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This is a so-called personal version (author's manuscript as accepted for publishing after the review process but prior to final layout and copyediting) of the article

Björk, Bo-Christer and Laakso, Mikael. 2010, CAD standardisation in the construction industry - a process view, Automation in Construction, Vol 19, No. 4, pp. 398-406

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CAD standardisation in the construction industry – a process view

Bo-Christer Björk & Mikael Laakso

Hanken School of Economics, Arkadiankatu 22, PO Box 479, 00101 Helsinki, Finland

Abstract

There has been a demand for uniform CAD standards in the construction industry ever since the large-scale introduction of computer aided design systems in the late 1980s. While some standards have been widely adopted without much formal effort, other standards have failed to gain support even though considerable resources have been allocated for the purpose. Establishing a standard concerning building information modeling has been one particularly active area of industry development and scientific interest within recent years. In this paper, four different standards are discussed as cases: the IGES and DXF/DWG standards for representing the graphics in 2D drawings, the ISO 13567 standard for the structuring of building information on layers, and the IFC standard for building product models. Based on a literature study combined with two qualitative interview studies with domain experts, a process model is proposed to describe and interpret the contrasting histories of past CAD standardisation processes.

Keywords: standardisation process, computer aided design, building information modelling, industry foundation classes

1. Introduction enable the seamless communication Standards provide an essential ingredient between computers and software to the ubiquitous use of IT in everyday life applications in a world-wide network. and business. The fundamental Internet Standardisation processes have received and web protocols provide a good example relatively little attention within the of established interoperability standards. research community despite the Numerous formal and de facto standards tremendous importance of standards in modern society. Only recently has IT

1 PERSONAL VERSION standardisation started to emerge as a international standard for CAD layering, research field of its own [1,2]. the ISO 13567, was defined in 1997 to harmonise the incompatible policies that Standardisation has always played a crucial had developed locally over time [4,5]. The role in the construction industry. Examples IFC file format for transfer of complete include: technical standards which enable building information models has endured parts to fit together, classification one of the most lengthy standardisation standards which facilitate quantity takeoff, processes within construction IT, however, cost estimation, and the compilation of it has still not managed to establish its searchable information databases. place in industry practice outside small Classification of functional building pilot projects [6]. elements (e.g. doors, windows, slabs etc.) is a particularly interesting parallel because Previously published articles have mostly it illustrates the difficulty of international been narrow in scope, focusing primarily standardisation without even bringing IT on individual standards in-depth, or into the mix; when slightly different reporting individual cases of standard national implementations have emerged implementation [7,8,9]. This study they have ultimately resulted in lock-in attempts to build a process framework for situations when incompatible standards standardisation, based on standardisation have clashed. experiences within the construction industry by taking a closer look at the The recent widespread integration of IT in processes of several already established construction makes use of several already and emerging standards. Such a framework existing standards, as the ones described would probably be helpful for above, but has also created the need for standardisation work within construction, new types of standards. This particularly but also other communities heavily concerns the description of a building in dependent on standardisation of IT for digital form. Human experts and even lay increasing interoperability. people can read drawings and interpret them, despite minor ambiguities. However, 2. IT Standardisation if software applications attempt to access data created by other applications, the data 2.1 General theory and needs to be formatted according to concepts common specifications in order to be of Terms regarding standards and any use at all. For the transfer of graphical standardisation have been used with some elements between different CAD systems, ambiguity in past literature, however, a the neutral standard IGES was developed firmer typology has gradually started to around 1980 [3], but in practice DWG, take form [10], which will also be used which is the native format of leading CAD throughout this study. vendor Autodesk, has become the de facto transfer standard when exporting and The word ‘standard’ is defined as follows: importing data from other CAD systems. For earlier generations of building ”A standard is an approved specification descriptions, or more precisely 2D CAD of a limited set of solutions to actual or systems, the layering approach combined potential matching problems, prepared for with standards for how graphics are the benefits of the party or parties exchanged greatly facilitated data sharing. involved, balancing their needs, and During the late 1980s numerous layer intended and expected to be used standards evolved within CAD user groups, repeatedly or continuously, during a and in some cases, on national levels. An certain period, by a substantial number of

2 PERSONAL VERSION the parties for whom they are meant.” (De ISO standard long after gaining its de facto Vries, 1999, p. 15) [11] status, in July 2008 [12]. Some formal standards have become very successful, Compared to many other definitions to be but there are also numerous which have found in the literature, this definition had no impact on the market. De facto provides an appropriate level of freedom standards are by definition successful. The for what kind of standards can be defined labels for the different processes have by its description without making it non- therefore no relation to the actual success descriptive [10]. Regarding scope and of the standard, they merely make it easier focus, this study deals with compatibility to compare and analyze the different standards, which is often the case when IT means by which standards are developed standards are concerned. These types of and establish their position the marketplace. standards are sometimes also referred to as functional standards [10]. Perhaps Analysing the stages a standard goes implicitly implied but certainly good to through on its path to the marketplace is an clarify is that standards in this category are important part of the IT standardisation usually international standards with literature. There have been some variations network externalities. in the stages suggested so far, however, most of the stages are agreed upon by Standardisation, which is the process of a researchers [13]. Variations are mostly due specification becoming widely used and to differences in purpose, typology, and accepted for its purpose by its users, is properties of particular standards analysed. ultimately achieved either through a formal, Generic stages in the progression of a semi-formal, or de facto process [10]. standard have been identified, which Formal and semiformal standards are the include: requirements definition, result of committee work, often involving development, agreement, marketing, lengthy negotiations and compromises deployment by vendors, and acceptance by between the interests of different end users. If any of these stages would stakeholders. Examples of this type of happen to fail during the standardisation standards include the building element process, the whole process fails. classification systems in use in many Furthermore, a long incubation time for a countries and EDIFACT messages standard may have harmful consequences developed for electronic procurement of on the marketing and deployment stages construction materials. The degree of [14]. formality involved depends on the status of the organisation defining the standard, Some researchers have noted that ranging from the International Standards analysing standardisation as a linear Organisation through national process omits important stages which standardisation organisations to different heavily shape the final product. A linear sorts of industry consortia. De facto model is not representative of how most standards arise through a Darwinian standard setting organisations function due selection process between competing to the lack of a feedback and refinement standards on the market, gaining support mechanism. Through this development, by becoming the preferred choice of the different models for the life cycle of users. A good example of a de facto standards have emerged [13,14,15]. Eva standard is the widespread adoption of the Söderström (2004) [13] generalised seven PDF format for document exchange on the published standard life cycle models into web; the platform-independent portable one core model in a recent literature review, document format was launched by Adobe of which the main result can be seen in Fig. Systems in 1993 and was made an official 1.

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consortia have long been used for other forms of standardisation as well [18].

In order to properly understand standardisation efforts, it is important to be aware of the relationship between the development of a technology, and the definition of the standards necessary for its use. In most cases the technology is developed first, including several different technically working alternatives, after

which the pressure for standardisation Fig. 1 Generalised standards life cycle model arises. Examples include rail widths for (based on Söderström 2004) [13] railroads, electrical current levels in power networks, computer operating systems, and Important to note is that the feedback video cassette recorders. A prerequisite for mechanism, which is one of the main the success of video rental stores in the arguments for a cyclical process, should be 1980s was the convergence of the market enforced and implemented by the standard to one dominating technical format, in setting organisation. However, once a final which struggle VHS emerged as a de facto version of a standard has been released, it standard. Similarly in the cell phone should remain stable for a longer period. If business, development of the technology new versions are released they should be and emergence of standards such as NMT compatible with earlier versions to avoid and GSM has gone hand in hand [19]. fragmenting and confusing the user base [16]. This has also been the order of evolution for CAD software; the need for standardisation has grown stronger as both 2.2 IT standardisation in the the number of users and uses for the construction industry software has increased [20]. Because of IT standardisation is particularly relevant this retrospective relationship, the technical in the context of the construction industry; complexity of a standard is also something with expensive and tightly-scheduled to consider when comparing different individual projects spanning over multiple standardisation efforts. Many of the most stakeholders, the demand for uniform tools, successful standards are relatively simple, and policies for how to use them, is crucial potentially leaving more resources if seamless collaboration is to be achieved. available for marketing and deployment. A new IT infrastructure is not something To take a nearby example, the overall work companies build up from scratch for each input into the definition of the ISO CAD individual project that comes along, not layer standard was in the order of one man only because of the massive investments in year. For the IFCs, the standard in itself is time and money involved, but also because highly complex with definition work still there is uncertainty and risk present in such going on over ten years after the start of endeavours [17]. This strive towards the standardisation effort [21]. One interoperability is one reason why interesting question is if there is a point consortia and other cross-organisational when a standard becomes so technically collaboration activities are so prevalent complex that the committee bargaining and concerning the development and decision-making processes to reach a standardisation of IT [16],and particularly decision become too cumbersome for a within the construction industry where successful outcome [22]. In the case of

4 PERSONAL VERSION building information modelling this is domain experts [20, 24], a simple process almost impossible to say since the standard model for standardisation was developed. has been influencing the development of The core objective was to combine the technology itself; distinguishing the concepts and frameworks used in the standardisation efforts from general general IT standardisation literature with development and testing work of the qualitative research results to improve our software tools is very difficult. knowledge about this particular standardisation domain. The name of the One of the interesting aspects of overall model is “Develop, deploy and standardisation is that seen as a project, a standardise CAD technology for standardisation effort to a large part construction”. Despite its name and consists of voluntary work, taking place in particular application here, the process committees and outside formal meetings, model is generic and not a priori restricted in a setting not controlled by formal to CAD and product modelling technology. contracts and budgets. Experts participating in standardisation efforts are The domain expert interviews concerned often granted permission to work and the standardisation processes of the funding from their companies, sometimes international CAD layer standard ISO also helped by outside funders such as 13567 [20] and the IFCs [24]. Since national or international research detailed results of the two sets of programmes. In many respects the process interviews have been reported elsewhere in is comparable to how open source software journal papers (referenced above), they development works [23]. Interestingly this will not be repeated in this paper. The way of working, to a degree, also method utilised in the previous studies was resembles the functions of the scientific semi structured interviewing with a community. This has important number of experts representing important implications for both the overall progress stakeholder groups in the overall process and final deliverable of the standard. of taking a standard into use; Complex standards have many aspects to standardisation committee members, work on before even the first revision sees researchers, end user company IT experts, the light of day; choices concerning which and software vendors. In these studies it aspects of the standard receive was determined early on that a qualitative supplementary attention, and in which research approach was more suitable order, are usually guided by an explicit compared to a quantitative one with regard overall strategy. However, the actual to the research questions which were of working order and emphasis is also to a explorative nature. large extent steered by the participants themselves. Factors affecting the outcome The process model was developed using include the individual working preferences the graphical IDEF0 notation, which has of the participants, their possibilities to frequently been used in construction IT obtain external funding, and perhaps also research and also by experts involved in their company’s blessing for participating. STEP/IAI work. The main concepts of the method are the activity and the flow. 3. A process model in the Activities are shown as rectangles and their context of CAD names start by verbs. Flows are represented standardisation by arrows and the names are nouns. A flow can be either an input, output, control, or

mechanism. An input represents As a result of the literature review something, which in an activity is presented in the previous section and consumed to produce an output. Typical lessons learned from interviews with

5 PERSONAL VERSION inputs could be raw materials, energy, mentioned in the previous sections that human labour, but also information when stadardisation efforts have considerable the purpose of the activity is to transform differences in how resource-intensive they the information. Outputs can be reused as are, largely depending on the complexity inputs to further activities, and feedback and maturity of the applicable technology. loops are possible. The execution of activities is guided by controls. Outputs consisting of information can also be used as controls. Mechanisms, which point at activities from below, are usually persons, organisations, machines, or software ,which carry out the activities. Presentation of IDEF0 diagrams is hierarchical [25].

The purpose of the model is to demonstrate the context of CAD standardisation work, in particular its relationship to actual use of the standard in construction projects and to the R&D work that predeeds the definition of the standard and the development of the software technology supported by it. The model consists of 5 diagrams on 3 hierarchical levels. The diagrams are presented in descending order, which should aid readability.

The context diagram, seen in Fig. 2, explains the surroundings of the model. It places standardisation into a broader context, as just one part of a wide effort to develop and adopt a particular technology into wide-spread use. It introduces the actors and stakeholders affecting the adoption of the technology. Resources are essential to developement work at many stages of the standardisation process. It was

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Fig. 2 The context of the process model

Fig. 3 The overall model

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Fig. 4 Develop CAD technology

The overall model, seen in Fig. 3, splits the The development diagram, seen in Fig. 4, entire process into three parts: the splits up the development activity of CAD development of the technology, the process applications into several smaller phases. of taking it into wide-spread use in practice Development is based on research results (deployment) and the development of the gained by researchers, development of standards needed to make the use of the applications can either be instantly initiated, technology cost-efficient. It is important to or alternatively, an anticipated need for note that the order of activity boxes does standardisation might be discovered for not necessarily imply a temporal order of future development. Applications can be doing activities (in the way time-table developed in isolation, but at some point charts imply). Thus standardisation can they might also be streamlined in order to either happen before or after deployment, be able to export and import data according sometimes even prior to development of to standards. The testing of applications is the technology. The importance of also a key phase, with an integrated resources cannot be stressed enough, they feedback mechanism to the development have to be available during all stages of the phase for further refinement in accordance process in order to enable a successful to collected feedback. Important to note is outcome. The input and influence of that vendors often like to claim standards researchers and software developers is compliancy for their products for dominant in the development and marketing purposes, even though the definition stages, while construction particular functionality may not work in process companies are mostly involved practice. This has been shown to be true with deployment and definition of the with IFC data exchanges in several studies standard. [6,26].

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Fig. 5 Deploy CAD technology The definition diagram, seen in Fig. 6, The deployment diagram, seen in Fig. 5, highlights the fact that a standardisation shows what happens after the standard has process is very a complex project in itself, been incorporated into commercial involving several different stages, which software. It is then up to the individual all need to be successful for establishing a companies to adopt the product and invest widely used standard. The need for in training and integration to use the standardisation originates from imminent application as intended. The competing market demand or anticipation for the need products, guidelines of client organisations, of standardisation for some emerging and decisions made by other construction technology. Formal R&D programmes, process companies heavily affect the client organisations, and construction decisionmaking. Once applications are process companies provide funding for available from vendors they have to be standardisation work. These resources are taken into use inside single companies, and then used to both develop a draft standard in project groups with several companies up until the point that agreement can be involved. Only use in real pilot projects reached for a formal standard. Then it is up can reveal some of the difficulties to software vendors, industry associations, involved. De facto standards do not go and formal standardisation bodies to through this process as they have already market and inform about the standard so been accepted and adopted by the users. that it becomes known to all stakeholders

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Fig. 6 Define CAD standards

version of the IGES standard was 4. Discussion - published in 1980. Therefore it was almost standardisation cases an anticipatory standard. It should be noted The process model presented in the that several big companies (i.e. Boeing, previous section will be used as a backdrop General Electric, Xerox) as well as the US to further highlight and discuss the department of defence were involved in its differences in the standardisation process development. The first release, IGES 1.0, between the four standards selected for this was published by the American National study. Table 1 gives a brief overview of the Standards Institute (ANSI) only one year origins, status and particular subdomain for after work had begun. Thus the the different standards. standardisation process preceded the large- scale deployment of the CAD technology 4.1 IGES in the industry. In the case of the IGES (Initial Graphics Exchange Specification) standard the standardisation was carried out at a rather early stage; the basic CAD technology (2D and 3D geometric modelling) was developed during the 1970s and the first

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Fig. 7 Test file used to demonstrate IGES vendor interoperability in the 1980s

Standard Developed Status Domain IGES 1978 - 1980 Official, ANSI CAD graphics DWG 1982 - 1990 De facto CAD graphics ISO 13567 1993 - 1997 Official, ISO CAD layering IFCs 1994 - Industry consortium building information model

Table 1. The standards discussed in the study

4.2 DWG DWG is the proprietary file format used by made by individual companies a de facto modelling software AutoCAD, its standard emerged, which forced other specifications have not been published by CAD vendors to develop the facility to the vendor. To offer interoperability import/export data in the AutoCAD format. AutoCAD developed the open ASCII- The overall cycle was thus development of based DXF (Drawing Interchange Format), the CAD technology by different software to be used by other CAD vendors for vendors, industry deployment and rapid importing and exporting CAD data. In the market penetration followed by the mid 1980s, DXF compliancy started to be emergence of a de facto standard based on more important than implementing support the proprietary format of the market for IGES as the market share of AutoCAD leading system. In very rough terms, the steadily increased. Later, as third parties basic software was developed in the 1970s, were able to reverse-engineer the closed industry uptake took place in the 1980s, DWG format and publish libraries for and the de facto standard was a reality building translators, most other CAD- around 1990. vendors started offering conversion tools to DWG rather than DXF. Considering the 4.3 ISO 13567 process model presented in this paper, Basic layering emerged during the late DWG emerged by de facto standardisation 1970s, first mimicking a technique which after wide-scale deployment of CAD already had been used in manual drafting. technology in industry. Due to the choices Support for detailed structuring of layers

11 PERSONAL VERSION was usually not embedded in basic CAD- on the international level to harmonise software which resulted in a wide number national standards. This led to the forming of practices being developed on project of a working group under ISO which and company levels. During the latter half delivered a standard in 1997 [27,28]. The of the 1980s, experiences from full name of the standard is “Organization construction projects led to a wider and naming of layers for CAD -- Part 2: demand for standards regulating the Concepts, format and codes used in allocation of drawing elements on layers. construction documentation”. The ISO Standardisation was attempted by CAD- standard was heavily influenced by already system specific national user groups but begun standardisation work in a number of also by national construction member countries and the approach can be standardisation bodies. There was also characterised as bottom-up. consensus that something ought to be done

Fig. 8 The core concept of CAD layering

4.4 IFCs While CAD systems facilitating the could not manage [29]. Digital building production of 2D drawings were being descriptions using objects which belong to taken into widespread use, some predefined classes have usually been called researchers and system developers started building product models, although some to envisage more advanced object-oriented software vendors have recently coined the building representations. These advanced new term building information model ( systems would enable solving some of the more demanding data sharing functions BIM) for essentially the same thing [30]. that purely graphics-oriented CAD systems Research concerning such models started to gain momentum around 1985, when the ISO STEP standardisation project started.

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STEP stands for Standard for the Exchange development of the tools. As early as in of Product Data and attempts to solve the 1985-86 the development of a building data exchange needs for a large number of product model standard was defined as a manufacturing industries. In the early high priority in the Finnish RATAS- 1990s there was some frustration that the programme [31]. Two influential high building construction work within the level models were proposed in parallel as a STEP community lacked proper part of the STEP-standard. These were the momentum and that the formal ISO rules GARM model [32] and the Building for reaching agreements were too slow Systems model [33]. STEP is the ISO [22]. The need for standardisation was product modelling effort, which at the time expressed early on by visonary researchers, also included an active subcommittee for industry experts and software developers building construction. which has driven the research and the

Fig. 9 IFC compliant BIM model

Independently from the efforts within International Alliance for Interoperability STEP, twelve US companies using (IAI) was established based on a structure AutoCAD initiated co-operation in 1994 in of regional chapters. The experts working order to make their software applications on the IAI standard, which received the compatible with each other. After a name Industry Foundation Classes, quickly demonstration at the AEC systems trade understood that there was no need to show, other companies expressed interest reinvent the wheel. Consequently, to join the effort and the co-operation was important parts of their definitions were extended both to other countries and also based on work done previosly within STEP. to users of other CAD systems. In 1996 the This included the EXPRESS language and

13 PERSONAL VERSION a model called the Building Construction Consequently the effort which had been Core Model, which had received a lot of put into the development of the IGES input from several EU funded projects. standard became redundant, at least for Among other benefits this entailed the CAD use in the building construction possibility to reuse such entity definitions domain. from STEP which deal with non construction specific items, such as basic Other kinds of standardisation, ranging geometry. The first version of the open from industrial consortia standardisation to standard, the Industry Foundation Classes very formal standards published by the (IFC), was issued in January 1997. Release ISO, have in this context proven to be very 1.5 was the first to see commercial difficult to manage. The ultimate success implementation in a CAD-application in of the standard hinges on the success of July 1998. Release 2.0, issued in 1999 was every one of a number of different much more comprehensive in scope. The activities related to different life cycle latest available version is IFC2x3 [34]. stages of the standard. Key issues include: Fortunately the quite frequent updates to the standard is something that the IAI has • The timing of the definition of the taken into account from the beginning standard to the general development ensuring backwards compatibility - as and deployment of the underlying standards designed for evolving technology. technologies should. • The overall level of the resources made IFC work in many respects resembles an available for the standard definition, open source software project. The end relative to the technical complexity of result is publicly available on the web and the standard. free for anybody to implement and use - in contrast to ISO standards which have to be • The management of the standardisation bought. And perhaps even more process, ranging from a top-driven importantly, the work itself is partly self- traditional project, to an open source organising, progress is tied to how the like collaborations based on voluntary motivated and skilled experts can manage contributions. to get funding.The downside is the reliance on the changing business strategies of a • The buy-in of software vendors for number of involved software companies as implementing the standard in well as on a number of time-limited R&D applications programmes (e.g. EC research funding, the VERA-programme in Finland). • The actions of key construction client organisations for promoting use of the Conclusions standard.

De facto standardisation is rather To study a complicated international uncomplicated to manage, because it standardisation processes, particularly happens if one particular software within construction IT, it would be application gets a large enough market- beneficial to utilise a wide interdisciplinary share to put commercial pressure on the perspective to enable thorough analysis of other vendors to provide conversion factors affecting the flow of the process. software to and from the format of the The model presented in this paper could leading system. This is what happened in function as the backbone for the case of geometrical primitives in CAD- comprehensive case-studies; not only systems with the DWG format. would this be fruitful for providing

14 PERSONAL VERSION structure to such an endeavor, but it would about standards, in particular the IFCs, also help refine the proposed generic which currently are the focus of much standardisation process model. In the interest. particular case of IFC standardization, involvement with first-hand sources like ACKNOWLEDGEMENTS software vendors, contractors and IAI consortia members would shed needed This research has been carried out with light on the whole situation by clarifying financing from the Academy of Finland the effect these stakeholders have on the (grant 108487), TEKES through the overall progress of IFC standardisation. It FoundIT project and the Hanken is hoped that the presented model can be of Foundation. Funding was also provided by some help in structuring the discussion the Waldermar von Frenckell Foundation.

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