The aim of this thesis is to determine total time of the Public building construction project, as well as determining the probability of that estimate. The Case study analyzed the example of a sports hall located in Northwestern Croatia. The complete estimated length of the project was calculated by two methods, Critical Path Method and Program Evaluation and Review Technique, based on statistical evaluation, and to determinate reliability of these solutions during transformation of the value of statistical parameter "Z" in the percentage value is applied statistical software package "Statistica 10". Importance of application of Critical Path Method and Program Evaluation and Review Technique for the construction project is of great importance due to their solutions indicated the total duration of the project and providing the graphical representation of the duration of the project applying dynamic and network plans. The concept of work consists several parts. The first section briefly describes methods of analysis and the subject of analysis. The second and third sections are demonstrating the most probable and expected time of construction of the sports hall. The fourth unit provides an analysis of the probable solutions. In the fifth unit are displayed histograms of workforce by categories, while the conclusion of the thesis gives an overview on the results of calculated time for constructing the project.