Modelling Second Order Effects of Changes in Civil Engineering Projects

Abstract

One of the most common hurdles especially in large infrastructure projects is scope change. Scope changes negatively affect time, quality and usually lead to cost overruns due to underestimating the change order impacts on the project. There are two main categories through which the impacts could be quantified: the first and second order effects. The first order effect is the impact of the change, cost, time, quality, and risk related. The second order effects are the impacts that resulted as consequences of the first order effects such as lower labour productivity and increase in errors.

The purpose of this research was to analyse and quantify the second order effect due to scope change in large infrastructure projects. The approach that was used to create the model is system dynamics modelling (SDM), since several studies confirmed the success of system dynamics modelling in solving similar projects’ problems in different industries.

Through the literature review and the case study, it was found that the second order effects of scope change are rework, schedule pressure, morale, overtime, productivity, hiring new staff, and office congestion. It was observed through the created dynamic hypothesis that productivity was directly impacted by morale, office congestion, schedule pressure and overtime. The simulated model showed that productivity and morale were the two mostly influenced factors by the scope change.

The main question of "How could second order effects of the project scope change be quantified through system dynamics modelling?" was answered as follows: First, a dynamic hypothesis should be created and confirmed through literature and continuous interviews till the hypothesis reflects the project case. Second, formulas should be created for the defined variables and values should be inserted in the model based on the case data. Third, the model should be simulated, and the perceived progress should be compared with planned progress. Then, the first order progress should be compared with the planned progress to quantify the first order of effects of scope change. Finally, to quantify the influence of the second order effect of scope change, the first order effects should be deducted from the total influence of scope change.