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One of the possible systems of project delivery is design & build (D&B), which is widely used in many countries. In the Polish public procurement market, the D&B system has been applied for a relatively short time, only since 2004, and despite the possibility, so far public clients have applied the D&B system only occasionally. This paper describes the current status of using the D&B method in the public procurement sector in Poland. Five hundred and fifty eight completed public-sector projects have been subject to analysis. Items analysed include the design/builder method of award, and types and value of contracts. The results provide insights for owners, the advantages and disadvantages of the D&B system, and highlight the need to change the method of selecting the contractor for the D&B system.

The choice of a particular architectural solution when designing a building considerably influences the costs of its construction. The aim of this paper is to present the indexes which may relate to the complexity of the building shape, and which were then specified and compared on a particular example.

The article analyses various indices of building shape evaluation, their influence on the changes in construction costs and their sensitivity to the changes in the dimensions of the building. The methodology adopted in this article concerns the analysis of the selected simple factors assessing the shape of the building against the cost‐effectiveness of constructing the basic elements of the building.

The authors established the best building shape in relation to the costs of constructing the walls and foundations (square), and to the layout of the inside of the building (rectangle). They believe that the best evaluations of building shape were achieved by the LBI index, which evaluated the shape correctly in all of the analysed examples and which is the most sensitive to the changes in building parameters in correct proportions to the changes in construction costs.

The article presents the indexes which may relate to the complexity of the building shape. The authors established the best building shape in relation to the costs of constructing. The authors provide the degree of the floor area usability in buildings of various shapes.

Cost overrun in infrastructure projects is a constant concern, with a need for a proper solution. The current estimation practice needs improvement to reduce cost overruns. This study aimed to find possible statistical modelling techniques that could be used to develop cost models to produce more reliable cost estimates.

A bibliographic literature review was conducted using a two-stage selection method to compile the relevant publications from Scopus. Then, Visualisation of Similarities (VOS)-Viewer was used to develop the visualisation maps for co-occurrence keyword analysis and yearly trends in research topics.

The study found seven primary techniques used as cost models in construction projects: regression analysis (RA), artificial neural network (ANN), case-based reasoning (CBR), fuzzy logic, Monte-Carlo simulation (MCS), support vector machine (SVM) and reference class forecasting (RCF). RA, ANN and CBR were the most researched techniques. Furthermore, it was observed that the model's performance could be improved by combining two or more techniques into one model.

The research was limited to the findings from the bibliometric literature review.

The findings provided an assessment of statistical techniques that the industry can adopt to improve the traditional estimation practice of infrastructure projects.

This study mapped the research carried out on cost-modelling techniques and analysed the trends. It also reviewed the performance of the models developed for infrastructure projects. The findings could be used to further research to develop more reliable cost models using statistical modelling techniques with better performance.