Decreasing Waste in Mechanical, Electrical and Plumbing Work

Eliminating wasted effort is an important part of lean philosophy. Waste has typically been measured with time sampling or time motion studies, where the share of direct work is estimated. However, few studies have taken the next step and investigated the root causes of wasted effort. This paper reports the results of an extensive time and motion study and focuses on qualitative evidence on the root causes of wasted effort. 15 MEP workers and foremen on four projects carried a helmet camera for one calendar week and quantitative time-motion analysis was done based on these videos. All participants were interviewed, and video footage was reviewed together with the participants to evaluate root causes of waste. The root causes of wasted effort were poor communication, issues with production planning and control, uncoordinated design, poorly organized material flow and a high share of preparatory work steps. The best direct work share was achieved in the only project which implemented takt production even though it was also the project with least repetitive work and largest distances due to large floor area. The biggest impact could be achieved with better constructability of design which would also enable just in time logistics and greater share of prefabrication. The results could be used to convince practitioners to adopt lean principles.