Research Article
Evolution of the China Railway Express Consolidation Network and Optimization of Consolidation Routes
Table 3
Parameters and variables used in the CRECN model.
| Symbol | Definition |
| Sets | | Set of CRE origin nodes, indexed by | | Set of CRE consolidation centers, indexed by | | Set of CRE corridor gateways (i.e., ports of exit between China and Europe), indexed by | | Set of Destination nodes, indexed by , which is Moscow |
| Parameters |
| | The unit setup cost of the consolidation centers | | The unit value of time | | Maximum daily cargo-handling ability of the consolidation center | | Rail distance between nodes and | | Annual freight volume of node | | Cargo cost (CNY/t-km) before consolidation | | Cargo cost (CNY/t-km) after consolidation |
| Decision variables |
| | Binary variable. If node j is selected as a consolidation center, then ; otherwise, | | Binary variable. If origin nodes consolidates to node , then ; otherwise, | | Binary variable. If corridor gateway m is selected as an exit point in the route from consolidation center to destination , ; otherwise, |
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