Determinants of construction duration for building projects in Germany

Purpose -Construction duration is referred to as one of the most crucial success elements for a construction project along with quality and cost. Modelling construction duration supports decision making at the early stages of a project. Exploring the complex structure of construction duration is necessary; hence this forms a basis to develop a predictive model. Therefore the main aim of this study is to determine the subset of variables for a descriptive model that explains the most substantial part of the variation in construction duration. Design/methodology/approach -Secondary data set which includes 1,695 observations with 30 quantitative and four qualitative variables was utilized. Multiple linear regression was employed to define the relationship between explanatory variables and construction duration. General procedure for variable selection was presented in detail for data sets that suffer multicollinearity and singularity. Findings -Analysis indicated that gross external floor area and cost of construction works are the major variables for describing the construction duration. In addition, categorisation with respect to type of facility, project location, availability of construction area, and market conditions was justified to be statistically significant. Research limitations/implications -The study was limited to the population: German building industry. Besides, the affect of various qualitative variables, identified in the literature, could not be assessed due to lack of data availability. Originality/value -To the authors' knowledge, the study is the first to assess construction duration for German building projects. Moreover, it provides a method for describing variable selection routine transparently.