The interests and focus have also changed and this is reflected in the topics. The first
conferences were strongly influenced by the tunnel incidents of the late 1990’s and related
safety issues. Nowadays road tunnel operation, the conflict between the needs for upgrading
existing road tunnels and requirements given in a legal framework dominate.

Traffic is increasing, at both a national as well as an international level. Thus, while in
densely populated areas there is much greater demand for sub-surface transportation, in rural
areas there is an increasing need to upgrade the road infrastructure. The implementation of the
EU Directive on the minimum safety requirements for tunnels in the trans-European road
network (2004/54/EC) forced many of the tunnel operators to upgrade the existing tunnels.
Many of the existing tunnels (i.e. those 20 to 30 years old), are currently being refurbished
and upgraded by the addition of a second tunnel tube. The upgrading process as well as the
construction of second tubes constitutes a big challenge in practice, as – in contrast to new
tunnel construction – several prevailing structures and systems act as constraints and have to
be taken into consideration in planning. There is also the additional need to ensure that traffic
flow can be maintained throughout the construction period.

The question of tunnel safety is a highly controversial field. It is often claimed that several
new techniques are now on the market and that these can help improve safety due to quicker
and more reliable detection, more efficient installations and/or additional equipment.
However, such ‘improvements’ often result in significant increases in complexity, as well as
in the cost of operation and maintenance of the new safety equipment.

Cost benefit analyses combined with risk assessment studies provide a valuable tool when
attempting to deal with questions of safety at an acceptable cost level. The time is now right
for us to discuss what safety standards are required in our tunnels and at what price. We hope
that the present conference will be of some value in such a discussion.

The papers of this conference are content of this proceedings.