Tehnomobil Tunnel Safety in Croatia

Tunnels are sensitive traffic bottlenecks and consequently extraordinary vulnerable in case of accidents or fire blasts. With life-threatening dangers and enormous economic consequences these tunnels are obvious subjects for technical solutions of prevention and limitation of damage.

NKT Photonics and its Croatian partner Technomobil have set new standards for modern fire safety solutions for the road tunnel network in Croatia. In Croatia you will find a vast variety of terrains with everything from rolling hills in the continental north, over densely wooded mountains to the rocky coastlines of the Adriatic Sea. With recent infrastructure developments focusing on the rapidly growing highway network a particular focus has been put on tunnels.

Tehnomobil’s excellent engineering and contracting background in traffic infrastructure and fire fighting industries perfectly match with NKT Photonics’ comprehensive experience in fire detection applications for tunnels and special hazard buildings.

Best fire surveillance for more than 90 % of the road tunnels in Croatia

At present an impressive share of more than 90 % of the Croatian road tunnels are equipped with the fiber optic fire detection system by NKT Photonics. In a total of 55 tunnel tubes Technomobil has fitted the purely passive fiber optic line sensor cable from NKT Photonics for superior and reliable fire detection. Those tunnels with tube lengths ranging from 500m to almost 6000m of lenght were opened in recent years or re-opened after full refurbishments where the conventional line type fire detection system could be replaced by the LIOS DE.TECT fiber optic system. On the long list of tunnel projects in Croatia which has had a LIOS DE.TECT system installed it is worth to mention the tunnels Veliki Glozac and Brinje which received best scores in recent European tunnel safety rankings.

EuroTAP: Brinje Tunnel on Dalmatina highway tops Europe’s safety ranking

The European Tunnel Assessment programme (EuroTAP) place a Croatian tunnel, the “Brinje” at the top of the list, as the best tunnel in Europe in 2007. EuroTAP 2007 inspected 51 major road tunnels important for transeuropean road traffic located in 13 countries across Europe and concluded that none could beat this Croatian tunnel. All this despite the fact that since 2004 tunnels in the European Union must comply with a Directive prescribing minimum safety standards for road tunnels . The Brinje, a 1570m tunnel opened in 2004, located on the A1 between
the cities of Zagreb and Split displayed top scores for the fire protection and winning features in all safety categories: low risk traffic flows using two tubes, 24 hour monitoring from a tunnel control center manned by trained staff; immediate notification of traffic disruptions, use of lay-bys or emergency facilities; additional escape and rescue routes well marked by evacuation lighting and good indications of the escape direction and the distance to the nearest exit.

State of the art fire safety

A proper fire protection concept is not simple when the protection area is affected by harsh environmental conditions. Conventional sensor technologies often fail and tend to produce false alarms. Great efforts are needed to keep the conventional fire detection system properly maintained. NKT Photonics’ unique Linear Heat Detection Systems are designed to reduce operational costs and offer maximum reliability even under severe tunnel conditions with dirt, dust, and corrosive atmospheres as well as high humidity and dynamic temperature fluctuations.


North portal of the Veliki Glozac tunnel during fire test

Safety systems demand reliable and quick fire detection. Furthermore, in harsh environments modern solutions require immunity to any interference, false alarm safety and easy handling. NKT Photonics offers a protection concept based on a simple fiber optic cable as a high–precision addressable heat sensor which is easy to install, maintenance free, and certified for several thousand meters. It leaves no space unmonitored and displays temperature development and heat transport in real-time along the entire tunnel. LIOS DE.TECT provide optimum safety for fire detection in tunnels and special hazard areas due to its ability to cope with extreme environmental conditions.
The line sensor used in NKT Photonics’ systems is based on optical waveguides, which are immune to electromagnetic disturbances. Based on years of experience within the field of fiber optic and measuring techniques combined with the input of research partners and customers, multiple characteristics have been added to offer reliable and adaptable measurement features for locally linear heat detection profiles.

Technologies creating values

The difference between conventional setup using single point-type sensors and the LIOS DE.TECT is that temperatures are recorded as a continuous profile along the entire sensor cable. The benefit of achieving highly accurate temperatures over great distances at short measuring times is combined with the ease in installation and data acquisition offering safe and reliable solutions of fire detection.

The LIOS DE.TECT Linear Heat Detection Systems have been developed for serving one purpose – sophisticated fire detection equilibrating response time, false alarm safety, and system reliability at an unbeatable level.
Based on the evaluation unit and an appropriate sensor cable the system fulfills the demands of modern fire detection technology.

Features of LIOS DE.TECT

  • A purely passive sensor unaffected by rough conditions and electromagnetic disturbances
  • A system architecture that allows stand-alone operation
  • Precise information about fire location, size and propagation
  • Easy to install
  • Easy to integrate in fire management systems

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