Making-do is an invisible form of waste (Koskela, 2004) that has been confirmed in recent empirical studies to be prevalent in construction (see Formoso et al., 2011, Brodetskaia et al., 2011; Emmitt et al., 2012; Fireman et al., 2013). It refers to starting a construction task before its preconditions are ready, or continuing a task although at least one of its standard inputs has ceased (Koskela, 2004). This wasteful activity often occurs for keeping the utilization of capacity high and also for the sake of schedule compliance (Koskela et al., 2013). As a result the task is not fully completed, leading to inefficiencies and unnecessary re-work (Emmitt et al., 2012). These preconditions necessary for starting and executing a task are described by Koskela (2000) as the seven types of flow in construction: (1) information; (2) space; (3) interdependence of tasks; (4) manpower; (5) materials; (6) equipment; and (7) external conditions. Thus, according to Formoso et al. (2011) Making-do could be defined as a reduction of performance that results from the fact that a task is started or continued even though one
or more of its standard inputs, required for its completion, are not available. Making-do can actually can be regarded as the opposite of buffering, hence work starts without the minimum amount of resources (inventory) for carrying out a task to completion (Koskela, 2004).
Interestingly, a study by Emmitt et al. (2012) sought to improve the attitude of the trades’ workers, foremen and site managers towards completing their work packages, so that the work flow and quality could be improved. Their study found that waste can occur due to lack of common understanding, amongst trades involved, about what constitutes a completed task. Consequently, work by Pasquire (2012 & 2013) suggested that 'common understanding', has to be managed as a soft flow in the same way as Koskela's (2000) seven flows mentioned above. She describes this as follows:
"In their paper about inappropriate processing, Emmitt et al. (2012) claim that the phenomenon of doing only just enough to allow the next trade to start necessitating operatives to come back to finish work...This waste should be included within the category of ‘making-do’ (Koskela 2004) but currently falls outside because it doesn’t arise as a result of starting work before all flows are in place. If understanding were one of the flows, then it can be argued more strongly that leaving work before it is at the best stage of completion is a form of making-do because in this example, a proper understanding of the hand-off stage was not present" (Pasquire, 2012, pp. 6).
According to Formoso et al. (2011), making-do is a result of the poor management of upstream processes, which may result in the execution of tasks under sub-optimal conditions. Consequences of making-do, as reported by Ronen (1992), Koskela (2004) and Formoso et al. (2011), Emmitt et al. (2012), and Fireman et al. (2013) include: • More work-in-progress, and longer lead time;
• Decline in overall productivity;
• High negative impact on site safety conditions; • Decline in workers' motivation;
• Increase in the share on non-value-adding activities;
• Unnecessary increased costs (e.g. due to need for re-work); and • Material waste.
Furthermore, a study by Formoso et al (2015) demonstrated through a causality framework that making-do, as a major category of waste in construction, can lead to the generation of a complex network of inter-related wastes. According to Ronen (1992), as cited in Koskela (2004), the possible causes of making-do are:
• The Efficiency syndrome: the urge to have the resources utilised as much as possible, based on the assumption that overall productivity increases if all workers and equipment have a high utilization rate;
• The pressure for an immediate response - based on the belief that by starting early, even if with an incomplete kit, the task will also be completed earlier. Another motivation could be to start the work just for getting the job. Also for trying to comply with the master plan; and
• Improver division into levels of assembly - a situation where the number of components per kit grows to an uncontrollable level, leading to high variability
Koskela (2004) accepts Ronen's conclusions; however he argues that the high occurrence of making-do in construction is not just caused due to a failure in implementing a conventional managerial system. Instead making-do is fundamentally caused by the phenomenon of variability in production. He criticised a number of underlying concepts adopted in construction, which in his opinion lead to the persistence of making-do in construction. These are as follows:
• The transformational view of production (Koskela, 2000), which characterises traditional construction, where managerial focus is on value-adding activities (transformation), while giving much less attention to the relationship between the activities (flow);
• Variability in task execution and upstream flows are often neglected and not properly managed;
• Using a standard utilisation rate as a performance measure may provide wrong incentives to managers;
• The conventional one-way top-down communication approaches, which are insufficient for managing highly complex production systems, such as construction projects.
Last Planner System (LPS) for production control (Ballard, 2000), is deemed to be an effective way for protecting production from upstream variability (Ballard and Howell, 1998), and therefore avoiding making-do waste. However the findings of an empirical study by Formoso et al. (2011) provided some empirical light on the limitations of LPS in avoiding making-do. For example, much of the work carried out by crews and workers in construction sites is done informally; thus not included in formal short term look-ahead and constraint analyses plans (Fireman et al., 2013). Furthermore, Bølviken et al. (2014) argue that from the perspective of the production system as a whole, focussing merely on reducing making-do can be counter-productive. That is because it can result in root-causes not being addressed; thus by that way increasing rather than decreasing the negative consequences (Bølviken et al. 2014). These arguments suggest the need for obtaining a better understanding about the fundamental paradigms that underlie wasteful behaviours and practices construction, and which also obstruct waste- minimisation efforts. Accordingly, the next section provides a review of various fundamental factors impeding waste-reduction and improvement efforts in construction.