Journal articles
Author(s) | Title | Journal | Issue | Page | Category |
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Barla, Giovanni; Debernardi, Daniele; Perino, Andrea | Lessons learned from deep-seated landslides activated by tunnel excavation | Geomechanics and Tunnelling | 5/2015 | 394-401 | Topics |
AbstractThe interaction between deep-seated landslides and infrastructure facilities is a topic of relevant interest in the rock mechanics literature. This paper discusses the case of deep-seated landslides reactivated during excavation of two large twin tunnels in Italy, with an overview of the geological, hydrogeological and geotechnical conditions. The efforts made in order to gain an understanding of the complexities involved and the necessary quantification of the stability problems during tunnel excavation are presented in each case. Two- and three-dimensional numerical modelling methods, used as a means to back-analyze the reactivated landslide and the interaction with the tunnels, are discussed. It is shown how modelling associated with advanced real-time monitoring may contribute to the understanding of the problems under study. x | |||||
Camus, Thomas; Therville, Fabrice | The Sydney North West Rail Link project tunnelling challenge with four double shield TBMs | Geomechanics and Tunnelling | 5/2015 | 402-408 | Topics |
AbstractNFM Technologies has designed and delivered four 6.99 m-diameter Double Shield TBMs that are excavating the North West Rail Link project, an extension to the Sydney rapid transit network. The project is led by a consortium comprising Thiess, John Holland and Dragados, acting on behalf of the Government of New South Wales Transport Authority. Altogether, the TBMs will build 15 km of twin tunnels in rock that is mainly formed of abrasive sandstone. TBMs 1 and 2 bore the 9 km section between the Bella Vista and Cherrybrook stations, while the remaining 6 km from Cherrybrook to the Epping interchange are bored by TBMs 3 and 4. x | |||||
Schubert, Wulf; Moritz, Bernd | The state of the art in monitoring and geotechnical safety management for shallow and deep tunnels | Geomechanics and Tunnelling | 5/2015 | 409-413 | Topics |
AbstractDue to uncertainties in the ground model and the spread of geotechnical properties, prediction of the exact system behaviour of underground structures is difficult in many cases. In order to manage this problem, the so-called observational approach is often applied. Monitoring plays an important role to verify or falsify design assumptions, to adjust excavation and support measures to the actual conditions and to assess the stability of the system. For the management of the residual risk a geotechnical safety management plan is implemented. The OeGG has recently published a handbook summarizing the state of the art in tunnel monitoring and geotechnical safety management. x | |||||
Day, Jennifer J.; Diederichs, Mark S.; Hutchinson, D. Jean | Optimization of structural contact stiffness and strength for discrete simulation of progressive failure of healed structure | Geomechanics and Tunnelling | 5/2015 | 414-420 | Topics |
AbstractGeotechnical analysis for underground excavation design in complex tectonic environments requires an increased understanding and more rigorous consideration of the impact of healed or "intrablock" structure, such as veins, on rockmass behaviour. Intrablock structure occurs between blocks of rock defined and bounded by "interblock structure", the network of joints and other fractures conventionally considered in classic rockmass characterization, classification or rockmass property estimation. Discrete simulation of fractures has become a more commonplace model analysis technique for excavations in jointed rockmasses. Here too, however, special attention is required to simulate intrablock structure within the model. In particular, the selection and evolution of stiffness and strength values for the model discontinuity elements must follow a different logic than that adopted for fractures and true joints. A new concept to better represent the behaviour of intrablock structure in explicit numerical models is proposed and tested in this paper by means of finite element method (FEM) analysis and case study data from a 1, 200 m deep drift. This approach changes the stiffness and strength values of failed intrablock structural elements between pre-peak ("primary"), post-peak ("secondary"), and ultimate ("tertiary") states. The FEM models in the tertiary state match 96 % of overbreak patterns along the case drift, versus 80 % in primary state models. These findings suggest that the proposed method is a good option to more accurately model the influence of intrablock structure on rockmass behaviour. x | |||||
Giger, Silvio B.; Marschall, Paul; Lanyon, Bill; Martin, C. Derek | Hydro-mechanical response of Opalinus Clay during excavation works - a synopsis from the Mont Terri URL | Geomechanics and Tunnelling | 5/2015 | 421-425 | Topics |
AbstractIndurated clay formations are under consideration as potential host rock formations for the disposal of radioactive waste in several countries. The favourable features of such formations for deep geological repositories include an excellent hydraulic barrier function, high capacity for dissolved radionuclide retention and considerable self-sealing potential. The development of a brittle fracture network (excavation-induced damage zone, EDZ) around underground structures during construction and operation cannot however be avoided. To assess the impact of the EDZ on long-term safety of the repository, a detailed structural inventory of the fracture network and the relevant hydro-mechanical phenomena and processes during excavation and the subsequent operation phase is required. This then forms the geomechanical basis for the development of conceptual and numerical models of the EDZ. Here we present some empirical and experimental evidence from the Mont Terri Underground Research Laboratory (URL), summarizing the key phenomena and processes associated with the creation and evolution of an EDZ in the Opalinus Clay. In particular, the significance of rock mass anisotropy is highlighted, both as a likely origin for far-reaching pore fluid pressure changes and as a controlling factor in EDZ development during the excavation process. x | |||||
Zhang, Chun-Liang | Deformation of clay rock under THM conditions | Geomechanics and Tunnelling | 5/2015 | 426-435 | Topics |
AbstractAs a potential host rock for deep geological disposal of radioactive waste, the Callovo-Oxfordian and Opalinus clay rocks have been extensively investigated in the laboratory with respect to deformation under various thermo-hydro-mechanical conditions: (1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation, (2) humidity variations representing ventilation during operation of tunnels as well as water migration from the far-field and (3) heating from ambient temperature up to 100 °C and a subsequent cooling phase. For these highly consolidated clay rocks, a new concept is theoretically derived to explain the effective stress in the particle matrix and experimentally confirmed. The mechanical deformation of the clay rocks is determined by means of short- and long-term compression experiments on quasi water-saturated samples at ambient temperature. Reponses of the clay rocks to humidity changes are examined by drying and wetting the samples under different loading conditions. Thermal effects are studied by heating and cooling the stressed samples under drained and undrained conditions. The main findings are presented and discussed in this paper. x | |||||
Pausz, Sebastian; Nowotny, Hans; Jung, Gerald | Rock mass classification and geotechnical model for the foundation of a RCC gravity dam | Geomechanics and Tunnelling | 5/2015 | 436-440 | Topics |
AbstractThe paper describes the development of a geological and geotechnical model produced for the design of a hydro power plant and its large RCC (roller compacted concrete) dam. Various in situ and laboratory investigation methods and rock mass classification were introduced for the definition of subsurface parameters and rock mass parameters were derived for design purposes. The mechanical parameters of the rock masses were the basic input for different finite element models that were used in order to evaluate the interacting static system of foundations and structures. The insights gained from this work were used to implement appropriate amendments to the design of the hydropower plant. x | |||||
Walton, Gabriel; Diederichs, Mark; Punkkinen, Allan | The influence of constitutive model selection on predicted stresses and yield in deep mine pillars - A case study at the Creighton mine, Sudbury, Canada | Geomechanics and Tunnelling | 5/2015 | 441-449 | Topics |
AbstractBased on recent advances in modelling the post-yield behaviour of brittle rock, the authors have developed a calibrated inelastic model of the 7,910 level (2.4 km depth) at the Creighton Mine in Sudbury, Ontario, Canada using data collected from the monitoring of pillar dilatancy. While this calibrated model represents a state-of-the-art continuum approach for capturing the progressive development of yield and stresses in mine pillars, alternative state-of-practice approaches (elastic and perfectly plastic material models, for example) represent potentially acceptable options for practical application. x | |||||
Galler, Robert | Development of resource-efficient tunnelling technologies - Results of the European research project DRAGON | Geomechanics and Tunnelling | 4/2015 | 302-309 | Topics |
AbstractA wide range of different minerals is found in materials excavated in tunnels. The DRAGON project therefore has the aim of investigating the requirements of the industries producing products from mineral raw materials and who thus could be interested in raw materials derived from underground construction sites. In parallel to the development of advanced online technologies for the analysis of excavated materials, DRAGON is researching the significant requirements for raw materials used in industrial processes; these include grain size distribution, mineralogical composition, geochemistry as well as water content and water absorption properties. x | |||||
Edelmann, Thomas; Himmelsbach, Christian; Barwart, Stefan | Direct use of excavated material in mechanised tunnelling - development of the prototype | Geomechanics and Tunnelling | 4/2015 | 310-314 | Topics |
AbstractThe DRAGON project (Development of Resource-efficient and Advanced Underground Technologies) is intended to improve resource efficiency in tunnelling processes by providing the excavated material as a raw material. The project deals with the systematic reuse of excavated material from tunnel boring machines (TBMs) and is mainly focussed on the development of specific automated analysis and separation technologies. This enables resource-efficient reuse of excavated material through the installation of innovative technology directly on the TBM. The physical characteristics of excavated material can be concluded by measuring the disc cutter load. The mineralogical and/or elementary parameters will be detected by a fully automated side pass analysis system. For this purpose, Herrenknecht AG and the Montanuniversität Leoben are working with other internationally renowned partners in the framework of the DRAGON project on various methods of characterising excavated material. x | |||||
Petitat, Manuel; von Allmen, Katja; Burdin, Jacques | Automation of rock selection and aggregate quality for reuse in tunnelling and industry | Geomechanics and Tunnelling | 4/2015 | 315-320 | Topics |
AbstractThe tunneling industry is flourishing around the world. But what about the spoil material? This paper presents the different steps achieved towards an automation of rock selection and aggregate quality assessment for tunnelling to reduce environmental impacts and maximize the use of excavation materials by analyzing and processing TBM muck on-line, inside the tunnel, on the tunnel boring machine. x | |||||
Erben, Hartmut; Galler, Robert; Grechenig, Thomas | MineralBay - the portal for raw materials and projects from subsurface construction / MineralBay - das Portal für mineralische Rohstoffe und Projekte aus dem Untertagebau | Geomechanics and Tunnelling | 4/2015 | 321-332 | Topics |
AbstractIn order to achieve higher utilisation rates for the material excavated from underground construction sites, one of the main objectives is efficient, digital processing of available data on material, mass and time parameters for the mined rock. Selected information needs to be made available to a wide audience at the same time. This initiates a value chain, which goes far beyond the construction industry and enables successful upcycling. The evolving software MineralBay is committed to this goal by using the internet to bring together owners or suppliers of mineral resources with customers easily, quickly and at any time to facilitate the exchange and trading of raw materials. MineralBay is a management and merchandising system for excavated material, whose speciality is access to and processing of real-time data, e.g. in the form of online material analysis results from tunnel boring machines. The information obtained is used for quality management of already placed excavation material and for gapless documentation of the material flow from the beginning to the end of the construction project. x | |||||
Shonfield, Peter; Anderson, Jane; Boyd, Sarah | A methodology for assessing the environmental benefits of DRAGON technology | Geomechanics and Tunnelling | 4/2015 | 333-339 | Topics |
AbstractMost excavated material generated from tunnelling projects ends up being deposited on land. The EU funded project “DRAGON” aims to develop technologies to analyse and characterise this material so that the potentially usable fraction can be easily separated from non-usable material. Increasing use of this material by external industries will improve resource efficiency while reducing landfill quantities and disposal costs. One of the project goals is to assess the potential environmental benefits/costs of applying DRAGON technology to planned future EU tunnelling projects. A three stage approach has been adopted to meet this goal. Firstly, the potential for diverting material from landfill must be assessed. To account for the diversity of tunnelling projects, this will be based on an average of 54 recent tunnelling projects. Secondly, a life cycle assessment (LCA) model will be created to allow each of these tunnelling projects to be analysed and the potential benefits of using DRAGON technology will be compared against the ‘business as usual’ case. These results will then be averaged to give the expected environmental costs/benefits per t excavated material. Finally, these costs/benefits will be scaled up to account for the expected amount of material from future European tunnelling projects - expected to be around 800 m. t. x | |||||
Posch, Helmut; Otto, Richard; Huber, Helmut; Murr, Roland; Kager, Matthias; Wagner, Hanns | Recycling of tunnel excavation using the example of the Koralm Tunnel, contract KAT2 - Status April 2015 / Verwertung von Tunnelausbruch am Beispiel des Koralmtunnels, Baulos KAT2 - Stand April 2015 | Geomechanics and Tunnelling | 4/2015 | 340-347 | Topics |
AbstractContract KAT2 will produce about 8.6 m. t of material excavated from the tunnel. In the course of the design work, maximum reuse of this material was intended, always considering economics and while reducing the environmental impact by minimizing transport and saving resources. More than half of the suitable tunnel spoil will be preliminarily screened and then processed for the production of aggregates for concrete production. After the first year of production, the high losses associated with the preliminary screening and processing demanded measures to improve the processing, which led to an improvement of the recycling quota. The aggregates produced on site so far fulfil the technical requirements for concrete production, even for high strength concrete grades. x | |||||
Maurer, Walter | Light management below ground: lighting technology in tunnelling / Lichtmanagement unter Tage: Beleuchtungstechnik im Tunnelbau | Geomechanics and Tunnelling | 4/2015 | 348-355 | Topics |
AbstractNew lighting technologies are everywhere and LED (light emitting diode) has become a popular search term for buyers of lighting equipment. The energy saving potential is enormous and energy efficiency has become important in any company, from agricultural and industrial businesses to service providers. To encourage this development, a new law was introduced by the Austrian Ministry of Science, Research and Business in 2014 that requires businesses to determine energy saving potential and reduce energy consumption. Replacement of outdated lighting technologies does have great potential for energy saving, but light is also an essential factor in the world of work, and companies have long underestimated its influence on the performance and motivation of staff. Lighting was and still is a precondition for working underground, but how much light is needed? The following article is intended to draw attention to the importance of light below ground and indicate possible effects on performance and health. x | |||||
Gratzer, Reinhard; Bechtel, Achim; Sachsenhofer, Reinhard F.; Gawlick, Hans-Jürgen | Geogenic versus Anthropogenic: Hydrocarbons in the Spoil from the Falkenstein and Spering Tunnels (A9 Pyhrn Autobahn, Austria) | Geomechanics and Tunnelling | 4/2015 | 356-363 | Topics |
AbstractIn the Falkenstein und Spering tunnels (A9 Pyhrn Autobahn; Northern Calcareous Alps), hydrocarbon contents (HC Index) in excess of the permitted threshold values were detected in the course of the routine statutory analysis of the excavated material. Comparative detailed geochemical analysis of retained reference samples, operational consumables and core samples from boreholes drilled into the tunnel wall show that threshold values of HC indices in the Reifling Limestone are exceeded due to the presence of locally generated natural hydrocarbons. The hydrocarbons were probably formed in marly zones of the carbonate rocks and migrated into the well-developed fracture network. These hydrocarbons are characterized by high contents of n-alkanes, high Ts/(Ts+Tm) ratios, a predominance of C27 and C29 steranes, and the lack of oleanane. Traces of hydrocarbons in the Wetterstein Limestone contain oleanane due to contamination by operating consumables. x | |||||
Thuro, Kurosch; Wilfing, Lisa; Wieser, Carola; Ellecosta, Peter; Käsling, Heiko; Schneider, Eckart | Hard rock TBM Tunnelling - on the way to a better prognosis? / TBM-Hartgesteinsvortriebe: Auf dem Weg zu einer verbesserten Prognose? | Geomechanics and Tunnelling | 3/2015 | 191-199 | Topics |
AbstractFive universities from Austria, Germany and Switzerland, working intensively together with partners from the industry, client organisations, companies, consultants and TBM manufacturers, have combined to develop a new prognosis model for TBM advance rate and disc wear (the “ALPINE MODEL”). This article presents some new results from the project. Fundamentally, the new model is to be a development of the model from Gehring, which calculates the penetration from the ratio of disc load to uniaxial compression strength. Since this equation was derived from data collected from a limited number of projects in the 1980s, it is of great importance to widen the data base and to establish a standardised process for this purpose. For on-site tests, the “Start-stop-penetration test” is considered the most efficient and suitable method. This test can be carried out with the TBM in the course of tunnelling and thus results in little delay. In addition to the recording of TBM data during the penetration test, detailed geological documentation of the face and the tunnel sides has to be undertaken, accompanied by geomechanical laboratory tests. A large number of such penetration tests have now been carried out on various tunnel projects in order to validate and improve the basic formula. Some of the first results are described in this article. Further themes include the rock mechanical parameters to be used, the influence of the primary stress conditions at the face and the abrasiveness of the rock. x | |||||
Schuller, Erik; Galler, Robert; Barwart, Stefan; Wenighofer, Robert | The transparent face - development work to solve problems in mechanized hard rock tunnelling / Die gläserne Ortsbrust - Entwicklungsarbeiten zur Lösung von Fragestellungen rund um maschinelle Vortriebe im Festgestein | Geomechanics and Tunnelling | 3/2015 | 200-210 | Topics |
AbstractWhile image-based face documentation is well established in conventional tunnelling, even photogrammetric 3D reconstruction, this technical aid is not available in mechanized tunnelling. In a research project of the Chair of Subsurface Engineering with Geodata GmbH, work is underway to develop an imaging device, which is mounted in the cutterhead of a TBM and takes pictures during the maintenance shift that can be used for a photogrammetric reconstruction of the face. In the present article, the results of the first test images are presented. These were undertaken on a tunnel boring machine on the ÖBB project Koralm Tunnel KAT2 in agreement with the research initiative of the ÖBB-Infrastruktur AG. x | |||||
Küpferle, Jakob; Röttger, Arne; Alber, Michael; Theisen, Werner | Assessment of the LCPC abrasiveness test from the view of material science / Bewertung des LCPC-Abrasivitätstests aus werkstofftechnischer Sicht | Geomechanics and Tunnelling | 3/2015 | 211-220 | Topics |
AbstractThe abrasiveness of crushed rock is determined in the design phase of a tunnelling project to estimate the wear on excavation and boring tools, using for example the LCPC abrasiveness test. Considered from the point of view of material science, there are problems with the validity of such an index value since important tribological factors, like for example the internal structure of the sample impeller (size, phase composition) are not considered in the current testing standard (AFNOR P18-579). In this investigation, LCPC tests were performed with impellers of various steels of the same and different hardnesses against two abrasives (Mohs hardness 7, 9) in order to determine the influence of the internal structure and the associated tribo-mechanical properties on the LCPC index value (ABR). In addition to the material hardness required by the standard (60 to 75 HRB ≈ 105 to 140 HV 10 according to DIN EN ISO 18265-2013), sample materials with higher hardness values were also used in order to extend the basis of the LCPC abrasiveness index to these practically applicable material groups. The results make clear that awareness has to be raised regarding the materials used for the LCPC test. An abrasive can be classified differently just by using various materials of the same hardness. In order to obtain reliable and reproducible index values for the abrasiveness of crushed rock, it is necessary to consider the influence of materials in future recommendations for the LCPC. x | |||||
Skuk, Stefan; Wegscheider, Daniel | Brenner Base Tunnel - a 10.5 km double shield TBM drive in granite / Brenner Basistunnel - 10,5 km Doppelschild-TBM im Granit | Geomechanics and Tunnelling | 3/2015 | 221-238 | Topics |
AbstractThe Brenner Base Tunnel, with two main bores and an investigation tunnel running parallel in the middle, crosses the main ridge of the Alps beneath the Brenner Pass and the border of Austria and Italy. The first construction contract was a 10.5 km long investigation tunnel bored by a double shield machine in granite. Numerous investigation measures, laboratory tests and geological face surveys were carried out, and the TBM data was recorded on a 10-second cycle. Due to the large amount of data and the very well known homogeneous geology, it seemed appropriate to develop correlations between the data of the rock mass, the rock and the TBM. Statistically reliable statements could be derived. The unconfined compression strength of the rock, discontinuity parameters and index parameters such as the RMR (Rock Mass Rating), GSI (Geological Strength Index) and RQD (Rock Quality Designation) were compared with the penetration behaviour. GSI values between 30 and 40 showed four times the penetration rate compared to GSI values between 90 and 100. This applies similarly for the RQD, RMR and discontinuity spacing values. x | |||||
Hassanpour, Jafar; Rostami, Jamal; Zhao, Jian; Azali, Sadegh Tarigh | TBM performance and disc cutter wear prediction based on ten years experience of TBM tunnelling in Iran | Geomechanics and Tunnelling | 3/2015 | 239-247 | Topics |
AbstractAccurate estimation of rate of penetration (ROP), daily rate of advance (AR), and cutter cost/life is necessary for the justification and successful use of a TBM on any tunneling project. Various models have been introduced over the years to provide such estimates. In many cases, these models have been successful with pin point accuracy, and in other instances off by a wide margin. Improving the accuracy of performance prediction models for hard rock TBMs has been the subject of many studies, some yielding project-based models and some more universal models that can be used elsewhere. This paper will discuss the latest version of a new empirical model for estimating penetration rate and disc cutter life for hard rock TBM tunneling based on recent tunneling projects, constructed during the period 2002-2009. The new model was then applied to predict TBM performance and disc cutter wear in different mechanized tunneling projects under construction since 2009. Accuracy and validity of the model for prediction of ROP were checked by comparing predicted and measured values of TBM performance in 24 km of newly bored tunnel. The results indicate that despite some minor deviations in estimates in some tunnel sections, reasonable agreement can be observed between predicted and actual ROP of TBMs. x | |||||
Köppl, Florian; Thuro, Kurosch; Thewes, Markus | Factors with an influence on the wear to excavation tools in hydroshield tunnelling in soft ground / Einflussfaktoren auf den Verschleiß der Abbauwerkzeuge beim Vortrieb mit Hydroschild-TVM in Lockergesteinen | Geomechanics and Tunnelling | 3/2015 | 248-257 | Topics |
AbstractThe wear to excavation tools is a central challenge for tunnelling with Hydroshield (TBM) in soft ground because it is one of the main causes of stoppages. Due to the inaccessibility of the processes involved and the wide range of influencing factors, there has been no method of forecasting the wear to excavation tools until now. Working from a detailed analysis of 18 tunnel drives with hydroshield TBMs, an empirical approach to investigate the factors with an influence on the wear to excavation tools was selected for the present work. The analysis enables the qualification and quantification of the essential factors with an influence on the tool life parameters of the excavation tools. x | |||||
González, Claudia; Arroyo, Marcos; Gens, Antonio | Wear and abrasivity: observations from EPB drives in mixed soft - rock sections | Geomechanics and Tunnelling | 3/2015 | 258-264 | Topics |
AbstractThis paper summarizes the main observations related to geotechnical properties and tool changes that characterize the different tunnel drives in a database of 33 km of EPB tunnel records from the Barcelona area. The data have been examined in detail with regard to cutting tool replacement and performance of the mechanized excavation. The database includes tunnels in soft soils, in hard and medium rocks and in mixed soil-rock conditions; tool changing records and geotechnical properties. Transverse and longitudinal geotechnical heterogeneity are accounted for systematically. Longitudinal heterogeneity is used to subdivide the drives in the database into homogeneous units. Transverse (within section) heterogeneity is described by a set of newly developed impact factors FI. x | |||||
Radoncic, Nedim; Kern, Martin; Weissnar, Martin; Moritz, Bernd | Strain gauges in pre-cast concrete segments: working principle, evaluation and interpretation / Dehnmessgeber in Tübbingsegmenten - Funktionsweise, Auswertung und Interpretation | Geomechanics and Tunnelling | 3/2015 | 265-272 | Topics |
AbstractIn order to obtain an enhanced understanding of the system behaviour, especially with regard to the capacity reserves of the support and general load conditions, measurement pre-cast concrete rings are used at the ÖBB construction lot KAT2 of the Koralm Tunnel. These are equipped with a strain gauge in each reinforcement layer, thus allowing direct measurement of the strains in every pre-cast concrete segment. x | |||||
Gisi, Bruno; Schöbel, Stefan | High-performance conventional tunnelling - The Bibra Tunnel on project VDE 8, Germany / Konventioneller Hochleistungsvortrieb - Der Bibratunnel im Projekt VDE 8, Deutschland | Geomechanics and Tunnelling | 2/2015 | 103-114 | Topics |
AbstractThe 123 km long Erfurt-Leipzig/Halle high speed train link connects in the north the cities of Berlin and Munich with Verona in the South as part of the EU's Trans-Europe Network. The project which is designed for a top speed of 300 km/h is being managed by DB Projekt Bau, a subsidiary of Deutsche Bahn. The total cost of this section between Berlin and Munich including tunnels and bridges is estimated at 13 Mrd. Euro. On the project section VDE 8.2 between Erfurt-Leipzig/Halle three tunnels are being built with a total length of 15.4 km, each composed of two single track tubes with centers approx. 25 m apart. One tunnel is being executed by mechanized tunnelling, the two others by conventional drill and blast method. The longer of these two - the Bibra tunnel with a length of 6,466 m was awarded in January 2008 to the by Marti Tunnelbau AG lead J.V. for 209 m. Euro. x |