 represents the start node, and i=end represents the end node;

Step 2: Obtain the traffic status and flow information of each coded intermediate node and road section on the delivery route;

Through real-time traffic monitoring and statistics, obtain the current traffic flow CF _i of each intermediate node Pi entering the main road of the distribution route, _i =2,3,...,end-1; obtain the current traffic flow RF _i of each road section RS _i itself and the traffic state S _i , i=1,2,3,...,end-1; S _i ∈[0,1], S _i =1 represents the high-density traffic state, S _i =0 represents the low-density traffic state; where , when the traffic density does not exceed 35 vehicles/km/lane, it is a low-density traffic state, and when the traffic density exceeds 35 vehicles/km/lane, it is a high-density traffic state.

Step 3: Obtain the length information _{Li, the number of lanes Ni and the speed limit VF i of each} coded road segment RS _i on the delivery route;

Step 4: solve the current limiting time of each coding intermediate node and the transportation time of each coding road segment;

Step 5: Based on the delivery start time, calculate the current limiting start time of each coding intermediate node;

Step 6: Generate the branch current limiting scheme of the delivery route.

The present invention can quickly formulate a set of traffic coordination guarantee scheme, scientifically and reasonably select the branch road of current limitation and control the time of current limitation, so as to meet the time requirement of material distribution to the greatest extent, and at the same time, the traffic impact caused by the limitation of current is minimized, and it is very useful for emergency decision-making. Commanders have important reference value.

Compared with the prior art, the present invention has the beneficial effects of providing a traffic coordination guarantee scheme for the operability of the theoretical route scheme from a practical level, and can minimize the insufficiency of the existing theoretical method for evaluating the actual dynamic traffic flow operating state. As a result, the emergency distribution time deviates. Meanwhile, the solution proposed by the present invention can ensure that when the branch current limiting solution is adopted, the traffic interference to the non-emergency distribution line can be minimized, which is of great significance to the post-disaster emergency response.

Description of drawings

1 is a flowchart of an embodiment of the present invention;

FIG. 2 is a schematic diagram of node and road segment coding according to an embodiment of the present invention.

Detailed ways

In order to facilitate the understanding and implementation of the present invention by those of ordinary skill in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, but not to limit it. this invention.

Referring to FIG. 1 , a method for generating a current limiting solution for an emergency material distribution path branch provided by the present invention includes the following steps:

Step 1: Encode the nodes and sections of the delivery route;

In this embodiment, the starting point of the delivery route is taken as the starting node, and the end point of the delivery route is taken as the terminal node. Starting from the starting node, the search is carried out along the delivery route to the end node, and the intersections that intersect with the delivery route and where the traffic flows into or are sequentially retrieved. The entrance of the ramp is used as an intermediate node, the node code is Pi, _i =1,2,3,...,11, and the road between nodes Pi and Pi ₊₁ is coded as RS _i as a road segment, _i =1,2,3 ,…,10; the specific coding is shown in Figure 2.

Step 2: Obtain the traffic status and flow information of each coded intermediate node and road section on the delivery route;

Through real-time traffic monitoring and statistics, obtain the current traffic flow CF _i of each intermediate node Pi entering the main road of the distribution route, _i =2,3,...,end-1; obtain the current traffic flow RF _i of each road section RS _i itself and the traffic state S _i , i=1,2,3,...,end-1; S _i ∈[0,1], S _i =1 represents the high-density traffic state, S _i =0 represents the low-density traffic state; where , when the traffic density does not exceed 35 vehicles/km/lane, it is a low-density traffic state, and when the traffic density exceeds 35 vehicles/km/lane, it is a high-density traffic state.

In this embodiment, through real-time traffic monitoring and statistics, the current traffic flow CF _i ( _i =2,3,..., 10) Obtain the traffic flow RF _i (i=1, 2, 3,..., 10) of each current road segment RS _i (i=1,2,...,10) itself, and the traffic state S _i (i=1,2 ,3,…,10). The specific values obtained are as follows:

CF=[0.3,0.3,0.3,0.3,0.6,0.6,0.3,0.6,0.3]

RF=[0.58,0.42,1.30,1.32,1.15,1.53,0.81,1.49,0.77,0.58]

S=[1,0,1,1,0,1,0,1,1,0]

Step 3: Obtain the length information _{Li, the number of lanes Ni and the speed limit VF i of each} coded road segment RS _i on the delivery route;

In this embodiment, the length information _Li ( _i =1, 2, 3, _. (i=1,2,3,...,10) and speed limit VF _i (i=1,2,3,...,10). The specific values are obtained as follows:

L=[39,131,605,493,4140,1760,6960,5700,4640,1320]

N=[2,2,3,3,3,3,2,3,2,1]

VF=[22.22, 22.22, 22.22, 22.22, 22.22, 22.22, 22.22, 22.22, 22.22, 22.22]

Step 4: solve the current limiting time of each coding intermediate node and the transportation time of each coding road segment;

In this embodiment, by solving the branch current limiting mathematical programming model, the current limiting time of each coding intermediate node and the transportation time of each coding road section are obtained.

Invoke the genetic algorithm to solve the following mathematical programming model:

Decision variable: τ _i

Objective function:

About speed conditions:

表示配送路径运输总时间不超过规定的配送时间要求。

Indicates that the total transportation time of the delivery route does not exceed the specified delivery time requirement.

表示中间节点的限流时间不超过配送车辆行驶至该节点的总时间。

Indicates that the current limiting time of an intermediate node does not exceed the total time for the delivery vehicle to travel to this node.

In the formula,

T _i =L _i /v _i

ρ _i,m =0.12N _i

In the formula, CF _i (i=2,...,10) represents the traffic flow of the coding intermediate node into the main road of the distribution route, unit: vehicle/second; τ _i (i=2,3,...,10) represents Current limiting time of each coding intermediate node, unit: second; RF _i (i=1,2,...,10) represents the traffic flow of each coding section, unit: vehicle/sec; T _i (i=1,2 ,...,10) represents the transportation time of each coded road section, unit: second; _Tw represents the specified delivery request time, unit: second; Li ( _i =1,2,...,10) represents each code The length of the road segment, unit: meters; v _i (i=1,2,...,10) represents the speed of each coded road segment, unit: m/s; VF _i (i=1,2,...,10 ) represents the speed limit of each coded road segment, unit: m/s; N _i (i=1, 2, . . . , 10) represents the number of lanes of each coded road segment.

The current limiting time of each coding intermediate node and the transportation time of each coding road section are obtained by solving, and the results are shown in the following Tables 1 and 2:

Table 1 Current limiting time of each intermediate node

code node P₂ P₃ P₄ P₅ P₆ P₇ P₈ P₉ P₁₀ Current limit duration/sec 10 6 31 30 103 16 223 89 746

Table 2 Transit time of each coded road segment

coded road segment RS₁ RS₂ RS₃ RS₄ RS₅ RS₆ RS₇ RS₈ RS₉ RS₁₀ Transit time/sec 14 6 133 106 225 306 385 1036 1184 87

Step 5: Based on the delivery start time, calculate the current limiting start time of each coding intermediate node;

In this embodiment, the delivery start time is defined as the reference time t _o =9:00AM. If the encoding intermediate node P _i ≠0 (i=2,3,...,end-1), then the intermediate node P _i The current limit start time is

Step 6: Generate the branch current limiting scheme of the distribution route;

In this embodiment, the scheme includes the starting time and duration of current limiting of each coding intermediate node, as shown in Table 3 below. The specific current limiting method can be implemented by adjusting and controlling the signal lights and intercepting the traffic jams.

Table 3 Current limiting scheme of distribution route branch (reference time t _o =9:00AM)

It should be understood that the parts not described in detail in this specification belong to the prior art.

It should be understood that the above description of the preferred embodiments is relatively detailed, and therefore should not be considered as a limitation on the scope of the patent protection of the present invention. In the case of the protection scope, substitutions or deformations can also be made, which all fall within the protection scope of the present invention, and the claimed protection scope of the present invention shall be subject to the appended claims.

Claims (3)

1. A method for generating an emergency material distribution path branch current limiting scheme, characterized in that, comprising the following steps: Step 1: Encode the nodes and sections of the delivery route; Taking the starting point of the delivery route as the starting node and the end point of the delivery route as the end node, starting from the starting node, searching along the delivery route to the end node, and sequentially retrieving the intersection or ramp entrance that intersects the delivery route and has traffic flow as the intermediate node , the nodes are coded as Pi, _i =1,2,3,...,end, the road between the nodes Pi and Pi ₊₁ is coded as RS _i as a road segment, _i =1,2,3,...,end- 1; wherein, i=1 represents the start node, and i=end represents the end node; Step 2: Obtain the traffic status and flow information of each coded intermediate node and road section on the delivery route; Through real-time traffic monitoring and statistics, obtain the current traffic flow CF _i of each intermediate node Pi entering the main road of the distribution route, _i =2,3,...,end-1; obtain the current traffic flow RF _i of each road section RS _i itself and the traffic state S _i , i=1,2,3,...,end-1; S _i ∈[0,1], S _i =1 represents the high-density traffic state, S _i =0 represents the low-density traffic state; where When the traffic density does not exceed the preset value, it is a low-density traffic state, and when the traffic density exceeds the preset value, it is a high-density traffic state; Step 3: Obtain the length information _{Li, the number of lanes Ni and the speed limit VF i of each} coded road segment RS _i on the delivery route; Step 4: Solve the current limiting time of each coding intermediate node and the transportation time of each coding road segment; Build a branch current-limiting mathematical programming model to solve the current-limiting time of each coding intermediate node and the transportation time of each coding section; Wherein, the mathematical programming model of the branch current limiting is:

Indicates that the total transportation time of the delivery route does not exceed the specified delivery time requirement;

Indicates that the current limiting time of the intermediate node does not exceed the total time for the delivery vehicle to travel to the node; T _i =L _i /v _i

ρ _i,m =0.12N _i In the formula, CF _i represents the flow of the coding intermediate node into the main road of the distribution route, unit: vehicle/second, i=2,3,...,end-1; τ _i represents the current limiting time of each coding intermediate node, unit: second , i=2,3,...,end-1; RF _i represents the traffic flow of each coded road segment, unit: vehicle/sec, i=1,2,3,...,end-1; T _i represents the traffic flow of each coded road segment Transportation time, unit: second, i=1,2,3,...,end-1; _Tw means the specified delivery time, unit: second; Li means the length of each coded road segment, unit: meter, _i =1 ,2,3,…,end-1; v _i represents the speed of each coded road section, unit: m/s, i=1,2,3,…,end-1; VF _i represents the speed limit of each coded road section, Unit: m/s, i=1,2,3,...,end-1; N _i represents the number of lanes of each coded road segment, i=1,2,3,...,end-1; _The genetic algorithm is used to solve the mathematical programming model of branch current limiting, and the current _limiting time _of each coding intermediate node and the transportation time of each coding road section are obtained. are τ ₂ , τ ₃ , . . . , τ _{end-1 , unit} : m/ _{s ;} the transportation time T ₁ , T ₂ , . , unit: m/s; Step 5: Based on the delivery start time, calculate the current limiting start time of each coding intermediate node; Step 6: Generate the branch current limiting scheme of the delivery route. 2. The method for generating an emergency material distribution path branch current limiting scheme according to claim 1, characterized in that: the specific implementation process of step 5 is to define a distribution start time as a reference time t _o , if the coding intermediate node P _i ≠0, i=1,2,3,...,end-1, then the current limiting start time of the intermediate node P _i is

3. The method for generating an emergency material distribution path branch current limiting scheme according to claim 1, wherein the specific implementation process of step 5 is that the scheme includes each coding intermediate node P ₂ , P ₃ , ..., P _{end- 1} The starting time of current limiting t _o +T ₁ -τ ₂ , t _o +T ₁ +T ₂ -τ ₃ ,...,

and the current limiting duration τ ₂ , τ ₃ , …, τ _end-1 , unit: m/s.

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