Page 343 - 360.revista de Alta Velocidad - Nº 5

Influence of Aerodynamics in Tunnels Design

circulating at 350 km/h, and an S-112 circulating at 330 km/h.

In all cases, trains of 200 and 400m long were analyzed. For the case of double track tunnels
the following train crossings were considered: 200-200m, 200-400m and 400-400m.

5.3 Construction stage. Aerodynamic studies

On many occasions, one of the problems that a contractor deals during the execution of a
tunnel is the "entry into section", or, in other words, the occurrence of convergences and
closure of the section. In these cases, it is considered appropriate to carry out an aerodynamic
effect study in which introducing the new characteristics of the tunnel, including the location
and length of the existing narrowing, demonstrates that aerodynamic health and comfort
criteria are still met, or if these are not met, determine the speed value that makes these
compliances possible

5.4 New explotaition speeds

Another benefit of aerodynamic studies is the analysis of the possibility of increasing the speed
of circulation aiming to achieve improvements in the operating conditions. In these cases, the
infrastructure is actually built and takes some time in service, so just the parameter of speed
is studied in these cases

As it can be observed, aerodynamic studies are an increasingly important tool for the
development of high-speed rail tunnels, since it is a typology of studies that can be carried out
over the entire life of the tunnel. It has influence on parameters as diverse as size and type of
the section and trains speed.

6. Sonic boom

6.1 Introduction

A major evolutionary step has been that the European high-speed networks are gradually
increasing traffic speeds as signaling and security systems allow. In both Asia and Europe,
highspeed tunnel networks with speeds in excess of 250km/h have developed considerably in
recent decades. Most of these tunnels were designed as a double track monotube since they
were more economical and because the tunnel lengths were lower than the current ones.
The construction of tunnels with one type or another of cross-section greatly conditions the
aerodynamic effects (overpressures, depressions and sonic boom) that occur in these tunnels.
However, there is a tendency for the design and construction of bitube tunnels.

Currently, due to the development that is taking place in the High Speed Railway, tunnels are
being built increasingly longer, so there is a generalized tendency to design the tunnels as single
track tubes. The main reasons are:

• They are considered safer due to the reduced probability of collision of trains, and due to
the better evacuation and rescue conditions.

• Maintenance is performed in better conditions of safety as it is possible to use one tube
while the other is closed to traffic.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 341