TY - CONF TI - Impacts of waiting-type non-physical waste on schedule deviation in lean-managed building projects in Indonesia C1 - Singapore, Singapore C3 - Proceedings of the 34th Annual Conference of the International Group for Lean Construction (IGLC 34) SP - 1677 EP - 1688 PY - 2026 DO - 10.24928/2026/0234 AU - Gazali, Abdhy AU - Wirdianto, Anang AU - Aminullah, Aminullah AU - Anisah, Anisah AU - Alaida, Refia AU - Sari, Lintang Tirta AD - Lecturer, Building Engineering Education, State University of Jakarta (UNJ), Jakarta, Indonesia, abdhy.gazali@unj.ac.id, orcid.org/0009-0004-1391-6533 AD - Lean Cosntruction Expert, Transformation & Information Technology Division, PT. Wijaya Karya (Persero), Jakarta, Indonesia, anang.wirdianto@wikamail.id AD - Lean Cosntruction Expert, Transformation & Information Technology Division, PT. Wijaya Karya (Persero), Jakarta, Indonesia, aminullah@wikamail.id AD - Lecturer, Building Engineering Education, State University of Jakarta (UNJ), Jakarta, Indonesia, anisah@unj.ac.id AD - Student, Building Engineering Education, State University of Jakarta (UNJ), Jakarta, Indonesia, refiaald@gmail.com AD - Student, Building Engineering Education, State University of Jakarta (UNJ), Jakarta, Indonesia, lintangtsari@gmail.com ED - Hamzeh, Farook ED - Poshdar, Mani ED - Garcia-Lopez,, Nelly P. AB - Waiting-type non-physical waste remains a common issue in construction projects, yet prior studies have mainly focused on identifying its causes rather than measuring its impact on schedule performance. Limited research has examined how waiting relates to activity-level schedule characteristics in Lean Construction practices. This study investigates how waiting-type non-physical waste contributes to schedule deviation in Indonesian building construction projects. A descriptive–quantitative approach was applied using data from four projects implementing the Last Planner System (LPS). Waiting events were identified and classified at the activity level using operational indicators derived from Lean Construction literature and LPS documentation. Schedule deviation attributable to waiting was then analyzed using a CPM-based approach incorporating activity duration and slack. The results show that labor shortages were the most frequent cause of waiting, followed by unprepared work areas and material shortages. However, waiting frequency did not directly correspond to schedule impact. Waiting affecting activities with limited slack contributed disproportionately to deviation, while shorter-duration activities showed higher proportional delays and longer-duration activities accumulated greater absolute delays. These findings highlight that waiting impacts should be assessed not only by frequency, but also by activity characteristics and schedule structure. KW - Lean construction KW - waiting waste KW - non-physical waste KW - schedule deviation KW - Last Planner System KW - Critical Path Method. PB - T2 - Proceedings of the 34th Annual Conference of the International Group for Lean Construction (IGLC 34) DA - 2026/06/22 CY - Singapore, Singapore L1 - http://iglc.net/Papers/Details/2531/pdf L2 - http://iglc.net/Papers/Details/2531 N1 - Export Date: 19 June 2026 DB - IGLC.net DP - IGLC LA - English ER -