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July/August 2019 Traffic Technology International 073
www.TrafficTechnologyToday.com
Effective and efficient
tunnel monitoring
In order for drivers to travel
through tunnels safely,
visibility and a continuous
breathable air supply are
crucial. Therefore, tunnels
require sensors that cooperate
with the control system to
ensure the correct lighting
and air conditions, both during
normal operations and in the
event of an incident.
Besides maintaining safety
through the tunnel, tunnel
operators are also responsible
for ensuring the tunnel operates
reliably and efficiently. Sensors
need to deliver correct and
reliable measurements, and they
should be durable and easy to
maintain too.
“For nearly 30 years, we at
JES – since 1990 – have devoted
ourselves to providing sensor
solutions for tunnels that
achieve a low lifecycle cost for
tunnel operators,” says René
Jung, managing partner at JES.
“In the past we have focused on
supplying to German speaking
countries. Having established
an international sales
organization with our partner
Durag, we will now bring the
modern sensor technologies we
have introduced to Austria to
other regions of the world.”
Earlier fire detection
The big tunnel fires in the Alps
around the millenium, such as
the Mont Blanc tunnel fire in
1999, showed the importance
of detecting fires as early as
possible to prevent more vehicles
from entering the tunnel and to
maximize the time for selfrescue
for those who are already
in the tunnel. Fire incidents
happen more often than
expected and are usually caused
by technical problems like overheated
engines, locked brakes
or faulty turbochargers. “All of
these problems result in a rapid
and drastic decrease of visibility
| Need to know
JES creates sensor
solutions for road
tunnels, including:
in the tunnel,” says Jung. “This
makes visibility sensors the first
tunnel sensors to reliably detect
a fire – long before linear fire
alarm cables or video detection
systems respond.”
It is, of course, in tunnel
users’ and operators’ interests
for visibility sensors to operate
reliably. Many tunnels still use
sensors that measure the optical
transmission along a path. As
an alternative, JES promotes
scattered light visibility sensors
that deliver reliable results and
require little cleaning or
maintenance. Only a single
device needs to be mounted
both during the daytime and at
night time. The lighting placed
at the tunnel entrance should
also be adequate in order to
avoid a black hole effect when
a driver enters the tunnel.
Luminance meters are the
sensors of choice for controlling
tunnel lighting in the access,
threshold and interior zones.
Measuring the luminance in
the access zone outside the
tunnel has become a standard
practice in many countries.
However, hardly any tunnel
operators outside of the Alpine
regions also use luminance
meters inside the tunnel.
Modern LED tunnel lights
can easily be dimmed.
Employing luminance meters
inside a tunnel to measure
actual lighting levels allows
lighting to be dimmed to
required levels, thus reducing
energy consumption and
extending the life time of
the luminaires.
instead of a precisely-aligned
transceiver and reflector.
The sensors’ optics are not
exposed to polluted tunnel air,
so collected data is not affected
by it.
Air flow monitoring
After a fire incident has been
detected, it is crucial to control
the ventilation in a way that
allows drivers to flee without
being suffocated by the smoke.
A precise and fast-responding
air flow measuring system is
required. In 2013, a study
published by the Swiss Federal
Roads Administration revealed
that only systems measuring the
air flow over the cross-section of
the tunnel deliver results with
only small deviations from the
average air flow.
“We are very proud that
our system could achieve the
highest rating in the summary,”
says Jung.
Energy savings
During normal operation, good
visibility in a tunnel is achieved
by appropriate tunnel
ventilation control, but even
more by the tunnel lighting.
It needs to be well controlled to
allow drivers to safely approach
and pass through the tunnel,
JES
To learn more about this advertiser, please
visit: www.magupdate.co.uk/ptti
> Luminance and
illuminance meters
> Traffic signal controllers
> Gas sensors
> Air flow measuring
systems
> Visibility monitoring
systems
> Road weather
information systems
Above: Luminance meters
adapt lighting in tunnels
to their surroundings. For
example, to daylight or dark
at the entrance/exit
Left: Only cross-section flow
meters deliver most reliable
results to precisely regulate
the air flow in a tunnel
especially in case of a fire
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