A pioneering security solution for underground HelsinkiThere is a huge network of tunnels beneath the streets of Helsinki. Siemens’ state-of-the-art FibroLaser system monitors and secures conditions in the tunnels. This ensures that the apartments of the inhabitants of Helsinki keep warm.
Many people use the underground walking routes in the city center as shelters during rainy days. People are accustomed to using the metro when going to and returning from work and taking care of their everyday matters. However, there is a much broader underground world beneath the streets of Helsinki than many of them know. An important part of this underground infrastructure is Helen Ltd’s energy tunnel network, through which heat, cooling power and electricity are delivered to homes. The length of the network, which extends from Lauttasaari to Vuosaari, is as much as 60 kilometers.
”The tunnel network is like an underground spider with 100 legs reaching up to the ground surface”, says Mats Fagerström, who acts as Chief Security Officer at the Helen Group.
The energy network is an important part of Helsinki's urban infrastructure. In a project launched in 2016, Siemens and Helen had a FibroLaser linear heat detection system built in the energy tunnels for monitoring and securing tunnel conditions and availability.
“We needed a comprehensive system for monitoring underground facilities. With the ordinary fire detectors we used earlier, we could only monitor about one per cent of the whole tunnel network. The FibroLaser system gives us a complete picture of the situation in the tunnels and we can monitor any changes in conditions”, Fagerström says.Hot water is delivered to different parts of the city through district heating pipes located in the tunnel network. The water is used to heat 94 per cent of all houses in Helsinki.
“Among other things, the new system allows us to monitor and locate any temperature differences in the tunnels”, Fagerström explains.
A system created for challenging conditions
The tunnel network is a very challenging environment for monitoring conditions. The air in the tunnels is humid and differences in tunnel levels create strong air whirls. The FibroLaser system uses an optical linear heat detection cable and has been designed for challenging conditions of this kind.
“The optical fiber cable in the system is completely hermeneutic, so humidity or dirt does not affect its measuring capability. The system monitors temperature changes over the whole length of the cable and can also be scaled for monitoring very large areas”, says Mika Lappalainen, Siemens’ Unit Manager.
In addition to heat conducted from air, FibroLaser measures radiated heat. Therefore, it is ideal for tunnels with air whirls. The system is capable of detecting temperature changes at an accuracy of 25 centimeters.
“Due to air whirls, the heat generated by fire can travel hundreds of meters in the tunnel before rising up to the roof. The FibroLaser cable is also capable of detecting radiated heat, allowing reliable detection of the actual site of fire”, explains Lappalainen.
In addition, FibroLaser is almost completely maintenance free. If ordinary fire detectors were used in the tunnels, their maintenance costs would be markedly higher.
A new approach to create a pioneering solution
Siemens’ FibroLaser system has already been adopted in two other underground facilities at Helen: The coal storage in Salmisaari and the heating and cooling center beneath the Katri Vala Park. The system built inside the energy tunnel network is ten times larger than earlier systems.
“The tunnel network is a complex whole, with zig-zagging tunnels that have hundreds of connections to the ground surface. All this must be taken into consideration in system installation, control room graphics and instructions”, says Fagerström.
The FibroLaser system is officially a fire alarm system, though in energy tunnels it plays a much more prominent role. A completely new approach was created in the project about how the system can be utilized.
“For us, FibroLaser is primarily a technical monitoring and control system, because the signal is used for much more than just sending fire information”, says Fagerström.
The system delivery includes linear heat detection cables, measuring units and fire control unit and a graphical management system for locating alarms and directing rescue personnel to the site. The tunnel network has been divided into almost 200 monitored zones, whose size varies from 50 meters to one kilometer.
“For us, it is very important that the graphical management system is reliable and easy to use. We wanted to have a clear visual layout of the tunnels that could be interpreted without being an engineer. The system also has special instructions for each monitored area that security and rescue personnel can interpret easily”.
Long-term cooperation the key to success
Cooperation between Siemens and Helen in fire safety solutions has already continued for about twenty years. The solution built inside the energy tunnel network in Helsinki is the result of long-term cooperation that benefits both the parties and allows them to develop their operations.
“The project has also been important in view of Siemens’ product development. We have developed new solutions together with the customer”, says Matti Helkamo, Siemens’ Business Line Director.
It was easy to turn to Siemens. We have slightly less than 100 real estates in Helsinki, many of which already have Siemens’ fire alarm system. We hope that in the future, all of them could be monitored through a single management system.Fagerström, too, emphasizes the importance of cooperation
Underground world of Helsinki
Helsinki is the only capital city in the world with an underground plan. A total of some 400 spaces or tunnels have been quarried beneath Helsinki. Its underground world includes pedestrian and metro tunnels, large air-raid shelters, wastewater tunnels, a center service tunnel from Ruoholahti to the Senate Square and Helen's energy tunnel network.
The building of he energy tunnel networks began in the 1970s and the last tunnel parts were completed in 2011. The labyrinth-like tunnel network also haslarge facilities with district heating and cooling plants. One of them is a huge artificial lake beneath the Esplanade Park, which is used for cooling.
Building underground facilities in Helsinki is carefully regulated and building permits are specified for different depths. The deeper the construction takes place, the higher the costs. The deepest part of the underground city is Helen's coal storage in Salmisaari, which extends to a depth of 120 meters. There are four silos in the coal storage, each capable of accommodating the tower of Helsinki Olympic Stadium in upright position.
- 5 FibroLaser measuring units
- 9 fire detection panels
- Charon 4 graphical monitoring system
- About 70 km of FibroLaser linear heat detection cable
FibroLaser linear heat detection system
The FibroLaser linear heat detector is a linear fire alarm system that consists of two parts: a separate measuring unit and an optical fiber cable connected to the unit and acting as a detector throughout its length. The system reacts to heat and radiation generated by fire and has been designed for use in challenging conditions, such as tunnels and indoor car parks. Siemens is the leading supplier of linear heat detection systems in the world. Among other things, the FibroLaser system is used in seven tunnels on the E18 motorway between Muurla and Lohja, the Vuosaari Harbor and Helsinki metro. In addition, Siemens’ FibroLaser system is also in use in the world's longest railway tunnel at Gotthard, Switzerland.