Streamlining Tunnelling Projects through BIM

Abstract

Currently, most academic discourse looking at the advantages of Building Information Modelling (BIM) is kept very general. This article evaluates how the use of BIM affects social and economic aspects of seven different tunneling projects. The analysis is based on internal project documentation and on-site visits, resulting in the authors subjective perception. Due to a confidentiality policy given by ongoing projects, the official documentation is anonymised. On one hand, the social analysis considers teamwork aspects. On the other hand, the economic assessment considers the optimised use of resources. The conclusion shows that the correct and complete implementation of all methods and tools from BIM increase social and economic sustainability, optimising project delivery in tunneling. As a result, among other things, on par communication, teambuilding, and mutual appreciation contribute to an increased social sustainability. Economic sustainability is directly associated with resulting short distances within the team and easy communication and coordination. Consequently, this leads to faster problem solving and a streamlined project execution.

1. Introduction

In most academic discourse, the added value of Building Information Modelling (BIM) in tunnelling projects is mentioned in general terms and concrete examples from the perspective of the various sustainability goals are only discussed in a subordinate manner. A recent study on sustainability in tunneling came to the conclusion that there is only one notable publication covering this specific topic [1]. Therefore, this article takes a look at BIM in tunnelling—Tunnel Information Modelling (TIM)—in the context of social and economic sustainability and the resulting added value.

The concept of corporate social responsibility (CSR) is based on the model of three pillars [2,3]: environmental, economic, and social sustainability which are found to be equal. Moreover, the model has found its way into various political principles regarding sustainability [4,5]. Since current research regarding sustainability in tunneling or BIM focuses mostly on ecological and economic sustainability, this work concentrates on the social dimension of sustainability, the resulting increase in economic sustainability, and thereby the streamlining of tunneling projects through BIM [1,6]. In order to narrow down the general definitions of sustainability in tunneling, we have to describe sub-areas of social and economic sustainability in the context of TIM. Regarding social sustainability in the field of TIM, our approach primarily focuses on the structures and work within a team or small group. We therefore utilise our findings from a qualitative study on the topic of current developments within BIM in tunnelling [7]. With respect to economic sustainability, our focus is mostly based on evaluating the improved use of resources, which might as well result from an increased social sustainability.

In order to determine whether BIM leads to a streamlining of tunnelling projects under the aspect of social and economic sustainability, several TIM projects in various project phases are examined and evaluated. These projects are scientifically supported by iBT—the Unit of Construction Management and Tunnelling from the University of Innsbruck regarding the topic of BIM. To conduct this study, an interim evaluation on seven different projects was performed. The focus hereon lay on the project culture as well as the project progress. Another important point of consideration was the impact of the different approaches and points in time of the implementation of BIM as well as the comparison of different projects with completely different requirements. The synopsis of these considerations provides a clear current picture of the increased and streamlined performance in TIM projects through improved social and economic sustainability.

2. Methodology

As stated, the basis for this research is a variety of research projects, which all focus on implementing BIM in tunnelling projects. Therefore, the individual TIM projects are briefly described as of May 2022 and existing interim objectives are stated. Furthermore, applied BIM structures [8,9], as well as the implementation of BIM in the course of the project in terms of time and scope, are briefly explained. The basis for this is provided by project tender documents, ongoing project documentation, meetings and their outcome, ongoing project work, and especially the results of individual conversations with those involved in the project. This is the basis for the formulation of the initial research results on the topic at hand.

Due to the necessary confidentiality over the fact of the different project stages, no project documents or statements can be quoted as sources. Moreover, all project information is anonymised to keep it confidential. Nevertheless, we want to supply an overview of the sources which were accessible to us. For the evaluation, not only official project documentation, e.g., tender documents, were used, but also meeting minutes and notes from several discussions and conversations. Consequently, the result is our interpretation from observing and supporting the projects, but they can hardly be quantified.

The discussion will include a comparison, an evaluation, and an outlook regarding the social and economic sustainability of the projects. In the conclusion, the potential benefits of BIM in tunnelling for improved social and economic sustainability and subsequently streamlined project delivery are described and summarised with regard to the interpreted results.

3. Results

All projects considered are pilot projects of Austrian public bodies on the topic of BIM in tunnelling. This status was deliberately set by those responsible, so that there is sufficient opportunity for further development and possibly even failure in the sense of a pilot project, which enables ongoing optimisation and streamlining. The following project descriptions reflect the authors’ perception from our work within these projects. We structured the project descriptions on the basis of their project phase within the life cycle. Figure 1 gives an overview of the allocation of the considered projects to the different project phases.

Accordingly, an overview of the key data for each project is shown in

Table 1. Key data of projects in regard to the tunnel and the BIM-implementation.

Project	Area	Length	Duration	Project Phase	Participants
Project 1	urban	950 m	since 2021 5 years	design	4: employer; design consortium; BIM consultant; iBT
Project 2	rural	4 km	since 2021 2 years	design	2: employer and iBT
Project 3	rural	21 km	2016–2021 5 years	approval	7: employer, four design offices, authorities, iBT
Project 4	rural	1.08 km	since 2021 approx. 6 years	procurement	9: employer, four design offices, construction supervision, geodesy, overall BIM coordinator, iBT
Project 5.1	rural	1.2 km	since 2020 approx. 5 years	design and procurement	8: employer, 5 design offices, BIM manager, iBT
Project 5.2	rural	2.6 km	since 2020 approx. 5 years	design, procurement, construction	6: employer, two design offices, BIM-manager, overall BIM coordinator, iBT
Project 6	rural	2.8 km	since 2021 approx. 2 years	operating phase	2: employer and iBT

to simplify comparisons between the different projects. Together, these allow for an easier understanding of the structure of the conclusions and comparisons of the different requirements for the model and for BIM. Therefore, Figure 1 and Table 1 have to be kept in mind when studying the following project descriptions.

3.1. Project 1

The first project is an urban branch line which is to be extended from its current underground end station. Due to a very tight schedule, the employer has decided to carry out the project with BIM. The employer wants to develop new structures for the model elements and the associated properties. Two requirements arise for this task. It has to be compatible with the existing parts of the branch line and be ready for further expansions after the completion of this extension.

Compared to similar projects, this project has set itself a tight schedule and is making good progress towards achieving its intended targeted goals. In line with the BIM method, the employer worked very closely and openly with the design consortium to define the necessary requirements for this project and also work on innovative solutions for the emerging issues. Due to the demand of a conflict-free model, not only design phase specific problems were dealt with, but critical, already identified issues from future project phases were solved as well.

3.2. Project 2

Project 2 comprises roughly 4 km of twin tunnels. Construction of the tunnel carcass in this project has already been completed. The next step is the design of the tunnel equipment, which is going to be completed BIM-based. In order to do so, the employer has decided to create an as-built model of the built tunnel structure and use this as a basis for the tunnel equipment designing. The employer works together with iBT in order to develop automation-supported processes, workflows, and data structures for the described requirements.

The employer’s requirements demand a modelling approach which on one hand can easily be extended; on the other hand, it has to allow for future additions and adjustments to the developed data structures. The solution for both requirements is reached with a computational design approach within BIM. By creating (semi-)automated workflows, which can be re-run when anticipated changes become effective, a powerful tool is created.

Another positive effect from this work, is the corporate social responsibility in practice. Due to ever rising operational periods for infrastructure, the employer as a public body has chosen a forward-looking approach to operate the tunnel as sustainable as possible. One of the advantages in this context is the extended service lifetime with a minimum of operational interruptions.

3.3. Project 3

The scope of this project is to increase the capacity of an existing railway line with two additional tracks which run mostly within a twin-tube single-track tunnel system. It was realised as a BIM pilot project during the phase of an environmental impact assessment. The focus of BIM implementation lay on covering all relevant topics for the environmental impact assessment, including tunnel structures, bridges, track, roads, geology, and hydrogeology. At the beginning of the project, missing specifications from the employer, software issues, and unfinished data structures decelerated the projects progress. Following joint efforts of all project stakeholders, reputable results were finally achieved.

One of the main results from this project is the introduction of a mandatory and capable common data environment (CDE). Prior to this step, all stakeholders communicated mostly via email and collaborative work was thereby time-delayed and not in line with a BIM approach. With the mandatory CDE, several birds were killed with one stone. Now all stakeholders had access to up-to-date models and data in general, which allowed for an integral and collaborative approach. It also made it possible to easily view coordinated models, without the authoring software.

Linked to the introduction of the CDE is the possibility to give the approval authorities a simple tool to view the models. With a browser-based model viewer and the appropriate permissions for the authorities within the CDE, a preliminary coordination can be achieved, without the need for special software on the part of the authorities. Furthermore, a powerful and very visual tool for public outreach is created for the authorities as well as the employer.

3.4. Project 4

The project comprises the services for the implementation of the construction of a new second tunnel tube, as well as the partial demolition and new construction of the existing structure (first tube). It involves two 2-lane road tunnels with a length of 1.08 km and is carried out as a BIM pilot project regarding the topics of design, tendering as well as construction and billing.

As part of the contract, the employer provides a “Guideline for the modelling of infrastructure models” as well as a default data structure. These serve as the basis for processing the project and the overall BIM coordinator checks the compliance with the specifications. Furthermore, it is the employer’s goal to further develop both with each project, but on a company-wide scale rather than on a project-specific scale.

It is evident that the project benefits from the fact that the employer has a clearly defined data structure in this early design phase. In addition to the employer, the overall BIM coordinator of the ongoing project was also involved in the development of this BIM data structure. This results in synergies and optimised workflows right from the start of the project. Furthermore, there are concrete projects and time schedules for data drops, such as monthly data drops and clear agendas for meetings. The overall BIM coordinator consequently provides classic project management. Having these structures in place and in operation makes it easier to enter the project at a later stage.

In the current course of the project, collaborative work and a positive working atmosphere are evident in the core design team. The areas of responsibility are clearly separated, but emphasis is placed on an interdisciplinary exchange of information. The existing 2D preliminary plans were coordinated and transferred to the BIM design. In the ongoing design process, there is constant constructive collaboration, in which a wide variety of issues are also openly discussed and dealt with. To simplify communication, an issue management software was introduced to enable efficient processing and solving of collisions and to optimise the project flow at an early stage. This is the result of a well-coordinated project team that generates a noticeably faster project process through the joint BIM processing of the project.

3.5. Project 5

Project no. 5 is divided into the site clearance (Project 5.1) and the associated construction of a carcass tunnel (Project 5.2). Both subsections are carried out as BIM pilot projects and are part of a larger infrastructure project.

BIM design started in the first quarter of 2021 with the detailed design. iBT began the scientific support of the projects in the last quarter of 2021. The separation into two single projects of the carcass tunnel and the associated site clearance took place in 2022 due to the different design and tendering levels and the differing parties involved. BIM management (structural engineering specialist) and the overall BIM coordinator (infrastructure designer) remained unchanged from this separation.

3.5.1. Project 5.1

The construction activities for the site clearance include forest clearance, establishing a construction site setup area, creating construction site access and exit, building a temporary road, drainage, various utility line relocations, and the construction of protective walls and noise barriers.

BIM is used in the designing of the tendering process and the preparation of tender documents, construction designing, plausibility checks for billing, as well as as-built modelling and maintenance planning.

The implementation of BIM in the design process of the project took place in 2021 with the detailed design and tender design. The BIM manager position is held by a BIM specialist with a background in structural engineering. The overall BIM coordinator is also the designer for the site clearance. This dual function results in significantly shorter work processes due to the in-house handling of a wide range of tasks. Due to the compact project team, the BIM processes are handled in an unagitated manner. Unresolved issues, also due to missing or unclear Employer’s Information Requirements (EIRs), were dealt with promptly and unpretentiously. First added values became apparent as soon as BIM aided design began. For example, in the course of the initial design activities for the foundations of the noise barriers, it was recognised that there was a collision with the existing gas pipeline. As a result, the design could be adjusted at an early stage. In the course of the project, it became apparent that the model deliveries and model checks worked consistently.

The models were created up to the specified tender readiness level and, in the course of construction, the billing is already carried out model-based. The as-built adaptions of the models have to be implemented by the designers. Thus, the model sovereignty remains with the designer.

3.5.2. Project 5.2

The measures of this subsection include the construction of the pre-cut for a construction site setup area and the tunnel groundbreaking of the carcass tunnel, the excavation and securing of the south tunnel (total length 2.6 km), the three orthogonally running blind tunnels for turning niches (lengths 7–27 m), six cross passages (lengths 6–22 m), as well as the north tunnel (length 110 m). This project processes the construction of an exploratory and later rescue tunnel for a railway tunnel.

BIM is used in the design of the tender and the preparation of the tender documents, construction designing, plausibility checks for billing, as well as as-built modelling and maintenance planning.

The implementation of BIM in the design process of the pilot project took place in 2021 with the detailed design and tender design. iBT started with the scientific monitoring of the project in the 4th quarter of 2021.

The position of BIM management is filled by a BIM specialist with a background in structural engineering. The overall BIM coordination is carried out by an infrastructure design office. Further project participants are exclusively infrastructure and tunnelling specialists, including tunnel designers and geologists.

The BIM implementation for this project and during this specific project phase meant that existing 2D designs from various trades had to be reworked for the BIM approach. From an outside view, it seemed as if the BIM process was off to a slow start. In fact, however, reaching an important employer decision regarding the tunnel sealing concept led to a considerable delay in the start of the BIM design. The resulting reduced time to carry out the necessary modelling work showed that a BIM approach can lead to time-saving and efficient results. Nevertheless, once again from an outside view, further potentials for improvement with regard to cooperation, collaboration, and team structure were identified. One of the reasons for time loss might have resulted from the different technical backgrounds and the resulting translation problems between the BIM management and the design offices. It repeatedly became apparent that issues led to unnecessary model adaptions and therefore showed that not only specifically defined employer requirements, but also a harmonious team are required.

In the end, models were created up to the specified tendering stage and in the course of construction, the billing will also be carried out model-based.

3.6. Project 6

Project 6 is a research project and comprises the post-modelling by the staff of iBT of the new construction of a second tube for a road tunnel which was completed in 2020. The aim is to create an as-built model of the ground according to the geological documentation of the 2016–2017 tunneling activities, as well as the tunnel structure in its final state and thereby in its operational state. The modelling is carried out “off the shelf”, without detailed requirements from the employer. The employer’s requirements for a BIM data structure and the modelling process (“Guideline for the modelling of infrastructure models”), which were developed in 2021–2022, will be evaluated in the course of the post-modelling work.

It should be noted in advance that the construction of this project has been completed and it is in operational phase now. Project and data management and data storage were consistent, comprehensible, and well-structured over the period of design and construction. New project members were able to quickly get an overview of the correct data storage and retrieval.

During the initial data collection for the post-modelling of the ground and the structure, a few results were already worked out. Data structures, no matter how good they were for project processing, cannot simply be used for BIM post-modelling. Existing data structures, such as formats and storage, cannot be adopted without friction. For example, certain data formats were not contractually required because they were not considered necessary. Thus, all design documents for the project were requested as unchangeable PDF files, whereas changeable data formats, such as Word, Excel or dwg.’s are not comprehensively available.

The necessary retrieval, sorting, filtering, and processing of existing data takes an incredible amount of time and expertise. Furthermore, it becomes apparent that historical knowledge of the construction site is also an advantage. By establishing a good working relationship with the involved design offices, it has become possible to obtain basic data in a reusable form in coordination with the employer. However, this is also associated with additional effort on both sides and includes data requests, searching and finding, transmitting, and processing.

It can therefore be concluded from the initial post-modelling work that harmonised structures prevent this increased time expenditure. This means that basic data can be collected and processed by a BIM modeler, for example, even without the corresponding expertise or knowledge of the construction site.

With appropriate data preparation and definition of the modelling objective, the BIM-compliant process can be started effectively, and initial results can be generated quickly.

4. Discussion

The discussion provides a comparison and evaluation of the results. As stated, the considered projects were specifically evaluated for this article with regard to social and economic sustainability. In view of the different project phases, among other things, the comparison of the projects shows that an increase in sustainability is possible with the use of BIM. In the following, these sustainability improvements are discussed for the individual projects.

Project 1: From the beginning of the project, a joint design approach is used. Especially in this early project phase, this resulted in a constructive and solution-oriented work philosophy. The joint development of the project requirements and the execution plan is socially sustainable due to the necessary teamwork. Due to the resulting early coordination on key design issues, efficiency and economic sustainability are increased.

Project 2: With the developed (semi-)automated modelling workflows themselves, a very economically sustainable approach was chosen. Due to the fact that anticipated future changes were integrated into the considerations from the very beginning, the additional effort for the development of more challenging (semi-)automatic workflows is more than compensated. These workflows are also the basis for the social responsibility of the employer, by exceeding the current legal requirements regarding model-based tunnel operation. In this case, social sustainability in a wider sense results in economic sustainability, when looking into the future.

Project 3: The introduction of a CDE led to a more collaborative and integral workflow and thus increased the social sustainability. A resulting effect is increased economic sustainability through a more efficient design process and more generally speaking, a quicker path towards the project’s approval. Linked to the approval is the possible integration of the approval authorities within the CDE which could lead to a closer coordination between employer, design offices, and authorities. In general, similar to the introduction of the CDE, this new possibility leads to an increase in social and consequently economic sustainability.

Project 4: The combination of a small initial BIM design team and a coordinated data structure results in a harmonised project workflow. This facilitates the frictionless growth of the project team. Social sustainability is based on considerate project management. Short distances, undisputed technical competence, and qualified interdisciplinary coordination lead to efficient work processes, which in turn is economically sustainable.

Project 5.1: The dual function of the BIM coordinator and designer automatically results in greater efficiency in processing, among other things through time savings. Leaving the model sovereignty with the designer during construction saves time and resources, since, for example, the professional and technical familiarisation with the model is no longer necessary. Being a harmonious and smaller design team enables a socially sustainable exchange within the project team, as for instance, the contact persons are known and questions and feedback can be given directly.

Project 5.2: It has been shown that even project teams that are not free of friction can become more sustainable through BIM. Individual conflicts and their solutions result in increased resilience of the participants in terms of stress management due to the inharmonious project team and the translation issues that occurred between BIM management and specialist design offices. This falls into the category of social sustainability and the learning effect. The project goal of future-proof BIM processing was achieved despite different approaches.

Project 6: From the initial post-modelling work, it is evident that harmonised structures can minimise time expenditure and thus be more economically sustainable. With the appropriate preparation of the data and the definition of the modelling objective, initial results can be generated quickly and thereby economically.

In the comparison of the projects, it is clearly evident that the degree to which sustainability can be increased depends to a large extent on the timing of the implementation of BIM in the course of the project and on the people involved.

The keys to social sustainability, which includes learning effects and improved project communication, are good project culture, collaborative working and development, and conflict resolution. Economic sustainability, and thus the saving of resources, is largely based on good teamwork, short distances, and well-considered workflows.

5. Conclusions

Considering the social and economic sustainability aspects of the projects under consideration, the key finding is that, on a small scale, social sustainability primarily comprises teamwork, appreciation, and knowledge gain. The ideal combination of these three topics strengthens the professional and social competences of all stakeholders. Furthermore, it leads to a knowledge transfer to the next projects (learning effects) and to a necessary paradigm shift in project management. On a larger scale, this leads to improved and more descriptive project and science communication—which also goes beyond the project teams.

Economic sustainability with BIM is also based on the improved use of resources. Harmonised, structured workflows enable more efficient, collaborative approaches. This results in shorter coordination times and better resource planning and utilisation. As a result, projects are completed more quickly from cradle to cradle, i.e., optimised projects.

In order to achieve the goal of streamlining tunnel projects through BIM, the following requirements are necessary in terms of social and economic sustainability.

The early establishment of a “comfort zone” for project participants through coordinated and harmonised structures in data and project management leads to shorter communication and work paths. Mutual appreciation and awareness of the boundaries of one’s own competencies are indispensable in this context. This makes it possible to develop targeted solutions, while ensuring a view beyond the end of one’s nose. Obstructive translation problems between disciplines must be avoided, as this generates project delays. Short distances within the project team in terms of communication, technical exchange, coordination, and review lead to quick solutions to problems and efficient project execution. Any conflicts that arise can be solved more harmlessly within these balanced structures. Other important aspects are the need to ensure that digitalisation does not permanently increase costs without simultaneously becoming more efficient, and that sufficient resources—both human and technical—are available to be able to provide the necessary services.

The early implementation of BIM in tunnel construction and the correct use of all tools (CDE, etc.) increases the social and economic sustainability of tunnelling projects. Ultimately, this also requires a change in the course of official procedures.

As these results represent the authors’ perception and interpretation, a further step has to be a comprehensive series of interviews within BIM project teams to elicit the perceptions of social and economic sustainability through BIM in a business environment. For this in-depth work, an interdisciplinary cooperation with social scientists should also be considered in order to do justice to the topic of social sustainability.