Abstract:
Labour productivity is an important indicator of the performance of the construction
industry. Due to the lack of a standard productivity measurement system and ignoring
various influential factors, labour productivity is constantly decreasing. Although different
construction labour productivity modelling techniques have been developed, they focused
on specific subjects, and their implementation is limited to particular countries. Therefore,
this study aims to investigate the application of Fuzzy logic and hybrid System Dynamic
(SD)-Discrete Event Simulation (DES) to predict construction labour productivity. To meet
the objective of this study, Construction labor productivity influencing factors were
extracted through Literature review, and a questionnaire survey was carried out. A relative
importance index was calculated to identify the most significant factors used for modeling
purposes. The production rate values of slab concreting and their influencing factors have
been collected through cause study on real building project. A Fuzzy expert system in fuzzy
logic concepts was used to predict the productivity rate by incorporating the influence of
qualitative and quantitative factors. The performance prediction of the Fuzzy expert system
was evaluated via Mean Absolute Percentage Error and Root Mean Square Error with
their error rate of 9.33% and 0.08 respectively. The intricate effect of relationships among
the contextual factors that influence labour productivity was modelled using the System
Dynamic approach. Stock and flow diagram of system dynamic was developed to model
complex structure of context variables. In addition, Discrete Event Simulation was applied
to model the operational influencing factors and their effects on labour productivity. The
performance measurement results show that the Discrete Event Simulation in this study
gave high numerical accuracy with 5.7% of MAPE value. The productivity result predicted
by a Fuzzy expert system, Discrete Event Simulation, and hybrid SD-DES in an 8-hour
workday is 162, 168, and 176 m3
respectively, while real case productivity was 181 m3
. The
predicted result by the models is slightly deviated by 168.67 ± 7.02. Therefore, the finding
shows that the value obtained by the hybrid SD-DES modelling technique is more realistic.
The proposed models can be useful in the planning stage and allow for a more precise
prediction of concreting productivity.
