Research Article
Study on the Optimization of Hub-and-Spoke Logistics Network regarding Traffic Congestion
| | Variable | Description | Unit |
| | Required data | | Set of nodes, (i.e., and denote nonhub nodes and and denote hub nodes) | — | | Unit transportation cost of OD flow from node to node | Yuan/km/ton | | Transportation distance from node to node | km | | Total OD flow from node to node | ton | | Discount factor of trunk line transportation | — | | The transportation cost when OD flow is transported through link, | Yuan/km/ton | | Total OD flow in node | ton | | Total OD flow out of node | ton | | The congestion probability of flow in the network | — | | The proportion of congestion flow | — | | Number of hubs | pcs | | Hub construction cost | Yuan | | Congestion cost | Yuan | | Constant coefficient of congestion function | — | | Power exponent of congestion function | — |
| | Decision variables | | Binary variable. If the freight flows through , . Otherwise, | — | | Binary variable. If node is assigned to hub k, . Otherwise, | — | | Binary variable. If node is selected as a hub, . Otherwise, | — | | Binary variable. If hub is congested and hub is used as a flow transfer hub, . Otherwise, | — |
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