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Focus on passenger safety

The Helsinki Metro is the major transit hub in Finland’s largest metropolitan region and the world’s northernmost metro system. Connecting downtown Helsinki with the neighbouring suburbs and cities, it is a vital traffic artery for citizens and commuters. Every year, 63 million passengers rely on the safe and efficient Helsinki Regional Transport Authority (HSL) rail system.

Since November 2017, the Helsinki Metro reaches even further. A massive expansion project, the Länsimetro (‘Western Metro’) extension, has added 14 kilometres of track and eight brand-new metro stops reaching all the way to the town of Espoo.

When it came to adding public address and emergency voice evacuation on such a massive scale, Helsinki Metro chose a fully digital system: Bosch Praesideo. Known for its scalability, high level of redundancy, interference-free audio, and operational versatility, Praesideo is installed in more than 20 000 applications worldwide; including the pre-existing Helsinki Metro network.

With its optical network, Praesideo proved the perfect solution to extend the system and integrate the Länsimetro’s 5 580 new loudspeakers, which are installed in 12 colours and 14 different speaker designs to match the state-of-the-art interior aesthetic.

Because every one of the eight new metro stations features a unique architectural design and different building materials, it took extra measures to ensure uniform audio quality: using Bosch speakers, sound experts conducted 3D-acoustics tests at all stations. This provided the basis to fine-tune audio controls on a station-by-station basis via 24 amplifiers on 600 channels with 91kW total amplifier power.

Ensuring interference-free audio at all eight new stations regardless of acoustic variations, Praesideo from Bosch now delivers passenger safety according to the highest specifications: Länsimetro has gained certification according to sound system standard SFS-EN 50849, as well as Fire Alarm Standards SFS-EN 54-16 and SFE-EN 54-24.

Fulfilling a key requirement set by HSL, Praesideo from Bosch is installed as a distributed system to allow for controlling broadcasts at all eight Metro stops individually.

Bringing customer safety full circle, Bosch Praesideo also interfaces with Helsinki Metro’s other security systems: a direct interface with fire safety allows the Bosch system to trigger automated evacuation messages in case of a fire alarm to guide passengers to the nearest exit or tunnel. Interfaced with the video surveillance system, Bosch Praesideo plays automatic warning messages and alerts operators when passengers are veering dangerously close to the tracks.

Construction is already underway for Stage 2 of Länsimetro to add seven kilometers of new track – and full-circle passenger security powered by Bosch Praesideo – by the year 2020.

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