An environmentally friendly traffic distribution method considering carbon emission cost

Abstract

The application discloses an environment-friendly traffic distribution method considering carbon emission cost, determines traffic demand, road capacity and road resistance coefficient in a road network, calculates time consumed by vehicle travel on a road ij and running speed of the vehicle on the road ij, and determines a carbon emission cost function and a maximum value of carbon emission minimization speed based on the running speed of the vehicle on the road ij; the application determines a constraint condition based on the carbon emission cost function, constructs an environment-friendly traffic distribution model considering carbon emission cost, solves the environment-friendly traffic distribution model considering carbon emission cost, and obtains an environment-friendly traffic distribution scheme considering carbon emission cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intelligent transportation, and relates to an environmentally friendly traffic distribution method considering carbon emission cost. BACKGROUND

[0002] China is a developing world power, and has been the country with the largest global carbon emissions since 2005. The proportion of China's carbon emissions in the total global carbon emissions is increasing, and has reached 31%. The carbon emissions of transportation account for about 10.4% of the total carbon emissions in China, and the carbon emissions of highway transportation account for more than 85% of the total carbon emissions of transportation in China, which is the absolute main body and the key of emission reduction.

[0003] Currently, in the traffic network, the driver generally tries to reduce his travel time and pursues the minimum time cost, and generally selects the route with the shortest time, so that the demand space-time distribution is uneven, which leads to road congestion, the traffic resources cannot be fully utilized, and the performance of the entire traffic network system is reduced and the environmental cost is increased. With the improvement of environmental awareness, China also vigorously implements the double carbon policy, and the ecological friendly traffic distribution should not only focus on the time cost of travel, but also pay attention to the environmental cost of travel. SUMMARY

[0004] The purpose of the embodiment of the application is to provide an environmentally friendly traffic distribution method considering carbon emission cost, so as to solve the problems of the existing traffic distribution method pursuing the minimum time cost, which causes the traffic resources cannot be fully utilized, the performance of the entire traffic network system is reduced, and the environmental cost is increased.

[0005] The technical scheme adopted by the embodiment of the application is an environmentally friendly traffic distribution method considering carbon emission cost, which is performed according to the following steps:

[0006] Step S1, determining the traffic demand, road capacity and road resistance coefficient in the road network, calculating the time consumed by vehicle travel on the road ij and the running speed of the vehicle on the road ij, and the starting point of the road ij is i and the ending point is j;

[0007] Step S2, determining the carbon emission cost function and the maximum value of the minimum carbon emission speed based on the running speed of the vehicle on the road ij;

[0008] Step S3, determining the constraint condition based on the carbon emission cost function, and constructing an environmentally friendly traffic distribution model considering carbon emission cost;

[0009] Step S4, solving the environmentally friendly traffic distribution model considering carbon emission cost to obtain an environmentally friendly traffic distribution scheme considering carbon emission cost.

[0010] Further, the time t consumed by the vehicle trip on the road ij ij (x) is:

[0011] t ij (x) = a ij + b ij (x ij / c ij ) 4 ; (1)

[0012] wherein a ij , b ij are the road ij delay parameters; x ij is the flow on the road ij; c ij is the capacity of the road ij;

[0013] The running speed v ij (x) of the vehicle on the road ij is:

[0014] v ij (x) = d / (a ij + b ij (x ij / c ij ) 4 ); (2)

[0015] wherein d is the length of the road ij, and the unit of the running speed v ij (x) of the vehicle on the road ij is km / h.

[0016] Further, the carbon emission cost function is:

[0017]

[0018] wherein c ij (x) represents the unit carbon emission of the road ij, and the unit is g / km, representing the emission of carbon monoxide and carbon dioxide per kilometer; a1, a2, a3, a4, a5, a6, b1 are all coefficients of the carbon emission cost function.

[0019] According to the carbon emission cost function, the maximum value of the running speed v ij (x) of the vehicle on the road ij when the unit carbon emission c ij (x) is minimized, i.e. the maximum value of the carbon emission minimization speed v max,ij .

[0020] Further, a1 = 3.952, a2 = -3.061, a3 = 2.949, a4 = 4.866, a5 = -9.170, a6 = 1.155, b1 = 223.559.

[0021] Further, based on the carbon emission cost function, the road capacity constraint, the road flow constraint, the path flow constraint and the emission minimizing speed constraint are added to construct the environment-friendly traffic assignment model considering carbon emission cost.

[0022] Further, the road capacity constraint is:

[0023]

[0024] wherein c ij is the capacity of road ij, λ ij is the Lagrange value of the capacity constraint of road ij, k represents the destination point, A is the road set, is the path flow on road ij with respect to the destination k, and is the projection of λ ij on .

[0025] The road flow constraint is:

[0026]

[0027] The path flow constraint is:

[0028]

[0029] wherein, and represent the path flow of the opposite direction of the same road with respect to the destination k, is the traffic demand from the starting point i to the destination k; N is the starting point set, and D is the destination set; is the carbon emission cost from the starting point i to the destination k;

[0030] The emission minimizing speed constraint is:

[0031] 0≤θ ij ⊥{v max,ij -v ij}≥0 (i,j)∈A; (9)

[0032] wherein θ ij is the Lagrange value of the emission speed minimizing constraint of road ij, and v max,ij is the maximum value of the carbon emission minimizing speed.

[0033] Further, the maximum value of the carbon emission minimizing speed is 68.2686 km / h.

[0034] Further, the GAMS software is used to call the MCP module to solve the environment-friendly traffic assignment model considering carbon emission cost, so as to obtain the environment-friendly traffic assignment scheme considering carbon emission cost.

[0035] The embodiment of the present application has the beneficial effects that: the embodiment of the present application proposes a traffic distribution method taking vehicle travel carbon emission as travel cost considering road capacity limit, path flow limit, road flow limit and emission speed minimization speed limit, considers the problem that current vehicles ignore environmental cost caused by travel in the process of driving on the road network while pursuing minimum time cost, constructs a carbon emission cost function of travel, adds various travel constraint conditions, takes carbon emission as travel cost, makes vehicles pursue minimum carbon emission, and solves the problems of road congestion caused by uneven demand space-time distribution, insufficient utilization of traffic resources, reduced performance of the entire traffic network system, and increased environmental cost, improves travel economy, reduces waste gas emissions such as nitrogen oxides, is conducive to sustainable development, builds an environment-friendly society, responds to low-carbon travel policy, and is conducive to China to achieve the double-carbon strategic goal; the Lagrange factor is introduced by using the Lagrange algorithm to complete the emission minimization speed limit in traffic distribution, and the non-monotonic carbon emission cost function is avoided to be introduced into the traffic distribution model to make the solving result be local optimum. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0037] Figure 1 is the flow chart of the environment-friendly traffic distribution method considering carbon emission cost of the embodiment of the present application.

[0038] Figure 2 is the carbon emission cost factor and speed relationship diagram of the embodiment of the present application.

[0039] Figure 3 is the traffic network diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0041] The environment-friendly traffic distribution method considering carbon emission cost of the embodiment of the present application is specifically performed according to the following steps:

[0042] Step S1, road network basic data determination, determine the traffic demand, road capacity, road blockage coefficient and other data required by the environmental friendly traffic assignment method considering carbon emission cost in the road network, and then calculate:

[0043] The time consumed by vehicle travel t ij (x) is:

[0044] t ij (x) = α ij + β ij (x ij / c ij ) 4 ; (1)

[0045] Wherein, α ij , β ij are road ij congestion parameters, the larger α ij , β ij indicates that the road ij is more prone to congestion, α ij , β ij is calibrated by field measurement data; x ij is the flow on road ij; c ij is the capacity of road ij; the starting point of road ij is i and the ending point is j; if there is no vehicle in the road under ideal conditions, the current vehicle travels freely, x ij can be understood as 0, t ij is α ij , so α ij can be understood as free-flow travel time;

[0046] The running speed v ij (x) of vehicle on road ij can be determined as:

[0047] v ij (x) = d / (α ij + β ij (x ij / c ij ) 4 ); (2)

[0048] Wherein, d is the length of road ij, the unit of v ij (x) is km / h.

[0049] Step S2, determine the carbon emission cost function and the maximum value v max,ij of carbon emission minimization speed.

[0050] First, according to the vehicle operation data, the relationship between vehicle running speed and carbon monoxide and carbon dioxide emission, i.e. carbon emission cost function, is determined as:

[0051]

[0052] Among them, c ij (x) represents the unit carbon emission of road ij, in g / km, representing the emission of various gaseous substances such as carbon monoxide and carbon dioxide per unit kilometer; preferably, a1 = 3.952, a2 ​​= -3.061, a3 = 2.949, a4 = 4.866, a5 = -9.170, a6 = 1.155, b1 = 223.559.

[0053] Then, based on the relationship between vehicle operating speed and carbon monoxide and carbon dioxide emissions, the unit carbon emission c is determined. ij (x) or the speed v of the vehicle on road ij when carbon emission costs are minimized. ij The maximum value of (x) is the maximum rate v that minimizes carbon emissions. max,ij .

[0054] Step S3: Determine and add constraints to construct an environmentally friendly traffic assignment model that considers carbon emission costs, such as... Figure 1 As shown:

[0055] Adding road capacity constraints ensures the solvability of the traffic assignment method; adding road flow constraints and path flow constraints ensures that the traffic assignment results are more realistic; adding emission minimization speed constraints ensures the authenticity of the solution results and guarantees that the global emission minimum is found, avoiding the result being a local minimum.

[0056] Step S31: Add road capacity constraints:

[0057] When a road is overloaded with vehicles, it will be unable to fulfill its transportation function. Therefore, road capacity constraints are a key factor in ensuring the solvability of traffic assignment methods. Thus, the road capacity constraint complementarity formula is as follows:

[0058]

[0059] Where, λ ij Here, k represents the Lagrangian value of the capacity constraint for road ij, k represents the vehicle's destination point, and A is the set of roads. Let λ be the path flow on road ij with respect to destination k, and ⊥ represent λ. ij exist The projection on the surface; obviously, if the capacity constraint is found to be unbound, the corresponding Lagrange value will be zero, otherwise it will be positive.

[0060] Step S32: Add road flow constraints:

[0061] Traffic assignment models must have information from path flow. Calculate the road flow xij The constraint condition is:

[0062]

[0063] Step S33, adding path flow constraint:

[0064] The path flow conservation constraint can be expressed as:

[0065]

[0066] Wherein, And Indicate the path flow of the opposite direction of the same road with respect to the destination k, that is, in order to reach the destination, the vehicle can select different travel paths, and in different travel paths, there can be travel paths that all pass through the road ij, but some travel paths can travel along the positive direction of the road ij, and some travel paths can travel along the negative direction of the road ij, so when calculating the path flow, the flow along the negative direction of the road ij needs to be removed; is the traffic demand from point i to point k, N is the starting point set, and D is the destination set.

[0067] The path flow conservation constraint must also be written in the NCP format, and the above formula is bound with the travel carbon emission cost as follows:

[0068]

[0069] Wherein, is the carbon emission cost from the starting point i to the destination k;

[0070] If the travel time, i.e., the time consumed by the vehicle to travel t ij (x) is always non-zero, then the equality condition formula (6) is always satisfied.

[0071] Step S34, adding emission minimization speed constraint:

[0072] The carbon-containing gas emitted by the fuel vehicle has a huge impact on the environment, which is an important obstacle to sustainable scientific development. In the fixed demand static traffic assignment model (fixed traffic demand) used in the embodiment of the present application, the road carbon emission cost function is a convex function of the average speed, but they are non-monotonic functions of road flow, which does not meet a basic assumption of the traffic assignment model. The traditional traffic assignment model requires that the cost function be a monotonic increasing function of road flow, that is, the more traffic on the road, the higher the cost of vehicle travel on the road, and the more the cost paid. Obviously, the road carbon emission cost function does not meet this requirement. The embodiment of the present application uses Lagrange algorithm to introduce the Lagrange value θ ij, the emission-minimized speed constraint NCP equation of the road ij is constructed to ensure that the traffic assignment model constructed in the embodiment of the application meets the standard assumption that the cost function is a monotonically increasing function of the road traffic:

[0073] v ij ≤v max,ij (i,j)∈A; (8)

[0074] Therefore, the complementarity format of the emission-minimized speed constraint can be expressed as:

[0075] 0≤θ ij ⊥{v max,ij -v ij}≥0 (i,j)∈A; (9)

[0076] Wherein, θ ij is the Lagrange value of the emission-minimized speed constraint of the road ij, and v max,ij is the maximum speed value when the carbon emission is minimized by the carbon emission cost function. It is obvious that if the emission-minimized speed constraint is not activated, the corresponding Lagrange value will be zero, otherwise it will be positive. Figure 2 is the carbon emission cost factor-speed relationship diagram of the embodiment of the application, and the maximum value v max,ij of the carbon emission-minimized speed is obtained by fitting formula (3) as 68.2686 km / h.

[0077] Step S4: The MCP module is called by the GAMS software to solve the environment-friendly traffic assignment model considering the carbon emission cost, and an environment-friendly traffic assignment scheme considering the carbon emission cost is obtained:

[0078] For the traffic network as shown in Figure 3 , there are 4 nodes, 4 road sections and 1 OD pair, wherein node 1 is the traffic starting point and node 4 is the traffic ending point. The network OD demand is 1500 veh, and the network road basic information is shown in Table 1, wherein α and β are the current OD road delay coefficients, c is the maximum traffic capacity of the road OD, the unit is veh / h, d is the road length, the unit is km, and in the example, the time-related unit is h, the flow-related unit is veh / h, the speed-related unit is km / h, and the carbon emission-related unit is g / km, which represents the emission of gas (after fuel combustion) per kilometer.

[0079] Table 1 Road basic information in the embodiment

[0080] Serial number Road segment α β c d 1 1-2 7 7 3000 9.33 2 1-3 5 7 1000 6.67 3 2-4 6 7 3000 8 4 3-4 4 7 1000 5.33

[0081] The traffic assignment results of the simple assumed network are obtained by GAMS programming in the embodiment of the application, and are shown in Tables 2-4.

[0082] Table 2 Road-related results in the example

[0083] Road Flow Speed Carbon emission factor Time Saturation 1-2 781.953 68.000 209.883 7.226 0.452 1-3 718.047 27.784 302.876 14.304 0.593 2-4 781.953 68.000 209.883 6.194 0.452 3-4 718.047 27.784 302.876 11.443 0.593

[0084] Table 3 Path-related results in the example

[0085] Path Time factor Carbon emission cost factor Path flow 1-2-4 13.420 36.373 781.953 1-3-4 25.748 36.373 718.047

[0086] Table 4 Total road network-related results in the example

[0087] Name Data Total fuel consumption 17150.22 Total carbon emission 54559.128

[0088] The embodiment of the present application determines a vehicle travel cost function as a carbon dioxide (CO2) and carbon monoxide (CO) related carbon emission cost function constructed by taking average speed as an input variable, adds a road capacity limit guarantee method to ensure the solvability, adds road flow constraints and path flow constraints to ensure that the results are more realistic and have stronger engineering practicality, and adds an emission minimization speed limit to ensure the authenticity of the method solving results, guarantee to find the global minimum value of the carbon emission cost, avoid the result being a local minimum value, construct an environmentally friendly traffic distribution model under the principle of user equilibrium (UE) path selection, solve by using GAMS software, and improve the solving speed of the method.

[0089] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An environmentally friendly traffic assignment method considering carbon emission cost, characterized by, According to the following steps: Step S1: Determine traffic demand, road capacity, and road blocking coefficient within the road network, and calculate vehicle travel time on the road. The time consumed and the vehicle on the road On the running speed, road The starting point is i, and the ending point is j; Step S2, determining a carbon emission cost function and a carbon emission minimization speed maximum value based on a running speed of the vehicle on a road ; Step S3, based on the carbon emission cost function, determine the constraint condition, build the environment-friendly traffic distribution model considering carbon emission cost; Step S4, solve the environment-friendly traffic distribution model considering carbon emission cost, obtain the environment-friendly traffic distribution scheme considering carbon emission cost; Vehicle travel on road Time consumed on the way Is: （1） wherein, , is a road delay parameter; is a flow on a road ; is a capacity of a road ; Vehicles on the road running speed for: （2） wherein is the length of the road on which the vehicle is running, and the speed of the vehicle on the road is given in km / h; The carbon emission cost function is: （3） wherein, represents the unit carbon emission of the road , unit g / km, representing the emission of carbon monoxide and carbon dioxide per kilometer; , are coefficients of the carbon emission cost function; According to the carbon emission cost function, the unit carbon emission amount The maximum value of the running speed of the vehicle on the road when minimizing, that is, the maximum value of the carbon emission minimum speed The road capacity constraint is: （4） wherein, is the capacity of the road , is the capacity of the road constraint, k represents the destination point, and A is the set of roads, is the path flow on the road to the destination k, denotes the projection onto ; The road flow constraint is: （5） The path flow constraint is: （7） wherein, and denotes the opposite direction of the same road with respect to the path flow of destination k, is the traffic demand from point i to the end point k; N is the set of starting points, D is the set of end points; is the carbon emission cost from the starting point i to the end point k; Constructing roads the emission speed minimization constraint NCP equation, to ensure that the traffic assignment model constructed by the embodiments of the present application meets the standard assumption that the cost function is a monotonically increasing function of road traffic: （8） The emission minimization speed constraint is: （9） wherein, is the road emission speed minimization constraint Lagrangian value, is the carbon emission minimization speed maximum value; 2. The environmentally friendly traffic assignment method considering carbon emission cost according to claim 1, wherein, Based on the carbon emission cost function, the road capacity constraint, the road flow constraint, the path flow constraint and the emission minimization speed constraint are added to build the environment-friendly traffic distribution model considering carbon emission cost.

3. The environmentally friendly traffic assignment method considering carbon emission cost according to claim 1, wherein, The maximum value of the carbon emission minimization speed is 68.2686km / h.

4. The environmentally friendly traffic assignment method considering carbon emission cost according to claim 1, wherein, The GAMS software is used to call the MCP module to solve the environment-friendly traffic distribution model considering carbon emission cost, and the environment-friendly traffic distribution scheme considering carbon emission cost is obtained.

Images