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After a long planning and approval phase, the main construction work on the A26 Linz motorway began at the beginning of 2019. The new A26 road section, large parts of which are underground, will not only significantly relieve the existing inner‐city traffic routes around Linz, but will also provide an additional Danube crossing in the form of a suspension bridge with a span of over 300 m. The main elements of the first Phase of construction are the Danube Bridge and two underground branches, north and south of the Danube, with excavated cross‐sections of up to 400 m2 and ramp tunnels with tight curves. The planning of an inner‐city construction project requires the comprehensive and careful consideration of the protection of the local residents with regard to the effects of noise and vibration. It also needs the impact of the construction work on the existing traffic routes to be reduced as much as possible. The material excavated from the Freinberg tunnel and the Danube South junction must be transported away via the Danube waterway. The project‐specific framework conditions, such as the very high number of tunnel portals, the sound reflections within the Danube valley and the low overburden require considerable measures to reduce their impact during the construction phase. [ABSTRACT FROM AUTHOR]

The small town of Weyer is located in Upper Austria on the B121 Weyerer Straße. The B121 leads through the historic market square of Weyer, which is characterised by confusing bottlenecks that can only be passed in one lane. For decades, these bottlenecks have caused congestion, mainly due to heavy traffic. For residents, the burden of air pollution and noise is high. The roads department of the Upper Austrian Government has been planning the construction of a bypass for many years. Construction finally started in the summer of 2022. The Weyer bypass construction lot is 1.2 km long and includes the construction of two NATM tunnels, a vertical escape shaft, a bridge over the river Dürnbach, two roundabouts, and one traffic junction. The tunnel construction works are carried out in urban areas, in loose material with little overburden and partly under existing buildings. These boundary conditions make the project a challenge for all involved at every stage. [ABSTRACT FROM AUTHOR]

In the past decades, Norwegian tunnelling has undertaken a major digital development in all operations from planning to the excavation phase. The breakthrough is driven by digital contract requirements from forward‐leaning clients and innovative industrial stakeholders, aiming for ever more efficient, quality‐oriented and risk‐reducing operations. A formal milestone documenting this development was the publication of Digitalisation in Norwegian Tunnelling in 2019. From 2019, most contracts of new infrastructure tunnels must deliver a level 3 Building Information Modeling (BIM) model. Control systems for drilling jumbos are fully digitalised. All drilling must be monitored and documented with Measurement While Drilling techniques. Via cloud servers, the drilling information is interpreted and delivered live to face engineers for decision support. Sensors are used to monitor rock grouting flow and pressure in each drill hole. Digital electronic detonators with exact delay time are used for blasting. Geotechnical mapping is carried out on field tablets. High‐resolution scans with RGB imaging must be carried out on the exposed rock surface and after rock support/linings. The next step is to utilise all the collected data to a higher degree by advanced analysis with machine learning (ML) and similar techniques for automation and optimisation. This study reviews and exemplifies the digital focus and achievements in core operations in Norwegian tunnel excavation. [ABSTRACT FROM AUTHOR]

The Stockholm bypass (E4 Förbifart Stockholm) is being built by the Swedish Transport Administration (Trafikverket) – the office responsible for transport infrastructure in Sweden. The project aims to improve connections between the regional town centres and reduce congestion on the main urban roads. The route, which runs mainly underground, employs numerous contractors and has a planned construction period of 14 years, preceded by a 10‐year planning phase. This article looks at three projects: the FSE 61 Akalla Interchange, the FSE 309 Lovön Interchange and in particular, the FSE 613 Akalla Tunnel. The Akalla Tunnel is driven as a conventional full‐face excavation with pre‐grouting and supported with rock bolts and steel‐fibre‐reinforced shotcrete. The tunnel excavation is followed by the interior work comprising precast concrete walls, a suspended membrane reinforced with shotcrete, ceiling foundations and the carriageway structure. [ABSTRACT FROM AUTHOR]

The approx. 3 km long twin‐tube Rudersdorf tunnel is part of the Fürstenfeld Motorway S7. In addition to jet grouting and steel pipe umbrella sections, the excavation is mainly carried out according to the NATM. After the contract had been signed, the contractor proposed a value engineering concept including a stepped (almost) full excavation with a short ring closure. This concept avoids jet grouting sections and reduces sections with steel pipe umbrellas and the temporary top heading invert. A fair risk transfer between both contractual partner enables the full technical and economic potential of the project to be released and guarantees a win‐win situation. The modified construction methodology consequently also requires a change of tasks and responsibility for the contractual partners for the project. This paper highlights the main topics of the contractual modifications required and explains the handling of the ground risk with examples. [ABSTRACT FROM AUTHOR]

The Artificial Ground Freezing (AGF) has demonstrated its versatility as an effective approach for both temporary ground stabilization and ground water control in almost all types of saturated soils. This paper describes the use of a closed circuit freezing system in the construction of four cross passages. The passages connect 4.8 km long twin road tunnels that have recently been constructed at depths of up to 60 m under Suez Canal in Ismailia, Egypt. The paper starts by describing the ground conditions at the locations of the cross passages and by presenting the results of laboratory tests conducted on unfrozen, frozen and thawed soil specimens. The main design criteria considered in designing the freezing works are discussed and the freezing and cross passages construction works are described. The frozen body was carefully monitored during the freezing process and construction of passages. Records of the adopted monitoring program are presented and discussed. Significant observations that contribute to effective planning of future freezing works are also presented. [ABSTRACT FROM AUTHOR]

The 8,900 m long Rohtang Tunnel lies in the Indian Himalayas north of the Manali tourist region. It avoids the dangerous route over the Rohtang Pass, which is at an elevation of almost 4,000 m, shortening the Manali‐Leh Highway by approx. 50 km and enabling access to the northern regions of the state of Himachal Pradesh and onto Jammu and Kashmir even during the winter. It was envisaged that the tunnel would be driven from two sides by drilling and blasting. The horseshoe‐shaped cross‐section with an excavation diameter of more than 13 m carries two lanes of vehicle traffic, two footpaths and an emergency egress beneath the carriageway. In addition to the extreme conditions that were a feature of this project – portals at an altitude of over 3,000 m, with corresponding severe winters, avalanches and mudslides, etc. – the NATM was also driven to its limits. Friable soils instead of blast rock, water ingress in excess of 250 l/s, high rock pressure with extreme deformations and rapid changes in rock formations presented major challenges to all involved. Tunnelling operations are now nearing completion and the road tunnel will be open to traffic later this year. [ABSTRACT FROM AUTHOR]

To secure the availability and usability of the motorway network, the Federal Roads Office (Fedro) developed new solutions for the renovation of road tunnels while keeping them open to traffic and initiated a pilot project. The aim is to replace a non‐reinforced inner shell at night and ensure the availability of all lanes during the day. The solution involves partially removing the existing inner shell, then installing a drainage and waterproofing system, and finally installing a new inner lining of self‐compacting concrete during the night. The success of this pilot project led to the decision to renovate two more tunnels without delay. The strategy is based on optimising the basic variant by reducing the lining thickness using ultra‐high performance fibre reinforced cementitious composite (UHPFRC) instead of conventional concrete or installing thin precast segmental lining in UHPFRC instead of conventional formwork. Fedro's innovative method will make it possible to renovate road tunnels over the long term while maintaining daytime traffic flow without massively impacting their substance. [ABSTRACT FROM AUTHOR]

Based on mining experience and historical conventional construction processes a new type of construction has evolved – the New Austrian Tunnelling Method (NATM). NATM changed the view on the rock mass surrounding the tunnel from the forcing to the load‐carrying component. NATM is a proven methodology for conventional tunnelling applied worldwide. New observation– and measurement techniques as well as digital models (e.g. geological model) will be increasingly integrated within the Building Information Modelling (BIM) process. BIM provides a sound basis of vital information for decision support across different project phases. [ABSTRACT FROM AUTHOR]

In current tunnelling practice, Finite Element (FE) simulations form an integral element in the planning and the design phase of mechanised tunnelling projects. The generation of adequate computational models is often time consuming and requires data from many different sources, in particular, when manually generated using 2D‐CAD drawings. Incorporating Building Information Modelling (BIM) concepts offers opportunities to simplify this process by using geometrical BIM sub‐models as a basis for structural analyses. This paper presents a Tunnel Information Model (TIM) as a BIM specifically tailored to fit the needs of mechanised tunnelling projects and a "BIM‐to‐FEM" technology, that automatically extracts relevant information (geology, alignment, lining, material and process parameters) needed for FE simulations from BIM sub‐models and subsequently performs FE analysis of the tunnel drive. The results of the analysis are stored centrally on a data server to which the user has continuous access. A case study from the Wehrhahn‐Metro line project in Düsseldorf, Germany, is presented and discussed to demonstrate the efficiency and the applicability of the proposed BIM‐to‐FEM workflow. [ABSTRACT FROM AUTHOR]

Transport infrastructure is a fundamental cornerstone for mobility of the population and also functions as a motor for the economy. New digital methods along the value chain will be used to digitally support the process in the future, from the very first project idea, through tendering and construction to the maintenance of infrastructure projects. The four levers of digital transformation – data, automation, networks and access – will have a significant impact on this process in infrastructure construction. Networking of data sources and storage of data in off‐grid databases is already possible, a development which enables project participants to analyse the construction data, process it and at the same time use it as a documentation basis during the development phase and for later maintenance measures. Such a well‐founded digital database can be used to evaluate, optimize and completely document construction‐related processes. This paper deals with various digital application areas in infrastructure construction and provides an overview of digitalisation developments in this field. [ABSTRACT FROM AUTHOR]

Starting with geological field mapping in the tunnel, a process can be implemented to transform all geological observations into data structures for later use in BIM systems. All necessary basics are already available and a reference implementation has been programmed. When corresponding standards become available, which will be the case in the next one to two years, universal interchangeability of the information will also be provided. This will ensure that the ground model can be maintained through the life cycle, and the ground – as part of the Digital Twin of the structure – is available in later project phases like operation, maintenance, enlargement und renaturation. [ABSTRACT FROM AUTHOR]

Abstract: Tunnelling in Scandinavia differs in several ways from the methods used in Central Europe. Porr Bau GmbH has been working since the end of 2016 with the subsidiary PNC on the first tunnelling project for the company in Norway. The project Fv.17 is located in Nordland, 10 km south of the Arctic Circle. The narrow coastal road is to be upgraded with two new tunnels. The Norwegian fjords are well known as vacation destinations and for their nature, but building tunnels in this environment is challenging, and the rock conditions are also demanding. The rock types described in the tender changed, leading to high water inflow. Systematic rock grouting needed to be carried out to finish the tunnel drive. [ABSTRACT FROM AUTHOR]

The construction of the Tauern Tunnel in the early 1970s was a milestone in the development of the New Austrian Tunnelling Method (NATM). The experience gained then formed the basis for the development of new technologies, which made tunnelling more efficient and safer and were applied consistently in the design and construction of the second tube. The present article describes the geological conditions, compares the geology with the original tunnel and then explains the starting points for the geomechanical design framework. The basic considerations for the planning of the tunnelling work are described, particularly for squeezing rock behaviour. Then there is a discussion of the geotechnical monitoring and implementation of the design during the excavation of the tunnel, with particular consideration of the problem of long-duration creep deformation and the difficulties in the project-specific determination of warning values. Finally, the conditions encountered along the new tube are summarised and compared with the design and geotechnical conditions of the first tube. This includes a description of the extremely complex and difficult tunnelling conditions in incompetent rock when passing through the approx. 300m long section in slope debris. Der Bau der ersten Röhre des Tauerntunnels in den frühen 70er Jahren des letzten Jahrhunderts stellte einen Meilenstein in der Entwicklung der Neuen Österreichischen Tunnelbauweise (NÖT) dar. Die damals gewonnenen Erfahrungen bildeten die Grundlage für die Entwicklung neuer Technologien, die den Tunnelbau effizienter und sicherer machten und bei Planung und Bau der 2. Röhre konsequent angewendet wurden. Vorliegender Beitrag erläutert nach einer Vorstellung der geologischen Rahmenbedingungen und einem Vergleich mit der Geologie der ersten Röhre die Ausgangspunkte für die geomechanische Rahmenplanung. Die grundsätzlichen Überlegungen bei der Vortriebsplanung, insbesondere für druckhaftes Gebirgsverhalten, werden dargestellt. In weiterer Folge wird auf die geotechnische Überwachung und Umsetzung der Planung während der Vortriebsarbeiten eingegangen, wobei besonders die Problematik von langanhaltenden Kriechverformungen und die Schwierigkeiten bei der projektspezifischen Festlegung von Warnwerten betrachtet werden. Abschließend werden die im Zuge des Vortriebs angetroffenen Verhältnisse zusammengefasst und eine Gegenüberstellung mit der Planung und den geotechnischen Verhältnissen der ersten Röhre durchgeführt. Dabei werden auch die äußerst komplexen und schwierigen Vortriebsbedingungen im Lockergestein bei der Durchörterung der ca. 300 m langen Hangschuttstrecke behandelt. [ABSTRACT FROM AUTHOR]