A systematic review of constraint management studies in construction: current status and future direction

Construction constraints are a foundational concept in Lean Construction. They are factors that restrict or regulate the execution of tasks and hinder workflow reliability. Their systematic identification and removal underpin production planning and control processes such as the Last Planner System (LPS). However, current constraint management (CM) has yet to reach sufficient implementation levels in most projects. Motivated by the need to improve CM in current construction practices, this article aims to identify current research gaps through a state-of-the-art review of CM-related research and propose future directions for addressing the gaps. To achieve this, we conducted a systematic literature review (SLR) using a sequential mixed-method design, combining bibliometric analysis (quantitative mapping) with thematic analysis (qualitative synthesis). First, a total of 128 papers were collected using a structured data collection approach from Scopus and the IGLC (International Group for Lean Construction) conference and then fed into a bibliometric analysis to construct science maps. Subsequently, an in-depth thematic analysis combined with the quantitative analysis results is presented to reveal the research topics, trends, gaps, and future directions of CM-related research. As a consequence, five primary research themes, along with their research trends and gaps, have been revealed. This article suggests five areas for improvement to overcome the identified gaps in current CM-related research. Through its findings and recommendations, this article contributes to the body of knowledge of CM-related research and provides future directions to enhance CM implementation in construction projects.