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Story: 19.02.2018

Rosenberg Tunnel: temporary power supply on the roof

KuMa Rosenbergtunnel

Kummler+Matter carried out an unusual project in St. Gallen: a temporary power supply unit was installed on the roof of the power supply plant for a tunnel.

The Hättern power supply plant is located above the Rosenberg Tunnel on the A1 motorway between St. Gallen West and St. Gallen East. It supplies the tunnel's operational systems and safety installations. After 30 years, the Hättern plant's power supply equipment had reached the end of its lifetime. For this reason, the Swiss Federal Roads Office (FEDRO) decided to replace it and carry out a structural refurbishment of the plant at the same time. This entailed replacement of the medium-voltage installation, the low-voltage distribution and control equipment as well as the emergency power unit for the uninterruptible power supply (UPS).

KuMa Rosenbergtunnel

Tunnel open to traffic – even during the refurbishment
If the power supply to the tunnel's operating systems and safety installations had to be interrupted while the equipment was replaced, the tunnel would need to be closed completely. As this would cause enormous disruptions to traffic, it was definitely something to be avoided. For this reason, Kummler+Matter installed a temporary power supply while the Hättern plant was undergoing refurbishment.

The challenge: shortage of space
There was no room for the temporary power supply in the plant itself – but there was space on the roof. The challenges were twofold: first, delivery of the equipment was problematic because the narrow, winding access road through the forest could not be used to position the containers. Second, it had to be considered, that the maximum total weight that could be placed on the tunnel roof was 100 tonnes.

KuMa Rosenbergtunnel

Efficient night-time working
The temporary power supply equipment, including the containers, the transformer station, the transformers themselves, the medium- and low-voltage switchgear and the UPS were delivered via the main Zurich-bound carriageway of the A1 motorway. Kummler+Matter completed the delivery in just one night, between 9 pm and 5 am. Traffic jams were kept within manageable limits. In an operation that required a great deal of sensitivity in managing the mobile crane, the equipment was hoisted onto the roof of the power supply plant.

Project duration
The preparatory period began in March 2017; the temporary power supply unit was commissioned in November 2017 and will continue operating until the end of February 2018. This project is a major contribution towards the large-scale project to refurbish the St. Gallen West-St. Gallen East section of the A1 motorway.

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