Page 543 - 360.revista de Alta Velocidad - Nº 6

Methodology to determine the optimal design speed in a High-Speed Line

7. Effect of the speed on the electrification costs. It can be highlighted that, the higher the
speed, the greater the power output of trains and, therefore, the power of the substations
must be greater (greater power of the traction transformer), and the electrical current
through the cable, increases. If the electrical current increases, it is necessary to use cables
with greater transversal section. Both effects (increase the power of substation and the
greater section of cables) imply an increase in the investment costs.
8. Effect of the speed on the signalling cost. The influence of the speed lies, essentially,
on the technology installed, both on-board and on ground. If the speed increases, the
signalling systems must be more technologically advanced, since the safety requirements
are increased, which means an increase in the investment costs.
Each and every effect of the speed on the different parameters or infrastructure elements have
been quantified in the doctoral thesis (González Franco, 2015b) and in (González Franco,
2015a) The following graph shows a summary of the results obtained after the application of
the different models developed.

Figure 5. Investment cost per kilometre.

From the results obtained it can be highlighted that:

• The higher the maximum speed, the higher the investment cost, and that happens in all
types of terrain. It can be said that, this growth is approximately linear in all analysed
cases.

• Under equal conditions, the costs increase with orographic difficulties. The range of
costs per kilometre, considering the same speed, is wide (i.e. for 300km/h the cost
varies between 4 and 25M€/km).

• The largest increases in cost, due to the increase in the maximum speed are observed
in slightly-rough profile and mountainous areas. In this type of terrain, an increase in
the maximum speed entails a larger increase in the percentage of tunnel over the total
length of the line.

• It is also remarkable that, the cost per kilometre of building a high-speed railway
infrastructure in a mountainous area can be ten times higher than build the line in a
flat profile. Even, it can be five times higher that build the line slightly-rough profile.
Regarding the difference between the cost per kilometre of building a line in mountainous
terrain or in a very mountainous terrain is approximately 2.5 time bigger.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 541