VENTILATION | INSIGHT
TUNNEL VENTILATION REFURBISHMENT: GISWIL
Refurbishing a tunnel ventilation system presents challenges from new standards
and physical constraints of the structure. Ingo Riess of Riess Ingenieur-GmbH discusses the challenges with Giswil road tunnel, in Switzerland, as an example
Tunnels require maintenance and refurbishment to ensure their safe operation over long periods. Refurbishing a tunnel ventilation system presents various challenges, due to the demands of new standards and constraints by the existing structure.
INTRODUCTION In road tunnels, the installations for operation and safety require regular maintenance and replacement. Replacement may require significant interruptions to normal tunnel operation. Although each sub-system may have a different design life, the replacement is coordinated to minimize tunnel closures. Some items may allow operation beyond their nominal design life; other items may require early upgrades. In 2004, the 2km-long Tunnel Giswil was one of the
first tunnels in Switzerland equipped with a local smoke extraction using remote controlled dampers1
Below: Tunnel Giswil Northern Portal
PHOTO CREDITS: INGO RIESS . After more
than 20 years in operation, some parts of the tunnel ventilation system reached their nominal design life. In this article, we discuss design decisions regarding continued operation, early replacement and system upgrades for the tunnel ventilation system.
TUNNEL GISWIL: VENTILATION SYSTEM SINCE 2004 Most road tunnels in Switzerland are fully automated. There is no local control centre for tunnel operation. All systems are designed to operate autonomously. Following the disastrous fires in the Montblanc, Tauern and Gotthard Tunnels in 1999 and 20012
Administration developed a new national design code for tunnel ventilation3
. Tunnel Giswil was designed based on an early draft of
this design code. Experience gathered in the operation of the tunnel was then used to update the code. Tunnel Giswil is operated with bi-directional traffic. It
is one of the first tunnels in Switzerland equipped with a local smoke extraction using remote controlled dampers. Smoke is extracted through an overhead smoke duct towards the fan building at the northern tunnel portal. The smoke dampers are not evenly spaced along the
tunnel. The damper actuators are controlled to allow open and closed positions, and an intermediate position. The smoke dampers receive their control signals via optical fibre. The smoke extraction system is designed for a minimum flow rate of 144m³/s.
, the Swiss Road
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