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Escobar, Adrián. Rico, Enrique . Escobar, Jorge

Figure 1. Total length of the Spanish High-speed network

As can be seen, the evolution of the Spanish High-speed rail network has experienced
an linear growth since 2002, with an estimated growth between 2012 and 2022 of 1636
km, compared to the 1735 km already built between 2002 and 2012 and the 471 km
built before 2002. This growth has been due to Europe's efforts to invest in the railways
as a priority means to increase the connectivity of member states, especially the most
peripheral, as is the case in Spain.

This strong investment derived from the political and social effort has progressed hand-
inhand with the strong evolution experienced by the construction companies and especially
by the consulting firms of design, which have improved the development and quality of its
products to be able to face the technological challenge of developing the Spanish High-
speed network, as shown above in the previous section.

3.2 Technological challenges of the Spanish engineering consultant

Some of these technological challenges have been due to the abrupt relief that exists
throughout the Spanish geography and which, has forced, among other aspects, the
construction of embankments with a height of more than 10 m. As shown by Melys (2006),
this fact has generated that the solution of rail superstructure used in the network is that
of ballasted track, since the slab track requires post-constructive settlements, that in
countries like Japan or Germany, are limited around 30 mm, which forces, according to
Esveld (2001), generally, to the construction of embankments that do not exceed 10 m in
height. For this reason, the use of the slab track has been reduced only to specific cases,
such as tunnels with a length of more than 1500 m, since their implantation in other
sections would require a significant reduction of the height of the longitudinal profile of
the infrastructure, generating a significant increase in the length of tunnels to be built
throughout the High-speed network, with its consequent cost increase.

This hard relief has turned Spanish consultants into great specialists in the design of
singular structures of great technical difficulty due to the number and length of tunnels and
viaducts that have been necessary to be able to overcome the multitude of geographical
features that exist in the environment of the Spanish High-speed network.

A clear example of this fact would be the project of the line Madrid - Galicia in its section
between Lalín and Santiago. This project consisted of the development of 47 km of High-

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