Department of Architecture and Civil Engineering Division of Construction Management CHALMERS UNIVERSITY OF TECHNOLOGY Master’s Thesis BOMX02-17-41 Gothenburg, Sweden 2017 Planning for Efficiency at Karlatornet Master’s Thesis in the Master’s Programme Design and Construction Project Management Oskar Andersson Simon Månsson MASTER’S THESIS BOMX02-17-41 Scheduling for Efficiency at Karlatornet Master’s Thesis in the Master’s Programme Design and Construction Project Management Oskar Andersson Simon Månsson Department of Architecture and Civil Engineering Division of Construction Management CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2017 Planning for Efficiency at Karlatornet Master’s Thesis in the Master’s Programme Design and Construction Project Management Oskar Andersson Simon Månsson © OSKAR ANDERSSON, SIMON MÅNSSON, 2017 Examensarbete BOMX02-17-41/ Institutionen för bygg- och miljöteknik, Chalmers tekniska högskola 2017 Department of Architecture and Civil Engineering Division of Construction Management Chalmers University of Technology SE-412 96 Göteborg Sweden Telephone: + 46 (0)31-772 1000 Cover: Karlatornet at Lindholmen, Gothenburg, (http://www.serneke.se/projekt/karlatornet/) Department of Architecture and Civil Engineering, Göteborg, Sweden, 2017 I Planning for Efficiency at Karlatornet Master’s thesis in the Master’s Programme Design and Construction Project Management Oskar Andersson Simon Månsson Department of Architecture and Civil Engineering Division of Construction Management Chalmers University of Technology ABSTRACT Construction of high-rise constructions has during past decades seen an incremental increase, which is now also evident in the Swedish market with the forthcoming construction of Karlatornet at Lindholmen in Gothenburg. When constructing high-rise constructions new constraints are imposed, connected to height and limited space at each floor, which calls for planning methods adapted for the challenges that emerges. However, present planning methods do not contribute sufficiently to value adding processes in regards to both production and logistics. Thereby, this master’s thesis has been conducted to investigate how Lean Construction (LC) and Building Information Modeling (BIM) should be incorporated when planning for production and logistics, and further how to synchronise production and logistics at Karlatornet to attain a higher efficiency. Research on LC and BIM is widespread, however commonly separated. This thesis aims to contribute in closing the gap between LC and BIM research in high-rise constructions. Further, the thesis intent to provide underlying barriers from both a theoretical and practical view to evaluate why implementation is lingering. In order to answer the research questions of this thesis, a qualitative research methodology was chosen, including a literature review followed by interviews from the industry regarding different planning methods. Focus has been directed towards planning methods within LC and how these can be combined with BIM, where Location-based Scheduling (LBS) and Location-based Management System (LBMS) has been applied to production. In regards to logistics, focus has been aimed towards Just In Time (JIT) which together with the LBS results in Location-based Planning (LBP). It has been concluded that to incorporate LBP in the production planning at Karlatornet, focus must first and foremost be shifted towards creating organisational and technical alignment within the own organisation. This will in turn provide means for creating further alignment throughout the production chain. JIT should be incorporated in logistics planning to support production, as failure can lead to downtime and obstruction for production resulting in major costs. Therefore, risk is entailed due to the repetitive characteristics of high-rise construction, which can be found at Karlatornet, where the whole production chain can be affected. There is much to do regarding synchronised planning for production and logistics at Karlatornet. Alignment is yet to be reached within the perspectives separately, giving that it cannot be reached when combined. Workshops and meetings are required to create systems which can be used from subcontractor to supplier in all parts of construction. Key words: Lean construction, High-rise construction, Push and pull, Location-based planning, Just in time, 4D BIM, and Virtual design and construction. II Planering för Effektiva Bygg- och Logistikprocesser vid Karlatornet Examensarbete inom masterprogrammet Design and Construction Project Management Oskar Andersson Simon Månsson Institutionen för bygg- och miljöteknik Avdelningen för Construction Management Chalmers tekniska högskola SAMMANFATTNING Byggnation av höga konstruktioner har under de senaste decennierna sett en successiv ökning, en trend som även den svenska marknaden blivit influerad av. Detta kan konkretiseras med den kommande byggnationen av Karlatornet på Lindholmen i Göteborg. Uppförandet av höga konstruktioner innebär nya utmaningar, kopplade till höjden på byggnaden och begränsad yta på varje våningsplan, därav måste planeringsmetoderna som används vara anpassade för att möta dessa utmaningar. Nuvarande planeringsmetoder bidrar emellertid inte i tillräcklig utsträckning till värdeskapande processer för produktion och logistik. Detta examensarbete har således genomförts för att undersöka hur Lean Construction (LC) och Building Information Modeling (BIM) kan implementeras vid planering av produktion och logistik. Vidare har arbetet undersökt hur synkronisering av produktion och logistik vid Karlatornet bör utföras för att uppnå en högre effektivitet. Forskning om LC och BIM är vidsträckt men generellt sett separerad där detta examensarbete syftar till att minska klyftan mellan LC och BIM-forskning relaterat till höga konstruktioner. Arbetet avser även att påvisa barriärer ur både en teoretisk och praktisk syn för att utvärdera varför implementation i branschen varit långdragen. För att kunna ge svar på arbetets frågeställningar valdes en kvalitativ forskningsmetod, vilken inkluderade en litteraturgenomgång följt av intervjuer med representanter från branschen gällande olika planeringsmetoder. Fokus har riktats mot planeringsmetoder som ingår i LC och hur dessa kan kombineras med BIM, där Location-Based Scheduling (LBS) och Location-Based Management System (LBMS) har tillämpats på produktion. När det gäller logistik har JIT legat i fokus som tillsammans med LBS resulterar i Location-based Planning (LBP). För att implementera LBP i produktionsplaneringen vid Karlatornet har arbetet konstaterat att fokus först och främst måste riktas mot att skapa en gemensam inriktning inom den egna organisationen. Detta för att skapa ytterligare förutsättningar för en projektövergripande tydlighet som inkluderar samtliga parter i kedjan. JIT bör implementeras i logistikplaneringen eftersom förseningar i produktionscyklerna kan leda till driftstopp och hinder för produktionen som medför stora kostnader. Mängden repetitiva arbeten vid höga konstruktioner, vilka kan härledas till Karlatornet, medför därför risker eftersom hela produktionskedjan påverkas. Det finns mycket att göra för att uppnå en synkroniserad planering för produktion och logistik vid Karlatornet. En gemensam inriktning är ännu inte uppnådd i varken produktion eller logistik, vilket ger att en gemensam inriktning inte heller kan nås när de kombineras. Nyckelord: Lean construction, High-rise construction, Push and pull, Location-based planning, Just in time, 4D BIM, samt Virtual design and construction. CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 III Contents ABSTRACT I SAMMANFATTNING II CONTENTS III PREFACE V NOTATIONS VI LIST OF FIGURES VII 1 INTRODUCTION 1 1.1 Background 1 1.2 Objectives 3 1.3 Research questions 3 1.4 Delimitations 3 1.5 Thesis outline 3 2 RESEARCH METHODOLOGY 5 2.1 Research design 5 2.2 Literature research 6 2.3 Ethical conduct 7 2.4 Data collection and analysis 7 2.5 Trustworthiness 9 3 THEORETICAL FRAMEWORK 10 3.1 Planning for production 10 3.1.1 Push and pull in production 11 3.1.2 Flow through activities or locations 13 3.1.3 Location-based planning 13 3.1.4 BIM for production 16 3.1.5 Coordinating production 18 3.2 Planning for logistics 19 3.2.1 Push and pull in logistics 20 3.2.2 Supply logistics 20 3.2.3 Just in time 22 3.2.4 BIM for logistics 23 3.2.5 Coordinating logistics 24 3.3 Synchronising production and logistics planning 25 3.3.1 Push and pull 25 3.3.2 Integrating LBS and JIT 26 3.3.3 Virtual design and construction 27 3.3.4 Coordination 29 CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 IV 3.4 Theoretical summary 29 4 EMPIRICAL FINDINGS AND ANALYSIS 32 4.1 Karlatornet 32 4.2 Planning for production 33 4.2.1 Push and pull in production 34 4.2.2 Flow through activities or locations 35 4.2.3 Location-based planning 36 4.2.4 BIM for production 38 4.2.5 Coordinating production 40 4.3 Planning for logistics 40 4.3.1 Push and pull in logistics 41 4.3.2 Supply logistics 42 4.3.3 Just in time 43 4.3.4 BIM for logistics 44 4.3.5 Coordinating logistics 44 4.4 Synchronising production and logistics planning 45 4.4.1 Push and pull 45 4.4.2 Integrating LBS and JIT 46 4.4.3 Virtual design and construction 48 4.4.4 Coordination 49 5 DISCUSSION 51 5.1 Incorporating LBP at Karlatornet 51 5.2 Incorporating JIT at Karlatornet 53 5.3 Synchronising planning at Karlatornet 54 5.4 Contribution and emerging questions 56 6 CONCLUSION 58 7 REFERENCES 61 8 APPENDIX 66 CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 V Preface This master’s thesis has been conducted at the Division of Construction Management at the Department Architecture and Civil Engineering at Chalmers University of Technology as a part of the M.Sc. Programme of Design and Construction Project Management of 120 ECTS. The study was performed during the spring semester from January to June 2017 and extends 30 ECTS. The case-study was carried out at the construction department at Serneke Group, where the work has benefitted from contribution from several persons that deserve acknowledgement. We would first and foremost like to thank Christian Koch, Professor at Chalmers University of Technology, for inputs, ideas, and feedback during the course of this master’s thesis. It has been of high value for the outcome of our work and thereby we would like to thank you for both your time and enthusiasm throughout the process. We would also like to thank Davor Sinik and Conny Segerdahl for giving us the opportunity to conduct our master’s thesis at Karlatornet, and providing supervision during the process. Your time and knowledge input has been of high value both for us and the outcome of the thesis. Finally, we would like direct a great thanks to all participating interviewees for your willingness to allocate time and knowledge together with information and perceptions of the case with us. Your contribution has enabled us to conduct this master’s thesis. This master’s thesis constitutes the final part of our education at Chalmers University of Technology. During the course of the thesis, we have gained extensive knowledge regarding complexities connected to construction and logistics planning that we will benefit greatly from in the future, as well as knowledge specifically connected to planning high-rise construction projects. Lastly, thank you to all involved in this master’s thesis. Göteborg, May 2017 Oskar Andersson Simon Månsson CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 VI Notations AB 04 Allmänna Bestämmelser för Utförandeentreprenader ABT06 Allmänna Bestämmelser för Totalentreprenader BIM Building Information Modeling / Building Information Model CPM Critical Path Method IGLC International Group for Lean Construction JIT Just In Time LBMS Location-based Management System LBP Location-based Planning LBS Location-based Scheduling LOB Line of Balance LPS Last Planner System VDC Virtual Design and Construction WBS Work Breakdown Structure CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 VII List of Figures Figure 1 - The main steps of qualitative research, adapted from Bryman and Bell (2015, p. 395). 7 Figure 2 - Pull vs Push. 12 Figure 3 - Flowline chart prior to optimisation (Lowe et al., 2012). 15 Figure 4 - Flowline chart after optimisation (Lowe et al., 2012). 16 Figure 5 - Conventional supply logistics vs supply logistics with consolidation centre. 22 Figure 6 - Example of logistics information flow. 24 Figure 7 - Floor 25 at Karlatornet. 32 Figure 8 - Floor 38 at Karlatornet. 32 Figure 9 - Flowline chart with initial inputs at Karlatornet. 38 Figure 10 -Flowline chart after optimisation at Karlatornet. 38 Figure 11 - Delivery methods at Karlatornet. 41 Figure 12 - Information and material flow from synchronised LBP and JIT at Karlatornet. 48 CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 VIII CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 1 1 Introduction Inefficiencies in construction have been highlighted in various research publications, stressing that present methods of planning do not contribute to value-adding processes during production (Barbosa et al., 2017, Josephson and Saukkoriipi, 2005). There are several reasons for these shortcomings, where literature points out one of them to be a mislead focus of trying to improve or refine current methods and techniques, rather than seeking for new solutions (Christiansen, 2012). Regarding planning, this includes incorporating float within and between activities, neglecting to recognise a collective approach, and software and systems which are difficult to synchronise (Lowe et al., 2012). Drawing upon research from the International Group of Lean Construction (IGLC), a trend towards planning more comprehensively through incorporating Lean Construction (LC) aspects with Building Information Modeling (BIM) can be found. Thereby, current practise is suggested to transform into integrated Virtual Design and Construction (VDC) systems, providing a new approach to planning and executing construction projects. These systems combine software and management systems to achieve improved visualisation, integration and automation. The trend can also be seen to improve focus towards solving problems during design and planning, and thus decrease errors and non-value adding activities at the construction sites. Planning for efficiency can thus be found a continuously actual topic for research, with Barbosa et al. (2017) stating that the industry is in need of a revolution to catch up, as it currently is stagnating in efficiency. Specifically for high-rise construction, where production is highly repetitive, efficiency faces extensive risks in carrying out non- value adding activities repeatedly (Russell et al., 2009). In addition, the amount of high- rise constructions that are being constructed worldwide is incremental, giving that the total effect of inefficiencies increases with it (Kayvani, 2014). This further implies that the importance of planning consequently increases when constructing high-rise constructions, resulting in that there are great means for improvements. 1.1 Background LC has been promoted since clear benefits were shown from implementing lean production in the manufacturing industry (Bertelsen and Koskela, 2004, Womack et al., 1990). It has gained governmental support from various countries where Egan (1998) explicitly presses the issue of enhancing efficiency through LC. The Swedish equivalent Gustavsson and Rupprecht Hjort (2009) support increased efficiency as it was deemed too low throughout the industry in Sweden. As late as in February 2017, McKinsey delivered a report stating that a revolution is required for the construction industry to change and become effective in its execution (Barbosa et al., 2017). Here, productivity was specifically evaluated, showing that Sweden was one of the countries where stagnation was most intrusive. However, it also showed that Sweden is one of the most prominent countries considering moving time spent from the production phase to the design phase to minimise non-value adding activities during production in advance. Parameters such as regulations, contract forms, supply chain management, improved on-site execution and increased use of technology were brought to surface as tools for change, giving that increased use of LC is vital. LC places focus on improving both production and logistics, striving towards increasing pull based mechanisms for production to achieve better workflow and CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 2 efficiency (Koskela, 1997). To focus on performing the right activity at the right time through delivering the right goods to the right place at the right time is pressed to minimise uncertainty, and thus facilitate efficient production. Several tools have been presented in LC research that could improve efficiency and facilitate both production and logistics. Location-based Scheduling (LBS) was introduced to enhance forecasting and achieve a location-based, rather than a conventional activity based, focus (Dave et al., 2016). It points out the importance of managing locations, in which the activities are to be performed, in order to evaluate activities in relation to each other. Location- based Management System (LBMS) is a system, which further embraces engaging in a social process of planning, promoting a collaborative planning process to reduce uncertainty, and decrease non-value adding activities. The location-based focus further highlights that increased efforts need to be aimed towards logistical issues in order to achieve adequate production efficiency, where Just In Time (JIT) is a frequently used LC tool (Seppänen and Peltokorpi, 2016). Moreover, issues related to logistics can result in substantial costs and obstruction of production workflow, giving incentives for increased focus on synchronising the two perspectives (Hulthén et al., 2015, Pérez et al., 2016). Hence, when constructing a high-rise building with limited space and time, synchronising production and logistics planning becomes vital, as both are highly dependent on each other (Lange and Schilling, 2015). It is thereby suggested that LBS and JIT, integrated, can provide substantial benefits in both production and logistical planning processes, resulting in Location-based Planning (LBP) (Seppänen and Peltokorpi, 2016). Furthermore, moving towards LBP generates arguments for implementation of VDC, as it imposes combinations of software and systems to achieve integration and automation (Andersson et al., 2016). Building Information Modeling (BIM), is an important tool as it encompasses modelling the construction before production begins, while also enabling for enhanced production and logistics systems. Simultaneously, it provides means for efficiently plan in locations rather than only activities (Seppänen and Peltokorpi, 2016). They further argue that the construction industry would benefit from planning with BIM as it would provide means for increased efficiency, by connecting scheduling to the model and thus achieve 4D BIM. Yalcinkaya and Singh (2015) stress that there are deficiencies in research, as even though implementation practises of BIM was one of the most researched area out of 975 articles reviewed, only 9 of them were directly connected to what can be learnt from practical implementation. However, this area of research is argued to increase, which also can be seen with research topics connected to interoperability and standards in research between 2009 and 2014 (Yalcinkaya and Singh, 2015). The lack of practical reflections results in that there is no general method for implementation throughout the industry, but instead implementation varies between countries and companies, where each project utilises it differently (Gu and London, 2010, Lin et al., 2016). This can further be connected to developing VDC systems, which utilises different software and systems (Andersson et al., 2016). Moreover, the thesis builds on previous research such as Sacks et al. (2009) where the interaction of LC and BIM is evaluated with addition on separate research from Seppänen et al. (2015) who elaborate on effects of implementation of LBS and LBMS, Seppänen and Peltokorpi (2016) who incorporate LBMS in BIM to create 4D BIM, and Bortolini et al. (2015) who apply 4D BIM to site logistics. This is further applied to high-rise construction, where a continuous workflow through phase scheduling is CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 3 aimed for to create incremental effects (Russell et al., 2009, Seppänen et al., 2015). As both LC and BIM strive to produce only value adding processes, there is an alignment, which according to theory should raise efficiency and reduce production time through faster production cycles and increased visualisation. Although, it is important to note that understanding is key, as the tools of LC and BIM are merely means for the humans using them. Further, combining software and systems to create automation, and thus 1.2 Objectives Research on LC and BIM is widespread, however commonly separated (Yalcinkaya and Singh, 2015). Both perspectives provide advantages to change the entire construction industry, and although the use of them is increasing, implementation in construction remains limited (Dave et al., 2016, Toledo et al., 2016). The objective of this thesis is therefore to contribute in closing the gap between LC and BIM research directed towards planning to present a VDC system for planning and synchronising production with logistics in high-rise constructions, as these are prominently used separately. Further, the thesis intends to provide underlying barriers from both a theoretical and practical view to evaluate why implementation is lingering. 1.3 Research questions To concretise the objective, it can be broken down into three research questions applied to lean high-rise construction, namely: • How should LBP be incorporated in production planning at Karlatornet? • How should JIT be incorporated in logistics planning at Karlatornet? • How should production and logistics planning be synchronised at Karlatornet? 1.4 Delimitations The scope of the thesis is delimited to planning and scheduling of production and logistics through combining software and systems, based in LC, on high-rise constructions. Planning and scheduling is limited to the segment between design and production. Research question one and two specifically investigates how LBP and JIT can be incorporated to form a foundation for planning, while the third question investigates how to synchronise them. Only high-rise construction is evaluated as the thesis consist of one specific case study, Karlatornet, which is going to be constructed in Gothenburg, Sweden. This does however not exclude the conclusions and suggested methods from being used in other type of projects. The thesis further strives to investigate how goods are managed to be utilised at the construction site from suppliers to subcontractors, and does therefore not include producing goods or managing wastes created on the site. Instead, a focus of continuous value addition is implied to shine light on efficiency. 1.5 Thesis outline The thesis is divided into 6 chapters, structured to give the reader insight to all the steps taken during the thesis, while also following the research design. The chapters are presented in the following order, containing the following: CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 4 Chapter 1 – Introduction, states the context within which the research has been conducted, introducing the subject and presenting the background. It also contains the objective, as well as a formulation of the research questions and the delimitations. Chapter 2 – Research Methodology, covers the approach that has been used to gather information and achieve the objective of the thesis. The chapter presents the chosen research design, and method, together with the course of action when searching for literature and collection of data from empirical studies. It also entails a description of how ethical conduct and trustworthiness has been managed. Chapter 3 – Theoretical Framework, provides the necessary knowledge as a foundation on which results, analysis, and conclusion has been developed. It is divided into three sections presenting current literature and research. The first section provides information on planning for production, the second is about planning for logistics, and the third and final concerns the synchronisation between production and logistics planning. In the end of the chapter, a theoretical summary is provided. Chapter 4 – Empirical Findings, aims to interpret the information retrieved from interviews and data collection. The chapter follows a similar structure as presented in the theoretical framework, commencing with planning for production, followed by planning for logistics and finishing with synchronising production and logistics planning. Chapter 5 – Discussion, contains the discussion which arises through synthesising the empirical findings and the theoretical framework. Thus, the research questions are investigated through both perspectives to provide suggestions on how to proceed with planning for achieving efficiency at Karlatornet. Chapter 6 – Conclusions, presents the concluding remarks about each research question specifically, in summarised form. This chapter aims to give clarity on which questions that Serneke needs to work with while also acknowledging what is in line with the suggestions from the discussion. CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 5 2 Research Methodology This chapter provides insight on the thesis methodology, which was developed to enable answering the research questions. It contains of the sections Research design, Literature research, Ethical conduct, Data collection and analysis, and Trustworthiness, aiming to describe how research was conducted for both the Theoretical framework and the Empirical findings and why specific methods were chosen. The chapter additionally discusses how validity was ensured during research, and how bias was avoided. Both authors contributed to all segments of this thesis, making it an even division of work. 2.1 Research design Research was elaborated through an iterative process concerning both theoretical and empirical aspects, hence an abductive research strategy was chosen. The abductive strategy differs from inductive and deductive as it considers a combination of both empirical and theoretical findings, reinterpreting them as the research proceeds (Alvesson et al., 2011). Given the iterative process, new questions were expected to arise as research progressed resulting in changes in the theoretical framework, which the abductive strategy is supposed to manage better than deductive and inductive. This is supported by Dubois and Gadde (2014) who claim that the abductive strategy is suitable in research where there is a continuous interplay between theory and empirical findings. Suddaby (2006) further explains that the abductive strategy differs from induction and deduction as it implies reflection on the subject in order to provide new reasoning, an approach that was desired. Neither deductive or inductive strategy was therefore assessed to suit the objectives, as interpolating answers to the research questions through continuously balancing theory with empirical findings was deemed necessary in finding alignment for the specific case and existing research. Thus, an abductive strategy was to enable for making adjustments applicable for Serneke, specifically at Karlatornet. As the objectives of the thesis were to investigate how production and logistics should be planned, and further how these should be synchronised, interviews were conducted with interviewees from both academia and practise. These were chosen based on both the interviewees own initiatives, due to their connection to research or the studied case project, and recommendations from connections and other interviewees. Due to having interviews as primary method for data collection, a qualitative research method was developed due to putting emphasis on words rather than numbers (Bryman and Bell, 2015). Moreover, qualitative method focuses on the importance of understanding a context, enabling for interpretations and development of new reasoning, which was assessed suitable for answering the research questions. Simultaneously, it is preferable for research of prescriptive and explanatory character, which were chosen due to the objectives of guiding the organisation in how to plan and synchronise production and logistics, and exploring new findings as well as barriers. Moreover, the thesis was conducted as a single-case study, which is the research method that conforms to the qualitative method, as it according to Bryman and Bell (2015) enables for extensive and detailed data collection. However, conducting a single-case study brings the disadvantage of not being able to generalise findings. Conducting multiple case studies would have enabled for broader generalisations, as project specific CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 6 findings could have been identified. However, as the time was limited, a single-case study was preferred due to providing the ability of performing an in-depth data collection. A multiple case study, in comparison, would have led to more shallow data collection and thus weaker answers to the research questions. In addition, connections could only grant access to information about the specific case study, Karlatornet, as comparable projects were few and widely spread across the country. Resulting in barriers both in accessing information and having substantial distance to similar projects. 2.2 Literature research Before and parallel to the single case study, literature research was conducted to provide a theoretical framework giving the case findings a contextual meaning (Dubois and Gadde, 2014). In order to provide up to date literature research, conference papers from IGLC formed a base for further findings. Other sources for literature were scientific articles and books, found by both own searches and recommendations from interviewees. Specifically, the databases Scopus, Summon from Chalmers Library and Google Scholar were used to find complementary research. The search words used to find relevant articles include “Lean Construction”, “Location-based Management System”, “Location-based Scheduling”, “BIM Planning”, “BIM Execution Plan”, “Just In Time”, and “Virtual Design and Construction”. The relevance of the articles was estimated with regards to number of citations, number of hits for the specific search word, and actuality. The search words were also combined, both as whole and in parts, resulting in higher specificity in the searches. In order to obtain sufficient and applicable literature during the course of research, a three-phase iterative structure was developed for the literature research. These correspond with the main steps, shown in Figure 1, of a qualitative research method (Bryman and Bell, 2015, p. 395). The first phase was conducted to obtain broad knowledge on the subject, needed to define general research questions and select relevant subjects, while the process of interpretation and conceptualisation of data also was initiated. In addition, this phase was used as a foundation for developing the initial interview questions. The second research phase was designed to collect relevant data, interpret it, conceptualise it, and create a theoretical framework. Having done so, interpolation was conducted to comprehensively compare the findings. During the phase, the research questions were further specified which enabled for collection of increasingly specified data. This phase also correlated to the development of interview questions, as these further were refined to correspond to the research questions. Finally, the third phase of the literature research was conducted to, in depth, determine the findings and draw up conclusions. Compared to the main steps described by Bryman and Bell (2015, p. 395) findings were continuously written up and revised as the iterations progressed. Dividing it into three phases rather than six steps as shown in Figure 1, was done to effectively systematically combine theory with empirical findings and have an aligned structure between them. CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 7 Figure 1 - The main steps of qualitative research, adapted from Bryman and Bell (2015, p. 395). To acquire knowledge regarding the researched methods, world-wide literature was investigated. This was considered applicable, as documentation of Swedish implementation was found limited. Thereby, literature was interpreted and applied to the Swedish construction industry’s point of view, as differences between national industries and companies does occasionally occur. 2.3 Ethical conduct To ensure that research was ethically conducted, all interviewees were briefed regarding the scope of the thesis prior to each interview. An example of the brief that was sent to the interviewees can be found in Appendix A. Further information concerning the selection of interviewees invited to participate in the research, together with information on their respective contribution, was presented for each interviewee. It was also clarified that interview participation was voluntary, and that only their current position would be presented to give anonymity in the thesis regarding their answers and perceptions. This method was chosen in order for interviewees to elaborate and speak freely during the interviews. Positions of all participants are presented in Appendix B, together with a brief explanation of their insight to the project, working experience, and general background. Moreover, interviewees were asked if recordings of the interview could be conducted, where the unanimous answer was yes, which is perceived to increase the transparency of the interviews. 2.4 Data collection and analysis The company Serneke was chosen due to three main reasons; they are going to construct the tallest building in Scandinavia, they are a young company with specific focus on efficiency, and they provided a possibility for further collaboration after previous CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 8 commitments. Serneke was founded in 2002 by the current CEO, Ola Serneke, and Andreas Fagerberg where the latter chose to depart from the company in 2007 (Serneke, 2017). A core value in the company is to continuously encourage and strive for efficiency, and they aim to work as visionaries in the industry. The single case study is conducted on the project Karlatornet, which is a 72-storey building that is going to be constructed at Lindholmen, Gothenburg, in the coming years, estimated to commence in 2017. A high technical standard was aimed in the design phase, where BIM was to be used progressively in comparison to common practise in Sweden. The objective was to impose extensive use in both the planning and production phase. The company have set an aim to continue in this direction and were therefore interested in front-edge planning for both production and logistics, and further synchronisation between the perspectives, which made them aligned with the objectives of the thesis. Data collection was conducted mainly through semi-structured interviews which were systematically combined with the theoretical framework throughout the process. Defining where theory and empirical findings correlated and were differentiated formed the foundation, on which conclusions could be drawn. This further corresponds to how an abductive research should be performed, described by Dubois and Gadde (2014). The semi-structured interviews were held with a progressive pattern, to continuously interpolate data. Initially, interviewees from academia were interviewed to provide direction on recent research, whereas interviewees from practise were interviewed in a sequence chosen to efficiently group arguments. The answers from the interviews were continuously interpreted and analysed by making comparisons between both different interviews and theory. When the empirical findings were considered to be complete, additional control interviews were held to ensure validity. In total, 15 interviews were held with interviewees both within and outside of Serneke’s organisation to avoid bias. The duration of the interviews differed from 60 to 90 minutes. Complementary, Skype was used for two interviews due to restricted possibility of physical meetings. For each interview, an interview form, Appendix C, was used to give structure and ensure relevance. An iterative process was used for the interviews. During the first phase, interviewees were chosen based on ability to provide guidance and assure scientific contribution. In the second phase, interviewees were directly connected or complementary to the studied case project. Finally, in the third phase, interviewees were chosen to control the outcomes both scientifically and practically. In regards to this, phase one consisted of interviewees from academia, phase two from practice whereas a mix was aimed for in phase three. Interviewees were also chosen by three attributes namely; experience from LC in regards to both science and practice regarding both production and logistics, connection to the case study Karlatornet and connection to comparable projects. Further, this iterative approach was used, as it entails the possibility of both creating an explorative approach and continuously imply control, while providing that analysis is incorporated throughout the process. Interviews were held in three stages, commencing with stage 1 where the interviewees were briefed with formal information about the thesis together with information on the objective of the specific interview. Each interviewee was prompted to apply the questions to their area of expertise to provide relatable examples, connected to their respective competence. Stage 1 also included short presentations of the interviewers and their respective roles for the specific interview, which varied between the different CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 9 interviews. The following stage 2 constituted the main part of the interview, where the interview forms were used as guidance. In this stage, the interviewees provided their views on the questions and were steered into discussions connected to the subject and relevant to their expertise. Finally, the interviewees were asked to summarise their perception of the discussed matters to avoid possible misunderstandings. 2.5 Trustworthiness One of the difficulties of working with a qualitative method concerns bias from the authors (Bryman and Bell, 2015). Qualitative research does however provide a self- correcting function in its iterative form, where the researcher is able to pose additional questions during the interviews and review the work continuously (Morse et al., 2002). By doing so, conformity can be reached to deepen the understanding. As Alvesson et al. (2011) argue, it can also become a risk to work in this manner due to that underlying cultural values differ at different locations. Interviews were carried out in two different countries, which opens up for differing interpretations because of having different cultures and regulations. Although, Dubois and Gadde (2014) state that by systematically combining theory and data collection, a nonlinear process is created which implies objectivity. This should result in that empirical findings eventually matches reality, through interpolation. Therefore, iterative processes were used for both literature review and interviews in order to achieve an objective standpoint, and furthermore increase trustworthiness in this qualitative study. Developing an early connection with the participating organisation could further provide means for deeper commitment and trustworthy data collection (Shenton, 2004). Thereby, extended engagement between the investigator and the participants contributes to establishing a relationship based on trust between the parties, and thus more elaborated answers leading to enhanced information supply. As previous collaboration with the company had been performed, a good relationship was already developed before initiating the thesis. This enabled for a well-developed commitment from all involved parties. It was however recognised that previous commitments may result in increased positivism, which was managed through triangulation of interviewees. Merriam and Tisdell (2015) describes that triangulation increases trustworthiness of data collection, where interviewees from different organisations both connected and disconnected to the project can be chosen to decrease positivism. Participation in the investigation was held voluntary to ensure that only genuinely interested participants were included (Merriam and Tisdell, 2015, Shenton, 2004). However, an already established interest in the subject may imply a risk as preconceptions can exist. Although, as all of the respondents chose to participate, nuancing was maximised. Furthermore, participants were informed prior to each interview that no right answers to the questions existed. This corresponds with the tactics to ensure honesty presented by Merriam and Tisdell (2015) and helped to ensure well elaborated and personal answers to the questions. During interviews, an iterative structure was present, where the final stage of the interview was used to return to previous discussed matters of the interview in order to detect perceptions and possible contradictions from the interview. CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 10 3 Theoretical Framework This chapter presents a theoretical framework on the research questions, provided to give insight on software and systems used for planning high-rise constructions. The chapter is divided into four sections, commencing with Planning for production which includes Push and pull in production, Flow through activities or locations, Location- based planning, BIM for production, and Coordinating production. The second section is called Planning for logistics and contains Push and pull in logistics, Supply logistics, Just in time, BIM for logistics and Coordinating logistics. The third section is named Synchronising production and logistics planning and includes Push and pull, Integrating LBP and JIT, Virtual design and construction, and Coordination. The fourth and final section is called Theoretical summary and contains a summary of the essential aspects of the investigated theory. 3.1 Planning for production Planning in the construction industry is generally associated with uncertainty and risks, which in turn hinders efficiency in production (Daniel et al., 2014). Hence, developing an effective plan with minimised risk is ultimately the goal of present planning methods. Moving from activity-based planning to LBP is considered to provide more comprehensive planning, as activities are related to each other to detect clashes and minimise float within and between activities (Christiansen, 2012, Seppänen et al., 2010). Furthermore, Gledson and Greenwood (2014) argues that conventional activity- based planning relies merely on experience of the individual planner where the plan originates from a set sequence of activities, not recognising the importance of managing the locations in which these are going to be performed. LBP does however consider the importance of location-based aspects, identifying the fact that locations link activities together which highlights collaboration between different parties. To minimise float within and between activities, and thus achieve increased pull for production, visualisation must be improved (Murguía et al., 2016). For all participants to fully understand the importance of increasing pull requires increased commitment, and that collaboration between parties working close to each other is high. Korb and Sacks (2016) also address the importance of committed participants, as the construction industry is generally associated by each participant trying to maximise their own profits resulting in decreased overall production efficiency. Implementing a BIM-based planning tool will according to Büchmann-Slorup and Andersson (2010) ensure sufficient information flow along with increased visualisation and communication possibilities. Thereby, BIM is thought to have potential for enabling an efficient planning process that will facilitate increased pull for production. Planning is conventionally conducted in two phases where the responsible party, usually the main contractor, produces a master schedule (Lange and Schilling, 2015). After this, each subcontractor plan their work to match the times that are set in the master schedule in the second phase. In this scenario, the plan of each subcontractor respectively is not related to each other, but rather create a long line of activities when combined by the contractor. The master schedule is thus only revised by the contractor, neglecting to include those who perform the activities resulting in subcontractors being pushed to perform accordingly. Planning should according to Seppänen et al. (2015) be conducted collective, implying that those who perform the work can provide input and CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 11 further relate activities to each other. By doing so, float is minimised within and between activities. LBS is thought to promote this approach as focuses on planning specific locations where the work conducted by the different subcontractors are interrelated and thus aims to minimise float (Lowe et al., 2012). Thus, activities are rather pulled to specific locations when they are needed instead of being pushed by the master schedule. This further results in that information is put into the plan when uncertainty is minimised to a greater extent, as those who have the best competence on when to perform a specific task are those who are going to do it. 3.1.1 Push and pull in production Planning conventionally implies extensive push for production, as the master schedule is used to schedule deliveries which production must cope with, to avoid having materials obstructing production (Kalsaas et al., 2015). Subcontractors rarely get the opportunity to give input on the master schedule, resulting in that they are pushed to perform certain tasks at certain times (Dallasega et al., 2016). However, as a delivery schedule is set, it can be argued to pull production giving that logistics is superior to production. Pull for production focuses on carrying out the right activity at the right time, providing that deliveries should be coordinated to when production is ready for them to avoid obstruction. According to Ballard (2000), the traditional Critical Path Method (CPM) only releases information or goods based on preassigned dates, neglecting to recognise the actual demand for production. By finding the critical line of activities before commencing production, the demand of production is set in advance rather than being evaluated continuously, and thus providing less opportunity for production to pull information or goods. Increased pull on the other hand aims to pull information from the production teams in order to minimise float, which conventionally is incorporated in master schedule to reduce risk (Kalsaas et al., 2015). It is thereby characterised by production pushing information to logistics in order to avoid obstruction, enabling for enhanced workflow compared to the pushing production with a master schedule. When pull is increased for production, actual demand at site is evaluated instead of relying on estimations made. Uncertainty is thus decreased, as accuracy can be improved as illustrated in Figure 2. According to Kalsaas et al. (2015), increased pull for production should result in more flexibility, higher delivery reliability, and higher production quality, as well as decreased variation of demand and changeover time. This is due to having the right goods delivered to the right place at the right time to for each specific activity. Moving to a solely pull based approach is however a complex task, as suppliers commonly have long lead times for delivering goods (Ballard, 2000). This results in having to balance push and pull rather than only adapting to one side, whereafter different activities and materials must be prioritised for each side depending on preferences in the specific project. CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 12 Figure 2 - Pull vs Push. Increasing pull in production requires better control systems, with exact measurements rather than estimations, as to ensure decreased push demands extensive information from production (Kalsaas et al., 2015). Estimations, which the master schedule commonly is based on, can be minimised by measuring actual demand in production. This gives that push is increased for logistics, as there is need of an increased flexibility from suppliers. Kalsaas et al. (2015) further argues that the Kanban system, where notes are used to visualise actual demand for production, and thus provide clear information on what is needed at what time, can help to achieve better workflow in production as it focuses on production flow without affecting excessive push in logistics. Dallasega et al. (2016) builds on this argument, stating that an IT-based delivery system where all deliveries are organised to meet actual demand is crucial for increasing pull for production. This system can further be applied to LBP, establishing pull signals of demand from different locations (Kalsaas et al., 2015). Applied to high-rise construction where repetition is implied, this can have beneficial effects as pushing deliveries may result in obstructing production, and hence failure in the production cycle (Russell et al., 2009). However, it is still important to establish estimations of what activities that are to be performed, similar to what is done in a push system, in order to determine the timeframe needed for each subcontractor in each specific location (Ballard, 2000). Combined push and pull is thereby a necessity, although the coordination between production and logistics become central in optimising workflow in production, as there are limitations to what degree pull can be achieved. For production specifically, activities should be evaluated to decide on whether to be push or pull logistics. Minimising float in production should according to Daniel et al. (2016b) be done through collaborative planning, where the subcontractors engage in the planning process, resulting in better estimations and improved communication. By doing so, activities are evaluated in relation to each other, and float can thereby be minimised in production scheduling. This further results in an increased demand of control, as decreased float implies a higher risk of clashes between different working teams. The Last Planner System (LPS) is described by Daniel et al. (2016b) to manage this as the working teams engages in a social process, which should imply better collaboration and CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 13 communication. Clashes are expected to be detected during planning as it is conducted collectively and therefore acknowledges the interaction between activities as well as between those who perform them. LPS further stresses that decisions should be made when uncertainty is minimised to ensure that non-value adding activities are avoided, moving the planning process closer to production, when more information is available. On the other hand, the system provides that logistics need to be flexible in order to continuously meet the demand at the site for the right activity to be performed at the right time resulting in excessive push for logistics (Russell et al., 2009). 3.1.2 Flow through activities or locations In contrast to industrial production, where a product flows through different locations where different activities are conducted until finished, construction production is performed at a set location with activities flowing through them respectively (Seppänen et al., 2010). This makes the location of assembly static and not shifting, as in industrial production, resulting in an issue where those who are to perform different activities may clash, as they wish to perform work at the same location. When planning production, Work Breakdown Structure (WBS) and CPM has conventionally been used, resulting in focus on activities as both methods aim to break down production and find the critical activities in the production chain (Christiansen, 2012). With influences from industrial production, LC has during the last decades resulted in development of new planning methods moving from activity-based planning to methods emphasising the importance of locations (Büchmann-Slorup and Andersson, 2010). Thus, recent research on LC promotes focus on locations to optimise production efficiency and reduce float, which is considered non-value adding. When assessing the different methods for planning, visualisation becomes an important factor where traditional planning provides a critical line, giving the full sequence of the activities (Freeman and Seppänen, 2014). Having focus on specific activities in the master schedule, and not breaking them down into specific locations, is thought to give measurements on the amount of work for each respective subcontractor, however the work relatively other subcontractors is neglected (Seppänen et al., 2010). To achieve this, coordination is needed between the contractor and the subcontractors, and the subcontractors respectively. By planning with a location-based method, subcontractors are forced to adhere to a collective mind-set as their work becomes related to others, giving that a more comprehensive plan is developed (Seppänen et al., 2015). The process is further thought to give better accuracy on measurements on the specific activities as opportunities and barriers are evaluated more extensively. Having focus on locations does however imply decreased control of the total workload and instead increased control of the specific activities within the planned location (Lowe et al., 2012). Visualisation is therefore limited to specific locations within the master schedule, giving that the method is connected to planning in phases rather than focusing on total workload. To track the total workload, there is thus need for back-tracking the location plan when conducted, to ensure that the master schedule is not affected but rather improved. 3.1.3 Location-based planning Planning in locations has been subject for research for over a decade, originating from a combination of linear scheduling and CPM, however practical documentation has CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 14 been limited (Kenley, 2004, Lowe et al., 2012). LBS was found beneficial in projects with a high degree of repetition where the first documented implementation dates back to the construction of Empire State Building in 1929 (Kenley and Seppänen, 2010, Lowe et al., 2012). Its repetitive character implied that phases could easily be formed, in which work could be conducted efficiently. At first, LBS was however primarily used as a tool for visualising and controlling production in locations rather than mere sequences of activities, neglecting to recognise the social process of collaboration in the construction industry. This resulted in the development of LBMS, where planning and scheduling further aims attention towards the knowledge and expertise possessed by those who are to perform the activities (Kenley and Seppänen, 2010, Lowe et al., 2012). LBMS is a management system, where LBP planning is implied through using LBS and further incorporating those who are to perform the activities in the planning process to increase alignment and minimise uncertainty. Further it should be noted that as LBMS originates from, CPM many similarities do occur, however the former has the advantage of providing answers to both what activities that should be included in the schedule, and where they are to be performed (Christiansen, 2012, Lowe et al., 2012, Murguía et al., 2016). Thus, while LBS is directed to software and scheduling, LBMS aims to connect scheduling to those who are to perform the work. In this way, clashes can be detected in advance, and phase scheduling can be done more accurately. The main goal of both LBS and LBMS is to facilitate planning and give continuous production flow by dividing a project into locations, which preferably consists of equal amount of work (Kenley and Seppänen, 2010). Having an even amount of work is claimed advantageous, as it simplifies execution by creating repetition. This is further aligned with Freeman and Seppänen (2014) who state “The focus of LBMS is on continuous flow of resources, completing locations in sequence and synchronizing the production rates of crews” (p. 1133). Creating production cycles with a continuous flow of resources is extensively beneficial when constructing high-rise buildings as they often already consist of repetitive work (Sacks and Goldin, 2007). This is supported by (Russell et al., 2009) who state that the repetition between different floors entails natural production cycles. Thereby, it is noted in Sacks and Goldin (2007) that construction of high-rise might benefit from implementing the Line-of-Balance (LOB) method, which is used to manage projects with high repetition by defining relationships between unit completed and rate of production. However, it is stated by Lowe et al. (2012) that LOB assumes that each work unit is identical to the previous, making it inefficient for the changing context of the construction industry even if repetition is perceived high. Thus, LBS and LBMS can help in streamlining production and developing a production cycle with continuous workflow as they aim to optimise each location respectively. Additionally, LBS has become progressively popular in the construction industry as it emphasises the importance of locations as a dimension in the production process, where activities are linked together (Lowe et al., 2012, Murguía et al., 2016). LBS is stressed to enable for improved visualisation of how activities affect each other, and where they are to be carried out, compared to traditional activity based CPM (Büchmann-Slorup and Andersson, 2010, Christiansen, 2012). Connected to the construction industry, where activities have set locations, it is therefore claimed to be more suitable. LBS produces a flowline chart that effectives visualisation in planning as illustrated in Figure 3, showing what activities that are planned and how they proceed through different locations (Lowe et al., 2012). As the flowline chart also take locations into CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 15 consideration, resulting in a view on activities that may falter in effectiveness. In comparison, the conventional usage of a Gantt chart to visualise planning provides an insight to timing of activities, as well as their sequence and durations (Christiansen, 2012). However, as Gantt charts are not able to visualise where activities are to be performed, neglecting to recognise the physical location of different work crews, effectiveness may be obstructed. Therefore, planning in activities does not consider nor identifies activities that could be performed simultaneously in each location. This has resulted in that the increased visualization provided by LBS has been argued to raise understanding of how activity delays impact the totality in a project, and how activities interact with each other (Lowe et al., 2012, Lucko et al., 2014). Figure 3 - Flowline chart prior to optimisation (Lowe et al., 2012). Planning with LBS focuses on achieving a continuous flow where interruptions between activities are kept to a minimum (Lowe et al., 2012). This means that the start of a task should be delayed until work can be guaranteed to proceed continuously from location to location without interruptions to increase workflow. In order to do so, Seppänen et al. (2015) suggest that the planning process is divided in master- and phase scheduling. Master scheduling consists of important project milestones with long lead times including main trades and tasks that should be carried out, together with a location breakdown structure (Dave et al., 2016, Freeman and Seppänen, 2014). The location breakdown structure should further in LBMS, compared to in LBS, be conducted collectively with those who are to perform the work within each location to create alignment and enhance collaboration (Seppänen et al., 2010). Locations are set to be equal in workload and possibly size to produce continuous production cycles which can be divided in phase schedules. However, it is noted by Christiansen (2012) that dividing certain parts of production in locations is a rather complex task, and not always perceived efficient among those who are to perform the activities. It is mentioned that some wide-ranging activities such as concrete formwork may be separated into different locations when the location breakdown structure is done, resulting in an inefficient division of locations in regards to production. This is exemplified by a case studied by Christiansen (2012) where production supervisors opposed the site manager’s division of locations, suggesting that certain activities were merged over the location boundaries in order to increase the efficiency in production. Hence, even if Christiansen (2012) promotes a LBP method, it is argued that problems may arise connected to how the locations are divided and executed in production. In this case, usage of a traditional CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 16 activity-based CPM would have implied that merging large activities could have had beneficial outcomes as it effectively shows which activities that needs to be finished to remain within the timeframe. Therefore, it also suggests that a combination of traditional CPM and LBS could be beneficial in striving for increased efficiency in production. Figure 4 - Flowline chart after optimisation (Lowe et al., 2012). Furthermore, when division of locations has been done through a location breakdown structure, the process moves into phase scheduling and schedule optimisation (Seppänen et al., 2015). Here, all involved parties jointly develop a logical sequence of work, and based on this develops a phase schedule. Generally, further optimisation is needed if the schedule exceeds the milestones of the master schedule. Optimisation is done collectively, where all involved parties discuss how to improve efficiency and productivity in the phase schedule to minimise float and increase workflow (Frandson et al., 2015). This is done by changing the production rates, attempting to align the inclinations, see Figure 4, of each task in the flowline chart to be as close to parallel as possible (Lowe et al., 2012). Production rates are adjusted by changing the amount resources requested for a specific task, increasing or decreasing the number of workers from different crews until the inclination of the task is similar to its prior task. Rearranging the order of activities can also help in minimising float, as some activities are less affected by changing the amount of resources. They further argue that by identifying bottlenecks, it is possible to evaluate whether to increase working speed for specific activities by adding resources or decreasing tempo for other activities to create continuous workflow. If done properly, the outcome should be a flowline schedule that finishes earlier than the initial end date and within all the participants’ satisfaction (Seppänen et al., 2015). Thus, it aims to minimise float both within and between activities to increase efficiency in production. 3.1.4 BIM for production Including planning in a 3D model by adding time and thus making it possible to visualise the different stages of production is usually known as introducing the fourth dimension, creating 4D BIM (Sacks et al., 2010, Sacks et al., 2009). Russell et al. (2009) state that 4D BIM provides a basis for planning as it visualises production in different CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 17 stages, making it easier to create a logical sequence of activities. Sacks et al. (2009) also stress that improving visualisation would entail a greater flexibility towards the changing character of the construction industry. This comes from visualisation enabling for increased understanding regarding project execution. Thereby it is suggested that BIM facilitates decision making and increases understanding, as the relationship between different activities becomes increasingly prominent. Further, the limitations of BIM are considered to be few as it for example can incorporate costs, environment, quality and facility management (Sacks et al., 2010). Although, VDC has become a prominent research area, claiming to incorporate a wider range of activities and information compared to BIM due to combining different systems and software to achieve integration and automation (Andersson et al., 2016). Thus, it rather implies a hybrid practise compared to BIM, where having all information gathered in the same system is prioritised. Developing a 4D BIM model provides a virtual environment in which production processes and operations can be viewed and evaluated, giving opportunity to identify time related resource conflicts (Harty and Whyte, 2009). In turn, this provides means for enhancing efficiency and reducing risk, as well as improving production flow. However, as pointed out by Jongeling and Olofsson (2007) going from 3D to 4D in regards to planning workflow requires additional information to be included in the model. This is supported by Andersson et al. (2016) who also press the importance of regular updates in order to ensure the reliance of the model. Generally, 3D models are restricted to only incorporate building components and does not include space as a resource. This will be needed if a proper workflow plan is to be established. Hence it is argued by Jongeling and Olofsson (2007) that BIM combined with other planning methods that recognize the importance of space and locations could facilitate workflow, resulting in the implementation of VDC to the industry. In this scenario, BIM is merely a software used to support and be combined with other software and systems, although a significant one. Korb and Sacks (2016) argue that the level of development in construction is specific for each project as different terms are provided. Thus, to set the appropriate level of development for each project should be based in the terms of the project. To be able to model each project in advance, getting the opportunity to build it before production begins, gives a chance to find clashes and plan activities ahead (Redmond et al., 2012). To become a value adding process, it must however be ensured that this is achieved, as the process is not of value if it does not provide means for enhancing production and improving integration. BIM does however imply a risk of increased non-value adding activities as it promotes testing before construction, which may result in excessive testing compared to what is necessary. This mainly comes down to the level of development in the model, which decides what information that should be in the model, alongside the level of development, which decides when a certain level of development should be reached in the process (Lin et al., 2016). Gledson and Greenwood (2014) stress that some of the main problems in construction are related to inadequate communication and competence among project participants. Thus, it is suggested that implementing BIM as an integrated model would address and resolve these issues, which in turn would enable and improve interaction and collaboration between involved parties (Tallgren, 2015, Toledo et al., 2016). Furthermore, Tallgren (2015) acknowledge the possibility to reduce uncertainty CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 18 connected to lack of appropriate information when using an integrated BIM model, as all of the information will be stored at the same place. However, it should be further noted that defining and ensuring that all involved parties are aware of responsibilities associated with the BIM model is essential in order to reduce uncertainty and gain efficiency when using BIM (Gu and London, 2010, Lin et al., 2016). Having an integrated model, instead of managing information separately, implies a collective mind-set where the involved parties provide an understanding about the big picture on the specific project or location within the project, instead of sub-optimising each activity (Redmond et al., 2012). This is supported by Andersson et al. (2016) who argue that having an integrated model provides a context where all project participants can access information from a central VDC information hub, resulting in increased compliance among participants. It is however stressed that the amount of information easily can become overwhelming, and that having the right information on the right place should be prioritised (Redmond et al., 2012). Having excessive information in the model can therefore also result in losing focus and further lower visualisation rather than enhancing it if managed insufficiently. Working in separate software and system can also be preferred due to excessive fragmentation in the industry, having broad variation of competence and ability in adapting to new methods. In order to establish clear instructions regarding execution and stipulate who will be responsible for what information, it is important to develop a BIM execution plan at the early stages of implementation (Lin et al., 2016). The BIM execution plan states responsibilities, defines appropriate times for specific level of development, and includes a detailed description of how BIM is used in the project. The execution plan should constitute a basis for alignment between all involved parties and ensure sufficient commitment from all participants as it divides the responsibilities. There is according to (Lin et al., 2016) no standard execution plan applicable to all projects today, however they see advantages in developing one in order to streamline the use of BIM and avoid double work between different projects. 3.1.5 Coordinating production The aspect of making planning into a social process where the subcontractors, that are to perform the activities, are included differs from conventional planning (Daniel et al., 2014). By engaging the subcontractors in a social planning process, it is suggested that alignment and increased commitment is achieved. Murguía et al. (2016) support this and stresses that the social process in planning results in better cooperation, as the parties who are to work side by side on the site get to know each other. It is also suggested to imply better understanding on each subcontractor’s respective work. When assessing key drivers for the subcontractors regarding commitment, Murguía et al. (2016) do however argue that the contracts act as base. Planning workshops can here be considered a barrier if seen as excessive to projects where conventional planning is used. Subcontractors cannot be expected to take part in collaborative meetings apart from what is standard, as this according to AB04/ABT06 should result in extra costs (Byggtjänst, 2011). Thus, extensive meetings must be regulated in the contracts to avoid later charges, and thereby avoid hampering efficiency. To engage the whole production team in a social process and plan collectively must therefore be planned for at an early stage to have the whole production team aligned. CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 19 Further, to create alignment throughout the supply chain, Daniel et al. (2016b) argue that a physical meeting place, where the participants are able to work together, is a critical factor applying to the whole process. When considering transfer of information, the physical meeting place provides means for a social process where parties can plan their work jointly. It is suggested by Daniel et al. (2016b) that there are gaps between subcontractors within the production team, resulting in faltering efficiency due to creating float between activities. To change this, Dallasega et al. (2016) claim that planning workshops, where the contractor and the subcontractors should plan the work jointly. Another benefit of collaborative planning is that risks can be derived to the party with the best competence to manage it, while also avoiding double work through having open communication. Involving the subcontractors in the planning process can thus give more accurate planning as they possess the best competence on how to solve issues within their field of expertise. This is supported by Seppänen et al. (2010) who stress that by including those who are to perform the work in the planning process, uncertainty can be decreased. Tallgren (2015) concretise this by giving an example from a project where a three-stage workshop was used when planning, resulting in efficient information transfers. Firstly, the production team was involved with the design team to walk through the construction. Secondly work was distributed where each party was to estimate and plan their own work. Thirdly, the specific work was planned collaboratively, where the result was a phase schedule which all subcontractors were committed to. A post stage was later used where the plan was controlled and evaluated to decide on whether to proceed or if changes are necessary. 3.2 Planning for logistics Achieving workflow reliability and labour productivity are key measures in LC (Seppänen and Peltokorpi, 2016). Pérez et al. (2016) claim that construction logistics is a cornerstone in achieving productivity, as problems can result in downtime and have major effects on time and cost. The densification of cities provides dense construction sites, which creates complicated logistics, as goods rarely can be stored on site (Hulthén et al., 2015, Said and El-Rayes, 2013). Thus having the right material on the right place at the right time according JIT deliveries becomes increasingly important to efficiently manage time and costs. Seppänen and Peltokorpi (2016) elaborates on this by stating that focus from the contractors is on lowering costs of logistics, however without losing out on efficiency on site where workers commonly must spend time on searching for the right material. This creates a catch 22, where investments are not made before they can be proved to give better results instantly. For logistics to promote efficient production, the supply chain must be managed to avoid obstructions without resulting in substantial costs. 4D BIM is thought to provide means for comprehensive planning, as it incorporates scheduling into the model, and thus visualises the conditions of different stages (Bortolini et al., 2015). Cheng and Kumar (2015) also stress the important of integrated planning, by pressing the importance of closely coordinating goods to be delivered to the right place at the right time to avoid non-value adding activities such as waiting times, double work and downtime. Software and systems must therefore be combined to develop one, aligned, system to support production rather than having separate systems which requires extensive and manual management. CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 20 3.2.1 Push and pull in logistics Logistics are generally scheduled to meet the demands of a predetermined master schedule rather than the actual demand on site (Hulthén et al., 2015). Thus, for deliveries to meet demand, production must match the master schedule. This implies that logistics pushes production to continuously meet the master schedule, which is based on estimations instead of focusing on delivering the right material to the right place at the right time. An increased flexibility is requested, as changes in the master schedule are common, resulting in that the delivery schedule becomes desynchronised with the production schedule (Seppänen and Peltokorpi, 2016). Increasing flexibility does however imply push for logistics as suppliers commonly are contracted long before deliveries due to having long lead times (Ballard, 2000). This puts increased pressure on suppliers, who are dependent on other customers, giving that flexibility also is limited. Push is required, to manage long lead times, however not desired as it does not imply supporting production by meeting the actual demand on site. Push from logistics is further promoted by suppliers providing rebates on big orders, fees for truckloads that are not filled, and extra costs for on time deliveries (Benton and McHenry, 2010). Thus, delivering the right materials to the right place at the right time commonly implies increased costs, compared to delivering full truckloads of specific materials on times that can be fitted to their supplier´s delivery schedule. As efficiency is connected to the total economy of the project, these costs must be derived to decreased costs in production to be motivated (Benton and McHenry, 2010). Thereby, deliveries should be coordinated to be optimised in regards to the efficiency of the specific delivery and its total economy and therefore, materials should be divided accordingly. In addition, when planning for efficiency, the alternatives must be balanced for each type of goods to find the best alternative for the specific project. Constructing high-rise constructions in dense environments requires both a well- planned and yet flexible logistics solution, suggesting that increased pull in production can be beneficial for achieving enhanced workflow (Russell et al., 2009). Sweden is not traditionally characterised by being dense, however the construction sites are incrementally densifying as the cities grow and become denser (Boverket, 2012). High- rise constructions entails density not only on the construction site, but also on each level as the height implies complexity in transporting materials inside the construction (Russell et al., 2009). Making sure that the right material is delivered to the right place at the right time is therefore of increased value in this type of projects. This further puts increased pressure on developing a system where push and pull is balanced to optimise workflow throughout the chain. However, there are reasons for increasing flexibility in logistics when constructing high-rise constructions, and thereby putting extra pressure on suppliers, as these advantages can be found in the repetitions that are implied. 3.2.2 Supply logistics Cheng and Kumar (2015) press the issue of having deliveries at the right time as overcrowding the workspace is considered a major risk. Incorrect deliveries should be directly avoided, which demands carefully planned logistics. It is however not only important to have a detailed plan, where logistics is synchronised with production; the plan must also be flexible to unforeseen events resulting in changes in the delivery schedule. Having the right material on the right place at the right time should therefore CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 21 be central for logistics planning, as it otherwise may directly obstruct production (Lange and Schilling, 2015). According to Seppänen and Peltokorpi (2016), the question of how material is stored impacts workflow reliability, as on site storage decreases available space on site and can be an obstacle for work that is to be carried out. On the other hand, off site storage can imply a risk for deliveries due to having less float for transportation. Material should according to them be stored close to where it is needed without interfering with production or risking to lower productivity. Hamzeh et al. (2007) claim that a consolidation centre can provide several benefits for construction projects as the projects become central for deliveries giving higher reliability. Hence, a lean signal system can be developed where production orders the goods, and thus ensure that the right materials are delivered to the right place at the right time. This can also be connected to modifications in the production schedule where the logistics schedule must be adjusted to become synchronised. This gives that off-site storage implies a higher tolerance to variations compared to on site storage (Cheng and Kumar, 2015). For example, a superintendent need to be able to change a delivery when it is obvious that the material no longer will arrive at the right time to create a lean process, regardless whether the delivery needs to be accelerated or postponed. Using a consolidation centre with intermediate and temporary storage would according to Kalsaas et al. (2015) facilitate JIT deliveries to the construction site, and thereby enable for the construction site to increase pull for production. The use of consolidation centres provides that logistics are kept in accordance with a pushing logistics, resulting in increased flexibility as goods can be coordinated before being delivered to the site. Simultaneously, it gives that big orders and full truckloads can be guaranteed to the consolidation centre while on time deliveries become redundant (Sullivan et al., 2010). This could according to Sullivan et al. (2010) also decrease the amount of goods damages and wrong deliveries, ensuring that production does not get obstructed. A consolidation centre could further be combined with an IT-based control system to synchronise supply and demand between the construction site and the supply chain (Dallasega et al., 2016). It is implied that this would facilitate increased pull for production, focusing on ordering goods when a demand arises at the construction site and thereby provide a JIT material supply. Deliveries do however increase in amount, resulting in more truckloads and extended coordination, which implies extra costs compared to delivering full truckloads to the site directly from the supplier (Cheng and Kumar, 2015). This is visualised in Figure 5, where conventional supply logistics are compared to having coordinated deliveries through using a consolidation centre. CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 22 Figure 5 - Conventional supply logistics vs supply logistics with consolidation centre. Furthermore, when using a consolidation centre, logistics coordination is moved away from the construction site resulting in need for well-established collaboration with one party off site rather than having to coordinate with several different parties from the site (Seppänen and Peltokorpi, 2016). By moving this process off site, extra costs are implied for the coordination which traditionally is made by production (Cheng and Kumar, 2015). If these costs however can be covered by the risks that otherwise are implied in production, there are advantages to find. 3.2.3 Just in time Delivering materials JIT, the right goods in the right place at the right time, has been increasingly common due to densification of cities where goods cannot be stored on site and later be distributed when needed (Said and El-Rayes, 2013). Even though space is a less common limitation in Sweden compared to more closely populated countries, the space for on-site storage is commonly limited due to having tight construction sites (Boverket, 2012). Therefore, focus has shifted to not deliver material before it is needed on site so it can be delivered to match actual demand to the place where it is needed on the site directly, without obstructing productivity. The approach puts high demands on suppliers, as a delivery that runs late risk obstruct the entire production cycle. Lange and Schilling (2015) argue that when each subcontractor manages their own delivery by truckload, the system is at risk as control over coordination is lost. Instead, optimisation through full truck deliveries with minimised distance is suggested by Seppänen and Peltokorpi (2016) in order to achieve JIT deliveries. This approach can be connected to LBS where deliveries are directed to specific locations to coordinate between different subcontractor trades. To do this, goods needs to be coordinated before arriving to the site resulting in excessive management. It does however provide better means to have full truck deliveries and having a system where the right goods is delivered at the right place in the right time (Sullivan et al., 2010). An issue with JIT deliveries is scheduling, where BIM often have been suggested to act as a supportive tool (Bortolini et al., 2015, Cheng and Kumar, 2015, Seppänen and Peltokorpi, 2016). The competence required is commonly missing in the production CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 23 team which has created a market for separate logistics companies and an increased focus on prefabricated building components in order to decrease work and waste on site. Skjelbred et al. (2015) argue that the production flow should never be harmed by lack of materials but materials should neither be stacked on site as they will become an obstacle for production. To achieve this, scheduling is critical as it implies a balance between the two measurements. To find a useful tool and arrange who is responsible for synchronisation between logistics and production will thus depend on the competence that is required in the specific project giving that logistically complex projects have higher demands on coordination than less complex projects. 3.2.4 BIM for logistics Given that BIM is under constant development, logistics planning is thought to be one of the major benefits providing simulations and clash control services for deliveries to ensure that they arrive to the right place at the right time (Pérez et al., 2016). Cheng and Kumar (2015) argue that through synchronising logistics planning and production planning in BIM models, visualisation can be improved compared to traditional planning. It is moreover stated by Andersson et al. (2016) that using information models to improve logistics is something that will increase as the proliferation of future research and implementation of VDC increases. However, there are limitations to the system as it requires a high level of development for the model, it needs to be constantly synchronised with production, and it does not consider the presence of buffer locations (Gu and London, 2010, Pérez et al., 2016). In addition to this, the supplier needs to be active in updating when goods are ready for dispatch and when it has been dispatched for the system to stay updated. Bortolini et al. (2015) support this and add that synchronisation between the level of development of the model and level of development in the construction schedule is key in achieving high accuracy in logistics. This requires extra administrative work which results in extensive planning costs giving that the savings from the benefits must be weighed against them. Bortolini et al. (2015) describe a case where a 4D model was used to support planning. The system was used in meetings to show sequences on how work was to be conducted giving that clashes were easier to discover. Storage locations were identified to minimise transportation and increase production flow. By visualising the building in the sequences, it was possible to plan where material was supposed to be at what time and thus minimise waste. The simulation was governed by a coordinator, having those affected by the specific simulation involved in the decision-making process and thus creating a collaborative approach. Having 4D BIM implied an interactive process where the different parties planned the logistics jointly. A similar solution was presented by Russell et al. (2009) where linear scheduling was applied to a high-rise construction project, and further incorporated in the 3D model, taking it to 4D. By including time as a parameter in the model, planning was enhanced due to having better control of the sequences in the production cycle. A BIM model can easily be divided into segments or locations that are going to be conducted simultaneously, which gives what deliveries of goods that risk to clash (Bortolini et al., 2015). By having improved visualisation, the logistics becomes easier to manage which implies less risk of having the wrong material delivered to the wrong place at the wrong time. As high-rise construction entails repetition of locations in form of floors, commonly with similar floor plans, BIM can thus provide means for enhanced CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 24 planning (Russell et al., 2009). This results in a delivery schedule which is connected to the production schedule, where the use of BIM can be used to visualise the logical sequence of activities within each respective zone. 3.2.5 Coordinating logistics Another core aspect of logistics planning is how information is transferred from production to suppliers, and who is responsible for which delivery. Cheng and Kumar (2015) claim that information can be extracted from BIM, as long as the level of development is high enough, meaning that suppliers can retrieve information on what goods that should be delivered to which place at what time. In this scenario, the model must be trusted to be correct and include all the materials needed for the specific segment or location which the material is going to be delivered to. More commonly, separated software is used, resulting in the deliveries are planned based on the master- or phase schedule. Cheng and Kumar (2015) further admit that it is tedious to have an updated model, where control of every single building component is included. However successful management of this process it thought to enhance production as material is delivered according to JIT and wastes are reduced. Moreover, using an efficient planning software for coordination is key in increasing pull for production (Dallasega et al., 2016). By using software to plan and manage deliveries, collaboration is enhanced throughout the supply chain, as information is easily distributed compared to having one party who distributes all information to each respective party. To further integrate the software with the production system to meet actual demand means that automation is achieved. This also implies extended flexibility in deliveries, as all parties can be made aware of changes by notifications from the software. As shown in Figure 6, information is gathered in the software and then distributed to the suppliers, thereafter each supplier can follow it to see when their respective delivery is to take place. Figure 6 - Example of logistics information flow. CHALMERS Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 25 Traditionally, each subcontractor is responsible for the material connected to their work (Lange and Schilling, 2015). However, in complex projects where logistics demand extra attention, there is need for more careful planning to avoid clashes. When constructing high-rise constructions, the height becomes an obstacle, providing that extensive communication and coordination is necessary. To govern this process, logistic companies can be hired as expertise to bring specific competence to the project (Lange and Schilling, 2015). Where subcontractors on logistically low complex projects can bring their own goods or have it coordinated by a superintendent, high complex projects provide that logistics planning require higher competence and extra attention to not obstruct, but rather promote, efficiency. Complexity connected to logistics can have several reasons, both related and unrelated to production complexities, such as density on and around the site, amount of parties involved in the supply chain and height or location of the place where the material is supposed to be delivered (Pérez et al., 2016, Said and El-Rayes, 2013). However, by having an integrated software, subcontractors can still order their own material but have it governed by the contractor. 3.3 Synchronising production and logistics planning Traditional construction planning implies a high level of uncertainty, as it commonly is carried out by the contractor and thus not including those who are to perform the work, making it a game of assumptions rather than an accurate plan (Bortolini et al., 2015, Daniel et al., 2014). By focusing on locations rather than activities, and planning collectively, estimations become more accurate while risks also can be distributed to be managed by the party possessing the best competence to manage it (Seppänen and Peltokorpi, 2016). Additionally, to ensure flow from suppliers to subcontractors, 4D BIM can be utilised to facilitate efficient risk management both in production and logistics (Cheng and Kumar, 2015). Separately however, production and logistics planning can hardly promote workflow significantly as their value comes when integrated properly. Both aspects build on the other working without interruption, implying high demands on the synchronisation between them (Hulthén et al., 2015). In order for one to run smoothly, the other must flow and vice versa providing a situation where focus often is lost for one of the aspects. Thus, planning for efficient synchronisation becomes vital in producing a system where flow is implied from suppliers to subcontractors. 3.3.1 Push and pull Production and logistics scheduling are highly dependent on each other, giving that changes in one is likely to affect the other (Lange and Schilling, 2015). This results in a situation where flexibility is key, as risks cannot be removed. For example, if suppliers cannot guarantee that deliveries will be on time for a specific activity or zone, it cannot be done before the delivery is made. In contrast, if a delivery arrives before it is necessary due to changes in the production plan it is likely that non-value activities will be generated in form of obstruction on the site. Planning is however commonly carried out separately, implying that synchronisation is a risk (Bortolini et al., 2015). Therefore, managing information is of utmost importance in creating flow throughout the chain, from suppliers to subcontractors, as changes in either production or logistics must imply reaction in the other. CHALMERS, Architecture and Civil Engineering, Master’s Thesis BOMX02-17-41 26 Contractors rarely include logistics management in their organisation resulting in that specific competence needs to be hired for projects where it is deemed necessary (Hulthén et al., 2015, Said and El-Rayes, 2013). Hence, a situation in logistically complex projects occur where there are two separate parties planning production and logistics, which results in a situation where synchronisation between the schedules to promote workflow is essential. Separate planning implies sub-optimisation, which is a common mean for poor flow in the otherwise fragmented construction industry. As both production and logistics planning promotes a social process in planning of specific locations, activities, assembly points or deliveries, synchronising should include both a top-down and bottom up approach, implying a balance for push and pull (Seppänen and Peltokorpi, 2016). This results in that a close collaboration is required between production and logistics planners to avoid clashes. The bottom up approach implies specific planning while the top-down approach provides look-ahead planning. Developing systems for how to work with both production and logistics is therefore also central to enhance the information flow from suppliers to subcontractors and vice versa, to promote the balance of push and pull that is chosen. Consequently, alignment must exist both within production and logistics separately but also when being combined. The repetition implied in high-rise construction further presses for increased pull for production, as the benefits become incremental due to streamlining the process for every round in the production cycle that is completed (Russell et al., 2009). The master schedule, which conventionally is the subcontractor's liability to fulfil towards the contractor, should therefore decrease in value providing decreased push while push for logistics is increased to ensure that the right material is delivered, enabling for the right activity to be performed at the right time (Said and El-Rayes, 2013, Sullivan et al., 2010). Engaging the subcontractors in a social process through planning collectively further supports an incremental pace in the production cycle, resulting in a higher effici