Investigation of wastes due to unfinished work and their impact on the cycle time of construction processes

Abstract Construction waste constitutes an obstacle for the improvement of productivity. Among the different kinds of construction waste, making-do stands out as a source of other types of waste. When Fireman et al. (2013) studied making-do waste, they concluded that it could be triggered by a kind of general waste called unfinished work. The aim of this study was to investigate the occurrence of unfinished work in construction processes and its impact on the cycle time of services. The study consisted in a field survey carried out on five construction sites, involving direct observation. The research tools used were forms, questionnaires and checklists, all adapted from the literature, with the aim of identifying and classifying unfinished work. In addition, semi-structured interviews were conducted with site managers and supervisors. Time measurements were taken to check the impact of unfinished work on cycle time. The results showed that failures in the sequence of tasks associated with failures in quality management were triggers for the unfinished work. The study showed that the construction sites that had formalised short-term plans were able to mitigate the impacts of this type of waste. On most of the construction sites investigated, the planned cycle time was not met, and also that those sites that had larger management teams presented lower added time.

摘要：建筑废弃物是制约工程生产效率提升的关键阻碍。在各类建筑废弃物中，凑合作业（making-do）作为一类核心废弃物，是诸多其他类型建筑废弃物的重要源头，其影响尤为突出。Fireman等人（2013）在针对凑合作业废弃物的研究中指出，该类废弃物可由一类被称为未完成作业（unfinished work）的通用废弃物诱发。本研究旨在探究建筑施工过程中未完成作业的发生情况，及其对施工循环周期的影响。研究通过对五处建筑工地开展实地调研，采用直接观察法采集数据；所用研究工具均改编自现有文献，包括记录表、调查问卷与核查清单，用于识别并分类未完成作业；此外，研究还对施工现场管理人员及监理人员开展了半结构化访谈。通过时长测量，本研究验证了未完成作业对施工循环周期的影响。结果显示，任务流程衔接缺陷与质量管理失效共同诱发了未完成作业。研究表明，制定了规范化短期施工计划的建筑工地，能够有效缓解该类废弃物带来的负面影响。在绝大多数受访建筑工地中，实际施工均未达到计划循环周期；且管理团队规模更大的工地，额外增加的作业时长相对更低。