|
| Symbol | Definition |
|
| Sets |
| Set of ECOWAS cities origin nodes, indexed by i |
| Set of ECOWAS cities destinations, indexed by j |
| Set of hubs, indexed by h |
| Set of transportation modes, indexed by which represents rail, , represents road and, represents waterway |
| Parameters |
| Trade volume from origin to destination |
| Unit transportation cost of unit flow between nodes and h using the transportation mode |
| Unit transportation cost of unit flow between nodes h and using the transportation mode |
| Set-up cost for establishing a hub at node with the transportation mode |
| Value of time |
| Freight cost per t-km before consolidation |
| Freight cost per t-km after consolidation |
| Transportation speed between nodes and using the transportation mode |
| Unit handling cost at hub |
| Maximum handling capacity at hub |
| Distance between nodes and using the transportation mode |
| Distance from hub to destination j via the transportation mode |
| Handling time at hub |
| Transportation speed between nodes h and j using the transportation mode |
| Transportation speed between nodes and h using the transportation mode |
| Decision variables |
| 1 if node is allocated to the hub at node ; otherwise, 0 |
| 1 if a hub is established at node using transportation mode ; otherwise, 0 |
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