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1. Introduction
Increasing demands for productivity and speed, in the face of severe labour shortage in construction and housing under-supply, have given rise to the need for offsite construction (Pan et al., 2007). Modular construction is perceived as the most advanced offsite construction, as it adopts manufacturing-style production systems and prefinished volumetric modules (Gibb, 1999). Wide-ranging benefits from using modular construction have been demonstrated, which include accelerated construction schedule, ensured building quality, enhanced productivity and improved sustainability (Gibb, 1999). Recently, more and more governments and institutions start to promote modular construction, with growing attention to and demands for modular high-rise buildings in cities (Pan et al., 2018, 2019; Chen et al., 2019). In Hong Kong, modular integrated construction (MiC) is introduced as an important policy initiative of promoting construction innovation, through “transforming fragmented site-based construction of buildings and facilities into integrated value-driven production and assembly of prefinished modules” (Chief Executive, 2017, 2018). MiC develops from modular construction but focusses on delivering high-rise buildings in complex high-density city contexts (Pan and Hon, 2018).
Despite the trend of rising demands for MiC, recent research shows that many challenges to module manufacturing and transport are yet to be addressed (Yu et al., 2011; Chen et al., 2019; Niu et al., 2019). Notably, module manufacturing still heavily relies on manual operations, which significantly constrains production speed and productivity. Generally, workers have to arrange and transport the materials required to work stations before any fabrication work starts (Lawson et al., 2014; Chen et al., 2019). This action has to be taken repeatedly during manufacturing because modules could be highly different in terms of materials requirements (Yu et al., 2011). Thus, much time will be wasted on in-factory logistics, which slows down production efficiency and productivity (Chen et al., 2019; Lee et al., 2017). Also, transporting large-sized modules across congested areas to the building site is quite complicated because of the constraints from the special conditions, drivers’ skills and inflexibility in vehicles movement and scheduling (Niu et al., 2019; Stroebele and Kiessling, 2017). Therefore, MiC suppliers and contractors are urged to embrace more advanced technologies in factories and during transportation so as to supply modules more efficiently and effectively...