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20th Annual Conference of the International Group for Lean Construction - San Diego, California, USA - 2012

The Robust Schedule - A Link to Improved Workflow

Søren Lindhard¹ & Søren Wandahl²

¹PhD student, Department of Mechanical and Manufacturing Engineering, Aalborg University, Fibigerstræde 16, 9220 Aalborg Ø, Denmark, Phone +45 21848004, [email protected]
²Professor, School of Engineering, Aarhus University, Dalgas Avenue 2, 8000 Aarhus, Denmark, Phone +45 41893216, [email protected]

Abstract

In today’s construction, there is a paramount focus on time, and on the scheduling and control of time. Everything is organized with respect to time. The construction project has to be completed within a fixed and often tight deadline. Otherwise a daily penalty often has to be paid. This pins down the contractors, and forces them to rigorously adhere to the initial schedule. If delayed the work-pace or manpower has to be increased to observe the schedule. In an attempt to improve productivity, three independent site-mangers have been interviewed about time-scheduling. Their experiences and opinions have been analyzed and weaknesses in existing time scheduling have been found. The findings showed a negative side effect of keeping the schedule too tight as it becomes inflexible and cannot absorb variability in production. Flexibility is necessary because of the contractors’ interacting and dependent activities. Variability delays the process and results in conflicts between the trades. Moreover, a tight schedule does to a greater degree allow conflicts to be transmitted from one contractor to another. This increases the number of hot spots between contractors and produces more conflicts. The result is a chaotic, complex and uncontrolled construction site. Furthermore, strict time limits entail the workflow to be optimized under sub-optimal conditions. Even though productivity overall seems to be increasing, productivity per man-hour is decreasing resulting in increased cost. To increase productivity and decrease cost a more robust schedule is needed. The solution seems obvious, more time has to be released and more robustness has to be put into the schedule. The downside is that a postponed completion data often results in other costs for the client. Therefore, the deadline set has to be realistic. By introducing flexibility into the deadline negotiations can help achieve win/win situations bringing productivity and value creation up.

Keywords

Lean Construction, Robustness, Work flow, Interview

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