Optimization Of Cold Chain Logistics Distribution Route Considering Road Traffic Conditions Research

With the improvement of consumption level,the demand of consumers for cold chain products is increasing,and the cold chain market in our country has entered a critical period of rapid development.Cold chain logistics as an important means to ensure the quality of fresh products get great attention from country and logistics enterprises.Cold chain distribution is the core link of cold chain logistics.Compared with ordinary products,cold chain products are perishable and require higher timeliness of distribution.However,congestion on urban roads is a growing problem,accounting for more than 80 percent of travel time lost in economic terms.From an environmental perspective,congestion leads to higher fuel consumption and greenhouse gas emissions.Therefore,it is of great significance to reasonably plan the distribution route of cold chain logistics on the basis of considering road traffic conditions.In this paper,based on the review of the existing research results of cold chain logistics vehicle routing optimization problem,firstly from the problem of quantitative characterization of road network traffic state,proposed the calculation method of actual travel time between road section nodes in different periods(working days,holidays and weekends).Then take this data as the support to further study the vehicle routing problem considering the road traffic condition.In order to obtain the actual travel time between nodes of road sections,this paper first selects Amap with high availability,low cost and massive data as the data source,and uses Python programming tool to enter the API port of Amap to obtain the traffic congestion index of Lianhu District,Xi ’an City and the name,length,travel speed,travel time and traffic congestion index of each section.Then,the zero flow time is calculated by using the traffic speed and length of the section,the traffic congestion index is analyzed and fitted statistically,and the evolution law of traffic congestion is studied according to the changing trend of the traffic congestion index.Finally,the calculation method of actual travel time between nodes of road sections in different festivals and different time periods is obtained,which provides data support for the construction of vehicle routing optimization model.In this paper,a multi-objective vehicle routing optimization model considering road traffic conditions is established.Virtual nodes are introduced into the model to build an abstract model of the actual road network.Considering that the shortest "space-time distance" is not the shortest time,the distance factor is transformed into the time factor,and the minimum sum of fixed cost,transportation cost,freight damage cost,refrigeration cost,carbon emission cost and distribution worker’s salary is taken as the cost objective function.An evaluation index combining the salary and work intensity of deliverers is designed,and an evaluation model of deliverer satisfaction based on grey whitening weight function is constructed,and an objective function considering the maximum satisfaction of deliverers is established.Considering constraints such as time window,customer satisfaction and load,this paper makes full use of the adaptability of large-scale adaptive domain search(ALNS)algorithm to balance the relationship between large-scale optimization and time consumption of fast non-dominated sorting genetic algorithm(NSGAⅡ)with elite strategy,and obtains the multi-objective Pareto optimal solution set.Finally,through the case analysis of a fresh food distribution enterprise in Lianhu District,Xi ’an City,different distribution schemes on working days,holidays and weekends were obtained.The results of the optimization model proposed in this paper were compared with those of the vehicle routing optimization model without considering the satisfaction of the deliverer.The results show that: The ALNS algorithm designed in this paper has good convergence and stability,and can generate effective Pareto optimal solutions and Pareto frontiers.Compared with the model without considering distributor satisfaction,this model has advantages in improving distributor satisfaction,customer satisfaction,load rate and shortening transportation time.In addition,sensitivity analysis of customer satisfaction and road traffic state is carried out to further verify the effectiveness of the proposed model and algorithm.