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Clearer, safer communication in tunnels

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Clearer, safer communication in tunnels
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A flexible, networkable solution was required

To help keep drivers safe in the event of an emergency, the tunnels are equipped with a public address (PA) system. When the system became outdated and flawed, the tunnel authority had to act. A fully IP-based distributed public address system with a high degree of flexibility was needed to help overcome the limitations of the current system.

A flexible and smart solution

The cost-efficient and dependable IP-based PRAESENSA public address and voice alarm system from Bosch was chosen as the ideal fit. The system features a smart-power concept and integrated redundancies, making it perfect for both centralized and decentralized network topologies. Its flexible design allowed for integration into both the tunnel’s existing fiber network and the loudspeaker system.

Now the two control rooms can broadcast pre-recorded or live announcements in crystal-clear audio quality along the 8 kilometers of tunnel. The 16 equipment outstations monitor and provide status reports remotely via the network in real-time.

Fully functional at all times

Designed to bypass a faulty device, the system stays fully functional even in the event of a major failure. The no-single-point-of-failure concept with built-in redundancy covers devices, network connections, critical signal paths and functions, all of which can be constantly monitored.

The tunnel authority was delighted to rollout the upgraded PA system quickly and cost effectively.


Today the solution is fully operational without any issues. What’s more, operators appreciate how easy PRAESENSA makes broadcasting messages and monitoring tunnel operations.

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