SecuriSens MHD 535 protects Seelisberg Tunnel
New on the market yet already making its presence felt, the SecuriSens MHD 535 multipoint heat detector has been specified for the refurbishment of the fire alarm system in the Seelisberg Tunnel. The 9.25 kilometre tunnel is on the A2 motorway and thus an important element in Switzerland’s busy north-south axis. The MHD 535 fully meets the requirements of the country’s Federal Roads Office.
Most traffic on the A2 Gotthard motorway passes through the Seelisberg Tunnel. The north portal is located high above Lake Lucerne near Beckenried, Canton Nidwalden, while the south portal is near Seedorf on the west bank of Lake Uri. Completed in 1980, its 9250 metres made it the world’s longest double-tube road tunnel at the time; it still remains Switzerland’s longest. The tunnel comprises two separate tubes with a maximum permitted speed limit of 100 km/h. In contrast to most other road tunnels in Switzerland, the carriageway is made of concrete sections. Linking the two tubes are 29 transverse escape passageways – one every 300 metres. Despite the length and monotony of the tunnel, accidents have been few and far between.
Extensive modernisation
The Federal Roads Office (ASTRA) is responsible for safety in the Seelisberg Tunnel. Since its opening, it has undergone a steady programme of major and minor works. Preparations are currently underway for a large-scale overhaul, which will include technical improvements such as replacing the fire alarm system. ASTRA specified a linear detector system, and Securiton came up with the best package when the contract went out to tender. The new SecuriSens MHD 535 multipoint heat detector provides the perfect solution for superior, rapid fire detection in one of Switzerland’s longest road tunnels. In awarding the contract to Securiton, ASTRA stated: “We are impressed by the integrated and comprehensive nature of the concept, which fully meets the client’s requirements.”
SecuriSens MHD 535 – an all-rounder
Built into the SecuriSens MHD 535 measuring cable are numerous ultra-sensitive sensors which immediately signal any rise in temperature or infrared radiation. The MHD 535 boasts extremely fast response and calculation times, its sensor positions are clearly defined, and installation is straightforward due to exceptional cable flexibility. The detection component consists essentially of three elements: sensor cable, cable terminal processor and software. The cable is installed as a stub line, and its cable terminal processors continuously analyse the measurement data fed by the sensors. Based on the programming, the cable terminal processors determine whether to trigger a pre-alarm or an alarm. In addition, the temperature values can be sent to a management system via a serial interface. The cable terminal processors are quick to program using the special MHD configuration software in response to conditions in the monitored environment. The SecuriSens MHD 535 is rugged and ideally suited for use in harsh environments. It is reliable at temperatures ranging from -55o C to +125o C and 100% relative humidity. As well as being easy to install, configure and commission, the system is maintenance-free and offers a long service life. All of which makes passing through the Seelisberg Tunnel a relaxed driving experience.