Quality in Tunnelling: ITA-AITES Working Group 16 Final Report Q

Tunnelling and Underground Space Technology incorporating Trenchless Technology Research Tunnelling and Underground Space Technology 19 (2004) 239–272 www.elsevier.com/locate/tust ITA/AITES Accredited Material Quality in tunnelling: ITA-AITES Working Group 16 Final report q

Claudio Oggeri a,*,1, Gunnar Ova b,1

a Dept. of Georesources, Tunnelling and Underground Space Center, Politecnico of Turin, Corso Duca degli Abruzzi 24, 1029 Torino, Italy b Selmer Skanska AS, St Olavsg 25, 0107 Oslo, Norway

Abstract

Quality in tunnelling means knowledge. Knowledge is necessary to answer correctly to the requirements of the Design that has been prepared for an underground work, planned for a solution in civil, environmental or industrial fields. Knowledge is necessary to learn and ‘‘copy’’ better what the previous Designers have done to find new solutions for tunnel construction. Knowledge is necessary to spread all over the technical world both the reasons of failures and the keys for success. Experience, good contracts, professionality, self responsibility and simple rules are the basis to reach the objectives fixed in the Design, that is to perform the underground work following the Quality procedures. The Working Group (WG) No. 16, appointed by the International Tunnelling Association (ITA) council during the annual meeting in Oslo on 1999, defined the main topics in Milan on 2001 and closed in Amsterdam on 2003 this document, which is aimed to give a comprehensive contribution for a good behaviour in the various stages of tunnelling. This is not a handbook, because each single phase is not analyzed in extreme detail, but it allows one to go through the interacting activities of the involved parties. It is not so easy to write about generics of Quality without the knowledge of what goes wrong: this was the main difficulty that the Working Group (WG) has encountered during its effort to give good suggestions. The members of the WG hope however that the culture of spreading of knowledge will reach the people involved in tunnelling, thus contributing to one of ITA aims, that is the contribution for a common language in the practice of tunnelling. It is necessary to promote a link between Committents or Contractors on one side and the national and international organizations, working groups and the Universities on the other, in each field of activity, aimed to a continuous and updated collection of references, because only this link will provide an enormous base of lessons learned directly from case histories. The difficulties due to the uncertainties of the geological characters can determine huge consequences and each effort should be done to define the position of the tunnel, the excavation and support methods, the environmental and safety effects, the time and cost of the alternative solutions. The purpose of this document is to encourage all the involved parties to develop and maintain good organization and communications and to put each stage of a work in a common layout. 2003 Elsevier Ltd. All rights reserved.

q Disclaimer: The International Tunnelling Association/Association Internationale des Travaux en Souterrain (ITA/AITES) publishes this report to, in accordance with its statutes, facilitate the exchange of information, in order: to encourage planning of the subsurface for the benefit of the public, environment and sustainable development to promote advances in planning, design, construction, maintenance and safety of tunnels and underground space, by bringing together information thereon and by studying questions related thereto. However, ITA/AITES accepts no responsibility or liability whatsoever with regard to the material published in this report. This material is: information of a general nature only which is not intended to address the specific circumstances of any particular individual or entity; not necessarily comprehensive, complete, accurate or upto date; sometimes collected from external sources over which ITA/AITES services have no control and for which ITA/AITES assumes no responsibility; may not be ITA position, not professional or legal advice (if you need specific advice, you should always consult a suitably qualified professional). * Corresponding address: ITA AITES, c/o EPFL, BatGC, CH1015 Lausanne, Switzerland. Tel.: +41 21 69323 10; fax: +41 21 69341 53. E-mail address: [email protected] (C. Oggeri). 1 Co-authors and Editors for the work made by WG16, whose members are acknowledged, and listed at the end of the paper.

1. Introduction sionally developed documents (such as the Eurocodes by European Committee for Standardization) is encour- 1.1. Summary and structure of the report aged. The professional tools used for implementing quality The recommendations put forward in this report are procedures are not covered in this report as each com- aiming to give practical guidelines to the various parties pany/organization can adopt the most suitable proce- engaged in tunnelling projects during the different stages dures when establishing the project quality plan. of a project. Since the basis for a successful tunnelling However, the WG has found it important to stress the project is often related to careful planning and man- need to specify the interaction between Employer (could agement rather than isolated inspections and tests, this be Employer, Owner, Client, Host Government), Engi- report focuses mainly on quality management measures, neer (could be Engineer, Designer, Consultant) and including iterative processes with the objective of se- Contractor (could be Contractor, Concessionaire). curing adequate and updated quality plans and procedures at any stage. Project prerequisites and risk 1.3. Definitions – ‘‘key words’’ assessment are dealt with in different sections of the report, recognizing the importance of these topics. The meaning of ‘‘Quality’’ was defined in ISO 8402- The report has been arranged according to different 1994 (replaced by ISO 9000:2000) as ‘‘The totality of project phases and give specific recommendations for features and characteristics of a product or service that each phase (Table 1). For practical reasons the Working bear upon its ability to satisfy stated or implied needs’’. Group (WG) has chosen to handle procurement as a As it is difficult to know, and particularly in advance, project phase, even though the procurement activities what the specific needs are, it is of great importance that can be related to all stages of a project. It should be these are expressed for a project. noted that the different project phases described are not In tunnelling the ‘‘stated needs’’ of the Employer completely separated from each other. The need to could mean the construction of a tunnel in accordance identify interactions between phases and between pro- with the technical quality defined by the Employer (i.e. ject participants is crucial to the success of any tunnel- technical specifications), within the estimated budget ling project. and predefined time schedule or programme. The ‘‘im- Conclusions and recommendations are given for each plied needs’’ are multifold and could be respect for laws project phase in the respective sections. and regulations, safety aspects, environmental protection, energy savings and sustainability of the works. It is of fundamental importance that the prerequisites are 1.2. Objectives and scope of work continuously updated and met both during construction and the operation phases. The Working Group has adopted the following ob- ‘‘Quality Management’’ means ‘‘all those systematic jective for the work: actions that are necessary to provide adequate confi- To give recommendations on how to achieve Quality in Tunnel- dence that a product or service will satisfy given quality ling and how to identify, evaluate and specify Quality Manage- requirements’’. The ITA recognizes that it is difficult to ment measures to be taken by all parties in the Conceptual completely assure quality in tunnelling, especially by Planning, Procurement, Design, Construction, Operation and third-party organisations. For this reason it is recom- Maintenance phases of underground projects involving tunnels. mended the adaptation of ‘‘quality management’’ to The WG supports the use of international standards tunnelling projects rather than quality assurance rules. and guidelines for Quality Management Systems such as Suggestions for comprehensive approaches are given in ISO 9000 with updates (ISO standards on quality), in- the report rather than prescriptive routine control and ternationally accepted forms of contracts and agree- testing activities (see Fig. 2 and Table 2). ments, but feels that specific attention should be paid to With regard to the ISO 9000 regulations for accred- topics relevant to tunnelling. The management systems itation and certification, the certification itself may not should be utilized as tools adapted to the particular be a practical quality requirement. It is acknowledged features of tunnelling. Thus, the report contains rec- that many employer/client bodies, engineers/consultants ommendations on ISO related topics, such as allocation and contractors consider that the ISO 9000 certification of responsibility, communication, etc., but also specific may go beyond their limits of affordability. However, recommendations on the necessary prerequisites needed the client and his contractors should strive to comply to achieve quality in various phases of an underground with the requirements of the ISO 9000 regulations in the project. formulation and achievement of the quality goals that Reference to and use of updated recommendations have to be reached. produced by international or national sister organiza- Bearing in mind that quality, defined as the sum of tions (ISRM, ISSMFE, IAEG etc.) and other profes- procedures and control tools that allow for the

ITA/AITES Accredited Material C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 241 achievement of goals in terms of set parameters and the • Determination of necessary competence concerning result of the planned actions, is connected to other geological conditions and geotechnical behaviour in technical and organisational tools, links with other ITA the various stages of the project, from the planning Reports, such as Contractual Practices, Subsurface to the construction. Planning, Tunnelling Risk Management and Mainte- Knowledge is crucial when it comes to dealing with nance and Repair, should be considered. uncertainties and the risk associated with those uncertainties. Results from site investigation have a direct 1.4. Organisation – working group members influence on estimates of cost, time, choice of equipment, professional quality of staff and safety conditions, The Working Group has been working actively since especially when tunnelling in difficult conditions is the Oslo ITA-AITES Congress in 1999, calling for foreseen. contributions in several occasions, mainly during the annual symposia. The working group members have been appointed regularly over the years and have all 2.2. Risk allocation – principles contributed to the discussions and the preparation of this report. The members of the group represent the Uncertainties in tunnelling projects arise from the in- different parties generally involved in tunnelling, em- ability to study the complete structure and behaviour of ployer/clients bodies, consultant/engineer bodies, re- the rock and soil formations in such detail that all pos- searchers and contractors. A list of the working group sible scenarios can be contemplated. It should be em- members who have compiled, or made contributions to phasized that tunnel failures have been the result of this report, is found in Chapter 10. The WG has been various reasons such as insufficient site investigation, meeting at the annual ITA congresses and has been inadequate evaluation at the planning stage, project un- conducting work sessions between congresses. A Draft derstaffing, mistakes during construction and operation Report was submitted in the beginning of 2001, and phases. comments received on this draft have been taken into An inventory of inherent risks for the project phases account in the final report. should be undertaken for all tunnelling and under- The WG has always been open to suggestions, and ground projects. Risk assessment should be made for: every effort has been made and will be made to take into • Rock and soil conditions versus the stability, physical account the corrections. properties and seepage. • Construction methods versus progress, rock/soil conditions, environment and safety. 2. General recommendations • Equipment versus suitability, capacity, energy con- sumption, environmental and safety aspects. 2.1. Project prerequisites The consequences on the total project cost and financial matters should always be included in risk In the early stages of the project, and before any de- evaluations. tailed agreements are made with the consulting bodies and Site investigations and geological exploration and construction companies, the client or implementing or- their use in design optimisation, coupled with well ganization should establish project prerequisites such as: matched construction techniques, can prevent most • Internal organisation with defined responsibilities in- kinds of collapses. The design cannot only be based on a cluding organisational access to the top management deterministic approach for the evaluation of a risk, a or decision-making body, minimum staffing require- probabilistic approach that takes into account the un- ments etc. certainties in the geological, geotechnical and construc- • Project budget and detailed budgets for the work to tion techniques and external constraints will enable the be carried out at any given time. project management to optimize the final design and • Approved scope of work for the work to be carried define the technical, administrative and financial man- out at any given time. agement of the risk. • Time limitations for the project phases and the work. It is recommended that detailed paragraphs dealing • Legal competence, including environmental and pub- with risk allocation should be included in all contracts lic relations/awareness. or agreements, and that risk is distributed by taking into • Contractual competence. consideration both technical and financial aspects. • Procurement competence. Contractual procedures should be simple and the role • Competence on evaluating the performed work at of the various parties should be made extremely clear, any stage. both from a technical and financial point of view. Ex- • Determination of all the obligations relative to con- cessive legal and bureaucratic complexity should be tractual matters. avoided, but specific attention should be given to those

ITA/AITES Accredited Material 242 C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 contractual aspects that deal with the information ob- extreme conditions during construction (given that tained on the natural ground conditions. the technical means are the contractorÕs responsibility), together with the definition of the administrative 2.2.1. Risk analysis and control responsibilities and procedures. Among the aims of Quality procedures the ‘‘risk as- Risk sharing is one of the step that Quality proce- sessment’’ has a significative role. It should be under- dures would identify. Risk associated with ground lined that a ‘‘risk analysis’’ is different than a ‘‘risk conditions is related to the conditions being different assessment’’, and not always necessary, because it in- from was expected or foreseen. This particular risk is creases the cost of the design and does not contribute considered to be the highest risk that contractors and proportionally to the actual handling of the risk. Risk owners are exposed to and is also considered to be the assessment, as far as the Quality procedures are con- major reason for tunnelling projects to falling into dis- cerned, is aimed to identify which risks are foreseen by array. Traditional forms of contracts provide clauses the design, which risks are undertaken by the contractor that deal with change in ground conditions, and the and who undertakes any further risks. client body generally carries the risk for these. Many As a guideline the following key steps should be taken new generation contracts provide clauses where the to define the risk occurrence related to unknowns and contractor bears the risk of cost overruns due to ground unforeseeables during planning and design: conditions. The risk carries in these cases will include As a guideline the following key steps should be taken those of cost overruns due to unforeseen conditions. to define the risk occurrence during planning and design: Contractors could however expect a premium for the • identify any hazards, acceptance of such risk. In these types of contract the • assess risks (likelihood and consequences), accuracy of preliminary and subsequent site investiga- • use engineering and other means to eliminate risks tions during design and construction becomes even more (already included in the design), important, whereas changed ground conditions will re- • identify actions (countermeasures) to handle the un- main beyond contractors responsibility. In each case foreseen risks, clear definition of ‘‘boundary conditions’’ between the • assess any residual risks (the uncertainties which have expected and actual ground conditions should be spec- not relevant consequences, including secondary ified, and as a consequence, all the related differences in risks), costs and progress for construction (see Fig. 4). • give approximate estimate of the costs and benefits of alternative risk mitigation options or strategies, 2.3. Allocation of responsibility – project manager • allocate responsibilities for the unforeseen risks, • select and implement any beneficial actions aimed to The experience and the opinion are that successful reduce the uncertainties. planning is the key to a successful project and that ad- Design should not be based on the most extreme herence to the plan is essential in order to develop and conditions even though this could protect the parties achieve the quality goals set. Decision making, based on from most of the possible risks. The design should the best information available and the transfer of in- however take into account any possible extreme condi- formation both upwards and downwards in an organi- tions in order to complete the construction sequence sation, in a format understood by all, are key issues in using: the process. The importance of timeous decision-making • modelling of the consequences (in terms of tech- cannot be stressed enough. niques, times and costs) that the occurrence of geo- It is recommended that the owner/employer/client logical unpredicted situations would have on tunnel should create a position of Project Manager for each construction. It means to model different scenarios project at the commencement of the conceptual plan- related to geological situations which are difficult to ning phase and that this position remains throughout be studied; each phase of the project until the project is completed. • demonstration of the relative cost-benefit that might The person/s appointed to this controlling position must result if sufficient preliminary geotechnical investiga- be thoroughly conversant with the breadth of potential tions and the appropriate design are carried out in or- problems in tunnel design and construction. It should be der to narrow down the spectrum of possible risks; carefully evaluated, whether this person should be the • a predefined monitoring plan, aimed in particular at same through all phases of the project, or whether it checking the extreme conditions, specifying criteria should be changed. for the analysis and evaluation of measurements A job description for the position should be prepared and the establishment of procedures for the use of in writing by the owner/employer/client stating the re- data; sponsibilities and the subsequent mandate given to the • verification that the design has considered the techni- project manager to carry the project through into the cal criteria for intervention in order to overcome the next phases. The project manager should report directly

ITA/AITES Accredited Material C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 243 to a senior executive of the implementing body who are concerned, an analysis of the numerous problems jointly will identify the quality goals to be set. In addi- that occur in a tunnel, independent of the adoption of tion, a resourcing organogram should be prepared, Quality System procedures, show how these may not be showing different positions (both internal and external) resolved automatically by Quality Systems. with job descriptions, timing/programme, budget/costs, Quality Systems should reflect the various stages and reporting procedures and responsibilities. assess the influence on the final result, mainly focusing Detailed and resourced programs of activities during on those aspects where the interpretation becomes de- the different phases, showing key dates for the different cisive in the technical choices. requirements, should be established. Performance in Tunnelling and underground projects are usually of accordance with the program should be monitored for significant financial value and are generally considered each resource on a regular basis, without involving too high risk in terms of final cost and time for construction/ many audits and auditors (see Fig. 1). delivery. In addition, tunnel construction often requires It is also recommended that the implementing body multinational input for both funding and technical ca- appoints an independent and periodic verification of the pacity. Performance to the set quality goals therefore quality issues for the project and that this appointment becomes a critical issue. is made in the early stages of the conceptual planning When it comes to the quality issues, it is not consid- phase so that assistance in the identification of the ered necessary to maintain a uniform approach for the quality goals and monitoring process can be obtained. duration of a project. Some issues might turn out to be Quality audits should be performed of both the im- more important than others and experience shows that, plementing body as well as within the consultantÕs/con- during the course of construction, some issues may well tractorÕs organisations, but repetition of the same be abandoned without harm to the project. auditing operations should be prevented. In tunnelling, Research into the appropriate local legislation and where the final result often follows a series of iterative regulations for such matters as health and safety, the processes, audits should also be performed of adherence protection of the environment and socio-economic to project prerequisites and the handling of derived consequences, as well as technical standards to be project and design parameters. Further reference to achieved should be carried out. These can then auditing is made in other sections of this report. be compared to best international practice, which can be Depending on the type of work, the owner should adopted to suit the particular project and then the define his expectations by a functional description of the quality goals can be set accordingly. project. The geotechnical information/description of the All phases of a project and all organisations/groups project shall be independent of construction methods of organisations involved should have a set of quality and tender and procurement procedure. Based on this, goals for the work to be performed. Quality goals risk exposure for tenderers/bidders and investors can be should be aimed at giving the project added value with defined. This first phase is fundamental because it pro- regard to cost, time, improved performance/physical vides the tools for investors to assess the degree of risk, properties and could be set relative to ‘‘soft parameters’’ but can also assist the owner in preventing speculative like improved competence or educational standards for offers/actions. Careful monitoring during construction involved parties, environmental aspects, safety stan- and final commissioning by an external engineer is in dards or benefits for the public in general. When quality some instances, like in Italy, required by law. goals are determined, these should be related to the Items related to responsibilities and risk allocation factors of success for the project and a strategy on how include, but are not limited to, the following; technical to achieve this should be included in the Quality Plan. and financial feasibility, environmental impact studies, Compliance and the degree of success in achieving the design issues, financial planning, construction budget/ set goals should be communicated to all project mem- costs and time for construction. bers/companies. It is recommended that requirements and detailed 2.4. Quality goals instructions for quality control for the design and the construction work should be specified in the contract. It There is a direct, linear relation between project is important that procedures for the registration and quality and project cost. In order to obtain a well communication of items such as test results are specified. functioning tunnel or underground structure, all project A project procedure including owner/employer, engi- stages are of fundamental importance; the stage of neer/designer and contractor for lines of communication knowing the geological and geomechanical characteris- and the responsibilities of each party for handling such tics, the planning stage, the stage of choosing the ma- information should be drawn up. The continuous pro- chinery and method of excavation, the installation of cess of evaluating, for instance, test results and any lining and rock support, and the organisational and fi- subsequent changes to the design and/or construction nancial coordination stage. As far as Quality Systems methods should be adequately defined and described.

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Table 1 LAYOUT OF THE ADAPTED QUALITY SYSTEM FOR TUNNELLING

STEPS FOR THE LIFETIME OF A TUNNEL ⇓ 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. QUALITY General Design Financing Procurement Characterization Monitoring Construction Approval Claims and Operation Maintenance Installations Statistics ITEMS planning controversies ⇓ Management responsibility Authority and mandates for involved people

Quality planning Definition of procedures for the various activities and co-ordination

Contracting Administrative, legal and technical rules

Control and All the tests, approval, inspections, verifications inspections Document Issue, control and approval of documents control Purchasing And Control of materials and contractual works Contractors Non Problem definition and notifications conformities Corrections and Accurate definition of problems and planning for preventive and remedial actions preventions Audits Independent check of the organization and methods

Training and Internal and external education information Data control and Data processing of all phases; economical, statistical, technical, measurements elaborations

This is a general layout of all the possible stages of an underground work (1st row) linked to all the specific actions of quality plans (1st column). Dependin g on the specific case, an interacting matrix can be implemented following the arguments listed in the various rows. C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 245

Fig. 1. Flow sheet of quality activities. Courtesy Swedish National Road Administration.

It is recommended that implementing bodies and • Ability to perform modifications to details. contractors make available technical data and statistics • Historical records of the design and of the performed from the construction phase and communicate such data works. to international bodies and universities. By doing so, • Reciprocity for communications and problem-solving objective views on the state-of-the-art of methods used attitude. and case histories could be obtained, all in line with a generally recommended quality goal regarding the transfer of knowledge. 3. Conceptual planning Methods for procuring, constructing, maintaining and operating private/public infrastructure are numer- The conceptual planning phase is defined as ‘‘the ous. They range from lump-sum contracts for the con- period of a project which commences when the request is struction of a designed facility, to complex transactions made to prepare estimates of feasibility, cost, viability involving ownership transfer, equity financing and novel and delivery options and ends when approval is given revenue features. Understanding and adapting available to proceed with the project into the design phase’’ contract options is crucial for the success of a project. (Table 2). The owner should be aware of how his precise requirements are best served and of the practical considerations 3.1. Organisation – allocation of responsibility associated with different contract strategies. The details of appropriate methods of financing and The importance of timeous decision making is em- remuneration, risk allocation, the nature of the different phasised again. The client body is expected to have es- partiesÕ obligations/responsibilities and the ownership tablished the general decision making process. If this structure are matters specific to the individual projects. process does not exist, it should be established upon It is possible to resume what have been described in commencement of the conceptual planning phase. terms of benefits of the application of Quality as follows: • Good organization and relationship. 3.2. Competence and communication • Definition of needs and constraints of the work. • Design adapted to needs and constraints. Recognising that many tunnelling and underground • Control on the evolution of design stages and selec- projects make use of ÔState-of-the-ArtÕ technology, it tion of appropriate contracts. is necessary to provide effective communication lines • Evaluation of risks and allocation of responsibilities. and a continuous upgrading of competence within the

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Fig. 2. Example of ﬂow chart for quality assurance system (for design/build civil engineering projects, Kaijima Corp., Japan).

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Fig. 3. Procedure for the handling of non-conformances (courtesy of Kaijima Corp., Japan). participating bodies/companies. Thus the following also the dates of the intermediate stages, as appropriate. measures should be established: Specific time allowance should be allocated for review of • Competence levels for the various project partici- critical inspections and testing. pants. • Procedures for the regular monitoring and reporting 3.4. Special recommendations of successes and failures. • Procedures for the circulation of information. These The phase of the conceptual planning of a tunnel is should include regular meetings between all the in- very important, since it is at this stage that the most volved disciplines, progress meetings and reporting serious project risks and constraints are identified, to the decision making body. alternative solutions are examined and costs are • Description of project iterative processes including evaluated. testing, evaluation and possible design and construc- It is recommended that during the conceptual plan- tion changes/modification, definition of responsibili- ning phase, particular attention should be paid to the ties and mandates for the respective project parties following: (as described earlier). • Risk identification and evaluation: It is of vital impor- • Documentation/Procedures for project modifications. tance to identify all the possible risks related to a spe- • General guidelines for procedures ensuring contract cific tunnel alignment. All possible alternative and project knowledge (Contractual Review). alignments should be examined and their risks identi- • Procedures ensuring that the extent of inspection and fied and evaluated. monitoring is known. • Investigation of surface and sub-surface conditions: • Education of all persons involved in the project in the This is the key factor to tunnelling and the main quality issues and goals to be achieved. cause for disputes, delays and ‘‘changed condition’’ claims. The investigation of rock/ground conditions 3.3. Time schedule should start at this stage, and include at least satellite and aerial mapping if appropriate, geological surface It is recommended that the time schedule includes not mapping, seismic risk analysis (where appropriate) only the dates of the final submission of the work, but and the collection of all available geological and

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geotechnical data. The investigation of the rock/ • Quality Control Plan: It is recommended that a Qual- ground conditions usually continues at the design ity Control Plan for planning/consulting services phase and is linked to the project risk evaluation. should contain the following: • Clarification of project constraints: Constraints such - Design coordinator responsible for the coordination as funding, laws and regulations, environmental re- of all the involved disciplines strictions, interference with other existing projects, - Team leaders for the various design disciplines possible public reaction, land expropriation and nec- - Design phases essary licenses should be identified. It is recommended that a Project Appraisal Report is • Establishment of design criteria: The Design Criteria compiled at the beginning of each design phase. This clarify the requirements of the tunnel owner (ClientÕs report should review the current status of the project needs). The more clearly these requirements are stated and identify the necessary actions/steps to be taken by the more easily quality is achieved and costs controlled. either the client or the designer. The Design Criteria should inter alia include tunnel - Time schedule of planning phases cross-section, which for transportation tunnels takes - Communication/reporting into account vehicle envelope, pedestrian sideways, It is recommended that regular meetings between the drainage, ventilation, electromechanical facilities, aero- Project Manager and the designerÕs project coordinator dynamics, permanent lining, etc. Other factors are tun- are specified in the Quality Control Plan. It is good prac- nel safety including accident prevention measures, fire tice to prepare these meetings in advance and to encourage fighting methods, type of fire, escape routes, rescue the participation of members of the respective teams of organization, etc. Environmental impact studies on both parties. Thus, information is circulated more easily. groundwater/ground conditions, noise, air pollution, Minutes of these meetings should be kept in writing. fauna/flora, social/town planning structures should be All queries, ambiguities and uncertainties can be re- included as well as location of tunnel portals, tunnel solved during these meetings. Both parties should be drainage and other facilities. aware of the usefulness of these meetings, provided that • Selection of Designer/Consultant including Consulting a spirit of co-operation prevails. The designer must al- Fees: It is recommended that bidding on tunnel plan- ways remember that the scope of his work is to meet the ning and design works should be avoided. Instead, ClientÕs needs. In turn, the Client must recognize that the selection of a designer should be based on: only through his clear statements and prompt and - Proven experience in similar projects. timeous decisions the final goal can be achieved. - Qualifications and experience of design team. - Documentation/Design Modification Records - Diversity of disciplines in the design team. - Allocation of Responsibilities It is recommended that geological studies, seismic - List of Key Elements of the Relevant Design Criteria. risk analysis and geotechnical evaluation studies are The list should serve as a checklist of the works to be assigned to the same consulting firm, whereas the geo- carried out. technical site exploration works could be carried out - List of Laws and Regulations to be taken into account either by the same or by a different entity. during the planning stage and any licenses which need It is recommended that prior to signing contracts for to be obtained. planning and design, an evaluation of professional re- - Conceptual Planning Review quirements should be conducted. The result of such an It is recommended that internal reviewers from the evaluation should be in writing and compliance should client body carry out the design review. They should be checked and verified. Professional requirements have similar experience and professional competence as should include adequate and available resources that demanded from the designer. If the client does not amongst senior personnel with documented competence. have such personnel, then a Technical Advisor should be Planning and design contracts should include para- appointed for this purpose. The internal reviewers graphs for the transfer of knowledge in cases where the should act as Ôsuppliers of servicesÕ to the Project client body needs further and defined competence. Manager making appropriate recommendations only. Since tunnelling and underground projects are usu- - Approval Procedure ally characterized by a long duration, it is recommended If during the design phase the procedures are fol- that planning and design contracts should contain lowed and meetings held at regular intervals, it is un- paragraphs that will provide for sufficient continuity likely that the final submission of a Conceptual Planning within the consulting organisations. Report will be rejected. However, in many cases the It is recommended that the fees for tunnel project reviewers may comment on the report. It is recom- design, during all stages of design, should not be a mended that the Project Manager obtains the response prefixed total sum. In addition, the fees should not be of the designer to these comments, within a specified related to the project cost estimate neither directly re- time, and only afterwards makes a decision on the ap- lated to the actual project cost. proval of the design.

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- Conceptual Planning Audit vestigations and during construction should be well It is recommended that an independent Conceptual defined in the contract time schedule. The responsibili- Planning Audit is carried out, if the size and the im- ties of the client body, designer and contractor in the portance of the tunnel justify it, and also if the Client iterative processes of testing/inspection – evaluation – feels that the internal review is not adequate. Such an design modification – construction method modification audit should focus on the following: should be clearly stated in the contract. • Fulfillment of project prerequisites and design A framework for Quality Audits and Audit Plans criteria. should be given in the contract. Design audits should • Identification and evaluation of all possible risks. focus on design criteria – establishment and updating, • Adequacy of the performed studies. methodology, results from design reviews, third • Investigation of all external constrains. party verifications and official approvals, resources and • Conclusions and recommendations for the next de- competence. sign phase. Audits of construction should include the physical • Compliance by the designer with regard to the clientÕs prerequisites – construction methods, evaluation requirements. of performed work, quality control, resources and • Evaluations concerning project economy/feasibility, competence. technical constrains, project time schedule. If not specified in the underlying contract standards, possible risk and subsequent allocation thereof should be defined in accordance with the specific type of con- 4. Procurement tract. Risk should be identified and evaluated for rock/ ground conditions, environmental impact, safety, The procurement phase is defined as ‘‘Those stages of methods and equipment. It is important that risk iden- a project when necessary prerequisites have been defined tified and evaluated during the planning and design and agreements and contracts are being established for phases should be brought forward to the construction the planning, design, construction and operation phases phase and subjected to further evaluations by the com- of tunnelling and underground projects’’. petent professionals and the prequalified contractors. In general, it is recommended that planning, design, The need for third party verifications by professional construction and operation services are contracted and official bodies should be considered. based on national or international approved standards. Assistance from external legal and technical profes- The client body should have the competence to per- sionals on the allocation and evaluation of risk should form evaluations and quality audits to secure compli- be considered. Risk allocation should be based on the ance with the necessary competence requirements that principle that the most competent party should bear the have been defined for the planning, design, construction major share of the consequences. and operations (Table 2). It is recommended that neither design nor construction contracts should be agreed before a joint meeting 4.1. Allocation of responsibility between the parties has been arranged and an evaluation of the physical and contractual aspects connected to the Two issues are related with the ‘‘Allocation of Re- above specified fields of risk assessment has been carried sponsibility’’, which should be dealt clearly in all con- out. Conclusions from such a meeting should be in tracts: writing and be made available to the relevant parties. 1. Who has the authority to decide on changes (especially design changes during construction). 4.2. Competence and communication 2. Risk undertaking during construction. The expected geological/ground conditions should be clearly de- It is recommended that Quality Plans for the plan- scribed in the contract. If the encountered conditions ning, design, construction and operation phases are during construction are different, the contract should established by the client body and that similar require- describe the procedure for the verification of changed ments are passed on to all involved in the further de- conditions and who will, then, undertake the respon- velopment of the project. The Quality plans, in addition sibility. to relevant requirements of systems like the ISO 9001 The various stages of planning and design contracts standard, should describe measurable quality goals for should be defined in the contract time schedule. It is of the work. vital importance that the client bodyÕs reaction/response It is recommended that, prior to signing the con- time with regard to altered prerequisites, design reviews tracts, an evaluation of the professional requirements or evaluations are specified. should be conducted. The results of such an evaluation Project milestones and decisions that depend on should be in writing and compliance should be verified. conditions revealed during geological mapping/soil in- Professional requirements should include adequate and

ITA/AITES Accredited Material 250 C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 available resources amongst the design and production allocated to provide necessary evaluations and possible planning personnel as well as an adequate and compe- changes in construction methods or the physical design. tent staff for the construction activities. It is equally It is recommended that a method for the handling of important that the contractors provide skilled operators the consequences of altered construction methods and and workforce. Requirements of suitable and well design should be specified in the construction contracts, maintained machinery and equipment should also be reference is made to the above paragraphs on iterative verified. processes. As previously stated, the planning capacity Programs for continuous education is a key factor to within the contractorÕs organisation should be well success within any organisation or company. Tunnelling documented. and underground projects are suitable for Ôon the jobÕ It is equally important that discipline is established in training since most large projects make use of Ôstate-of- relation to given time limits. Continuous reporting of artÕ technology in one or more fields. It is recommended progress relative to fixed milestones is crucial to any that educational programmes be established within all project and the requirements and methods of reporting organisations and companies, and that the goals and should be given in all contracts. requirements of the detailed education plans are specified in the contracts. 4.4. Financial aspects Contracts should include paragraphs concerning the transfer of knowledge, especially in cases where the cli- Financial constraints in relation to the client bodyÕs ent body needs further and defined competence. estimated total cost as well as to the contractorÕs ability Since tunnelling and underground projects are usu- to handle altered conditions can have many adverse ef- ally characterised by a long duration, it is recommended fects on the total quality of the project development. It is that contracts should contain paragraphs that will pro- recommended that financial capacities are well docu- vide for sufficient continuity within the consultantÕsand mented for both contract parties before construction the contractorÕs organisations. Requirements to back-up contracts are signed. and reserve machinery and equipment should also be Experience has proved that financial constraints or specified in construction contracts. the desire to accept low bids for planning and design It is recommended that requirements and detailed work can lead to many adverse effects on the total instructions on the quality control of the design and the quality of the project. As stated earlier, it is recom- construction work should be specified in the contracts mended that planning and design contracts should not including the establishment of Quality Plans, Inspection be awarded on the basis of a fixed total sum, but on the and Test Plans identifying all control and verification basis of a split of competence and price. activities. Special emphasis should be placed on the design and activities related to rock and ground conditions (stress monitoring, rock- and ground support, shot- 4.5. Contract forms creting, etc.) and environment related topics (hydrology, hydraulics, seepage) (see Fig. 5). During recent years different contract forms have The need for third party verifications should be evolved. The recommendations of this report generally considered when evaluating topics like stress monitor- reflect the ÔtraditionalÕ parties in tunneling projects with ing, critical rock-/ground support, issues related to the Client, Designer and Contractor acting as separate environment and conditions calling for changes in bodies. methods or equipment. The requirements or guidelines However, the principles of the report should be ap- for third party verifications should be given in both the plicable even to new contract forms, like BOT and EPC design and construction contracts. The construction Turnkey contracts, given that the Client body is sup- contracts should specify any actions to be taken when plied with competent and independent expertise to the given physical properties are exceeded or otherwise evaluate fulfillment of project prerequisites, design cri- not being fulfilled (regular or ad hoc reviews – external teria and the physical properties relative to specified professional assistance, e.g. dispute review boards functions. should be considered).

4.3. Time limitations 5. Design

It is generally acknowledged that tunnelling and un- The design phase is deﬁned as ‘‘the period of a project derground projects are in a continuous state of devel- which is embodied after approval is given to proceed opment throughout the project phase prior to with the Project into the construction phase, when the commissioning. When sub-surface conditions are un- conceptual planning is evaluated from various aspects certain or not adequately investigated, time should be such as cost, viability and quality.’’

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The design of a tunnel is usually carried out in stages checks. The use of more than one design team in tunnel that are often related to the type of the construction design is generally unavoidable, and usually involves a contract. For example, there are ‘‘design-and-build’’ variety of scientific disciplines. It is recommended that contracts or ‘‘build only’’ contracts. In either case the the number of design team interfaces is reduced to a first stage of the design, at an engineering report level, minimum. leads to bidding and the preparation of contract docu- The Project Manager or the Project Design Coordi- ments. The final design is carried out at a later stage nator is responsible of ensuring that all design teams are either by the Contractor or by the Client. These two involved in the preparation of the relevant plans. The stages of tunnel design are crucial for the achievement of staff members who are responsible for implementing the quality. necessary actions should be identified by name. It is Most cases of tunnel non-quality, especially in terms important to ensure that the procedures for the design of cost and time, are attributed to the changes to the team interface control are clear and the persons re- engineering report during the final design. The most sponsible for the implementation are named. common reason for the changes is the uncertainties connected to the ground/rock conditions. It is true that 5.2. Design input – communication tunnels are characterized by a number of particular features, such as the geological medium through which 5.2.1. Review of conceptual planning the structure is built, the variety of construction meth- The Conceptual Planning studies should be reviewed ods and technologies, the involvement of various sci- at an early stage of the tunnel design and all constraints, entific disciplines, the sharing of responsibility for the risks, applicable statutory and regulatory requirements construction risks, the variety and complexity of con- are listed and taken into consideration for the next de- struction contracts, etc. sign steps. Particular emphasis should be given to the In light of this, the formulation of a Quality Man- adequacy of the available geological and geotechnical agement System for the design of a tunnel is not a information. straight forward process and should be adapted to every The basis for adequacy and approval of the concep- particular case. The recommendations of the following tual and final design should be clearly stated for the paragraphs give only an outline of the main factors to be benefit of, in particular, the design consultant. This will considered (Table 2). form part of the design input.

5.1. Allocation of responsibility 5.2.2. Contract review Any contract related to tunnel design should be re- As stated earlier, it is recommended that the Project viewed upon commencement of the design in order to Manager is responsible for the entire project including identify the design conditions. This might include ap- the design. A division of responsibilities between the plicable specifications, standards and criteria, construc- project manager and an independent design party tion methods and policy, key dates, method of payment, should be avoided. If an independent design consultant any particular requirements of the Client, etc. A list of and/or design department within the Client body is to the main contract provisions is made by all the involved review a tunnel design, they should act as consultants to parties and circulated to the personnel engaged in the the project manager. design activities. Likewise, the consulting firm (contractor of design services) should appoint a Project Design Coordinator. 5.2.3. Design criteria The job description of such a position should include It is again emphasized that the establishment of De- coordination of the design team, communication with sign Criteria for each tunnel clarifies the ClientÕs re- the ClientÕs Project Manager, assignment of tasks to quirements and it is an essential prerequisite to a good various design teams, work progress control in accor- tunnel design. An indicative list of tunnel design criteria dance with contract requirements, reporting to the Cli- is as follows: ent and the top management of the consulting firm, • Methods of analysis of both temporary and perma- meetings with the design teams. nent lining. Further allocation of responsibilities is good practice, • Load cases and load combinations. for both the Client and the Consultant. All parties in- • Construction sequence. volved should know who is responsible for what. Ex- • Applicable safety factors. perience has shown that the allocation of responsibilities • Materials. for a specific project is a practical and flexible alternative • Standards and regulations. to an organogram. • Drainage and sewage. All studies, reports and drawings should state the • Environmental requirements (portals, groundwater, names of the designers and those carrying out the design pollution, toxic compounds, etc.).

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• Ventilation/fire fighting. 5.3.2. Design check/review/verification • Electromechanical facilities. All calculations and drawings should be checked re- • Deliverables (design output). garding assumptions and input parameter accuracy, the suitability of modeling and method of analysis, com- 5.2.4. Verification of design input pliance with standards, consistency of calculations, The Project Manager or the Project Design Coordi- drawings and reports, dimensional accuracy, satisfac- nator is responsible for the collection and evaluation of tory interface coordination and constructability. It is all the design input requirements. Any ambiguities and recognized that it is not feasible to check the accuracy of conflicts regarding these requirements should be re- all the calculations, but sample checks should be made. solved with those who are responsible for imposing If an innovative method of design is adopted, then them. It is important to have all the design input cross-checking with other methods is advisable and a documented. more detailed design review is necessary. All documents Finally, a list of all the design goals should be drawn should state the name of checker and date of the check. comprising all the above design requirements. It is recommended an independent design check by a third-party consultant only if the size and importance of the tunnel justifies it. However, the checker should have 5.2.5. Relations with client body at least the same qualifications as those of the designer. Regular meetings should be held between the ClientÕs Project Manager and the ConsultantÕs Design Coordi- 5.3.3. Revisions/design changes nator with the participation of representatives of the A procedure should be established for handling the involved design teams. These meetings should be pre- revisions of any part of the design. This could include pared in advance. The design progress, design team in- the following: terfaces and the ClientÕs requirements should be kept in • Request for revision and relevant documentation. writing and constitute a part of the design input. • Authorization of revision/change. • List of the parts of the design that are influenced by 5.3. Design output – control and verification the revision. • Procedure for the distribution of information to the 5.3.1. Output contents involved design teams. The design output should meet all earlier mentioned • Names of the staff authorized to implement the revi- input requirements and, in particular, conform to design sions. criteria, regulatory requirements and contract provi- • Procedure for document filing and updating with re- sions. An important element in the design output is the vised reports and drawings. description of the rock/ground conditions and the way The request for tunnel design changes requires special these influence the tunnel excavation and support. This attention, when made at the construction stage, since it is addressed further in Section 5.5 of this report. usually has significant consequences on the costs and A typical tunnel design output should contain the construction time schedule. For this reason it is recom- following: mended that special provisions should be made in the • Technical description of the project. contract documents to handle requests for design • Calculations. changes. • Drawings. Similar provisions should be made in the consulting • Specifications. service contracts. Design changes requested by the Cli- • Bills of quantities. ent body might involve significant additional design • Tender documents and Contract conditions (design work and influence the design time schedule. The rele- for bidding purposes). vant cost and delays should be agreed on by the Client It is recommended that all types of documents are and the Consultant. Reference is made to Section 4 – standardized according to type and format, e.g. stan- contractual provisions for iterative processes leading to dard calculation sheets, drawing size and layout, refer- design and construction modifications. ence numbers, etc. The calculations should follow a logical sequence with sufficient explanations on the real 5.3.4. Final design verification conditions, how these are modeled, what assumptions All checks, reviews and examinations carried out at are made, the method of analysis, the geotechnical pa- the various design stages should be listed and signed off rameters used in the analysis and how these were derived by the persons authorised to do so. However, it is rec- and, the standards used. ommended that the Project Manager should ultimately All computer programs used in the analysis should be be responsible for the final design verification. He must fully documented and sufficient information supplied on be fully satisfied that all the necessary checks, examin- the program input and output. ations and design reviews have been carried out and that

ITA/AITES Accredited Material C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 253 all major prerequisites of the Client body are fulfilled. 5.5. Special recommendations Thus the final Design Verification should bear the sig- nature of the Project Manager. The underground structures are characterized by an inherent degree of uncertainty due to the surrounding 5.3.5. Design quality control plan ground or rock mass. The objective of the design is to The design quality control plan should incorporate all reduce this uncertainty but at the same time to maintain the points mentioned in Sections 5.1, 5.2 and 5.3. Key a balance between uncertainty and construction cost. elements of the plan should be (see Fig. 3): Thus, the issue of ‘‘geotechnical risk’’ becomes a major • Design criteria/basis for the design (listed or with ref- factor in tunnel design. erence to identified documents). Another important consideration for a tunnel design • Procedures for contractual review. is its link to the excavation method and construction. • Procedures for design control and final verification. The phases of excavation, the equipment used for the • Detailed description of the various design elements various support measures, the timing of the entire ex- and degree of verification (Control Plan, tabular cavation sequence and particularly that of the applica- form). tion of support measures are part of the tunnel design. • Procedures for design review. In this sense the following special recommendations • Procedures for design changes for a tunnel design can be outlined. • Procedures for non-conformances of the design 5.5.1. Geological – geotechnical risk The best available scientific knowledge should be 5.4. Development of competence used in order to set up an accurate geological model for the tunnel site. The inevitable uncertainties concerning The education and training of the staff involved in the ground/rock conditions should be identified and tunnel design is very important. Tunnelling requires stated clearly in the design reports. The construction specialized knowledge based on advanced technology, contract should then take care of the relevant risks. A not only on the theoretical methods of analysis, but also concept that is worthy of consideration, is that of the on the practical construction methods and technologies. Geotechnical Baseline Report. Risks associated to con- For this reason it is recommended that a global ap- ditions consistent with or less adverse than those de- proach to the professional development of the tunnel scribed in the Baseline Report are allocated to the design staff is adopted. Indicative recommendations are contractor and those significantly more adverse than the the following: Baseline Report are accepted by the owner. • On the job training of personnel. This might involve In order to have the anticipated conditions clearly rotational relocation from one team to another in or- defined, the baseline statements should be described in der to increase knowledge and experience and to re- quantitative terms that can be measured and verified fresh interests. during construction. • Collective training through specialised lectures or seminars. 5.5.2. Rock mass classification • Encouragement of publications on tunnel design, The quality of rock mass and the relevant geotech- construction and performance. nical parameters should be evaluated for every single • ITA particularly recommends the participation in the tunnel case in order to reduce the geotechnical risk. It is international tunnelling conferences, where experi- preferable that the parameters used should be measur- ences are exchanged and specialists meet. able, such as those suggested by the various rock clas- • Regular visits of the design team staff to tunnel con- sification systems (RMR, Q, GSI, etc.). struction sites. However, the indiscrete use of rock mass classifica- • It should be stressed that an absolute prerequisite of a tion systems for contractual purposes and specifications good tunnel design is the knowledge of and experi- should be avoided especially for weak rocks or fault ence on tunnel construction. zones. • Library – archives – manuals. • The consulting firms are advised to maintain a library 5.5.3. Guidelines for construction quality control accessible to all design staff with bibliographical ref- Tunnel design should specify in detail the necessary erences relevant to tunneling. The library must also quality control to be applied during construction. An contain complete series of relevant Standards (as ap- indicative list of the relevant topics is as follows (see plicable), Laws and Regulations. Fig. 6): • Finally, as a minimum requirement, all computer • Rock mass classification. programs used in the tunnel design must be docu- • Detailed sequence and timing of excavation and ap- mented with their manuals. plication of tunnel support measures.

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• Monitoring of stresses and deformations and relevant • Handling of contract non-compliances. limits for emergency steps and remedial measures (de- • Responsibility for monitoring and surveillance. sign and construction modifications). • ITA recommends that the instrumentation is installed • Material specifications (shotcrete, rock bolts, etc.). by the contractor, but the monitoring and evaluation of the tunnel behavior is performed by the ClientÕs supervising team. 6. Construction • Emergency procedures. The inspection staff should be fully aware of the The construction phase of a project is defined as ‘‘the contract provisions and technical specifications. A period of a projectÕs development that commences with complete contract review should be carried out by the the award of the construction contracts and terminates Resident Engineer and the Supervisors. A list of the with the commissioning of the structures’’ (Table 2). main items will be attached to the Construction Quality Control Plan. 6.1. Organisation – allocation of responsibility

The establishment of a Quality System for construc- 6.1.2. Contractor tion management is very important for both the Client A basic activity in the early stages is to conduct a body and the Contractor. contract review which should include all technical as well as administrative requirements. In long duration pro- 6.1.1. Client body jects and with a number of construction stages it is of It is recommended that the Project Manager of the vital importance that the contract review should be Client body maintains the overall responsibility. At an conducted prior to the commencement of these stages. It early stage and prior to the commencement of con- is recommended that the contract review should be struction the Construction Supervising Authority/Board conducted at planned stages and includes the various is established. Depending on the size of the project this functions of the management and the production could be a small or a larger team. It is usually to the personnel. benefit of the project to have a strong supervision con- Based on the early preparation for the work and the sisting of experienced personnel. initial contract review, the contractor should set up an It is recommended that all works performed by the organisation that provides for sufficient allocation of the contractor are supervised and checked. The Client body resources and competence. The allocation of responsi- is advised to bear the cost of the supervision in order to bility is directly related to the planning of the works. For minimize the final time schedule and project cost this reason, the ContractorÕs organization chart, job overruns. descriptions and qualifications of the key personnel is If deemed necessary, the Client body could employ a recommended to be subject to approval by the Client Quality Control consultant to assist with the technical body. issues. However, the authority of the construction su- The demands for specific competence (knowledge, pervision should be the responsibility of the Client and experience, ability) should be evaluated prior to signing its Resident Engineer. a contract. It is the responsibility of the contractor to The ClientÕs Resident Engineer is responsible to the secure an ample supply of competence throughout the Project Manager. A detailed job description should in- construction phase. Identification and availability of clude the quality goals to be attained, frequency of re- back-up personnel should be regularly determined. porting to the Project Manager, limits of authorization The allocation of responsibility should at least cover to handle contractual non-compliances by the contrac- the following fields of activities: tor, resources allocated (personnel, vehicles, laboratory • Supply of materials and parts. equipment, etc.). • Evaluation and approval of suppliers and subcon- All inspections of works should be documented and tractors. signed by the inspector. The inspection forms should • Equipment maintenance and repairs. comprise a short description of the performed works, • Adherence to defined construction processes and pro- items and quantities, time of application, compliance or cedures. not with the contract provisions, key remarks for the • Quality control of materials and works. attention of the supervisor or the next shift inspector. • Rock mass classification. It is recommended a clear definition of the responsi- • Characterisation of tunnel support categories. bilities and authority of the key inspection staff. Par- • Evaluation and handling of non-conformances. Pre- ticular attention should be given to the following issues: ventive measures. • Responsibility for rock classification. • Requirement for design changes. • Extent of authority to handle design change requests. • Handling of emergencies.

ITA/AITES Accredited Material Table 3 Quality aspects related to tunnel collapses (Vlasov et al., 2001) Type Phenomenon Cause Remedial measures 1 Ground collapse Ground collapse near the During the excavation of the Ground collapse was caused • Installation of anchors to prevent landslides portal upper half section of the por- by the increase of pore water • Construction of counter-weight embankment tal, the tunnel collapsed and pressure due to rain for ﬁve which can also prevent landslide the surrounding ground slid to consecutive days • Installation of pipe roofs to strengthen the loos- the river side ened crown .Ogr,G v unligadUdrrudSaeTcnlg 9(04 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. 2 Landslide near the portal Cracks appeared in the Excavation of the toe of the • Caisson type pile foundations were constructed to ground surface during the ex- slope composed of strata dis- prevent unsymmetrical ground pressure. cavation of the side drifts of turbed the stability of soil, and • Vertical reinforcement bars were driven into the the portal, and the slope near excavation of the side drifts ground to increase its strength. the portal gradually collapsed loosened the natural ground, which led to landslide 3 Collapse of the crown of 10 to 30 m3 of soil collapsed The ground loosened and col- • Roof bolts were driven into the ground in order to cutting face and supports settled during lapsed due to the presence of stabilize the tunnel crown. excavation of the upper half heavily jointed fractured rock • In order to strengthen the ground near the portal section mass at the crown of the and talus, chemical injection and installation of cutting face, and the vibration vertical reinforcement bars were conducted. caused by the blasting for the lower half section (hard rock) 4 Collapse of fault fracture zone After completion of blasting The fault fracture zone above • Reinforcement of supports behind the collapsed and mucking, ﬂaking of the collapsed cutting face location (additional sprayed concrete, additional sprayed concrete occurred be- loosened due to blasting, and rock bolts) hind the cutting face, follow- excessive concentrated loads • Addition of the number of measurement section ing which, 40 to 50 m3 of soil were imposed on supports, • Hardening of the collapsed muck by chemical collapsed along a 7 m section causing the shear failure and injection from the cutting face. Later it collapse of the sprayed • Air milk injection into the voids above the col- extended to 13 m from the concrete lapsed portions cutting face and the volume of • Use of supports with a higher strength collapsed soil reached 900 m3 5 Distortion of Distortion of tunnel supports During excavation by the full Bearing capacity of the • Permanent foot protection concrete was placed in supports face tunneling method, steel ground at the bottom of sup- order to decrease the concentrated load. supports considerably settled ports decreased due to pro- • An invert with drainage was placed. and foot protection concrete longed immersion by ground cracked water

T/IE crdtdMaterial Accredited ITA/AITES 6 Distortion of lining concrete During the excavation of the Landslide was caused due to • Earth anchors were driven into the mountain side due to unsymmetrical ground upper half section, horizontal the steep topography with ground to withstand the oblique load. pressure cracks ranging in width from asymmetric pressure and the • Ground around the tunnel was strengthened by 0.1 to 0.4 mm appeared in the ground with lower strength, chemical injection. Subsidence location was ﬁlled. arch portion of the mountain leading to the oblique load on side concrete lining, while the lining concrete subsidence reached the ground surface on the valley side 255 256 T/IE crdtdMaterial Accredited ITA/AITES

Table 3 (continued) Type Phenomenon Cause Remedial measures .Ogr,G v unligadUdrrudSaeTcnlg 9(04 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. 7 Distortion of tunnel supports Hexagonal cracks appeared in Large swelling pressure was • Sprayed concrete and face support bolts on the due to swelling pressure the sprayed concrete and the generated by swelling clay cutting face were provided to prevent weathering. bearing plates for rock bolts minerals in mudstone • A temporary invert was placed in the upper half were distorted due to the section by spraying concrete. sudden inward movement of the side walls of the tunnel 8 Heaving of a tunnel in service Heaving occurred in the A fault fracture zone contain- • In order to restrict the plastic ground pressure, pavement surface six months ing swelling clay minerals, rock bolts and sprayed concrete were applied to after the commencement of which was subjected to hy- the soft sandy soil beneath the base course. service, causing cracks and drothermal alteration, existed • Reinforced invert concrete was placed. faulting in the pavement. in the distorted section. Plastic Heaving reached as large as 25 ground pressure caused by this cm fracture zone concentrated on the base course of the weak tunnel section without invert 9 Adverse effects on the Adverse effects of vibration During the construction of a The voids behind the existing • Steel supports and temporary concrete lining were surrounding environ- due to blasting on the adjacent new tunnel, which runs paral- tunnel loosened and the lining provided to protect the existing tunnel. ment existing tunnel lel to the side wall of the was distorted due to the vi- • Backfill grouting was carried out. existing portal, cracks ap- bration of the blasting for • Excavation was carried out by the non-blasting peared in the lining (made of construction of the new tunnel rock breaking method and the limit for chemical bricks) of the existing tunnel agent was set to mitigate the vibration. 10 Ground settlement due to the Considerable distortion of Since the soil characteristics in • Pipe roofs were driven from inside the tunnel to excavation for dual-tunnel di- supports occurred in the em- the embankment section were reduce ground surface settlement. rectly beneath residential area bankment section. Although worse than expected, the additional bolts were driven ground settlement was con- into ground and additional siderably increased by the sprayed concrete was pro- construction of tunnels fol- vided, ground surface settle- lowing the dual-tunnel ment exceeded 100 mm Summary table of different conditions for tunnel collapses, caused by geological unforeseen conditions, inadequacy of design models or support systems. C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 257

Fig. 6. Collapse due to a sinkhole in the crown of loosen material in a tunnel supported by steel arches and shotcrete.

• Health, safety and environmental protection mea- topics for discussion should be the progress of work, the sures. conformity to the technical specifications, the applica- • Communication and amicable resolution of disputes bility of the design provisions, the ContractorÕs response with the ClientÕs representative. to the ClientÕs requirements, the regularity of payments, • Reporting to both the Client and the top manage- and the resolution of any responsible problems. These ment of the company. meetings should be conducted in a spirit of cooperation. The job of the site personnel is to implement the pro- 6.2. Communication and development of competence visions of the contract. Any arguments or disputes arising from different in- Tunnelling and underground projects in many ways terpretations of the contract clauses should be referred represent a situation of continuous education. Given to a higher level. If necessary, a permanent panel of that basic competence requirements are determined, a experts, with representatives from both parties, should refinement of the project management systems and up- be appointed in order to objectively review the overall grading of the required/formal knowledge should be progress of the works. The conclusions of such a panel conducted. It is recommended that the contractorÕs or- should be taken into consideration by both parties. ganisation establishes education plans for the various functions or parts of the organisation. 6.3. Construction quality plan Tunnelling projects are well suited for ‘‘On the Job Training.’’ Such training could preferably be directed A basic part of the construction management system towards construction methods and the operation of is the Construction quality plan. The plan should give equipment. In establishing the programs, necessary co- guidelines for all important functions and activities. It is ordination with the client/designer and equipment sup- recommended that quality plans be established, contin- plier is essential. uously refined/developed and thoroughly communicated The communication of all the involved personnel of within the organization. The contents and practice of both the Contractor and the Client is vital during the quality plans may vary within the tunnelling and un- construction phase. The ClientÕs supervising team derground community – but the essential parts to be should hold regular meetings preferably on a weekly treated should be: basis to discuss the progress of the work and whether the • Establishment and communication of quality goals. set quality goals have been obtained or not. If delays or • Contract review, control of drawings and specifica- contract non-conformances are registered on a regular tions. and systematic basis, then preventive and remedial ac- • Organization, administration, and document han- tions should be discussed and implemented. dling. Similar meetings should be held by the Contractor • Description of construction processes and proce- with the participation of the Site Manager and all Sec- dures. tion Foremen and Supervisors. It is recommended that construction methods and Regular meetings should also be held between the processes, including equipment requirements, should be ClientÕs and the ContractorÕs representatives. The main evaluated and approved by competent personnel, and if

ITA/AITES Accredited Material 258 C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 desired or required, by a representative of the Client or a stated in writing will facilitate the adherence to relevant third party. If a process is innovative, a testing program procedures. prior to production should be conducted. This type of validation of a process or procedure 6.4.2. Design applicability and design changes should also aim at supplying the production personnel It has been emphasized throughout this report that with sufficient competence as well as at determining the design changes during construction cause chain reac- amount of documentation needed to verify the results. tions and normally have implications on the project cost As the amount of technical documentation often rep- and completion time schedule. It should be made clear resents a point of conflict between the client and the that generally no major design changes will be allowed contractor – a validation process can contribute to a during construction, except for minor adaptations to the common understanding. applied construction method and equipment. • Inspection and test plans. It is recommended that clear and strict clauses should It is recommended that verification activities con- be included in the contract with the aim of minimizing ducted by the client or third parties be clearly specified any requests for tunnel design changes by the con- in the plans. Test results requiring evaluation by others tractor. However, it is recognized that the in-situ ad- and that such evaluations may introduce constraints on aptation of the design to the real rock/ground conditions the progress shall be highlighted. Reference is made to might be necessary. As discussed earlier, provisions for previous discussion on iterative processes leading to such conditions should be included in the contracts design and construction modifications. (Table 3). - Evaluation and qualification of suppliers and subcon- tractors. 6.4.3. Construction documentation - Handling of non-conformances and follow up of pre- Detailed, accurate and timeous data recording is very ventive measures. important in tunnelling. These records facilitate - Handling of design and project changes. A detailed the back analysis of the tunnel performance and the procedure will provide necessary guidelines for any causes for possible failures, assist in the future main- contract updating. tenance of the tunnel but are also the main source of - Systems follow-up and improvement based on audits information for the resolution of future disputes and and management review. claims. The contractorÕs management should genuinely be Thus, a complete record of all relevant construction committed to the establishment and development of data should be kept by the Contractor and a copy of it the quality management system for a project. A basic given to the Client at regular intervals, as specified. part of the system is the quality plan. The concept of The recorded data should include the geological management review should be adopted in all major mapping of tunnel face, roof and sides with all the rel- tunnelling and underground contracts. Items to be evant geological, hydrological and geotechnical infor- evaluated are: mation, sequence and method of excavation and • Quality goals – current performance and effectiveness support measures with respective timing, installation of of the management/quality system. instrumentation and measurements, as-built drawings, • Non-conformance – statistics, determination and ef- any special operation and maintenance requirements. fects of preventive actions. The construction data should be subject to document • Evaluation of processes and procedures both techni- control procedures in order to eliminate any malpractice cal and administrative. of data alteration or loss of data. • Educational plans. • Audit plans with results from both external and internal audits. 6.4.4. Environmental considerations The construction of a tunnel generally causes less 6.4. Special recommendations environmental disturbance than other projects of com- parable size. The organisation and layout of the con- Experience has shown that during construction cer- struction activities should take care of the environment. tain issues have direct impact on the quality goals and The disposal areas must be carefully selected in order not in the following these special recommendations are to cause public reaction. If the waste disposal is perma- emphasized. nent, the design must make provisions for the complete rehabilitation of the environment. The use of chemicals 6.4.1. Quality control and quality testing and toxic compounds should be approved by the Client Adherence to procedures for control and testing is and relevant authorities. Dissolution of nitrous com- respected by all personnel right from commencement of pounds may have adverse effects on ground- and surface construction. A management commitment explicitly water and the consequences should be assessed.

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7. Operation and maintenance parameters, rock or soil characteristics (as measured) and all test and inspection data. If the organisation does The operation and maintenance phase is defined as not have expertise in the fields of structural analysis or the period after the works have been commissioned. installations design, contracts should be established to As far as this stage is concerned, it is necessary to provide for instant assistance. evaluate particular conditions that require special at- It is recommended that the physical condition and the tention in order to establish effective quality procedures. inherent risk of failure is calculated or otherwise verified As a part of the commissioning it is necessary to conduct at regular intervals with respect to structural conditions a formal acceptance of the structural properties as well (rock, soil, support- and lining structures), environ- as the various technical installations. mental aspects within and outside the structure (water, It should be underlined that the Operation and smoke, seepage of chemical compounds) and the func- Maintenance concepts should be evaluated at an early tioning of the technical installations. The responsibility stage of the design and any an eventual Operation and for this checks lies mainly to the Owner, who also sets Maintenance Manual be prepared with the cooperation for the relevant safety criteria. For public transportation of the Contractor. structures the safety level of the daily operation should The operation phase involves the regular inspections be assessed at regular intervals. Preventive actions and of linings and installations and the checking of the necessary repair work should be identified. regular operating conditions of the tunnel as planned in In addition to a regular inspection plan, the organi- the design stage. The maintenance, intended as either sation should establish an inspection aimed at examin- restoration or significant modification of the linings and ing the physical conditions and prerequisites, operation the installations, cannot always follow the same accep- and maintenance procedures as well the organisationÕs tance criteria as new tunnels, because the standards ability to handle operational and safety aspects. evolve with time and it is impossible to expect all old The inspection plan should include the survey of tunnels to comply with the new standards (safety, lining conditions, eventual progressive damages and cracking of lining, etc.). In case of technical problems evaluation of repair reports and significant monitoring for adaptation, limitations for use should be introduced. data. The main expenditures of the operation phase are due to installation operations, safety facilities, maintenance 7.2. Development of competence needs and insurance fees. From the contractual point of view, the term main- The ownerÕs organisation should establish a plan for tenance is normally used to refer to the various tasks the continuous education of its personnel in order to involved with the upkeep of the physical structure of the provide necessary competence for the daily operation facility as opposed to the day to day running of its duty. and maintenance. External expertise should be sought, if The term operation is understood to encompass the not available within the ownerÕs organization. This latter. could be true for particular monitoring in which the use The ultimate purpose of an operation/maintenance of instrumentation is a specialistic way. contract is generally to ensure the facility performs the Transfer of knowledge from design and construction way intended and to the standard required by the owner should be conducted according to approved plans and, and the law. At such, it seeks to attract the commercial as stated earlier, according to contract specifications. interest of the operator in the life cycle cost of the Internal communication and motivation should be project, motivating the operator to consider the future based on available statistical data and experience from maintenance costs of a project as it carries out its design the operation as well as project and design prerequisites and construction obligations (Table 2). and data from construction and testing. It is recommended that the ownerÕs organisation es- 7.1. Organisation. Allocation of responsibility tablishes a library containing all relevant technical information as well as relevant laws and regulations. It is It is recommended that the owner of a tunnel or fundamental that each tunnel has its own record/data underground structure establishes an organisation that base. is well suited for and competent to evaluate and conduct repair works and improvements. Public transportation 7.3. Time aspects structures should have an organisation that is qualified for daily operations and maintenance. The responsibility The text that follows should rather have a different for the structureÕs fulfillment of national or otherwise title than ‘‘Time Aspects’’ e.g. ‘‘Operation Criteria’’. valid safety regulations should be clearly defined. It is obvious that external requirements and prereq- The ownerÕs organisation (or the concessionaire) uisites change during the lifetime of an under- should have access to all design prerequisites, design ground project. Methods for structural and geotechnical

ITA/AITES Accredited Material 260 C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 analysis have been refined over the years. Any under- extent of the inspections should be stated. The instal- ground project should be re-examined with respect to lations should be verified regularly and any anomaly structural conditions when considered necessary or noted. when applicable technical standards are revised (see The responsible parties for the inspection and moni- Table 2). toring are usually the field Engineers appointed by the The effects of environmental impacts (landslides, Committent; they can have both a technical and an floods, earthquakes, etc.) shall be assessed. Technical administrative role. and traffic regulating installations should be subject to 3 Maintenance procedures. The maintenance and substi- similar evaluations (see Table 1). tution or adjustment interventions should be planned Cost estimates should be carried out with the aim of to minimise disturbance of the use of the tunnel. The determining the most cost effective scheduling of main- interventions when it comes to repair works for the tenance, repair works and improvements. linings vary considerably depending on the type of damage and the reasons for ÔfailureÕ. The maintenance and repair interventions should also be verified 7.4. Special recommendations through adequate testing procedures. It should be differentiate between ‘‘maintenance’’ and 7.4.1. Operational tools for large scale and critical ‘‘repair’’ works. The maintenance should be prescribed projects with extensive public use or involvement in the Operation Manual and it should be regular, The following aspects are recommended for the Op- whereas the repair is necessary in case of damage or eration and Maintenance stages: in order to prevent damage or failure. Recommen- • Records of complete documents regarding site inves- dations for the necessity of repair works should be tigations, planning results, design assumptions and included in the Evaluation Report of the Inspection and analyses, ‘‘as built’’ drawings and technical specifica- Monitoring. tions, test records, instrumentation monitoring, sta- Finally, communication with external organisations tistical data. is strongly recommended and should be encouraged (for • Identification of the involved professional people and example with universities) as far as relevant statistical organisations. data are concerned (frequency, cause and repair inter- • Summary tables with information about geological ventions) in order to validate the maintenance measures decisions, selection of support systems/structures and procedures. and the materials used for waterproofing, injections, additives etc. • Provisions for Safety. 7.4.2. Approval tests • Environmental monitoring with regard to interfer- The approval test has the purpose of verifying and ence with wells, springs, flammable gases, accidents certifying that the tunnel has been excavated according to with fires, etc. regulations and established technical specifications • Monitoring of the critical areas, portals, crossing of in agreement with the contract, design modifications faults etc. and approved procedures. The approval test should above The tunnel becomes a product with some data that all be accompanied by instrumental tests, whose amount can no longer be modified (geology, excavation method) and type is decided according to the specific situations. and with others that can be updated and modified In general this procedure will lead to a ‘‘final com- (monitoring, conditions of the linings, hydrogeological missioning certification’’ or ‘‘approval certification’’. regimes, conditions of the installations, conditions for The structural test, considering the type of work here use, etc.). dealt with and the consequent impossibility of com- It is necessary to have three operational instruments: pletely inspecting it when finished, should be performed 1. Approval test (Pelizza et al., 2000). The test results during the construction phase. from the construction stage constitute the basis for The commissioning certification procedures should the observations as the tunnel is commisioned/con- include: signed. The results should give the qualitative and • Type of tunnel and its conformity to general (state) quantitative indications of the measurements that technical and safety criteria (or requirements). have been carried out measuring displacement, load • Verification of those who are involved in the works and hydrogeological conditions. and the administrative procedures. 2. Operation and inspection procedures. A Manual with • Examination of the constructed project and verifica- the visual inspection and instrumental monitoring tion of the conformity of the works. plan should be prepared by the Owner following • Verification of the technical reports. the indication of the Designer to function for the type • Verification, when it is possible, of the results of any of works and the final lining. The frequency and the legal and technical claims; these claims seldom are re-

ITA/AITES Accredited Material Table 2 Practical quality assurance in tunnelling example of tables Tunnelling stage: Geological Step of the work Concerned elements Negative eﬀects Actions Notes and topographical surveys Work planning Deﬁnition of directions and Uses, functions, future trends Inadequacy of informations Appropriate preliminary interconnections studies

Design and characterization Study of geometry and Geology, hydrogeology, geo- Wrong characterization and Preliminary studies and 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. formations. Installations technics, type of work, occur- inadequate geometry for investments for geophysical surveys and rence of gas and karst. Technical traffic evolution drilling references. Adequate timetable Financing, procurement and Evaluation of alternatives Basic elements for choices of Incomplete evaluation of the Evaluation of alternatives Accurate balance between contractual phase suitability of the work whole project Possible investments for investigations increase of controversies and risk mitigation Construction and monitoring External and underground Details of rock and soil Unexpected conditions, Training, appropriate site Great delays if inadequately controls and investigations formations, definition of profiles difficulties for supplying of inspections considered and geometries. Adequate time- construction materials table Operation and maintenance Verification of changes in Change of conditions, both for Difficulties in the operation; Record of data conditions designed and involved aspects excess of cost for maintenance Tunnelling stage: Hydrogeology Step of the work Concerned elements Negative effects Actions Notes and environment Work planning Evaluation of influences on Natural and modified condi- Water pollution, settlements, Severe regulations and Basic decision stage the environment including tions, at short and long time vibrations, traffic studies water sources scale. Special awareness for subsea tunnelling. Location of landfills Design and characterization Investigations and Water flow, modifications of Undesired damages to struc- Adequate investments for simulations traffic conditions, influence on tures and natural resources studies stability Financing, procurement and Detailed description of Adequate estimates for rock Additional or new costs Allocation of responsibilities, External costs

T/IE crdtdMaterial Accredited ITA/AITES contractual phase constraints support. Environmental delays consequences, for example ground water table, vegetation Construction and monitoring Application of methods for Water quality, dust and Nonconformities, claims Procedures for prevention Critical phase for claims reduction of damages vibration controls. Muck dis- and mitigation posal Operation and maintenance Constant control of Analysis and mitigations Increase of pollution, Respect of traﬃc limitation environmental parameters loss of credibility and regular maintenance 261 Table 2 (continued) 262

T/IE crdtdMaterial Accredited ITA/AITES Tunnelling stage: Design and Step of the work Concerned elements Negative effects Actions Notes construction concepts Work planning Selection of the geometry of Type of the work, size and Inadequacy of the methods Experience and lessons Discussions and agreements the work and of installations shape, profile. Use of reamer or type of work learned from similar cases. with external parties. TBM Adaptability of the project parameters Design and characterization Selection of parameters and Overburden, water, faults, set- Accidents, damages, instabil- Revision of the design and Fundamental step of the design methods tlements, accessibility. Evalua- ity, delays and additional cost risk assessment whole process .Ogr,G v unligadUdrrudSaeTcnlg 9(04 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. tion of landslides and rock fall Financing, procurement and Detailed description of costs Complete knowledge of Difficulties for the Prepare detailed contracts In this step economics, contractual phase and supplies alternatives; Selection of the relationship with the involved and establish severe economic regulations and engineering appropriate type of contract parties; Resolution of con- constraints must agree completely tract Construction and monitoring Selection of construction Selection of equipment, Surface occupation, Detailed and daily control Fundamental step of the method (traditional or personnel, instrumentation, vibrations, dust, settlements, by the field engineers whole process. Daily mechanized) and site organization of the personnel stability of landfills discussions and claims. measurements; landfilling and phases. Particular condi- or rock waste recovery tions for microtunnelling and subsea crossing. Control of blasting cross sections Operation and maintenance Provisions for future works Provisions for future work. Per- Difficulties for maintenance Provisions of the state of formance of the installations and inspections the tunnel after long periods of use Tunnelling stage: Rock support Step of the work Concerned elements Negative effects Actions Notes and reinforcements Work planning Type of support elements and Geologic formations. Surface Inadequate support Further verification in design. Coordination with surface reinforcing techniques tunnels. Works in urban areas Vibration and noise structures in urban areas. Design and characterization Detailed description of type, Calculation methods, Inadequate support Observational methods; It is a fundamental stage for quantity and time for adop- mechanized equipment. lessons learned stability and safety tion of support and eventual Organization of the operative reinforcing elements timetable. Rock burst. Preven- tion of sink-holes and water inflow Financing, procurement and Consideration of the alterna- List of costs Delays and additional costs Refine design contractual phase tives Construction and monitoring Installation of the support Equipment, type of support, Failures, collapses, subsi- Observations and measure- Fundamental phase of the and preliminary or late rein- type of reinforcing, verification dence ments; respect of the design whole process forcing element; measure- of adequacy of used support ments. Particular attention systems. Techniques for face for urban areas and surface reinforcement tunnels

Operation and maintenance Evaluation of long term Stability Failures Periodic monitoring, careful behaviour to new external conditions Tunnelling stage: Step of the work Concerned elements Negative effects Actions Notes Sealing and linings Work planning Objective of the drainage and Hydrogeology of the formations High stresses on linings; Detailed studies. Monitoring type of final lining excess of drainage of stresses and piezometric conditions Design and characterization Detailed selection of materi- Rock and soil parameters; Type Inadequacy of the choices Experience from similar cases als. Proved experience for of geosynthetics; quality of the precasting firm concrete. Heavy stresses due to

water pressure 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. Financing, procurement and Preparation of dedicated Influences on the surrounding Claims, delays and extra Allocation of responsibilities Several claims with external contractual phase report environment costs parties. Construction and monitoring Proper installations. Selected Choice of materials, organiza- Unexpected flows and Prevention; special materials. procedures for mechanized tion of the work subsidence Fast countermeasures tunnelling, both in small and large diameter Operation and maintenance Regular controls Verification of damages and Degradation of linings Planning of works measurements Tunnelling stage: Excavation Step of the work Concerned elements Negative effects Actions Notes and construction equipment Work planning Selection of equipment Safety, increase of mechanized Inadequacy of the machinery; Verification of similar cases, The choice of the equipment phases, organization Delay due to mechanical adequate organization is the most important feature problems. ContractÕs renego- which determines the evolu- tiation. Resolution tion of the work. Design and characterization Selection of methods and Geometry, power, pollution, Limitations for space, inade- Preliminary adaptation to the reuse of waste organization of phases quacy of safety devices. tunnel conditions Training of personnel Financing, procurement and Evaluation of important Detailed knowledge of equip- Large loss of time and Adequate consideration for contractual phase investments (TBM) ment and work organization increase of costs the machinery suppliers and maintenance Construction and monitoring Power supply, proved orga- Geometry, phases, velocity of Safety of personnel, delays, Adoption of well tested nization in particular for advance. Anti-detonating de- increase of costs equipment with preliminary mechanized tunnelling vices. Treatment of EPB-Slurry field tests shield muck T/IE crdtdMaterial Accredited ITA/AITES Operation and maintenance No influence No influence No influence No influence 263 Table 2 (continued) 264

T/IE crdtdMaterial Accredited ITA/AITES Tunnelling stage: Installations Step of the work Concerned elements Negative effects Actions Notes and safety Work planning Type of work Traffic, geometry, regulations. Consequences at each level of Prevention; quick counter- Fundamental for the modern Preventive actions damage, both in construction measures acceptance of the work. and operation Design and characterization Choices of ventilation, Access, length, secondary Inadequacy of installations. Select the heavy operation Very high responsibility. lighting, escapes installations. Amount of per- Controversies conditions sonnel in the tunnel .Ogr,G v unligadUdrrudSaeTcnlg 9(04 239–272 (2004) 19 Technology Space Underground and Tunnelling / Ova G. Oggeri, C. Financing, procurement and Consideration of present Technical requirements for Inadequacy of regulations Important investments, also contractual phase safety standard installations in training and communications Construction and monitoring Verification of good materials Acceptability tests. Rescue Nonconformities. Suspension Detailed field controls This is the crucial phase for and equipment devices and procedures of the construction the effective safety of the workers. Operation and maintenance Regular functioning of the Respect of updated regulations Accidents, at each level Prevention, periodic tests and This is the crucial phase for equipment and procedures. Rescue devices increase of performance the effective use of the and procedures structure. Tunnelling stage: Monitoring, Step of the work Concerned elements Negative effects Actions Notes maintenance and statistics Work planning Report of the statistical data Measurements, used materials, Problems for the use of the Periodic adaptation of the Adequate organisation, data of the tunnel new works structure structure base, planning of maintenance works. Design and characterization Selection of adequate Materials, alterations, pollution New costs Indication of methods for measurement types and periodic inspections indication of future work requirements Financing, procurement and con- Contract details Data base of the tunnel. Periodic Unappropriate allocation of Clear definition of contract tractual phase controls and repairs costs roles Construction and monitoring Use of corrected procedures Phases and adopted materials Loss of technical documents Complete record of each and materials and unexpected damages tunnelling phase

Operation and maintenance Organization of roles Measurement and maintenance Degradation of the work Adequate investment for the planning improvement of operational conditions of the work For each underground work it is suggested to resume in a series of tables the various interacting phases, both as time evolution and actions are concerned to determine a direct or indirect inﬂuence on the success of the work. The result of these tables should be a pragmatic tool. A simple example from whom any adaptation is possible, is shown in the following. C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 265

Fig. 4. Diversion in road tunnel, conventional tunnelling (Bolzano, Italy, courtesy S.Tua, Soc.It. Condotte dÕAcqua).

Fig. 5. Hydroelectric tunnel, mechanized tunnelling (Bormio, Italy, C. Oggeri with permission of M.Concilia, SELI).

solved prior to the commissioning of a tunnel. In that 7.4.3. Operation and inspection procedures case they should not be dealt with in such a final ap- These procedures are in particular dedicated to safety proval report; any substantial modification to the ori- when a tunnel is used for the transport of goods or people. ginal project should be verified. The procedures should include: • Examination of the statistical data of a construc- • the availability of a general plan for the use of the tion type, including any deduced from the quality tunnel (permitted traffic, working personnel) and of plan. the safety (escape routes, fire extinguishing systems, • Examination of the materials used in the construc- smoke detectors), tion. • management of geotechnical, hydrogeological and • Examination of the instrumentation measurements environmental instruments, carried out during the work and those performed • management of safety installations and systems, during use of the tunnel. • information for the users and for the operating per- • Examination of any extraordinary situation. sonnel,

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• acquisition of statistical data, It would be useful to correlate these points to the • periodical inspection plan of the tunnel in working different aspects of tunnel construction and especially and non-working conditions of both structures and to the operation and maintenance phases in order to installations. create a proper standard management approach to these operations. 7.4.4. Maintenance and repair procedures Operation and maintenance of the tunnel can easily The maintenance stages should include: be connected to some of the previous points: • the availability of a technical manual in which the 1. Customer focus construction details of the various sections of the tun- It is not possible to do anything without considering nel, the encountered geological formations and prob- the customer aspect; both the client who pays for the lems; construction of the tunnel and the general public who at • an examination of the available monitoring equip- the end use the tunnel should be considered as ‘‘cus- ment; tomers’’. • an examination of the results from the previous in- It is of primary importance to consider the customerÕs spection stages and any remedial interventions al- needs and satisfaction to plan the operation mode of the ready carried out; tunnel and to decide how and when to carry out the • a detailed inspection through non-invasive techniques maintenance works, i.e.: not to plan the maintenance of (photographic, thermographic and georadar survey- road tunnels during holiday periods ing) or even invasive techniques (core drillings and 2. Leadership and destructive tests); 3. Involvement of people • maintenance and remedial interventions; It can be useful to define in advance the various re- • entrusting of the works to specialised companies; sponsibilities for the different areas or aspects of the • testing of the performed interventions. work to ease the solution of possible problems during The repair procedures are part of a detailed design, as operation phase or during emergency repairs. they involve sustantial modification of the actual situa- 4. Process approach tion. For this reason, design documents should list all Definition of procedures for the various activities and the specific stage for the works. co-ordination. 5. System approach to management Scheduling the maintenance in advance, from the 8. Conclusions building phase, to be able to operate before real damages occurs to the structure and installations, to be able to al- 8.1. Updating low a continuous functioning of the structure. 6. Continual improvement Quality is a concept that is constantly evolving. There The maintenance phase in itself is based on the idea are unique features in tunnelling due to the great num- of a continuous improvement and should be approached ber of involved parties, both in minor and in major with such a goal in mind. projects and due to the non-repeatable nature of tun- 7. Factual approach to decision making nels. However, the trend of the concept of quality, in All decisions should be converted into interventions this field, is towards both a good planning / management on the basis of correction and prevention criteria, fol- and suitable technical results. lowing the experience obtained from data control and In December 2000 the ISO committee introduced a statistics processing. revised version of ISO 9000:2000 series for quality 8. Mutually beneficial supplier relationship management systems based on management principles: New materials, new construction technologies and 1. Customer focus. the special requirements for underground works should 2. Leadership. always be compared, in order to improve safety and 3. Involvement of people. usability standards. 4. Process approach. Energy savings can also be obtained moving by a 5. System approach to management. simple and rational planning towards a correct organi- 6. Continual improvement. zation of transportation, the development of railroads 7. Factual approach to decision making. and roads systems etc. 8. Mutually beneficial supplier relationships. These principles are defined in ISO 9000:2000 8.2. Summary of recommendations ‘‘Quality management systems – Fundamentals and vocabulary’’, and in ISO 9004:2000 ‘‘Quality manage- Quality is the sum of the clientÔs needs and expecta- ment systems – Guidelines for performance improve- tions and the level of performance achieved by satisfying ments’’. the needs, whether delivering a service or a structure.

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In tunnelling there are two levels of quality as far as Each involved party should estimate and describe the performance is concerned. One is related to the use and uncertainties and risks that are connected to their efficiency of the underground structure, and this is taken responsibilities such as the owner for the planning and into account during the planning and operation phase. for the tender and the project manager for the coordi- The other is related to the characteristics of the works, nation and financing. and this is taken into account during the design and These responsibilities should be assigned taking due construction phase. cognisance of the type of contract/contract conditions Quality goals as far as expectations are concerned are and national laws and regulations. Eurocode 7 on linked to the adherence to the construction programme, Geotechnical Design is an example of detailed technical keeping within foreseen costs and limiting the number of recommendations for the geotechnical investigation and claims. design. These desired features can be fulfilled through well The final objective for quality in tunnelling is to limit planned and controlled stages (Muir Wood, 2000): the number of uncertainties, whether these are related to • planning during which the effective needs are high- communication, allocation of risk, technical or financial lighted; issues. • progressive investigation and monitoring; Procedures should be activated in order to • well defined preliminary design; guarantee the transferring of experiences and • correct choice of the type of contract, conditions of knowledge, for example by exchange of informations contract, financing and procurement procedures, with universities and other independent cultural as- depending on the type of project; sociations.

9. Working Group Members May 1999 – March 2003:

Jindrich Hess Metrostav Prague Czech R WG Tutor Kai A Sorbraten Vannkraft Ost Lillehammer Norway Former WG Tutor Claudio Oggeri Politecnico di Torino Torino Italy Animateur Renato Arfe Cavet Bologna Italy Gunnar Ova Selmer Skanska AS Oslo Norway Former Animateur Vasso Stavropoulou Consultant Athens Greece Vice Animateur Ulrika Hamberg Vagverket Stockholm Sweden Tina Helin Skanska International Lima Peru Takahiro Aoyagi Kajima Corporation Tokyo Japan Takashi Fujita Kajima Corporation Tokyo Japan Karl Kuhnhenn BUNG GmbH Heidelberg Germany Mike Trissler Uhmlanga Rock South Africa Jiri Belohlav Metrostav Prague Czech R Joe Kellogg Kellogg Corporation Denver, CO USA Gerard M. Letlatsa LHTP Maseru Lesotho Ntsoeleng Mohale MCG Maseru Lesotho Weining Liu NJTU Beijing China Maeng Doo Young Kistec Seoul South Korea Vanjia Keindl Ministry of Environmental Pro- Soel South Korea tection and Physical Planning Hae-JinOH CHEIL Engr. Co Soel South Korea

• well considered design with veriﬁcation of both the Special thanks for the contributions and corrections to: technical and economical aspects; • appointment of consultants and auditors for all the Sir Alan Muir Wood United Kigdom phases including the commissioning and approval. Ola By Norway In general if the scheduled actions, the design re- G. Mazzoleni France quirements, the indications of the investigations and the Jean Paul Godard France contractual rules are observed, a good result for the work Francois Vuilleumier Switzerland is possible. Harald Wagner Austria

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10. Report Summary quirements’’. It is difficult to completely assure quality in tunnelling, especially by third-party organisations. For The recommendations of the report on Quality in this reason it is recommended the adaptation of ‘‘quality tunnelling are aimed to give practical guidelines to the management’’ to tunnelling projects rather than quality various parties engaged in tunnelling projects during the assurance rules. Suggestions for comprehensive ap- different stages of a project. Since the basis for a suc- proaches are given in the report rather than prescriptive cessful tunnelling project is often related to careful routine control and testing activities. planning and management rather than isolated inspec- All along the project a coordination of activities is tions and tests, this report focuses mainly on quality necessary in order to reach significative results for: management measures, including iterative processes technical features with the objective of securing adequate and updated economical results quality plans and procedures at any stage. Project pre- contractual agreements requisites and risk assessment are dealt with in different environmental effects sections of the report, recognizing the importance of safety standards these topics. All these goals can only be obtained by means The report has been arranged according to different of high professionality, self responsibility, clear project phases and give specific recommendations for requirements. each phase. For practical reasons the WG has chosen to The rational development of scheduled activities is handle procurement as a project phase, even though the one of the main instrument for success. Other sugges- procurement activities can be related to all stages of a tions for good results show the importance of knowl- project. It should be noted that the different project edge of state of the art and of case histories which have phases described are not completely separated from each given problems. As the non-quality is clear when: other. The need to identify interactions between phases 1. time for providing the work are exceeded and between project participants is crucial to the success 2. new costs alter the budget of any tunnelling project. 3. claim within the involved parties occur without reso- The Working Group has adopted the following ob- lution jective for the work: 4. controversies between the project parties and external To give recommendations on how to achieve Quality in Tunnel- arise ling and how to identify, evaluate and specify Quality Manage- 5. accidents and failures determine loss of lives or goods ment measures to be taken by all parties in the Conceptual the quality procedures should coordinate each action Planning, Procurement, Design, Construction, Operation and Maintenance phases of underground projects involving tunnels. aimed to: 1. a good knowledge of the geologic formations Reference to and use of updated recommendations 2. evaluate the interaction between the tunnel struc- produced by international or national sister organiza- ture and the surrounding environment tions (ISRM, ISSMFE, IAEG etc.) and other 3. evaluate any development on a long time base professionally developed documents (such as the Euro- Uncertainties in tunnelling projects arise from the codes by European Committee for Standardization) is inability to study the complete structure and behaviour encouraged. of the rock and soil formations in such detail that all The meaning of ‘‘Quality’’ is ‘‘The totality of features possible scenarios can be contemplated. It should be and characteristics of a product or service that bear upon emphasized that tunnel failures have been the result of its ability to satisfy stated or implied needs’’. various reasons such as insufficient site investigation, In tunnelling the ‘‘stated needs’’ of the Employer inadequate evaluation at the planning stage, mistakes could mean the construction of a tunnel in accordance during construction and operation phases. with the technical quality defined by the Employer (i.e. An inventory of inherent risks for the project phases technical specifications), within the estimated budget should be undertaken for all tunnelling and under- and predefined time schedule or programme. The ‘‘im- ground projects. Risk assessment should be made for: plied needs’’ are multifold and could be respect for laws • Rock and soil conditions versus the stability, physical and regulations, safety aspects, environmental protec- properties and seepage tion, energy savings and sustainability of the works. It is • Construction methods versus progress, rock/soil con- of fundamental importance that the prerequisites are ditions, environment and safety continuously updated and met both during construction • Equipment versus suitability, capacity, energy con- and the operation phases. sumption, environmental and safety aspects ‘‘Quality Management’’ means ‘‘all those systematic The consequences on the total project cost and actions that are necessary to provide adequate confidence financial matters should always be included in risk that a product or service will satisfy given quality re- evaluations.

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Site investigations and geological exploration and pacity. Performance to the set quality goals therefore their use in design optimisation, coupled with well becomes a critical issue. matched construction techniques, can prevent most When it comes to the quality issues, it is not consid- kinds of collapses. The design cannot only be based on a ered necessary to maintain a uniform approach for the deterministic approach for the evaluation of a risk, a duration of a project. Some issues might turn out to be probabilistic approach that takes into account the un- more important than others and experience shows that, certainties in the geological, geotechnical and construc- during the course of construction, some issues may well tion techniques and external constraints will enable the be abandoned without harm to the project. project management to optimize the final design and Research into the appropriate local legislation and define the technical, administrative and financial man- regulations for such matters as health and safety, the agement of the risk. protection of the environment and socio-economic It is recommended that detailed paragraphs dealing consequences, as well as technical standards to be with risk allocation should be included in all contracts achieved should be carried out. These can then or agreements, and that risk is distributed by taking into be compared to best international practice, which can be consideration both technical and financial aspects. adopted to suit the particular project and then the Contractual procedures should be simple and the role quality goals can be set accordingly. of the various parties should be made extremely clear, All phases of a project and all organisations/groups both from a technical and financial point of view. Ex- of organisations involved should have a set of quality cessive legal and bureaucratic complexity should be goals for the work to be performed. Quality goals avoided, but specific attention should be given to those should be aimed at giving the project added value with contractual aspects that deal with the information ob- regard to cost, time, improved performance/physical tained on the natural ground conditions. properties and could be set relative to ‘‘soft parameters’’ Among the aims of Quality procedures the ‘‘risk as- like improved competence or educational standards for sessment’’ has a significative role. It should be under- involved parties, environmental aspects, safety stan- lined that a ‘‘risk analysis’’ is different than a ‘‘risk dards or benefits for the public in general. When quality assessment’’, and not always necessary, because it in- goals are determined, these should be related to the creases the cost of the design and does not contribute factors of success for the project and a strategy on how proportionally to the actual handling of the risk. Risk to achieve this should be included in the Quality Plan. assessment, as far as the Quality procedures are con- Compliance and the degree of success in achieving the cerned, is aimed to identify which risks are foreseen by set goals should be communicated to all project mem- the design, which risks are undertaken by the contractor bers/companies. and who undertakes any further risks. It is recommended that requirements and detailed instructions for quality control for the design and the 10.1. Quality goals construction work should be specified in the contract. It is important that procedures for the registration and In order to obtain a well functioning tunnel or un- communication of items such as test results are specified. derground structure, all project stages are of funda- A project procedure including owner/employer, engi- mental importance; the stage of knowing the geological neer/designer and contractor for lines of communication and geomechanical characteristics, the planning stage, and the responsibilities of each party for handling such the stage of choosing the machinery and method of ex- information should be drawn up. The continuous pro- cavation, the installation of lining and rock support, and cess of evaluating, for instance, test results and any the organisational and financial coordination stage. As subsequent changes to the design and/or construction far as Quality Systems are concerned, an analysis of the methods should be adequately defined and described. numerous problems that occur in a tunnel, independent It is recommended that implementing bodies and of the adoption of Quality System procedures, show contractors make available technical data and statistics how these may not be resolved automatically by Quality from the construction phase and communicate such data Systems. to international bodies and universities. By doing so, Quality Systems should reflect the various stages and objective views on the state-of-the-art of methods used assess the influence on the final result, showing above all and case histories could be obtained, all in line with a those aspects where the interpretation becomes decisive generally recommended quality goal regarding the in the technical choices. transfer of knowledge. Tunnelling and underground projects are usually of Methods for procuring, constructing, maintaining significant financial value and are generally considered and operating private/public infrastructure are numer- high risk in terms of final cost and time for construction/ ous. They range from lump-sum contracts for the con- delivery. In addition, tunnel construction often requires struction of a designed facility, to complex transactions multinational input for both funding and technical ca- involving ownership transfer, equity financing and novel

ITA/AITES Accredited Material 270 C. Oggeri, G. Ova / Tunnelling and Underground Space Technology 19 (2004) 239–272 revenue features. Understanding and adapting available Each involved party should estimate and describe the contract options is crucial for the success of a project. uncertainties and risks that are connected to their re- The owner should be aware of how his precise require- sponsibilities such as the owner for the planning and for ments are best served and of the practical considerations the tender and the project manager for the coordination associated with different contract strategies. and financing. The details of appropriate methods of financing and These responsibilities should be assigned taking due remuneration, risk allocation, the nature of the different cognisance of the type of contract/contract conditions and partiesÕ obligations/responsibilities and the ownership national laws and regulations. Eurocode 7 on Geotech- structure are matters specific to the individual projects. nical Design is an example of detailed technical recom- It is possible to resume what have been described in mendations for the geotechnical investigation and design. terms of benefits of the application of Quality as follows: The final objective for quality in tunnelling is to limit • Good organization and relationship the number of uncertainties, whether these are related to • Definition of needs and constraints of the work communication, allocation of risk, technical or financial • Design adapted to needs and constraints issues. • Control on the evolution of design stages and selec- Procedures dealing with planning, control and how to tion of appropriate contracts deal with changes to set procedures and design can en- • Evaluation of risks and allocation of responsibilities sure that the end product is such that client satisfaction • Ability to perform modifications to details can be achieved, time and cost overruns limited and • Historical records of the design and of the performed resulting claims minimised. At the same time proper works procedures can ensure that knowledge is transferred not • Reciprocity for communications and problem-solving only between parties during the project phases but to attitude parties after completion of a project, including for instance universities and other independent organisations. 10.2. Summary of recommendations

Quality is the sum of the clientÔs needs and expecta- References tions and the level of performance achieved by satisfying the needs, whether delivering a service or a structure. ISO International Organization for Standardization: the ISO In tunnelling there are two levels of quality as far as 9000:2000 Standards on Quality, Geneve, Switzerland. Muir Wood, A., 2000. Tunnelling: management by design. E & FN performance is concerned. One is related to the use and SPON. efficiency of the underground structure, and this is taken Pelizza, S., Oggeri, C., Peila, D., Brino, L. 2000. Key points for static into account during the planning and operation phase. approval test of underground works. In: Proceedings of the World The other is related to the characteristics of the works, Tunnel Congress, ITA, Durban, 13–18 maggio, pp. 395–398, and this is taken into account during the design and SAIMM. Vlasov, S.N., Makovski, L.V., Merkin, V.E. 2001. Accidents in construction phase. Transportation and Subway Tunnels. Elex KM., Moscow. Quality goals as far as expectations are concerned are linked to the adherence to the construction programme, keeping within foreseen costs and limiting the number of claims. For further reading These desired features can be fulfilled through well planned and controlled stages: Aftes, G.T., 1995. 14: Les methodes de diagnostic pour les tunnels - planning during which the effective needs are high- revetus. Tunnels Ouvr. Sou., 131. lighted; Aftes, G.T., 2002. La demarche qualite en travaux souterrains. Tunnels Ouvr. Sou., 174. - progressive investigation and monitoring; CEN/TC 250/SC 7, 1997. ‘‘Eurocode 7 – Geotechnical Design, draft - well defined preliminary design; EN, Delft. - correct choice of the type of contract, conditions of FIDIC Contracts, 1999–2000. International Federation of Consulting contract, financing and procurement procedures, de- Engineers, Lausanne. pending on the type of project; ITA Report of WG 6, Maintenace and repair: Study of methods for repair of tunnel linings. - well considered design with verification of both the Anderson, J.M. 1997. World wide research points to the need for new technical and economical aspects; approaches to control tunnelling risks. In: Proc. Tunnelling Under - appointment of consultants and auditors for all the Difficult Ground Conditions, Basel. phases including the commissioning and approval. Harrison, F.L. 1981. Advanced Project Management, Gower, Alder- In general if the scheduled actions, the design re- shot. Pelizza, S., Grasso, P. 1999. Increasing confidence in the expected quirements, the indications of the investigations and the safety factor using information from tunnel collapses and closures. contractual rules are observed, a good result for the In: Proceedings of the International Symposium on Ground work is possible. Challenges and Expectations in Tunnelling Projects, Cairo.

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Rawlings, C.G., Lance, G.A., Anderson, J.M. 1998. Pre construc- Contractor Society or group whose tender tion assessment strategy of significant engineering risks in has been accepted and who is tunnelling. Underground Construction in Modern Infrastructure, Stockolm. responsible for providing the works. Conventional The drill and blast method tradi- Glossary method tionally adopted in hard rock formations. Short glossary DB The design-build is a type of contract under which the contractor Adit The entrance of a tunnel into the provides the design and the con- mountain slope. struction of the work. Approval engineer Engineer authorized to verify the DBFO The design-build-finance-operate is fulfillment of technical require- a type of contract under which the ments during or after the con- concessionaire obtains financing struction of the work. and design, and provides the works Arbitration A procedure for the resolution of a for operation, and then operate dispute, administrated by an arbi- and maintain the works during the tral team. concession period.At the end of the BOTT The build-operate-train-transfer is concession period the works are a type of contract under which the taken over by the project owner. concessionaire designs and pro- EPC The engineering-procurement and vides the works ready for opera- construction contract is an agree- tion and then operate and maintain ment under which the contractor the works.After the concession pe- provides the works ready for oper- riod the works are taken over by ation by the client, and may include the project owner, following the financing parts of the works. training of the new operators. Final support The lining that surround the section BOT The build-operate-transfer is a type of the tunnel, usually made of of contract under which the con- casted concrete, precasted seg- cessionaire designs and provides ments, masonry or sprayed concrete the woks ready for operation; after Geotechnical The investigations and the tests the concession period the works are characterization aimed to find direct values or taken over by the project owner. indirect correlations with the geotechnical parameters of the geo- BOOT The build-own-operate-transfer is logical materials and of the type of contract under which the geological formations. Also the concessionaire designs and provides carrying out of the geomechanical the works ready for operation, and classifications. then owns, operates and maintain Monitoring The measurement plan and opera- the works during the concession tions aimed to obtain a continuous period.At the end the works are or periodic survey of geotechnical, revert to the project owner. structural or hydrogeological pa- Concessionaire Society or group who has been rameters. given the rights to design the work. Pilot tunnel Small section tunnel driven for Concession period The period during which the con- detailed investigation or for pre- cessionaire has the responsibility liminary reinforcement or for for the operation of the project. safety reasons. Consultant A professional who carries out Performance The technical report in which the services or studies for a client, a certificate approval engineer or a certifying contractor, a concessionaire or a body declares that the contractor owner. has performed all obligations un- Contract The set of documents which con- der contract. stitute the legal and technical Preliminary The methods for supporting the agreement between the parties for support rock or soil excavation: usually the design, construction and oper- they consist of bolting, sprayed ation of a work. concrete, wire mesh, steel arches.

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Portal The final structure or completion of the adit of the tunnel. Shield Mechanical equipment for the Profile of the Both the longitudinal and lateral tunnel excavation in soil formation tunnel sections of the tunnel, referred to (EPB shield, slurry shield, mix topographical and geological con- shield etc.) ditions. TBM Mechanical equipment for the Quality assurance Actions oriented to verify the ful- tunnel excavation in rock forma- fillment of quality requirements. tion (open TBM, shielded TBM). Quality Organisation methods aimed to Tender The set of documents which allow management coordinate parties and procedures the various competitors to submit during a project. to the employer (owner or com- Reinforcement All the technical actions aimed to mittent) the respective proposals ameliorate the geotechnical condi- for the work. tions of the formations, both be- Tests on-after The tests which are required to be fore and during the excavation: completion carried out to verify the technical drainage, grouting, nailing performance of the structures and etc. installations. ROT The repair-operate-transfer is a Turnkey The type of contract under which type of contract under which the the contractor designs and provides concessionaire repairs an existing the works, ready for operation. work and then operate and main- Waste The rock debris or soil material tain it during the concession pe- produced by the excavation of tun- riod. The work is the taken over by nel (mucking). It can be disposed in the owner. landfills or partially re-used.

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