# Logistics Distribution Vehicle Routing Problem with Time Window under Pallet 3D Loading Constraint
## 5 Example Analysis
### Management Insights  
Optimization of 3D loading is a crucial link in the process of transportation and distribution. The improvement of the loading rate can reduce the occurrence of unreasonable transportation. It is a more standardized and specific form of zero-load transportation in the development process of modern logistics. In this study, for the logistics distribution vehicle routing problem with a time window under the constraint of 3D pallet loading, a pallet with adjustable support structure height is introduced as the intermediate carrier of loading and unloading. Combined with the customer point routing problem as well as the time window, a two-stage 3D loading optimization scheme is carried out, which improves the loading rate and reduces the time cost. The management insights can be summarized as follows.  
(1) The use of pallets improves the efficiency of cargo handling. Compared with the traditional space division strategy, hundreds and even thousands of goods can be integrated by taking the pallet with the height of the retractable support structure as the unit of the minimum customer point goods. Using a forklift to remove the pallet greatly improves the loading and unloading speed, reduces the residence time of the customer point, and enables the distribution vehicles to flow more flexibly in the path. In the future, this method can be operated on the basis of existing equipment, such as pallets, forklifts, and box trucks, as well as computers, and can also be further adapted to the development and application of fully automatic AGV vehicles, bar codes, PDA, RF, and other technologies. It adapts to the development trend of automation and information technology of modern logistics that will make production more efficient.  
(2) High loading rates reduce the number of vehicles used. Reducing the loading gap in the distribution carriage can reduce the occurrence of irrational transport. Through the 3D loading optimization and the cooperative use of loading and unloading equipment, the carriage can no longer strictly follow the principle of \"first in, last out\", which can make full use of the interior space and reduce the use of distribution vehicles. It not only promotes the sharing of logistics resources and reduces logistics costs, but more importantly, it can reduce carbon emissions and promote the development of green logistics.  
(3) Two-stage three-dimensional loading can save more time. In this paper, two stages of three-dimensional loading are proposed, which can greatly save delivery time and reduce the time cost by optimizing the line and considering the time window. The first stage is to integrate the goods from the same customer point and load the goods into the pallet, which is more convenient for centralized operation. Different specifications and different natures of the goods need independent packaging to meet the special protective requirements. In the process of dealing with a large number of express delivery, a chaotic situation is easy to appear, and this hidden danger is not perceived in the process of transportation. Multi-stage loading can not only meet the transportation requirements of different goods but also centralize the processing of multi-batch goods. In the express industry, the customer attribute is more complex than in enterprise transportation. Often, there will be a variety of single processing, especially when it is time to find a lost delivery or pick up goods in the new transfer station; the sorter can handle only the inside of the pallet or the whole pallet, which is much more convenient than handling an entire carriage of express goods.