INTEGRATED LEAN CONSTRUCTION AND SIMULATION APPROACH TO IMPROVING ON-SITE MODULAR CONSTRUCTION EFFICIENCY: A PREFABRICATED AND PREFINISHED VOLUMETRIC CONSTRUCTION (PPVC) CASE STUDY

Abstract

Off-site Manufacturing (OSM) and prefabrication techniques, such as modular construction, are seen as ways for the construction industry to enhance its productivity and competitiveness. Its uptake has however, been impeded by several barriers to adoption such as high capital costs. One way to address this problem and boost adoption rates is to improve the efficiency of prefabrication operations, which mitigates its drawbacks and makes it more attractive to non-adopters. Lean Construction principles have been widely applied to improve the productivity and efficiency of construction operations, while simulation augments Lean theory by allowing its benefits and issues to be analysed quantitatively before implementation. This research presents an integrated Lean Construction and Discrete Event Simulation (DES) approach to improve modular construction operations, otherwise known as Prefabricated Prefinished Volumetric Construction (PPVC) in Singapore. Using an ongoing PPVC project Case Study, a detailed DES model of current operations was created. Recommendations based on Lean Construction principles were proposed and applied to the baseline model to eliminate waste, which led to the development of two Lean DES models. The outputs from the baseline and Lean models were compared to assess the impact of the proposed recommendations. The findings demonstrate reductions in cycle time and process time of up to 81% and 77%, and increases in process efficiency and labour productivity of up to 74% and 398% in the current process respectively. Although these are indicative values, the results were congruent with similar studies, which substantiate the efficacy of Lean Construction principles in optimizing PPVC operations. In contrast with existing research, which are focussed on studying the barriers and drivers to the adoption of OSM, this study provides and evaluates recommendations to improve the efficiency of PPVC operations, which is useful for encouraging the uptake of PPVC in Singapore and modular construction abroad. The detailed simulation methodology provided will also be useful in future off-site construction research.