Above: CCTV
cameras for
incident detection
and fire mitigation
equipment are two
essential pieces of
kit in any tunnel
Tunnel Management |
road network and one of three such
centers in Sweden, will remotely
manage the Stockholm Bypass.
“Around Europe, traffic management
centers look much alike,” says
Trafikverket senior traffic engineer,
Gunilla Thyni. “Today, Trafik
Stockholm use the NTS system to
make pre-programmed action plans
for the roads if there is an accident or
roadworks. That system is connected
to subsystems including our
motorway control system, barriers,
variable direction signs and cameras.
A video wall can display different
cameras, depending on
what’s happening where in
the network.” Many
providers must feed their
solutions into Trafik
Stockholm, which already
manages Northern and
Southern Link (Norra and
Södra länken) tunnels, so
that interfacing is an important
project focus for Siemens. “They have
already identified the interfaces, but
we must make sure we can deliver
images to their video wall and that
our tunnel actually speaks to their
piece of system,” says Hegedus, “It’s
a very close co-operation.”
Bottleneck avoidance
Tunnel safety traditionally entails
regulating traffic flow to pre-empt
With a fixed fire-fighting system
and longitudinal ventilation to
handle smoke or vehicle emissions,
we may need fewer restrictions on
slow-moving traffic
Leif Eklöf, project manager for installations, Trafikverket
An escape
route will be
available every 100m
inside the tunnel
congestion, not only to prevent
hazardous concentrations of fumes.
“Congestion inside a tunnel is
considered a dangerous situation,”
explains Hegedus. “You may have
other vehicles entering at higher
speed, going from light to dark so the
eyes have to adjust: therefore you
want to keep traffic flowing.”
Congestion usually originates
somewhere upstream of a tunnel.
Using its high-definition cameras to
count vehicles inside together with
stop-lights or variable speed limits
upstream, a tunnel system
dynamically regulates the number of
vehicles permitted to enter,
precluding congestion inside. But this
traffic-flow imperative may be
diminished by other state-of-the-art
systems. “With a fixed fire-fighting
system and longitudinal ventilation
to handle smoke or vehicle emissions,
we may need fewer restrictions on
slow-moving traffic,” says Leif Eklöf.
Due to the multitude and
complexity of tunnel systems,
comprehensive testing will
be paramount. “There’s always
a challenge connecting things and
that’s included in the project,” says
Thyni. “Many different kinds of
testing will ensure that all equipment
is correctly installed and connected
and that we can actually demand
from it the things we require.”
Siemens expect much
corroborative testing to take place not
in the tunnels themselves, but in
virtual space. “When you design
your system on paper then put it into
tunnel, a simple fault like a broken
wire can be hard to detect,” explains
Hegedus. “We build the whole tunnel
with a digital twin, a 3D model
which can test all tunnel scenarios
and actually simulate the real-time
behavior of components. It’s a very
comprehensive model, which can
also be used to train operators.”
“It’s a long journey and lots of
work, but it will be a good feeling to
see the big changes it will bring to
everyone in Stockholm,” Gunilla
Thyni concludes. “If you see the map,
we have a lot of water, a lot of
bridges. This is an entirely new road
and if something happens – because
something always happens to traffic
on any road network – then we can
reroute people and make traffic flow
more easily, instead of everything
coming to a standstill.”
IMAGES: MICHAEL ULLÉN, TOMAS ÖHRLING, BIGERT AND BERGSTRÖM, EBBA BOHLIN, BACKA CARIN IVARSDOTTER
Traffic Technology International July/August 2019
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