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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]

The drainage system is a core element of tunnel construction and operation. Frequently, natural as well as technical boundary conditions lead to the deposition of scales (especially calcium carbonates) in the drainage system. As a preventive measure – in contrast to post‐depositional cleaning procedures – the use of scale inhibitors to treat the drainage water (hardness stabilisation) is an option. 'Green inhibitors' are tailored green organic substances that delay or prevent scale formation when added in small concentrations. Moreover, green inhibitors can change the material consistency of scale deposits (soft sinter). An additional advantage of their use is the good environmental compatibility compared to conventional inhibitors. Suitable test procedures can be used to select a substance or product and evaluate or optimise its dosage. The application of polyaspartic acid or polysuccinimide products as ecologically harmless and readily biodegradable agents has proven advantageous in tunnel structures. The choice of liquid or depot stone conditioning essentially depends on the scaling mechanism, in addition to the technical considerations, flow rates and water chemistry. Regarding discharge to existing receiving water bodies, the inhibitor concentration in the water can be measured and controlled by DOC analysis and fluorescence spectroscopy. This article presents contemporary and tunnel‐specific case studies. [ABSTRACT FROM AUTHOR]

The unknown subsurface conditions in tunnelling projects have led to their management with many uncertainties. From these uncertainties, we can mention the geological condition of the tunnel route and the time and costs required for construction. In order to significantly reduce these uncertainties, techniques that have a high predictive power must be used. For this purpose, in this study, an autoregressive model was used to reduce the uncertainties related to geology and construction time and cost in tunnelling projects. A comparison between the predicted results and the actual values through several statistical indices showed the high-performance prediction of the autoregressive model in the prediction of tunnel resources. Also, three input parameters affecting tunnel construction time and costs, such as RQD, groundwater, and RMR, were considered. The sensitivity analysis of these parameters on the time and cost of tunnelling projects was investigated through mutual information test (MIT). The groundwater was the most effective parameter on the tunnel's time and cost. [ABSTRACT FROM AUTHOR]

Building information modelling (BIM) is a frequently discussed topic in tunnelling since it promises less loss of information and reduced lifetime cost of underground infrastructure. There is still some way to go as standardisation in this sector is immature, the implementation of three‐dimensional (3D) BIM models is developed for pilot cases of tunnelling only, and data transfer between software tools is a challenge. The long linear structures of tunnels make a specific approach of parameterised and adaptive modelling necessary to meet the requirements of repetitive construction elements and the natural differences of forecast and actual excavation conditions. This approach renders the matching of construction elements in the model and service items feasible for determining quantities for the tender and billing in tunnel projects. In this article, we show that only 57 % of service items can actually be linked to a physical item in traditional two‐dimensional (2D) design and highlight the need to consider how to incorporate these items into a BIM model. We also use a case study to propose an approach for parameterised and adaptive modelling of repetitive construction elements and show a way of a continuous data transfer from the forecast tunnelling class distribution via 3D BIM modelling to a billing software without data loss. [ABSTRACT FROM AUTHOR]

In the operating phase of a road tunnel, not only maintaining or increasing the availability in the network but the economic optimization regarding the life cycle costs of the structure are also important priorities. A consistent application of the Building Information Modelling (BIM) methodology can theoretically make a useful and targeted contribution, as it provides a complete digital model of the structure with all installed elements and the information required for the operator tasks. In the research project FE https://doi.org/15.0623/2016/RRB "Building Information Modeling (BIM) in Tunneling," the Institute of Tunneling and Construction Management and the Institute of Computing in Engineering (both Ruhr University Bochum) in cooperation with BUNG Ingenieure AG developed the basics for a BIM‐based operating model of road tunnels with funding from the Federal Highway Research Institute commissioned by the Federal Ministry of Transport and Digital Infrastructure. In the article, the results of the research are presented on the basis of specific use cases of a BIM‐based operation and maintenance management. [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]

This paper discusses the concept and the practical experiences of excavating an under‐river crossing with a slurry shield (D = 13.45 m) to construct a single‐tube road tunnel. Unstable sand and gravel as well as harder chalk zones in the invert area combined with high groundwater pressure require the tunnel face to be actively supported at all times. Over long stretches the overburden to the river bed is only around 0.5 D, which means that a delicate balance has to be struck between achieving the minimum support pressure required to stabilise the tunnel face while at the same time preventing blow‐out. An innovative segment sealing system with integrated expanding insert combined with a push‐fit dowel system achieves a high degree of protection from moisture and voids. The evacuation and rescue concept for the single‐tube road tunnel is based on a refuge running under the carriageway. This evacuation channel is accessed via staircases in recesses at the side. Ground freezing is used to stabilise the sand during excavation of the recesses at around 4 bar water pressure. [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]

Tunnels are nowadays key elements in transport networks worldwide. To achieve a safe and efficient operation, a proper integration and design of Mechanical, Electrical and Intelligent Transportation Systems is required. Among these systems, tunnel ventilation is one of the most critical ones from the Fire Life Safety perspective, being smoke control to maintain safe conditions during self-evacuation and rescue operations one of its main objectives. Traditionally tunnel ventilation systems are sized following a deterministic approach. Designers, based on requirements and design criteria from Standards and Recommendations, focus on a limited number of fire scenarios and design parameters to reach a solution considered acceptable from a fire safety perspective. This paper proposes the use of a probabilistic approach to assess, in terms of probability of failure, the capacity of a tunnel ventilation system for fire scenarios. The model applied in the proposed process uses a 1D steady state model based on pressure losses, where critical design variables are considered random (unlike with the deterministic approach) to calculate a failure probability associated to an installed ventilation thrust. A case study example is used to analyse results using both, the traditional deterministic approach and the proposed probabilistic one. Results obtained with the deterministic approach show how, under the same design requirements, tunnels with similar characteristics allow different safety margins for the capacity of the ventilation system. These results are confirmed numerically using the probabilistic approach by evaluating failure probabilities. To avoid this, the paper proposes the use of the probabilistic approach to allow a definition of an equivalent uniform safety margin (to achieve a certain probability of failure) which would be of significant help for designers, administrations and tunnel operators. It is not the aim of the study to define the limit for the probability of failure or to characterise the design variables, but to present a useful tool with which important conclusions about the design criteria can be obtained. [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]

The sealing of tunnel walls involves the use of membranes which, depending on the situation, are constantly exposed to the leaching action of groundwater, or of water emanating from the surrounding rock. In terms of ecological product compatibility, the question arises as to whether pollutants may be released in the process. Various geomembranes are examined in more detail and subjected to an evaluation system. It emerges that in particular geomembranes with especially worrying components such as phthalates should generally be kept away from the environment for precautionary reasons, even though some phthalate plasticisers have not yet been evaluated by the EU. Phthalates are characterised by the fact that they are released from the membranes in considerable quantities. [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]

A fire can occur in many areas of a transport system. Detecting fires at an early stage and rapid automated fire‐fighting can significantly minimize or completely prevent damage to rolling stock and infrastructure. In addition to effective fire‐fighting, people should be safeguarded, the systems should be economical, and activation should cause a minimum of damage. Despite the positive effects of using automatic fire‐fighting systems in terms of building protection and reducing the fire load, there may be negative effects on escaping persons during the escape phase. Different systems such as the high‐pressure water mist system and the deluge system are investigated by CFD simulation and evaluated with regard to their use during the escape and external rescue phases. [ABSTRACT FROM AUTHOR]

The E4 Stockholm Bypass is a new route for the European highway (E4) past the Swedish capital Stockholm. The bypass will connect the southern and northern parts of Stockholm. To reduce the impact on the surroundings, 18 km of the total of 21 km of the Stockholm Bypass are being constructed in tunnels. The Bypass will be one of the longest road tunnels in the world, with a construction cost of 3.1 billion Euro (2009 prices). The challenges have been many, for example how to evaluate the hydraulic rock mass properties for such a vast tunnel stretch and then find the most suitable grouting design, the contractor's ability to deliver proper grout properties and suitable grouting equipment, the time and resources needed for QA/QC of the grouting works and the need for adaption of the grouting works to true geological conditions. Not to mention the complexity of monitoring water ingress during construction for the Client to show that the sealing demands are being met according to the environmental permits for water works operations. The Stockholm Bypass is by far the largest rock fissure grouting operation undertaken for road tunnels in Swedish history. [ABSTRACT FROM AUTHOR]

Highlights • The paper investigates on crash frequency of accidents occurred in Italian motorway over a 4-year monitoring period. • Statistical models based on unrelated and correlated-random parameters approaches are examined. • Independent variables investigated are related to traffic and tunnel geometry. • It is shown that the correlated- random parameters model is statistically superior to the unrelated-random one. • Comments for practical applications in design of tunnels and tunnel management are also given. Abstract The paper provides an analysis of the frequency of total accidents (accidents involving material damage, physical injuries and fatalities), which occurred in 226 unidirectional motorway tunnels over a four-year monitoring period, based on unrelated and correlated random-parameter models. The so-called random-intercept model, in which only the regression intercept is assumed to be random, was also developed a priori for recording the random-effects (temporal correlations among accidents occurring in the same tunnel in different years). The independent variables were: tunnel length (L), annual average daily traffic (AADT) per lane, percentage of trucks (%Tr), presence of a sidewalk (SW), longitudinal slope (LS), and mechanical ventilation (MV). The comparison among the aforementioned three models showed that the correlated random-parameters model, which takes into account the cross correlation among the random-parameters, provided a better goodness-of-fit than the corresponding uncorrelated random-parameter and intercept-random models. This means that more precise estimations of accidents can be obtained when the random-parameters are assumed to be correlated in statistical analysis. The developed model also offers additional insights into showing how different combinations of parameters affect tunnel safety. In particular, through the correlation coefficient matrix of random-parameters, we found that the non-constant longitudinal slope (LS) alleviates the effect of the annual average daily traffic (AADT) per lane on increasing crash frequency. In addition, the presence of the mechanical ventilation (MV) in tunnels makes less significant the influence of AADT per lane on increasing crash frequency, too. The knowledge of these correlations may be useful for future applications, for example, for road engineers in designing tunnel. The model proposed can also be used by Tunnel Management Agencies (TMAs) for estimating possible variations in accident frequency in a specific tunnel due to modifications of traffic control systems. [ABSTRACT FROM AUTHOR]

Designs of loading and transport modules applied for the construction of road tunnels are considered. The distinctive feature of modules from conventional designs is the use of wedge working elements in combination with power hydraulic cylinders as a drive. Basing on health monitoring of the tunneling equipment expected values of loading modules reliability indicators are defined. The forecast is carried out based on the known regularities of change in the reliability of analogs and prototypes of the investigated modules and their elements. The units and parts of modules limiting reliability are used for the assessment of reliability. The decision on the efficiency of application and feasibility of the studied designs of loading and transport modules is made on the basis of simulation of their operation and is determined by the magnitude of operational costs with the account of stochastic nature of the flow of module elements failures. [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]

Based on the experience of former tunnel construction projects, the project management appointed an independent quality assurance consultant in addition to quality control by the site supervision for the construction of the intermediate slab and the concrete pavement of the new second tube of the Tauern Tunnel (direction Salzburg). In relation to the concrete pavement with exposed aggregate finish and the intermediate slab, quality assurance measures included the inspection of the suitability certificates and expert support in construction preparation and concreting. Compliance with the technical conditions of contract was also monitored continuously. For the road pavement construction, particular emphasis was placed on the quality of the pavement concrete and the exposed aggregate finish. For this reason, the first few days of pavement construction were subjected to increased checks, until the concrete production, transport logistics and construction crew had got used to the specific conditions in the tunnel and a homogeneous exposed aggregate finish could be guaranteed with the required functional properties like skid-resistance and noise-reducing texture. Construction of the intermediate slab was prepared in advance by casting a test slab as agreed with the specialist in order to check that the required construction quality could be achieved with the chosen process. The experience with the test slab led to an optimisation of the construction process and the implementation of this and maintenance of the quality requirements were supervised during the construction work. Für die Herstellung der Zwischendecke und der Betonfahrbahn der neuen zweiten Röhre des Tauerntunnels (Richtungsfahrbahn Salzburg) wurde von der Projektleitung aufgrund der Erfahrungen aus vorhergehenden Tunnelbaulosen zusätzlich zur Qualitätskontrolle durch die örtliche Bauaufsicht eine begleitende Qualitätssicherung durchgeführt. In Bezug auf die in Waschbetontechnik ausgeschriebene Betonfahrbahn und die Zwischendecke umfassten die qualitätssichernden Maßnahmen die Begutachtung der Eignungsnachweise und die sachverständige Unterstützung der Bauvorbereitung und des Deckeneinbaus. Zusätzlich erfolgte eine laufende Beurteilung der Einhaltung der technischen Vertragsbestimmungen. Für den Straßendeckeneinbau wurde besonderes Augenmerk auf die Qualität des Deckenbetons und der hergestellten Waschbetonstruktur gelegt. Zu diesem Zweck wurden die ersten Tagesleistungen bei der Deckenherstellung einer verdichteten Kontrollprüfung unterzogen, bis sich die Betonproduktion, die Transportlogistik und die Einbaumannschaft auf die spezifischen im Tunnel vorherrschenden Verhältnisse eingespielt hatten und eine homogene Waschbetonoberfläche mit den geforderten funktionalen Eigenschaften bezüglich Griffigkeit und lärmmindernder Textur sicher gestellt werden konnte. Für die Herstellung der Zwischendecke wurde im Rahmen der Arbeitsvorbereitung ein Probefeld in Abstimmung mit dem Sachverständigen hergestellt, um die Erreichbarkeit der geforderten Bauwerksqualität mit dem gewählten Einbauverfahren zu überprüfen. Die Erfahrungen aus dem Probefeld führten zu einer Optimierung des Einbauverfahrens. Die Umsetzung der Erkenntnisse aus dem Probefeld und Einhaltung der Qualitätsanforderungen wurden bei der Ausführung begleitend überwacht. [ABSTRACT FROM AUTHOR]

This report gives an overview of the ventilation scheme for both tubes of the Tauern Tunnel with particular attention to the rebuilding of the multi-storey ventilation cavern. The cavern was designed and constructed in the 1970s – along with most of the ventilation system – and provides the ventilation for the central sections of both tubes with a ventilation shaft about 600 mm deep. While the original scheme intended sheet metal ducts partly suspended from the cavern vault, all the extract air ducts now had to be constructed of reinforced concrete as part of the construction of the second tube on account of the requirement for fire resistance. This also included the replacement of existing suspended sheet metal ducts. The design work was a particular challenge because the structural design and detailing also had to consider the complicated existing structure and the aerodynamic (flow resistance) and logistical (maintenance of traffic and continuous operation of ventilation) aspects. Im vorliegenden Bericht wird eine Übersicht über das Lüftungskonzept der beiden Röhren des Tauerntunnels gegeben, wobei besonders auf die Umbauarbeiten der mehrgeschossigen Lüfterkaverne eingegangen wird. Die Kaverne wurde – wie der Großteil der Lüftungsanlage – bereits in den 1970-er Jahren für beide Tunnelröhren geplant und errichtet und gewährleistet mit einem rund 600 m hohen Lüftungsschacht die Be- und Entlüftung der zentralen Lüftungsabschnitte für beide Tunnelröhren. Während beim ursprünglichen Konzept zum Teil vom Kavernengewölbe abgehängte Blechkanäle vorgesehen waren, müssen im Zuge des Neubaus der zweiten Tunnelröhre und der Sanierung der Bestandsröhre sämtliche Abluftkanäle wegen der geforderten Hitzebeständigkeit in Stahlbetonbauweise ausgeführt werden. Daher musste auch für die bereits bestehenden, aufgehängten Blechkanäle Ersatz geschaffen werden. Die Planungsarbeiten erwiesen sich als besonders herausfordernd, da die statisch-konstruktive Planung auch die komplexen bestehenden Bauwerke und zusätzlich lüftungstechnische (Strömungswiderstand) und logistische (Verkehrsaufrechterhaltung und laufender Lüftungsbetrieb) Aspekte zu berücksichtigen hatte. [ABSTRACT FROM AUTHOR]

The extent of tunnel refurbishment has increased constantly in recent years. The particular importance of meticulous and thought-out planning has been demonstrated on recent projects. The original drawings often provide an insufficient basis for design work and have to be checked, verified or supplemented by targeted investigation measures. A brief glance at the list of claims from a refurbishment project can clearly demonstrate the potential savings, which could have been produced by relatively cheap investigations. For the planning and design of the refurbishment of the first tube of the Tauern Tunnel, many staged investigation surveys were therefore carried out. The investigation measures carried out and their results and effect on the design and tender documents for the refurbishment of the existing tube of the Tauern Tunnel are described in this article. In den letzten Jahren ist der Umfang der Tunnelsanierungen stetig gestiegen. Die bei Sanierungsmaßnahmen besonders große Bedeutung einer sorgfältigen und durchdachten Planung konnte bei den jüngst ausgeführten Projekten erkannt werden. Alte Baupläne sind oft nur eine sehr unzureichende Planungsgrundlage, die durch gezielte Erkundungsmaßnahmen abgesichert, verifiziert oder ergänzt werden sollten. Ein kurzer Blick auf die Liste der Mehrkostenforderungen bei Sanierungsprojekten zeigt in eindrucksvoller Weise das Einsparpotenzial, das mit vergleichsweise kostengünstigeren Erkundungsmaßnahmen hätte erzielt werden können. Für die Planung der Sanierung der ersten Röhre des Tauerntunnels wurden daher mehrere, zeitlich gestaffelte Erkundungsprogramme durchgeführt. Die durchgeführten Erkundungsmaßnahmen sowie deren Ergebnisse und Auswirkungen auf die Planung und Ausschreibung der Sanierung der Bestandsröhre des Tauerntunnels werden im vorliegenden Beitrag vorgestellt. [ABSTRACT FROM AUTHOR]

A number of different Water and Frost Protection Systems, or so-called inner linings, have during the years been introduced and tested in Norwegian road tunnels. At present a limited number of such systems have been approved by the Norwegian Public Roads Administration (NPRA). These systems will all be described in brief. A system based on pre-cast concrete segments will be described in details, including the installation procedure. Experience and limitations associated with this system will also be discussed. A basic design concept for using an inner lining as water and frost protection is that there is no interaction between the inner lining and the rock support. The rock support practise in Norwegian traffic tunnels will also be briefly described in this paper. Sprayed concrete and rock bolts are the main support measures. In-situ cast-in-place concrete lining is only used locally to solve severe stability problems. [Copyright &y& Elsevier]

• Prediction of tunnel construction time and costs using Markov Chain method. • Access to input data with the help of tunneling expert staff. • Demonstrate the impact of expert opinions on the predictions accuracy. • Updating the previous predicted results during tunnel construction. • Specify the prediction model accuracy by comparing with the actual mode. The impact of uncertainty on decision-making is increasingly prioritized, especially for large geotechnical projects such as tunnels. In this article, the effects of geological/geotechnical uncertainties in tunnel construction time and costs were reduced. The forecasting of geological/geotechnical conditions in a tunnel project was based on the Markov chain. To accessing the more accurate input data of the Markov chain and estimate the construction time and cost required for tunnel construction, tunneling experts were interviewed through a questionnaire. Also, to assess the updating effect on obtained outcomes during the tunnel construction, the model was updated for one time. Finally, comparing the predicted results with the actual results, the effects of the interviewing and updating process were investigated. According to the results, the uncertainties in the predictions were found to be reduced significantly. Lastly, this research can provide guidance or reference for the evaluation and decision-making of complex systems engineering problems, and indicate a direction for further research of risk assessment and decision-making issues. [ABSTRACT FROM AUTHOR]

• A model for estimating Life Cycle Cost of road tunnels. • A homogeneous database of 32 road tunnels, with a total length of 55 km. • Artificial Neural Networks are employed to estimate final costs. • Rapid cost pre-estimation of alternatives at early stages. • Development of tunnel operation & maintenance strategy. The estimation of road tunnel costs is crucial for motorway operators and transport infrastructure project managers. This paper presents a life cycle model for estimating costs in road tunnels. The research is based on a data set of 32 dual bore road tunnels, with a total length of 55 km, which are part of the Egnatia Odos Motorway in Northern Greece. The factors affecting civil engineering construction works and electromechanical installations are analyzed in great detail. Energy consumption and operation and maintenance costs are examined. Additionally, replacement costs are studied for an operation period of 75 years. Overall, Artificial Neural Networks are employed to estimate final costs in relation to tunnel design input parameters. The life cycle cost model uses depreciation and price escalation on all costs. It is concluded that the proposed framework can assist tunnel operators and asset managers in reliable costing of alternatives as well as developing operation and maintenance strategies. [ABSTRACT FROM AUTHOR]

Given the frequent cost overruns and schedule delays associated with tunnel construction projects, it is imperative that a detailed estimation of both be developed and considered prior to starting construction. To this end, two artificial intelligence tools of Gaussian Process Regression (GPR) and Support Vector Regression (SVR) were used to forecast geology, construction time and construction costs of a road tunnel project. The initial training datasets applied in the prediction tools were accessed from the previously-constructed road tunnels and the pre-existing observations of the tunnel under consideration. Also, during the tunnel construction, more training datasets obtained in the constructed parts were added to the previous datasets and the pre-constructed predictions of the GPR and SVR tools were updated. Lastly, comparing the predictions made by the GPR and SVR tools with the actual mode of the tunnel, and comparing the pre-updating predictions with the post-updating ones, it was concluded that, the GPR and SVR tools have presented very good predictions and they have reduced the uncertainties regarding geology and construction time and costs to an acceptable level. But, the GPR tool has presented more accurate results than the SVR tool. Also, the updating procedure can significantly increase the predictions accuracy. [ABSTRACT FROM AUTHOR]