The Mersey Tunnel that connects Liverpool with the Wirral had an ageing and faulty emergency public address system, that needed replacing. PAS Sound Engineering won the tender, quoting the Praesensa product by the manufacturer Bosch.
The Mersey Tunnel consists of two separate road tunnels – Queensway and Kingsway. Both start in central Liverpool; the Queensway Tunnel runs to Birkenhead and the Kingsway Tunnel to Wallasey. Both also feature their own control rooms.
The tunnel authority had struggled with various equipment faults on its largely unsupported system and required something networkable. The Praesensa could interface with the fibre network and loudspeaker circuits; a solution at a lower cost and in a shorter timeframe than if an entirely new system needed to be installed.
Engineers would have to update the failing distributed public address, while also maintaining the operation of as much of the older equipment as possible. The loudspeakers in place were tested, inspected and refurbished where necessary.
The IP-based Praesensa system was able to connect with the fibre network. All devices are IP-connected, for centralised and decentralised set-up as well as interconnectivity with other systems. PAS installed 29 Praesensa eight-channel amplifiers, each featuring a capacity of 600W, two Praesensa system controllers, four desktop LCD call stations with the same number of call station extensions, and 144 Praesensa end-of-line devices.
The new products have sufficient power with integrated channel options to allow for a compact form factor in the various equipment racks. The reduced size of the equipment now allows for tidier and more compact rack layouts, while the system offers more options for zone grouping across multiple amplifiers at equipment locations in both tunnels. When adding or defining new audio zones or groups, the system updates the changes. Now 16 equipment outstations can provide real-time monitoring and fault reporting to maintenance and operations staff remotely over the IT network.
The two control rooms are able to communicate anywhere on the 8 km of tunnels with pre-recorded or live broadcasts. Controllers at each location allow for redundancy in the event of a major failure, bypassing a faulty device. Praesensa’s no-single-point-of-failure concept with redundancy includes all devices and network connections, critical signal paths and functions, which can all be supervised.
