# Construction Schedule versus Various Constraints and Risks
## 1 Introduction  
The management of a construction project is a very important issue, determining both the cost and time of investment implementation. The planning and organization of construction works are important elements of project management that generate many problems. This is related to the heterogeneity and discontinuity of construction processes, as well as the existence of technological and organizational limitations, which have a decisive impact on the sequence of works and, therefore, on their effectiveness. When preparing a project plan (schedule), the risks and uncertainties arising from the nature of the work being carried out should be taken into account. Research based on predicting the implementation time of construction processes is conducted by many researchers around the world, and scheduling methods are constantly being developed. This is a difficult subject due to the complexity nature, organizational level, multidisciplinary, and accumulation of the projects, as well as the presence of interdependent components, and the scale of implementation difficulties [1; 2; 3; 4; 5]. Research studies [6; 7; 8; 9; 10; 11] have provided statistical evidence confirming the existence of significant differences in project implementation compared to the planned costs and duration. The literature provides numerous examples of delays in actual implementation [9; 11], regarding hydrotechnical facilities [7; 8; 10]. Despite advanced technology and project management techniques available to practitioners, over 80% of implemented construction projects showed delays [9; 11]. The author's construction experience and research conducted on construction sites provide information that delays not only result from improperly adopted scheduling methodologies or impact factors (technological, organizational and risk-based) but also due to the input data used in making calculations and assumptions. The times estimated in theschedules differ significantly from the implementation times. In the bloc of Eastern European countries, the traditional method used to design the implementation time of construction investments involves material outlay catalogs (in Poland called Katalogi Nakladow Rzeczowych (KNR)). Construction schedules are developed based on the knowledge and experience of their designers, who use material outlay catalogs containing standard working times. [PERSON] and [PERSON] [12] present calculations in their work that prove the existence of significant differences between schedules prepared using material outlay catalogs and actual investment implementation times. The main reasons for these differences are the lack of any proper scheduling of works and the lack of appropriate workload updates included in the material outlay catalogs. Normative data are theoretically updated, but they have not changed for many years, even though the technology, equipment and materials used in construction have changed significantly. Very good results can be achieved using artificial intelligence and data analytics methods in forecasting the implementation time of construction processes. Artificial intelligence and data analytics provide promising data-driven opportunities to improve the delivery of products and services through the improved use of limited resources. The use of modern computational methods not only improves work but also allows us to obtain forecasts very close to the actual time of their implementation. In recent years, a breakthrough approach to Building Information Modeling (BIM) has been the use of Artificial Intelligence, thanks to which an unprecedented level of efficiency, precision and optimization within project management has been achieved [13; 14; 15; 16; 17; 18; 19]. AI algorithms are able to analyze historical data of various investments and then compare them with current data of the construction project and predict potential risks or project delays [20; 21; 22].