Tunnelprojekt för transportinfrastruktur är ofta stora, komplexa och riskfyllda investeringar som innebär avancerade tekniska lösningar, logistiska, politiska och organisatoriska utmaningar samt målkonflikter. Historien visar dessutom att flertalet stora tunnelprojekt överskrider såväl tidplan som budget. I dessa projekt kombineras hög komplexitet med hög osäkerhet om bland annat markförhållandena vilket ställer stora krav på beställarens förmåga på att organisera såväl kommunikation som riskhanterings-arbete. Otillräcklig kommunikation är en ofta återkommande orsak till problem i byggprojekt och en välfungerande kommunikation inom projektet såväl som med dess intressenter anses ofta vara en nyckelfaktor.

Föreliggande rapport handlar om kommunikation kring georisker i stora tunnelprojekt, eftersom denna typ av risker är speciellt utmanande och många olika aktörer är involverade i arbetet med att identifiera, värdera, hantera och kommunicera dessa risker. Dessutom saknas vetenskapliga studier och litteratur som belyser kommunikation av georisker i stora tunnelprojekt.

Syftet med studien var att undersöka, identifiera och kartlägga kommunikationen kring georisker under planering och projektering i stora tunnelprojekt och vidareutveckla rådande praxis och riktlinjer. Målet var att skapa bättre förutsättningar för beställare och projekterande konsulter att planera och organisera kommunikationen kring georisker så att tunnelprojekt kan genomföras mer effektivt. Som forskningsmetod har semistrukturerade intervjuer använts. De intervjuade har haft olika roller i beställarens respektive den projekterande konsultens organisationer under projekteringen av två stora svenska bergtunnelprojekt. Intervjuerna utfördes under perioden 2022–2025.

Resultatet av intervjuerna tecknar en bild av hur olika roller under planering och projektering kommunicerar information om georisker till varandra i tunnelprojekten. Studien visar att samordningen av kommunikationen kring georisker inom såväl beställarorganisationen som den projekterande konsultorganisationen ligger på den relativt nya rollen risksamordnare. Studien har identifierat minst en risksamordnare inom beställarorganisationen och minst en risksamordnare inom den projekterande konsultorganisationen. Risksamordnarens främsta verktyg för risksamordningsarbetet är den så kallade risklistan som ska samla och beskriva de identifierade riskerna, samt dokumentera eventuella åtgärder som beslutats kring respektive risk. Det finns alltså flera olika risklistor inom ett och samma tunnelprojekt eftersom det finns flera olika  risksamordnare. Studien visar också olika utmaningar som uppkommer i arbetet med risklistorna.

Övergripande ger intervjuerna bilden av att informationen kring georisker ofta är tydlig när den överförs från den projekterande konsultorganisationen till beställar-organisationen, men att återkopplingen från beställarorganisationen till den projekterande konsultorganisationen är mer otydlig. Intervjuerna visar också att kommunikationen inom den projekterande konsultorganisationen, dvs mellan olika konsultgrupper, är i behov av förbättring.  

Baserat på resultaten av studien ges ett antal förslag hur riskhanteringsarbetet i svenska tunnelprojekt kan förbättras, specifikt avseende organisering av kommunikation kring georisker. Ett konkret förslag är att beställaren tar fram policydokument och/eller vägledningar för hur riskhanteringsarbetet förväntas gå till inom och mellan beställare och projekterande konsultorganisation. Liknande policys och vägledningar kan också tas fram på branschnivå, exempelvis hos branschorganisationer eller föreningar.

Tunnel projects for transport infrastructure are often large, complex, and high-risk investments that involve advanced technical solutions as well as logistical, political, and organisational challenges and conflicting objectives. Historical experience furthermore shows that many large tunnel projects exceed both their planned schedules and budgets. These projects combine high complexity with considerable uncertainty, not least regarding ground conditions, which places substantial demands on the client’s ability to organise both communication and risk management activities. Inadequate communication is a frequently recurring cause of problems in construction projects, and effective communication within the project as well as with its stakeholders is often regarded as a key factor for project success.

This report addresses communication related to georisks in large tunnel projects, as this type of risk is particularly challenging and involves many different actors engaged in identifying, assessing, managing, and communicating these risks. In addition, there is a lack of scientific studies and literature that shed light on the communication of georisks in large tunnel projects.

The purpose of the study was to investigate, identify, and map communication related to georisks during the planning and design phases of large tunnel projects, and to further develop existing practices and guidelines. The objective was to create better conditions for clients and design consultants to plan and organise communication related to georisks so that tunnel projects can be carried out more efficiently. Semi-structured interviews were used as the research method. The interviewees held different roles within the client organisation and the design consultant organisation during the design of two major Swedish rock tunnel projects. The interviews were conducted during the period 2022–2025.

The interview results provide a picture of how different roles involved in planning and design communicate information about georisks within the tunnel projects. The study shows that the coordination of communication related to georisks within both the client organisation and the design consultant organisation is assigned to the relatively new role of risk manager. The study identified at least one risk manager within the client organisation and at least one risk manager within the design consultant organisation. The risk manager’s primary tool for risk coordination is the so-called risk register, which is intended to compile and describe the identified risks and to document any measures decided for each risk. Consequently, several different risk registers exist within a single tunnel project, as there are multiple risk coordinators. The study also identifies various challenges associated with the use of these risk registers.

Overall, the interviews indicate that information related to georisks is often clear when transferred from the design consultant organisation to the client organisation, whereas feedback from the client organisation to the design consultant organisation is less clear. The interviews further show that communication within the design consultant organi-sation, that is, between different consultant groups, needs improvement.

Based on the study results, proposals are presented for improving risk management practices in Swedish tunnel projects, with a specific focus on the organisation of communication related to georisks. One concrete proposal is that the client should develop policy documents and/or guidelines describing how risk management is expected to be conducted within and between the client organisation and the design consultant organisation. Similar policies and guidelines could also be developed at an industry level, for example by industry organisations or professional associations.

Tunnels passing through faults and weakness zones require more extensive support. To secure the tunnel from collapse during excavation, pre-support known as spiling is a frequently applied solution. For more disintegrated rock mass conditions, the preferred technical solution is often thicker steel pipes (hereby referred to as pipe spiles). When pipe spiles are used as pre-support in disintegrated rock masses, a potential failure mode is progressive fall-out of smaller rock blocks between the spiles. In this paper, the critical block size for which pipe spiles can be applied without progressive failure was studied. Small-scale laboratory tests were conducted with the use of a specially manufactured box made of steel plates and plexiglass panels.The width, depth and height of the box was approximately 0.7 m, 0.7 m and 0.6 m respectively. Steel tubes, representing pipe spiles, were inserted into the box through holes drilled in the plexiglass panels. Gravel, representing the surrounding rock mass, of various particle sizes between 2 and 32 mm was filled in and compacted. The locking mechanism was then released, and the subsequent re-arrangement of granular material was observed. The results of the tests are presented and discussed with respect to the required spacing between pipes to prevent this mode of failure. For the specified testing conditions, the critical limit of the ratio between the pipe spacing and block size was determined to be between 3.7 and 4.6 for a rougher steel-rock interface and between 2.8 and 3.2 for a smoother one representing a pure steel-rock interface.

Budget overrun and schedule delay of infrastructure projects result in the mismanagement of huge amounts of resources. Studies show that accounting for uncertainties in time and cost estimation of such projects can help the decision-makers in better understanding the involved risks. Several probabilistic models have been developed during the last two decades to facilitate such estimations. A common aspect of all these models is the subjective assessment of unit activities' duration, which affects the accuracy of the estimated time and cost significantly. Despite this, the mechanism governing the variability of unit activities' duration has seldom been studied. Thus this paper focuses on addressing this gap by using a unique set of data from a tunnel project. The variability in unit activities' duration (construction performance variability) is governed by three main components: typical performance variability, minor machinery delays and minor performance delays. Using these components, a novel method for modelling construction performance variability in probabilistic time estimation of tunnelling projects is proposed. The application of the proposed method is demonstrated through a case example with a discussion on its important aspects, advantages and limitations. The findings of this paper offer a resource to improve the accuracy of time estimation for tunnelling projects.

Design of support for rock slopes has traditionally used deterministic safety factors for verification of the structural safety. Following the introduction of limit state design concepts to modern design codes like the Eurocodes, there is a strong trend to implement limit state design also to rock engineering structures. A recent example is the second generation of Eurocode 7, which suggests that limit states be set up for bolted rock slopes and verified using partial factors. There is, however, a lack of research regarding the applicability of limit state design principles in general – and the partial factor method in particular – to bolted rock slopes. In this short paper, we investigate the appropriateness of applying limit state design principles to bolted rock slopes. We aim to establish a way forward toward a consistent and rational design approach for rock slopes that satisfies societal safety requirements without being overly conservative, while still being user-friendly to practicing rock engineers.

The partial factor method is the most common approach to verify structural safety in Eurocode 7. Given the ongoing discussion on the European level to include also underground excavations in rock in the scope of the Eurocodes, there is a clear need to investigate the applicability of partial factors to the design of rock tunnels. However, implementing fixed partial factors, in accordance with the suggestion in the current Eurocode 7, may not be appropriate to account for the large uncertainties and variable conditions prevalent in rock engineering. This paper studies the critical characteristics and underlying assumptions of different reliability-based partial factor formats. The suitability of the analyzed partial factor formats to evaluate safety is analysed and discussed with reference to a design example of a rock-shotcrete interaction system for support against block failure in an underground opening. The results show that reliability-based partial factor methods outperform the traditional partial safety format suggested in the Eurocode in terms of accuracy and consistency.

The effective shear strength is a critical parameter for evaluating ultimate and serviceability limit states of geotechnical structures. To conduct a fully probabilistic assessment or to determine characteristic values according to the second generation of Eurocodes, it is essential to quantify the uncertainty of ground properties due to inherent variability, measurement error, transformation, and statistical uncertainty. However, unlike other ground properties, shear strength parameters are not directly measured, even in laboratory settings. Instead, they are derived from the relationship between shear and normal stresses, making uncertainty analysis nontrivial. This study applies two regression approaches and the extended multivariate approach (EMA) to estimate the effective friction angle for non-cohesive soils. Firstly, an ordinary least squares (OLS) and a Bayesian linear regression (BLR) approach are utilized to quantify the uncertainties inherent in data from direct shear and tri-axial tests from an offshore wind project. Secondly, the EMA is utilized to integrate cone penetration tests (CPT) and shear test data via Bayesian inference. The results are discussed based on characteristic values according to Eurocode 7 (EN 1997-1:2024) highlighting the importance of accurately and precisely estimating mean and uncertainty.

Budget overrun and schedule delay of infrastructure projects result in mismanagement of huge amounts of resources. Studies show that accounting for uncertainties in time and cost estimation of such projects can help the decision-makers in better understanding the involved risks. Several probabilistic models have been developed during the last two decades to facilitate such estimations. A common aspect of all these models is the subjective assessment of unit activities’ duration, which affects the accuracy of the estimated time and cost significantly. Despite this, the mechanism governing the variability of unit activities’ duration has seldom been studied. Thus, this paper focuses on addressing this gap by using a unique set of data from a tunnel project. The variability in unit activities’ duration (construction performance variability) is governed by three main components: typical performance variability, minor machinery delays, and minor performance delays. Using these components, a novel method for modeling construction performance variability in probabilistic time estimation of tunneling projects is proposed. The application of the proposed method is demonstrated through a case example with a discussion on its important aspects, advantages, and limitations. The findings of this paper offer a resource to improve the accuracy of time estimation for tunneling projects.

Time and cost estimation of tunnelingprojects is usually performed in a deterministic manner.However, because the deterministic approach isnot capable of dealing with uncertainty, probabilisticmethods have been developed over the years to betteraccount for this problem. Three models of this typeare the Decision Aids for Tunneling (DAT) and twomodels developed at KTH Royal Institute of Technologyand the Czech Technical University in Prague.To conduct a probabilistic time and cost estimation,it is important to understand and account for not onlythe uncertain factors that affect the project time andcost but also the involved parties’ different interestsand contractual responsibilities. This paper developsa risk model for the specific purpose of time andcost estimation of tunneling projects. In light of thismodel, the practical application of the three probabilisticmodels is discussed from a risk-aware decisionmaker’sperspective. The acquired insights can behelpful in increasing the experts’ risk-awareness inmodeling time and cost of tunneling projects.

Considering that a large part of Sweden is covered by glacial till, which is classified as an unsorted sediment formed by glaciers that can contain fragments of rock known as boulders, driving piles constitutes a substantial economic risk. Piles driven into glacial till may encounter boulders and undergo structural damages leading to premature refusal and to the loss of piles. Even though geotechnical investigations as of today form a solid basis for the design of pile foundations, the unpredictable presence of boulders and their hard resistance to breakage, makes it challenging to penetrate boulders by standard investigation methods. Currently, the only available source of information used by the Swedish construction industry to confirm the existence of boulders is a dynamic penetration test known as soil–rock sounding. Relying on the results from only one testing method may for most projects underestimate the existence of boulders and their potential impact to piles, leading to an unsuitable design of the entire piling system. This paper discusses the benefit in using the input from soil–rock soundings for quantifying the probability of boulder encounters in glacial till based on Poisson point process.