Page 341 - 360.revista de Alta Velocidad - Nº 5

Influence of Aerodynamics in Tunnels Design

5. Aerodynamic calculations

Different aerodynamic studies have been carried out at INECO over the years looking for
improving the circulation conditions of the infrastructure and the design of tunnels in general.
The studies have been carried out working with ADIF and other private entities in a collaborative
approach improving the circulation conditions of these infrastructures and the design of tunnels
in general.

5.1 Tunnel cross-sections optimization

From 2008 until the end of 2012, a study was developed that enabled the analysis of almost 50
tunnels included in the High Speed Railway Network of Spain. The objectives are summarized
in the following aspects:

• Analyse compliance with aerodynamic regulations in terms of health and comfort criteria.
At that time the 2008 ETI was in force, which was used for dimensioning of the health
criterion. The ADIF IGP-4.1 standard was used for the analysis of the comfort criterion.

• In the case of compliance with the initial data (type of cross- section, longitudinal profile
and speed), a section optimization was carried out, resulting in section reductions that
were implemented for the following project phases.

• If these criteria were not met, two alternatives were considered: a bigger cross-section
was analysed or, if considered appropriate, a possible reduction of speed was contemplated
assessing reductions of 5km/h at a time with the aim of not penalizing in excess the final
exploitation of the line.

It should not be forgotten that the objective of the development of the High Speed Railway
Network was and still is to obtain a High Speed Railway Network that allows acceptable travel
times at a relatively inexpensive cost.
With all these premises, the following are the most important results obtained in the project:

• A large majority of the proposed tunnel cross-sections were optimized. There was only one
tunnel in which it was not possible, (3rd Tunnel of the Pancorbo - Ameyugo section) in which
the section had to be increased by 10m2.

• There were very specific tunnels in which it was only a question of checking compliance with
both health and comfort criteria since the starting sections were the minimum stipulated by
ADIF in the IGP-4.1. This suggests that the minimums established by ADIF in its regulations
are optimised to the aerodynamic needs. These values were 85m2 for the case of double
track section and 52m2 for the single track case.

• Given the great versatility of the calculation code used (ThermoTun), it was possible to
model the tunnels in different situations. For example, in the case of the Temerosa tunnel,
the actual conditions of the analysed tunnel was modelled. In this tunnel three specific
narrower sections exist due to constructive needs and were analysed with detail.

It is noteworthy that with the UIC 779-11 Code it is not possible to reflect this situation of the
tunnel, which means that the results obtained when using these leaflets are not completely
accurate.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 339