By rosebell
Considering that the path geology of the M11 line of the Istanbul Metro due to existence of underground water in the soil makes it impossible to construct cross-passages that can be used as escape tunnels, the M11 uses a high-pressure water mist system from SEM-SAFE Fire Safety A/S, Fully owned by Siemens. As the world’s first water mist system to be installed in a metro, this system by quickly suppressing fires using water mist, the system ensures passenger safety in the absence of escape tunnels.
Providing water for the affected areas through section valves in the event of a fire will be up to the pumps of the high-pressure water mist system, whereas the water is forced through nozzles at high pressure to create a fine mist that simultaneously lowers the temperature and removes oxygen, suppressing the fire. The water mist is completely harmless to staff and passengers on the metro.
The system is activated in the affected zone plus the adjacent zone to ensure efficient fire protection and preventing the fire from propagating quickly.
Serving one of Europe’s busiest airports
As Istanbul Airport has evolved into one of Europe’s busiest airports since inaugurating in 2019 and served around 80 million passengers in 2024, efficient public transportation is therefore very important, and the M11 line, which opened in 2023, links the airport with central Istanbul and has a capacity of 800,000 travellers daily.
Including two tunnel segments with two tubes each,the SEM-SAFE® solution is using on the M11 line. While the first segment is 3,083 metres long and has 3,150 open nozzles connected by 4-inch water pipes divided into sections using 150 section valves, 1,596 nozzles and 76 section valves are the contents of the second segment.
Other benefits for metro systems
Along with efficient fire suppression, the SEM-SAFE® system provides other benefits in metro tunnels:
Delivering the required hydraulic performance, the compact SEM-SAFE® system uses 4-inch pipes while a sprinkler system usually requires the use of 10 or 12-inch pipes.
Due to usage of very little water compared to sprinklers, this system decreases the volume of water in the tunnels, making evacuation easier and reducing the need for drainage, and the smaller water tanks reduce installation footprint and cost.
One high-pressure pump unit for each tunnel segment was enough on the M11 line, because the small pipes can transport pressurised water over long distances and a SEM-SAFE® high-pressure water mist system does not require several pumping stations.
System test in Norway
On the M11 project, SEM-SAFE Fire Safety A/S had several meetings with the customer on how to ensure adequate protection in the absence of escape shafts or tunnels. Guided by design criteria developed by consultants and the Turkish ministry of transport and infrastructure, SEM-SAFE Fire Safety proposed a solution and carried out a live test in Norway.
The test was witnessed by external fire system consultants RISE and the client, contractors, and the ministry. Based on the successful test, SEM-SAFE Fire Safety designed and delivered the solution for the M11.
