The Glatscheras Tunnel – restoring a 100-year-old landmark

The Rhaetian Railway is renowned for its historic rail network and numerous engineering structures. These include some 115 tunnels, the majority of which are over 100 years old and in need of restoration – an ambitious large-scale project for the coming decades. A standardised construction method was developed so the work could be carried out as efficiently as possible, and was used for the first time on the Glatscheras Tunnel near Bergün. As part of the Albula Line, the 334-metre-long Glatscheras Tunnel is a UNESCO World Heritage Site.

Client

Rhaetian Railway RhB

Aiming for the state-of-the-art in safety

The Glatscheras Tunnel was blasted through slate rock in just 144 days in 1903, and opened in January 1904. Today, the tunnel bears signs of damage that are typical of many historic tunnels. Water is penetrating through the roof, the brickwork is damaged, the side walls are bulging at certain points, and the tunnel floor has softened or risen due to frost shattering in some places. At the same time, many of today’s technical requirements are no longer met, such as a clearance profile with sufficient space for windows and doors, or space for escape and side routes. All of this is to be resolved as part of the renovation work.

The demands of a World Heritage Site

The tunnel is being thoroughly renovated using the standardised tunnel construction method to be applied to all maintenance work on the Rhaetian Railway. The clearance profile is being enlarged, the tunnel lined completely with precast concrete, and a concrete floor and a drainage system installed. The portals are also being renewed. The structures in particular are required to meet the demands imposed by UNESCO on a World Heritage Site: for example, the ratio between the height and the width must be maintained. The portals are being enlarged slightly, but the brickwork is being recreated to match the originals, primarily using stones from the two original portal structures and the old tunnel lining.

All without interrupting operations

Rail services need to be maintained throughout the construction period – a particularly challenging requirement on a single-track line. Most of the renovation work is taking place during the maximum 9-hour overnight break in operations. Blasting is being used to enlarge the profile, section by section. The transition area between the enlarged tunnel and the existing one must be secured for rail operations the following day to prevent stones from falling out of the old stone masonry. A mobile, tunnel-shaped structure was used to protect the trains. 

A standardised approach

Over the coming decades, some 70 historic tunnels will be renovated using this method and prepared for another 70 to 100 years of use.

Night shift in the Glatscheras Tunnel: laying the pre-cast concrete parts. Image: Andrea Badrutt, Chur, Copyright: RhB

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