SAFETY - The Westerschelde Tunnel: Approaching Limits - page 46

- set a speed restriction;
- stop the traffic;
- close off the tunnel;
- effectuate contra-traffic in the tunnel tubes;
- prevent the cause of a traffic jam in the tunnel by admitting incoming traf-
fic in doses.
Congestion is detected timeously via the traffic detection loops in the road
surface and the closed-circuit video system cameras. With this information,
the tunnel operators can take traffic controlling measures, for example by
setting a speed restriction via the matrix boards in the tunnel to indicate or
warn about the traffic jam or accident. A vehicle that drives too slowly or is
standing still can also be signalled by the detection loops.The control room
warns the traffic about this via the public address system and traffic control
measures.
Under the road surface there is a cable gallery and electrical equipment
cellars which are completely separated from the traffic tube. All the facilities
for the operation of the tunnel are housed in here. Due to the separation, the
carrying out of maintenance activities on the systems for the operation of
the tunnel, does not cause unsafe situations for the traffic. The ventilation
system in the cable gallery ensures there is a permanent excess pressure
so that smoke or hazardous fumes that occur during a fire in a tunnel tube,
cannot spread into the cable gallery.
Correction and repression: self-rescuing ability and providing
adequate emergency services
At every 50 metres in both tunnel tubes, there is an emergency post with
an intercom system, fire extinguishing system and other facilities. The
Fig. 4.8
Emergency post