WHAT IS SLACK AND WHY IS IT NEEDED?
What should you do when you must get home as fast as you can in rush hour? It is possible to choose an alternative route through your phone’s Map application to avoid traffic looking at different routes before leaving. This is an example of flexibility that illustrates what slack means that is dependent on the capacity of individuals to change and adapt in the face of uncertain situations.
Slack can be used to manage the uncertainty and fluctuation in a strategic or opportunistic method by utilizing different kinds of resources. Slack is not limited to the use of more or unproductive resources. Existing resources can be used to manage the uncertainty and fluctuation. Slack also opens up opportunities for innovation, by allowing organisations and individuals to experiment with new approaches (Bourgeois 1981; Lawson, 2001).
Buffer is one of the most well-known types of slack. It’s defined as a cushion used to ensure that processes are protected from fluctuations. Buffers are utilized to deal with the existing, known variations, assisting in achieving the desired outcome (Alves and Tommelein 2003; Buchmann and Slorup 2014). But, different types of slack can be utilized to handle other types of uncertainties or organizational needs.
From a business perspective, Slack is a resource needed to satisfy demand or implement actions at an organizational level (e.g., creating new products and forming coalitions). From a perspective of the production system, it is essential because of the complexity of construction projects. Consequently, construction projects should be considered as a complex system of sociotechnical technology (CSSs).
The complexity that construction-related projects or any other CSSs is characterized by their structure’s complexity and their the degree of uncertainty (Williams 1999). The structural complexity is present in systems with many interconnected parts. The level of complexity is correlated with the amount and distinctiveness of components and the strength of the interrelationships between them. Uncertainty is a result of the goals of the project (i.e., how clearly defined the objectives are) and the methods (i.e., how clear the means of reaching these objectives are). It is also referred to as a predetermined form of uncertainty. But, uncertainty can be defined as a state of uncertainty where there is the absence of knowledge about the situation.
In CSSs, a lot of the uncertainty stems from the influence of social and human factors or organizational circumstances, which make the operation of a system challenging to forecast and manage. Complexity can make it difficult for individuals to comprehend, explain, and manage the systems. Additionally extremely complex projects or systems produce results that are unpredictable, i.e., outcomes which are not predictable in the future.
Figure 1 shows a concept map that shows the connections between concepts that were studied during the investigation (see Formoso et al. 2021). This map can be divided into three areas: (i) why is the need for slack? (antecedents); (ii) what exactly is the definition of slack? (classification as well as development) (antecedents); (iii) what are the effects of Slack? (consequences).
Figure 1. Slack Concept Map (from Formoso and co. 2021)
HOW TO IMPLEMENT SLACK
Inventory, time, equipment, cash, people, and information are just a few examples of resources that are slack. These resources can be used to help CSSs by providing:
- Redundancy Additional resources (in more) which are available, e.g. redundant functions or procedures.
- Flexibility Resources which can be utilized in various ways – e.g. multi-skilled workforces and multi-purpose equipment or adjustments made by workers to handle an unpredictable set of events.
Secondary slack strategies comprise Margin of Manoeuvre, the combination of redundancy with flexibility based on the independence of a group of people, as well as work-in-progress (WIP) which is a kind of redundancy. Margin of maneuver is a way to determine the ways resources can be modified in accordance with the current and necessary circumstances as well as the current conditions, WIP (a type of slack commonly seen when working on construction) is usually manifested as inventory of products that are not finished or backlogs of workspaces which are frequently employed as a way to address the issue of flow reliability.
WHAT ARE THE IMPACTS OF SLACK
In CSSs, anticipating the emergence of situations is difficult and slack could be seen as a major risk-reducing strategy. Risks associated with construction projects are typically assessed in a fragmented manner in management processes like procurement design and security, quality manufacturing planning and management. Production teams also implement informal risk management during their daily work, when they make decisions to evaluate trade-offs and prioritize the distribution of resources, e.g. when considering the risk of working over to finish an undertaking.
The major positive outcomes of slack are discussed below. They affect the efficiency of construction projects by increasing productivity, providing greater value for the clients, and reducing the length of the project.
- Resilience Resilience is the capability of a system to modify its functions before or during certain events, such as changes in the environment, disruptions, or opportunities, in order that it is able to sustain actions under unexpected or anticipated circumstances (Hollnagel and co. 2015). Reliability is the capacity of an entire system or its parts to fulfill their functions in stipulated conditions for a certain duration (Rausand and Hoyland 2004).
- Robustness is the capability of a system to keep its functionality intact when subjected to an array of environmental or internal disturbances and conditions. Robustness can be observed when there is a sufficient array of options to withstand disturbances (Saurin 2017).
- The flexibility of the output Flexibility of output: adapting products to meet specific customer demands without incurring significant costs for transitions or causing significant variations in the performance outcomes (Petroni and Bevilacqua 2002). It is in direct relation to the strategy of mass customization.
From an Lean Production perspective, a negative impact of slack could be the result of actions that require time resources or take up space, but don’t add value for the customer. Certain types of slack can be considered waste when they are excessive, including an inventory of materials, work-in-progress and inefficient time.
Eliminating waste is an effective driver for improvement, allowing issues which could lead to improvement opportunities to be discovered. So, slack as possible source of waste must be analyzed and eliminated in line with the Lean principle of continuous improvement.
EXAMPLES OF SLACK
Daily Huddles
The strategy of deployment is redundancy.
People (problem-solving viewpoint).
What is the reason, and how do you implement Slack? Daily huddles allow participants to share information or discuss the current status of production as well as tasks that must be completed. These meetings are crucial when you are constantly in a changing environment in which unplanned events occur. Two kinds of slack could be identified: (i) double checking the conditions in place to complete tasks (e.g. safety measures, resources available) and (ii) taking into consideration diverse perspectives in making decisions since no one actor is usually capable of conceiving and implementing efficient solutions.