An optimization method for realizing passenger and freight mixed transportation of urban rail transit

Abstract

The present application relates to a kind of urban rail transit and realizes the optimization method of passenger and freight co-transport, comprising the following steps: step 1: obtain rail transit timetable information and passenger flow data;Step 2: select research period, and carry out discretization processing to research period;Step 3: construct space-time network to describe the running state of rail transit train;Step 4: the passenger and freight co-transport problem of urban rail transit is converted into passenger and freight train type division problem and passenger and freight allocation problem;Step 5: realize the optimization of urban rail transit passenger and freight co-transport.The present application comprehensively considers the coupling relationship between passenger transport, freight transport, rail transit train, describes the running process of rail transit train by constructing space-time network;Train is divided into passenger train and passenger and freight co-transport train and considers the constraint of train loading capacity, constructs the integer programming model with minimum freight revenue and maximum passenger full load rate as target, realizes the collaborative transport of passenger transport and freight transport of rail transit line.

Description

Technical Field

[0001] This invention belongs to the field of urban rail transit operation organization technology, specifically relating to an optimization method for realizing passenger and freight transport in urban rail transit (especially subways). Background Technology

[0002] With further socio-economic development, people's living standards have greatly improved, and the urban population and number of vehicles have continued to increase. Simultaneously, to meet people's material needs, many industries have flourished, such as the logistics industry, whose coverage and transportation volume have significantly increased. Urban freight transport demand is growing daily, and urban environmental pollution is becoming increasingly serious. How to achieve low-carbon and sustainable development of urban transportation and related industries is a problem that is currently receiving continuous attention from all sectors.

[0003] In the process of urban rail transit network development, the imbalance between supply and demand, and the waste of capacity caused by the unbalanced temporal and spatial distribution of passenger demand and the excess capacity of existing lines, have become urgent problems to be solved in urban rail transit. Many cities' rail transit lines experience high passenger demand during morning and evening peak hours, with actual passenger volume often far exceeding the rated capacity in some sections; simultaneously, during off-peak hours or on some suburban lines where passenger demand is lower, line and vehicle resources are not fully utilized. Urban freight transport demand is constantly increasing with the development of urban logistics. At the same time, urban freight transport mainly relies on urban road transport, exacerbating road congestion and increasing urban carbon emissions. To alleviate environmental pollution and traffic congestion, some cities have proposed slow-moving traffic, vehicle restrictions, and the promotion of public transportation. For example, Beijing stipulates that freight vehicles are prohibited from traveling on roads within the Fifth Ring Road (excluding the Fifth Ring Road itself) from 6:00 to 23:00 daily for locally registered vehicles. Under such measures, freight transport time inevitably extends, and the timeliness of transport cannot be guaranteed.

[0004] Therefore, considering both the remaining passenger capacity of urban rail transit trains and the difficulty in delivering some time-sensitive goods to their destinations on time, a rail transit freight train mode is being considered. This involves transporting goods by rail freight trains to hub stations where railway and urban rail transit intersect, where staff transfer them to rail transit trains. This shared-line, shared-vehicle passenger and freight transport model based on urban rail transit not only makes more efficient use of train resources but also increases the revenue of operating companies while reducing transportation time for freight operators.

[0005] In existing technologies, many studies on logistics freight route planning involve urban rail transit freight, where rail transit freight is proposed as a transportation strategy. However, these studies lack a reasonable theoretical framework and mathematical model, and fail to adequately consider rail transit passenger services and timetables. The realization of rail transit freight requires not only operational planning but also infrastructure support. Existing technologies, while considering passenger trains towing freight trains and the establishment of dedicated freight lines, lack consideration of infrastructure investment costs. The goal of rail transit freight is to improve line utilization and increase operational revenue; therefore, to maximize the use of existing line conditions and reduce freight costs, it is necessary to optimize rail transit passenger and freight co-transport. Summary of the Invention

[0006] The purpose of this invention is to provide an optimized method for realizing passenger and freight transport in urban rail transit, so as to solve the problem that passenger service, rail transit timetables and investment costs are not fully considered in the prior art.

[0007] To achieve the above objectives, the technical solution of this invention is: to provide an optimized method for realizing passenger and freight transport in urban rail transit, the innovation of which lies in including the following steps:

[0008] Step 1: By analyzing historical data of rail transit operations, obtain rail transit timetable information and passenger flow data;

[0009] Step 2: Select any time period of rail transit operation as the study period, and discretize the study period;

[0010] Step 3: Combine the rail transit timetable information within the research period to construct a spatiotemporal network to describe the operating status of rail transit trains;

[0011] Step 4: Based on the spatiotemporal nodes of passenger and freight arrival and the spatiotemporal network of rail transit train operation, the problem of passenger and freight co-transport in urban rail transit is transformed into a problem of passenger and freight train type classification and passenger and freight allocation.

[0012] Step 5: Based on the loading and unloading time of urban freight, study the changes in train stopping time and the number of passengers getting on and off the train. With the goal of minimizing freight revenue and maximizing train load factor, construct and solve the urban rail transit passenger and freight co-transport model to achieve optimization of urban rail transit passenger and freight co-transport.

[0013] Furthermore, the rail transit timetable information obtained in step 1 includes the arrival and departure intervals and stop intervals of rail transit trains, and the passenger flow data obtained includes the origin and destination data of passengers.

[0014] Furthermore, in step 2, the off-peak period of rail transit operation is selected as the research period.

[0015] Furthermore, the study period is discretized, that is, a complete period is discretized into many time intervals with a unit time length of 1, and the discretized time set is represented by the set T = {t|1,2,...,q}, where 1 and q represent the start time node and end time node of the study period, respectively.

[0016] Furthermore, in step 3, the specific method for constructing the spatiotemporal network is as follows: a two-dimensional coordinate system is used to describe the spatiotemporal trajectory of the rail transit train; the train's operating status is described by variables with values ​​of 0 or 1, where the variable is equal to 1 when train i has arrived at or passed station k at time t; and equal to 0 when train i has not yet arrived at station k at time t.

[0017] Furthermore, in step 4, the classification of passenger and freight train types and the allocation of passengers and goods are specifically as follows: by considering passengers and goods arriving at different times as control units, the rail transit trains are classified into passenger trains and passenger-freight trains based on the spatiotemporal matching of goods and rail transit trains; based on the classification of rail transit trains into passenger trains and passenger-freight trains, the matching situation of passengers and goods with rail transit trains is obtained by combining the time of passenger arrival at the station and considering the constraints of the loading capacity of rail transit trains.

[0018] Furthermore, the urban rail transit passenger and freight transport model constructed in step 5 specifically includes the following decision variables:

[0019] Define decision variables as non-negative integers. Let i represent whether the i-th (∈I) rail transit train is a passenger and freight train; where I = {i|1,2,...,n} is the set of rail transit trains, i is the index of the rail transit train, and n is a constant representing the total number of rail transit trains;

[0020] Define a non-negative integer decision variable γi,l,p (∈[0,1]) to represent whether the i-th (∈I) rail transit train needs to transport goods lp (usually measured in freight containers); where L={l|1,2,...,f} is the set of railway freight trains, l is the index of the railway freight train, and f is a constant representing the total number of railway freight trains; P={p|1,2,...,e} is the batch of goods on the railway freight train, p is the index of the goods on the railway freight train, and e represents the batch number of goods on the train. Goods are identified by combining railway freight train numbers and batch numbers. The set of all such goods is denoted as LP.

[0021] Define an integer variable K = {k|1,2,...,m} to represent the set of rail transit stations, where m is the number of trains, k is the index of the rail transit station, and m is a set representing the total number of rail transit stations. Define a non-negative integer decision variable. This represents the number of passengers arriving at station k per unit of time.

[0022] Furthermore, in step 5, the process of constructing and solving the urban rail transit passenger and freight transport model is as follows:

[0023] (1) Train arrival constraints

[0024] The arrival time of train i at station k is the sum of the departure time of train i at station k-1 and the running time of the interval. At the same time, the interval from station k to station k+1 is defined as interval k.

[0025]

[0026] In the formula: This indicates the time when train i arrives at station k. This indicates the time when train i leaves station k-1. This represents the travel time of train i in section k;

[0027] The train's arrival time should meet the arrival interval constraint:

[0028]

[0029] In the formula: This represents the minimum arrival interval of train i at station k. This represents the maximum arrival interval of train i at station k;

[0030] (2) Train departure constraints

[0031] The departure time of train i at station k is determined by the arrival time of train i at station k and the dwell time at station k:

[0032]

[0033] In the formula: This indicates the dwell time of train i at station k;

[0034] Train departure times should also meet departure interval constraints:

[0035]

[0036] In the formula: This represents the minimum departure interval for train i at station k. This represents the maximum departure interval of train i at station k;

[0037] (3) Train stopping time constraints

[0038] The stopping time of a train at a station should meet the maximum and minimum interval constraints:

[0039]

[0040] In the formula: This represents the minimum stopping time of train i at station k. This indicates the maximum dwell time of train i at station k;

[0041] The time constraints for stopping on passenger and freight trains are as follows:

[0042]

[0043] In the formula: This indicates the dwell time of train i at the originating station of freight lp. This indicates the additional stop time that train i experiences at the originating station of freight lp due to loading of goods. This represents the minimum stopping time of train i at the originating station of freight lp, and its value is related to... equal, This represents the maximum dwell time of train i at the originating station of freight lp, and its value is related to... equal;

[0044]

[0045] In the formula: This indicates the dwell time of train i at the destination station of freight lp. This indicates the additional stop time that train i experiences at the terminal station of freight lp due to unloading of goods. This represents the minimum stopping time of train i at the destination station of freight lp, and its value is related to... equal, This represents the maximum dwell time of train i at the destination station of freight lp, and its value is related to... equal;

[0046] (4) Matching of goods with trains

[0047] Goods p on railway train l can be transported by a certain rail transit train i:

[0048]

[0049] Goods arriving at station k will be transported by the train that arrives immediately thereafter, i.e.:

[0050]

[0051] In the formula: This indicates the time when cargo lp arrives at station k on the rail transit line;

[0052]

[0053] (5) Train rated passenger capacity constraints

[0054] The rated passenger capacity of a passenger train is C, and the rated passenger capacity of a passenger-freight combined train is c:

[0055]

[0056] (6) Calculation of train load factor

[0057] The methods for calculating the passenger load factor for the two types of trains are as follows:

[0058]

[0059] In the formula: This indicates the passenger flow at the cross-section after train i leaves station k; w i,k This indicates the load factor of train i after it leaves station k;

[0060]

[0061]

[0062]

[0063] (7) Representation of train operation state variables

[0064] Use variable b i,k (t)(∈[0,1]) describes the train's operating state:

[0065]

[0066]

[0067] Introduce variable y i,k (t)(∈[0,1]) is further calculated for the train's operating state variables:

[0068]

[0069] (8) Passenger flow calculation

[0070] The arrival time of passengers at rail transit stations is dynamic, and the number of passengers boarding is the cumulative number of passengers arriving at the station within the arrival interval of the rail transit train.

[0071]

[0072] In the formula: This represents the number of passengers boarding train i at station k;

[0073] The passenger flow disembarking at station v on train i is equal to the total passenger flow boarding at the preceding stations whose destination is this station:

[0074]

[0075] In the formula: β represents the number of passengers disembarking at station k for train i. v,k (t) represents the proportion of passengers arriving at station v and heading to station k within time period t;

[0076] Passenger flow calculation for section cross-section:

[0077]

[0078] All passengers arriving at the station can board the train to leave, fulfilling their travel needs:

[0079]

[0080] (9) Objective function

[0081] While meeting freight demand, the goal is to maximize train load factor in order to improve train capacity utilization.

[0082]

[0083] In the formula: v l,p This indicates the revenue generated from the freight of goods.

[0084] Furthermore, the constraints and objective functions in steps (1)-(9) are compiled and solved using the cplex solver, that is, the urban rail transit passenger and freight transport model is solved to achieve the optimization of urban rail transit passenger and freight transport.

[0085] Compared with the prior art, the beneficial effects of this invention are as follows:

[0086] (1) The optimization method for realizing passenger and freight transport in urban rail transit described in this invention comprehensively considers the coupling relationship between passenger transport, freight transport and rail transit trains. By discretizing the research time, a spatiotemporal network is constructed to describe the operation process of rail transit trains. Considering the dynamic arrival characteristics of passengers and goods, combined with the spatiotemporal network of train operation, the trains are divided into passenger trains and passenger and freight trains. Considering the constraints of train loading capacity, an integer programming model with the objectives of minimizing freight revenue and maximizing passenger load rate is constructed, thereby realizing the coordinated transport of passenger and freight transport on rail transit lines.

[0087] (2) The optimization method for realizing passenger and freight transport in urban rail transit described in this invention can be used as a transportation scheme for realizing passenger and freight transport in urban rail transit during off-peak hours. Specifically, based on the allocation strategy of goods and trains and the selection strategy of passengers for trains, the method takes into account the change of the stopping time of urban rail transit trains due to the loading and unloading of goods, so as to realize the reasonable allocation of passengers and goods and make full use of rail transit operation resources. Attached Figure Description

[0088] To more clearly illustrate the technical solutions in the implementation of this invention, the following will use accompanying drawings to describe the implementation process of this invention.

[0089] Figure 1 This is a flowchart illustrating the steps of an optimized method for achieving passenger and freight transport in urban rail transit according to the present invention.

[0090] Figure 2 A schematic diagram illustrating two modes of transportation under urban rail transit passenger and freight combined transport;

[0091] Figure 3 A schematic diagram of the freight transport process for urban rail transit trains;

[0092] Figure 4 A schematic diagram illustrating the spatiotemporal relationship of passenger and freight transport in urban rail transit;

[0093] Figure 5 This is a schematic diagram of the train's operating status. Detailed Implementation

[0094] The present invention will be further described in detail below with reference to the accompanying drawings. This detailed description is merely illustrative to aid understanding and is not intended to limit the scope of the invention.

[0095] This invention provides an optimized method for achieving passenger and freight transport in urban rail transit, the specific process of which is as follows: Figure 1 As shown, it includes the following steps:

[0096] Step 1: By analyzing historical data of rail transit operations, obtain rail transit timetable information and passenger flow data; the obtained rail transit timetable information includes the arrival and departure intervals and station intervals of rail transit trains, and the obtained passenger flow data includes the origin and destination data of passengers.

[0097] Step 2: Select any time period of rail transit operation as the study period, and discretize the study period;

[0098] This invention preferably uses off-peak hours of rail transit operation as the research period. Off-peak hours are selected during rail transit operation periods with lower passenger flow.

[0099] The study period is discretized by dividing a complete period into many time intervals with a unit time length of 1. The discretized time set is represented by the set T = {t|1,2,...,q}, where 1 and q represent the start and end times of the study period, respectively.

[0100] Step 3: Combining the rail transit timetable information within the research period, construct a spatiotemporal network to describe the operating status of rail transit trains; the specific method for constructing the spatiotemporal network is to use a two-dimensional coordinate system to describe the spatiotemporal trajectory of the rail transit trains, such as... Figure 4 As shown, the spatiotemporal network illustrates the spatiotemporal trajectory of urban rail transit trains, where the horizontal axis represents time and the vertical axis represents the track line and stations; the train's operational status is as follows: Figure 5 As shown, the arrival status of urban rail transit trains is described by variables with values ​​of 0 or 1. When train i has arrived at or passed station k at time t, the variable is equal to 1; when train i has not yet arrived at station k at time t, the variable is equal to 0.

[0101] Step 4: Based on the spatiotemporal arrival nodes of passengers and goods, and combined with the spatiotemporal network of rail transit train operation, the problem of passenger and freight transport in urban rail transit is transformed into a problem of classifying passenger and freight train types and a problem of passenger and freight allocation, such as... Figure 2 As shown, rail transit refers to rail transit that can serve both passengers and goods simultaneously, that is, rail transit has the infrastructure to provide passenger and freight services. Figure (a) shows a rail transit passenger and freight train, and Figure (b) shows a rail transit passenger train.

[0102] The classification of passenger and freight trains and the allocation of passengers and goods are as follows: By considering passengers and goods arriving at different times as control units, and based on the spatiotemporal matching of goods with rail transit trains, rail transit trains are classified into passenger trains and passenger-freight mixed trains. Based on this classification, and considering passenger arrival times at stations and the constraints of rail transit train loading capacity, the matching of passengers and goods with rail transit trains is obtained, such as... Figure 3 As shown, urban rail transit freight refers to the following: goods from railway freight trains arrive at the platform via freight trolleys, waiting for train transfer; after arriving at the destination station, they are transferred to customers via freight transport vehicles.

[0103] Step 5: Based on the loading and unloading time of urban freight, study the changes in train dwell time and the number of passengers boarding and alighting. With the objectives of minimizing freight revenue and maximizing train occupancy rate, construct and solve an urban rail transit passenger-freight co-transport model to optimize urban rail transit passenger-freight co-transport. Figure 4As shown, people and freight containers of different colors illustrate the process of passengers getting on and off and freight containers loading and unloading when the train stops. The origin and destination of the passengers and freight containers are different, or the arrival time is different, or both are different.

[0104] The constructed urban rail transit passenger and freight combined transport model includes the following decision variables:

[0105] Define decision variables as non-negative integers. Let i represent whether the i-th (∈I) rail transit train is a passenger and freight train; where I = {i|1,2,...,n} is the set of rail transit trains, i is the index of the rail transit train, and n is a constant representing the total number of rail transit trains;

[0106] Define a non-negative integer decision variable γ i,l,p (∈[0,1]) indicates whether the i-th (∈I) rail transit train is to transport goods lp (usually measured in freight containers); where L={l|1,2,...,f} is the set of railway freight trains, l is the index of the railway freight train, and f is a constant representing the total number of railway freight trains; P={p|1,2,...,e} is the freight batch of the railway freight train, p is the index of the freight of the railway freight train, and e represents the batch number of the freight on the train. The freight is identified by combining the railway freight train number and the freight batch number. The set of all such freight is denoted as LP.

[0107] Define an integer variable K = {k|1,2,...,m} to represent the set of rail transit stations, where m is the number of trains, k is the index of the rail transit station, and m is a set representing the total number of rail transit stations. Define a non-negative integer decision variable. This represents the number of passengers arriving at station k per unit of time.

[0108] The process of constructing and solving the urban rail transit passenger and freight combined transport model is as follows:

[0109] (1) Train arrival constraints

[0110] The arrival and departure of a train should both comply with the basic rules and logic of train operation; the arrival time of train i at station k is the sum of the departure time of train i at station k-1 and the running time within the interval; at the same time, the interval from station k to station k+1 is defined as interval k.

[0111]

[0112] In the formula: This indicates the time when train i arrives at station k. This indicates the time when train i leaves station k-1. This represents the travel time of train i in section k;

[0113] To ensure safe train operation, train departure intervals must meet certain requirements. On the one hand, a certain distance must be maintained between trains to avoid conflicts and meet technical requirements. On the other hand, trains should respond to passenger travel demands within a certain timeframe. Excessive train intervals are detrimental to the operation of urban rail transit companies. Therefore, train arrival times should meet arrival interval constraints.

[0114]

[0115] In the formula: This represents the minimum arrival interval of train i at station k. This represents the maximum arrival interval of train i at station k;

[0116] (2) Train departure constraints

[0117] The departure time of train i at station k is determined by the arrival time of train i at station k and the dwell time at station k:

[0118]

[0119] In the formula: This indicates the dwell time of train i at station k;

[0120] Because train dwell time changes with the loading and unloading of goods, in addition to establishing interval constraints on train arrival times, train departure times should also satisfy departure interval constraints:

[0121]

[0122] In the formula: This represents the minimum departure interval for train i at station k. This represents the maximum departure interval of train i at station k;

[0123] (3) Train stopping time constraints

[0124] Trains stop at stations to allow passengers to board and alight. The stopping time should be controlled within a suitable timeframe, and the stopping time at stations should meet the maximum and minimum interval constraints.

[0125]

[0126] In the formula: This represents the minimum stopping time of train i at station k. This indicates the maximum dwell time of train i at station k;

[0127] Loading and unloading of goods at the station must be completed within the train's stop time. At both the origin and destination of the goods, loading and unloading will increase the train's stop time. The stop time constraints for passenger-freight combined trains are as follows:

[0128]

[0129] In the formula: This indicates the dwell time of train i at the originating station of freight lp. This indicates the additional stop time that train i experiences at the originating station of freight lp due to loading of goods. This represents the minimum stopping time of train i at the originating station of freight lp, and its value is related to... equal, This represents the maximum dwell time of train i at the originating station of freight lp, and its value is related to... equal;

[0130]

[0131] In the formula: This indicates the dwell time of train i at the destination station of freight lp. This indicates the additional stop time that train i experiences at the terminal station of freight lp due to unloading of goods. This represents the minimum stopping time of train i at the destination station of freight lp, and its value is related to... equal, This represents the maximum dwell time of train i at the destination station of freight lp, and its value is related to... equal;

[0132] (4) Matching of goods with trains

[0133] Goods p on railway train l can be transported by a certain rail transit train i. Once the goods are transported by train i, they cannot be transported by other trains, and the same batch of goods cannot be divided as a whole.

[0134]

[0135] Goods arriving at station k will be transported by the train that arrives immediately thereafter, i.e.:

[0136]

[0137] In the formula: This indicates the time when cargo lp arrives at station k on the rail transit line;

[0138]

[0139] (5) Train rated passenger capacity constraints

[0140] The rated passenger capacity of a train is affected by whether it carries freight. The rated passenger capacity of a passenger train is C, and the rated passenger capacity of a passenger-freight combined train is c:

[0141]

[0142] (6) Calculation of train load factor

[0143] The methods for calculating the passenger load factor for the two types of trains are as follows:

[0144]

[0145] In the formula: This indicates the passenger flow at the cross-section after train i leaves station k; w i,k This indicates the load factor of train i after it leaves station k;

[0146]

[0147]

[0148]

[0149] (7) Representation of train operation state variables

[0150] Use variable b i,k (t)(∈[0,1]) describes the train's operating state, when b i,k When (t) = 1, it means that train i has arrived at or passed through station k at time t; when b i,k When (t) = 0, it means that train i has not yet arrived at station k at time t:

[0151]

[0152]

[0153] To facilitate passenger flow calculation, the variable y is introduced. i,k (t)(∈[0,1]) further calculates the train's operating state variables to reduce the computational load when calculating passenger flow; for the first train, passengers who have arrived at station k before the train leaves station k can take the train to leave; for subsequent trains, passengers who arrive between the time period after train i leaves station k and the time period between the time period after train i leaves station k and the time period after train i+1 leaves station k can take train i+1 to leave:

[0154]

[0155] (8) Passenger flow calculation

[0156] The arrival time of passengers at the rail transit station is dynamic. The number of passengers boarding is the cumulative number of passengers arriving at the station within the arrival interval of the rail transit train. By summing the number of passengers arriving in each discrete time particle, the passenger flow during the study period can be obtained. Since we are considering the passenger and freight transport situation during off-peak hours, we assume that passengers arriving at station k can take the first train arriving after their arrival to leave. Therefore, the passenger flow of train i boarding at station k is calculated as follows:

[0157]

[0158] In the formula: This represents the number of passengers boarding train i at station k;

[0159] Since the origin and destination points of passengers' journeys are known, the proportion of passengers boarding at a station going to different destination stations is also known. The passenger flow disembarking at station v on train i is equal to the total passenger flow boarding at the preceding stations whose destination is v:

[0160]

[0161] In the formula: β represents the number of passengers disembarking at station k for train i. v,k (t) represents the proportion of passengers arriving at station v and heading to station k within time period t;

[0162] Passenger flow calculation for section cross-section:

[0163]

[0164] All passengers arriving at the station can board the train to leave, fulfilling their travel needs:

[0165]

[0166] (9) Objective function

[0167] While meeting freight demand, the goal is to maximize train load factor in order to improve train capacity utilization.

[0168]

[0169] In the formula: v l,p This indicates the revenue generated from the freight of goods.

[0170] The constraints and objective functions in steps (1)-(9) are compiled and solved by the cplex solver, that is, the urban rail transit passenger and freight transport model is solved to realize the optimization of urban rail transit passenger and freight transport.

[0171] This invention discloses an optimized method for achieving passenger and freight co-transportation in urban rail transit. The aim is to provide an optimized method for achieving passenger and freight co-transportation under shared rail transit lines and vehicles, enabling passenger and freight co-transportation during off-peak hours in urban rail transit to fully utilize rail transit operating resources. The above description is merely a preferred embodiment of the invention, but the scope of protection of the invention is not limited to the above-described embodiment. Simple variations or substitutions made by those skilled in the art within the technical scope disclosed in this invention should all be included within the scope of protection of this invention.

Claims

1. An optimized method for achieving passenger and freight transport in urban rail transit, characterized in that, Includes the following steps: Step 1: By analyzing historical data of rail transit operations, obtain rail transit timetable information and passenger flow data; Step 2: Select any time period of rail transit operation as the study period, and discretize the study period; Step 3: Combine the rail transit timetable information within the research period to construct a spatiotemporal network to describe the operating status of rail transit trains; The specific method for constructing the spatiotemporal network is as follows: A two-dimensional coordinate system is used to describe the spatiotemporal trajectory of rail transit trains; the train's operating state is described using variables with values ​​of 0 or 1 to represent the arrival state of urban rail transit trains. i exist t The time has arrived or passed through the station. k When the train is in motion, the variable equals 1; when the train is in motion... i exist t The time has not yet arrived at the station. k When the variable equals 0; Step 4: Based on the spatiotemporal nodes of passenger and freight arrival and the spatiotemporal network of rail transit train operation, the problem of passenger and freight co-transport in urban rail transit is transformed into a problem of passenger and freight train type classification and passenger and freight allocation. Step 5: Based on the loading and unloading time of urban freight, study the changes in train stopping time and the number of passengers getting on and off the train. With the goal of minimizing freight revenue and maximizing train load factor, construct and solve the urban rail transit passenger and freight co-transport model to achieve optimization of urban rail transit passenger and freight co-transport. The constructed urban rail transit passenger and freight combined transport model includes the following decision variables: Define decision variables as non-negative integers. Indicates the first Is the rail transit train a passenger and freight train? , ;in, It is a collection of rail transit trains, and i It is an index for rail transit trains. n It is a constant representing the total number of rail transit trains; Define decision variables as non-negative integers. Indicates the first Does the rail transit train need to transport goods? lp , , ;in, l For indexing railway freight trains, p It is an index of goods on railway freight trains; goods are identified by a combination of railway freight train number and cargo batch number, and the set of all such goods is denoted as . LP ,in, It is a collection of railway freight trains. It is a constant representing the total number of railway freight trains; It is a collection of cargo batches on railway freight trains. e Indicates the number of batches of goods on the train; Define integer variables It represents a collection of rail transit stations. m For the number of trains, k It is an index of rail transit stations, defining non-negative integer decision variables. Indicates arrival time at the station per unit of time. k The number of passengers.

2. The optimized method for realizing passenger and freight transport in urban rail transit according to claim 1, characterized in that, The rail transit timetable information obtained in step 1 includes the arrival and departure intervals and stop intervals of rail transit trains, and the passenger flow data obtained includes the origin and destination data of passengers.

3. The optimized method for realizing passenger and freight transport in urban rail transit according to claim 1, characterized in that, In step 2, the off-peak period of rail transit operation is selected as the research period.

4. The optimized method for realizing passenger and freight transport in urban rail transit according to claim 3, characterized in that, The study period is discretized, that is, a complete period of time is discretized into many time intervals with a unit time length of 1, and a set is used. Represents the set of time after time discretization, where 1 and q These represent the start and end times of the research period, respectively.

5. An optimized method for realizing passenger and freight transport in urban rail transit according to claim 1, characterized in that, In step 4, the classification of passenger and freight train types and the allocation of passengers and goods are specifically as follows: by considering passengers and goods arriving at different times as control units, and based on the spatiotemporal matching of goods and rail transit trains, rail transit trains are classified into passenger trains and passenger-freight trains; based on the classification of rail transit trains into passenger trains and passenger-freight trains, and considering the time of passenger arrival at the station and the constraints of the rail transit train's loading capacity, the matching situation of passengers and goods with rail transit trains is obtained.

6. The optimized method for realizing passenger and freight transport in urban rail transit according to claim 1, characterized in that, In step 5, the process of constructing and solving the urban rail transit passenger and freight combined transport model is as follows: (1) Train arrival constraints train i At the station k The arrival time is the train i exist k The sum of the departure time and the interval running time at station -1, and at the same time... k Station to k The interval defined by +1 station is k Interval: In the formula: Indicates train i arrive k The station's time, Indicates train i leave k The time at station -1 Indicates train i exist k The running time of the interval; The train's arrival time should meet the arrival interval constraint: In the formula: Indicates train i exist k Minimum arrival interval of the station Indicates train i exist k Maximum arrival interval at the station; (2) Train departure constraints train i At the station k The departure time is determined by the train i arrive k Arrival time at the station and at k The station's stopping time is determined by: In the formula: Indicates train i exist k Station dwell time; Train departure times should also meet departure interval constraints: In the formula: Indicates train i exist k The minimum departure interval at the station, Indicates train i exist k Maximum departure interval at the station; (3) Train stop time constraints The stopping time of a train at a station should meet the maximum and minimum interval constraints: In the formula: Indicates train i exist k The minimum stopping time at the station, Indicates train i exist k The maximum dwell time at the station; The time constraints for stopping on passenger and freight trains are as follows: In the formula: Indicates train i exist lp The dwell time of the goods at the originating station. Indicates train i exist lp The additional stop time at the originating station of the freight due to loading of goods. Indicates train i exist lp The minimum stopping time at the originating station of the goods, its value is related to equal, Indicates train i exist lp The maximum dwell time at the originating station of the goods, its value is related to... equal; In the formula: Indicates train i exist lp The dwell time of the goods at the destination station. Indicates train i exist lp The additional stop time at the destination station due to unloading of goods. Indicates train i exist lp The minimum dwell time at the destination station for goods, its value is related to equal, Indicates train i exist lp The maximum dwell time of goods at the destination station, its value is related to equal; (4) Matching of goods with trains Goods p in railway freight train l can be transported by a certain rail transit train i: Arrival at the station k The goods will be transported by subsequent arriving trains, namely: In the formula: Indicates goods lp Arrival at the rail transit line k Station time; (5) Train rated passenger capacity constraints The rated passenger capacity of passenger trains is C The rated passenger capacity of the passenger-freight combined train is c : (6) Calculation of train load factor The methods for calculating the passenger load factor for the two types of trains are as follows: In the formula: Indicates train i leave k Passenger flow at the section behind the station; Indicates train i leave k The occupancy rate behind the station; (7) Representation of train operation state variables Use variables Describe the train's operating status. Introducing variables Further calculations were performed on the train's operating state variables. (8) Passenger flow calculation The arrival time of passengers at rail transit stations is dynamic, and the number of passengers boarding is the cumulative number of passengers arriving at the station within the arrival interval of the rail transit train. In the formula: Indicates in k Take the train at the station i Passenger volume; train i At the station v The alighting passenger flow is the sum of the boarding passenger flows at the stations preceding this station that are the destination station: In the formula: Indicates train i exist k The number of passengers disembarking at the station, Indicates time period t Inside, arrival route v Station and head to k The proportion of passengers at the station; Passenger flow calculation for section cross-section: All passengers arriving at the station can board the train to leave, fulfilling their travel needs: (9) Objective function While meeting freight demand, the goal is to maximize train load factor in order to improve train capacity utilization. In the formula: This indicates the revenue generated from the freight of goods.

7. An optimized method for realizing passenger and freight transport in urban rail transit according to claim 6, characterized in that, The constraints and objective functions in steps (1)-(9) are compiled and solved by the cplex solver, that is, the urban rail transit passenger and freight transport model is solved to achieve the optimization of urban rail transit passenger and freight transport.

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