# Railway Lines across the Alps: Analysis of Their Usage through a New Railway Link Cost Function
## 2 The Proposed Cost Function
### Detailed Characteristics of the Alpine Railway Lines Taken into Account in This Study
#### 3.1.6 The Lines Trieste-Divaca, Koper-Divaca, Rijeka-Pivka, and Rijeka-Zagreb  
Other lines 'with special operation characteristics' are those running from the ports of Trieste, Koper and Rijeka to the internal Karst plateau. In particular (see Figure 3):  
* Line Trieste-Divaca: The railway line from Trieste Campo Marzio to Villa Opicina (border Italy--Slovenia), 15 km, is a part of the line Trieste-Divaca; it shows a sum of grade and curve resistances of 25 N/kN. This railway is part of the Trieste--Ljubljana path and it is operated with triple traction from Trieste Campo Marzio to Villa Opicina (Source: interviews to Alpe Adria, the main MTO operating railway connections to/from the Trieste Campo Marzio rail terminal) and in single traction in the opposite direction. Between Villa Opicina and Ljubljana, instead, the sum of grade and curve resistances is below 20 N/kN and the line is operated with double traction in both directions. * Line Koper-Divaca: A portion, of about 18 km, of the line from Koper to Divaca, shows a maximum sum of grade and curve resistances of 23 N/kN. This line is operated in double traction (source: interviews to Metrans, the main MTO operating on this line) from Koper to Divaca and single traction in the opposite direction. But, the second locomotive is not added at the beginning of the train but at the end of the train, in order to reduce the stress on train couplers. This line is part of the Koper--Ljubljana path. * Line Rijeka-Pivka: A portion of 15 km, close to Rijeka port (from Rijeka to Jurdani), of the line Rijeka-Pivka, shows a sum of grade and curve resistances of 27 N/kN. This line is operated with triple traction in this line portion of 15 km, and with double traction in the rest of the line. In the opposite direction, i.e., from Pivka ro Rijeka, the entire line is operated in double traction (source: interviews to Metrans). This line is a part of the Rijeka--Ljubljana path. * Line Rijeka-Zagreb: A portion of about 25 km, between Rijeka and Moravice, of the line from Rijeka to Zagreb, shows a maximum sum of grade and curve resistances of 28 N/kN. Considering the entire line from Rijeka to Zagreb: the line is operated with triple traction from Rijeka to Moravice and the rest of the line is operated with double traction; while in the opposite direction the entire line is operated with double traction (source: interviews to Metrans). Some new lines are planned (Figure 3), but only the Koper-Divaca is under construction (since March 2019). All these new lines have been considered in the 'project scenario':  
* New line Trieste-Divaca (Figure 3): several projects have been proposed, but none is approved yet. The new line will have a maximum slope of 17%, and a maximum sum of grade and curve resistances of 18 N/kN. This line will be operated in double traction from Trieste to Divaca and single traction in the opposite direction. It is not possible to design a line with lower slopes because of geographical constraints due to the high degree of urbanization of the Trieste area. * New line Koper-Divaca (Figure 3): a new line is under construction (since March 2019), which will be long 27 km, against the 39 km of the line currently in operation, and its sum of grade and curve resistances will be 10 N/kN. This line is strongly supported by the Slovenian government because it will improve the competitiveness of the port of Koper against that of Trieste. * New line Rijeka-Zagreb: A new railway line between Rijeka and Moravice (Figure 3), which is part of the Rijeka-Zagreb line, is planned. The new line will have a maximum slope of 12.5% and a maximum sum of grade and curve resistances of 13 N/kN. It will be operated in double traction because the rail Moravice--Karlovac, which is also part of the Rijeka-Zagreb line, requiresdouble traction. However, an improvement of the entire line Rijeka-Zagreb, that is, also between Moravice and Zagreb, is planned, also because the great majority of this line has only one track.