Definition of types, amount and positions of cranes in construction site planning has a big impact on the overall productivity and cost effectiveness of a construction project. It is not rare, that engineers during preparation phase of construction fault in crane selection. It implies big financial losses for the company because of wrong crane rent. In visualisation of mobile crane operation in 3D is noticeable that working radius of the crane is considerably less then number listed in crane technical documentation (capacity chart). The built construction itself can reduce the crane radius when the crane boom snags the built object edge. Several computer applications were developed in order to help practitioners in selecting and using of cranes. In the paper is presented one version of non-commercial software tool (Mobile Crane Simulator) useful in construction preparation as a tool for selecting and locating of the mobile crane at construction sites. The tool was developed by authours of the paper. The principles of the tool creation are also explained.