The concept of transportation network has not been mentioned in relevant academic works at home and abroad. Here we define the connotation and extension of transportation network from different aspects. From the perspective of enterprises, transportation network refers to the circulation channel for products to move from the place of supply to the place of sale. From its basic elements, transportation network refers to the different interrelationships, mutual configurations, structures, compositions, contact methods, etc. between lines and nodes; From the perspective of network, transportation network refers to the network formed between various functional elements of the transportation system, including the physical network and information network Website production 。 
This section mainly understands the transportation network from the perspective of the process of logistics activities and the graph theory network. From the perspective of the process of logistics activities, logistics activities can be divided into movement and temporary pause. Generally, there will be a temporary pause between two movements, and a philosophical pause often connects two different movements, Logistics activities are composed of this kind of "move stop move stop". All logistics activities are completed between movement and pause, and transportation network is an important material basis for completing logistics activities and the premise for realizing logistics movement. From the perspective of graph theory, network refers to the overall or connected graph that several line segments (measurement with direction and value) connect some points (with grade difference), It can be used to study the state, change and trend of the internal connection of various spatial entities. From the perspective of regional economics, the network is the "vein" of regional economic society, the combination of nodes and lines. Nodes are the core of the network. The line is an indispensable channel for the interconnection between nodes. The transportation network is the carrier of logistics activities, so the transportation network is composed of two basic elements: various transportation routes (railways, highways, airlines, waterways, etc.) that provide movement and various nodes that provide temporary pause. The composition and connection mode of transportation routes and various nodes are different, forming transportation networks with different topological structures, And it directly determines the size of the radiation range of the transportation network and the strength of its functions. The core of transportation network planning is to determine the number and location of transportation nodes, as well as the transportation routes between transportation nodes and between transportation nodes and customer nodes
The transportation network structure refers to the structure of the entire distribution channel of goods from the starting point to the destination, including the number and location of transportation nodes, the corresponding customer groups served by transportation nodes, the corresponding product categories, and the way products are transported between nodes. It is mainly composed of transportation nodes, customer nodes, transportation routes and other elements. The following focuses on the classification of transportation network structure Principles of development and planning
The transportation network is a system structure composed of transportation nodes, transportation routes and economic "organizations" at all levels, which are interrelated and interacted with each other. Due to the difference of regional geography and social economy, the transportation network presents different structural forms, which can be roughly divided into radial network, radial ring network, sector network, axial belt network, ring network and branch network. The classification, development and planning principles of the transportation network structure are introduced again
The development of Yunhan network structure.
The transportation network structure has evolved from the earliest fully connected transportation network to the current axis like radial transportation network, which is in turn: fully connected transportation network structure (without transportation nodes), single transportation node transportation network structure, single transportation node transportation network structure with partial loops, multi transportation node transportation network structure Multi transport node with partial loop transport network structure, multi transport node axis radial transport network. The evolution process of transport network structure is shown in Table 2.1. This multi transport node axis radial transport network is actually the "LNCEI]" mode widely used in the fields of economy, national defense, science and technology, namely logistics center And the distribution center (distribution. enter). The above is referred to as "LD". Adding "CED" means collection, exchange, and delivery. "L warehouse CEL user mode.
