Modernization of the tunnel radio systems – Ofenauer and Hiefler tunnels

Starting in September 2022, initial work on electrical safety systems was carried out as the first step. These activities were performed during normal tunnel operations. From September 2023 to June 2024, the second construction phase took place, during which one tunnel tube was closed at a time, with the opposite tube operating in bidirectional traffic. During the summer months, both tubes remained open due to the high volume of holiday traffic. Beginning in September 2024, renovation work continued in a third construction phase, again with only one tube open to traffic at a time. The works were completed as scheduled in June 2025, and the 14 km section was reopened to traffic.

Throughout these extensive refurbishment works, it was essential to ensure the safe and continuous operation of the tunnel radio systems at all times. This required multiple (temporary) commissioning phases, during which parts of the existing legacy systems were interconnected and operated together with newly installed components.

SISS was entrusted with this critical task as a subcontractor to SPIE Dürr Austria GmbH, the general contractor. As part of the project, approximately 20,000 meters of coaxial cable – including 13,000 meters of radiating cable – were delivered and installed by SPIE Dürr Austria. In addition, 20 radio cabinets were manufactured, and a total of 350 RF connectors and 20 antennas were installed.

SISS benefited from the extensive experience of its employees on ASFiNAG construction sites and enjoys strong trust in its established and modern in-house developments in the field of radio technology. With the signing of the framework agreement "Life Cycle Radio Infrastructure", the maintenance of all ASFiNAG tunnels in Austria has been exclusively in the hands of SISS since October 2022 — and will remain so until at least 2027!