This report deals with tunnelling over and under existing tunnels with unreinforced concrete linings and tunnelling under an existing tunnel only supported with shotcrete. The uppermost task was to avoid damage to the existing tunnel and this could be fulfilled through carefully staged advance steps, technically correct construction by the contractor and a dense observation network. The experience tunnelling over an existing tunnel supported only with shotcrete shows that despite slight deformation, cracks and spalling occurred to the shotcrete support layer of the tunnel beneath. This damage did impair the serviceability of the support layer although the structural safety of the tunnel was never in danger. The impairment of the serviceability was temporary and could be remedied by installing overhead protection. In the long term, repair measures were necessary to the support layer in zones with poor geological conditions.

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Digitalisation in the construction industry has been progressing continuously and bringing major changes for everyone involved in virtually all areas. Austrian Federal Railways ÖBB has been pushing BIM (Building Information Modelling) for the construction and rehabilitation of their infrastructure. By means of various pilot projects, the basics and the processes required for design and construction are developed and applied with a strong focus on system operation. For Granitztal tunnel and a total length of ≈6.1 km, the as‐built design of the civil structures is done with an element‐based, open BIM model. As part of the handover to the maintenance and operation division, the data of civil structures relevant for operation are derived from the BIM model, validated by means of automatic methods and transferred to the facility management system (AVS, Anlagen‐Verzeichnis‐System). In the absence of an IFC (Industry Foundation Class) structure tunnel, a semantic and spatial data structure is developed. Furthermore, the model will be enriched with components of railway equipment. On the other hand, there is the over‐100‐year‐old Karawanks tunnel as part of the railway section between Villach and Jesenice. The line has been in operation since 1906 and includes the ≈8 km‐long, single‐tube Karawanks tunnel. The current situation of the tunnel including the superstructure and technical equipment no longer meets performance, safety and durability requirements and is being rehabilitated within an international cooperation project between Austria and Slovenia. The focus in this BIM project is set on the as‐built design and merging data of the existing historic tunnel structure with information of new components implemented during refurbishment. A core task is the structured transfer of data contained in the BIM model to the facility/asset management system of ÖBB (AVS) and the Slovenian infrastructure operator. The case histories of Granitztal tunnel and Karawanks tunnel are used to describe the implementation of BIM, including the development of required data structures, validation mechanisms and data delivery to the asset management.

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