Kim, J (2007) An investigation of activity duration input modeling by duration variance ratio for simulation-based construction scheduling. PhD thesis, Rutgers The State University of New Jersey - New Brunswick, USA.
Abstract
Monte-carlo simulation (simulation) is a better tool than Critical Path Method (CPM) in predicting major milestone completion dates of construction projects because it can provide unbiased distributions for those dates rather than single deterministic numbers. However, its use as a construction scheduling tool has been confined in academic research due to the lack of a reliable method in determining activity duration input statistics. This study developed a practical activity duration input modeling method for simulation-based scheduling by generalizing historical data using the variance ratio between originally estimated activity duration (OD) and actual activity duration (AD) from previous projects. The duration variance ratio (DVR) was calculated by project owner to normalize the uniqueness of each construction project in type, size, and location, which has been the major obstacle in employing historical data for activity duration input modeling for construction scheduling. The performance of simulation-based scheduling by the proposed method in predicting major milestone completion dates was evaluated by comparing those dates from the CPM using actual dates as performance measures. Through the extensive investigation of the actual CPM schedules, this study also categorized the slippage of construction project schedules into two major types: the slippage caused by schedule revisions during construction; and the slippage caused by the inaccuracy in estimating the original durations of activities in the baseline schedule. To separate the two types of schedule slippages for an improved performance evaluation of construction schedules, a new kind of baseline schedule named as "As-built Baseline (ABBL)" is proposed. The ABBL is a baseline schedule with all schedule revisions made during the life of a project in it. A new term of "Retrogressing" is also coined to refer the procedure for creating the ABBL schedule from the as-built schedule. To enhance the accuracy of the proposed activity input modeling by the DVR, it also studied a method narrowing the DVR by project owner down further by work type. According to the evaluations, when the DVR by project owner narrowed down by work type is used, the predicted major milestone completion dates show less deviation from the actual dates than when only the DVR by project owner is used.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Thesis advisor: | Williams, T P |
| Uncontrolled Keywords: | accuracy; bias; duration; construction project; critical path method; estimating; performance evaluation; scheduling; owner; simulation |
| Index terms: | variance, construction scheduling, deviation, owner, investigation, statistics, duration, modelling, scheduling, performance measure, accuracy, construction project, bias, performance evaluation, critical path method, estimating |
| Subjects: | project controls, sociology, measurement and scaling, production management, professional development, probability and distributions, performance measurement, analytical methods, financial and cost management, operations research, data collection methods, mathematical modelling |
| Topics: | Engineering Principles, Project Management, Quality Management, Stakeholder Management, Cost Management, Information Management, Research Practice, Time Control |
| Descriptive scope: | 3 PCA |
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