Construction cost performance under quality-gated framework: the cases of Norwegian road constructions

Cost increase during the planning phase of major infrastructure projects is a crucial challenge which is typical in construction management. This research aims to provide a better understanding of the cost development of road-construction projects and enhance the knowledge on various project attributes that affect cost development. A detailed cost development study (quantitatively chart the cost- trends) and analysis on cost departures at each key-milestone starting from the initial to the final cost is conducted. The impact of different project attributes/settings (size, location, and quality assurance) on cost development are investigated. The research used a dataset of 110 projects from the last two-decades and analyzed using various statistical tests such as trend-analysis, probability-plots, and cost development over-time at the different project milestones. The results showed a decrease in cost-deviation after quality assurance scheme implemented (except few projects). The overall cost development showed an average increase of 5%. The research found different project-setting affect cost development at different magnitude. It provides new insight for construction managers, quality assurers, and cost-estimators to consider different project settings at the early-phases of the project. It helps to understand the individual and combined effects of project-settings and enable decision-makers to act proactively in cost decisions.