Evaluation of the Impact of Dynamic Work Stations Versus Static Work Stations in Wood Framing Prefabrication using Hybrid Simulation

Abstract

Offsite manufacturing has introduced significant improvements in terms of both time and cost savings to the construction industry. The fabrication of modular units and construction components in factories has permitted the reshaping of the traditional stick-built process. By reallocating the majority of onsite activities to offsite facilities, onsite preparation tasks can be performed concurrently to the offsite production. The success of offsite manufacturing relies on the efficiency of the factory’s production line. Continuous workflow improves factory efficiencies by reducing or eliminating fluctuations and bottlenecks among work stations. Imbalance in the production line is a result of work station capacity errors and other conditions unique to the construction industry. Unlike other industries, construction projects are often customized and have lower repetition quantities. The variations in the modular units or components being produced poses a challenge in balancing traditional work stations along the production line due to continuous changes in complexity level, which in turn affects productivity. This research proposes the use of dynamic work stations along with traditional ones, using multi-skilled workers relocating among specific work stations in response to product complexity levels. Two approaches are evaluated in order to balance the production line: (1) increase number of workers in static work stations; and (2) use dynamic work stations. A production comparison is performed using a hybrid simulation model, combining discrete-event and continuous simulation. The plotted results identify the optimum number of workers in the two stations, static versus dynamic, to meet demand. The model is validated and is found to achieve a reduction of 18.68% and 32.00% in the total production time for two different scenarios without increasing the original number of workers.