The classic triad "owner-architect-general contractor" are the main participants of traditional projects. They make contracts that regulate the rights and obligations of the parties and establish procedures for solving the entire range of issues during the operation of contractual relations. However, modern projects, especially large ones, require a wide range of participants. Taking into account the large number of project participants, it becomes very important to optimize the cooperation between them. The problems with communication leads to the division of the construction process to the stages, the significant number of changes and non-operating costs, and as a result to the increased project duration and increased costs. The research analyzes the core, characteristics and principles of the Integrated Project Delivery (IPD) and establishes the connection between it and the traditional project delivery methods. The IPD accumulates some of their special features and becomes the next stage in the evolution of the construction industry. One of the main characteristics of the Integrated Project Delivery is an early involvement of key participants, based on the following principles: early involvement, early goal definition, intensified planning, and organization and leadership. The aim of the research is to compare the effectiveness of the traditional project delivery methods and the Integrated Project Delivery by the criterion of the total cost for project modification. Methods of mathematical modeling were used to compare the effectiveness of the various project delivery methods. Thus, such curves and functions of dependence were modeled: between the increase in the cost of the project modifications and the period of their delivery; between the intensity of changes made to the project and the time when traditional project delivery methods are used; between the intensity of project modifications and the time on application of the Integrated Project Delivery. By means of the integral calculus (Simpson's rule) it was determined the total cost of the project modifications, which is a function of the method of project delivery and the cost of making the appropriate changes. The result of the calculations proves that the use of the integrated project delivery model reduces the total cost of making changes by 33%.

The construction industry of Ukraine has a number of problems and barriers that hinder its development. The main problems affecting Ukraine are corruption, high level of opacity, inefficient use of resources and inefficient process management. Moreover, ineffective design and construction management reduce labor productivity and leads to reworks. Unfortunately, in Ukrainian construction industry most cases of rework have been accepted as a part of construction activities. Rework is one of the main factors in the growth of total costs and the excess of the schedule for the construction project. The problem of rework costs is important and needs to be studied more to alleviate these overruns in the future. However, rework data are usually quite difficult to obtain and most studies have been conducted in developed countries. It can be assumed that there is a greater probability of reworks and rework costs in developing countries than in the developed ones. Thus, the purpose of this article was to determine and systematize reworks factors, quantify amount of direct rework costs, determine the relationship between actual project costs, project duration variation and rework costs.

The paper presents methods of determining the location of cost buffers and corresponding contingency costs in the CPM schedule based on its work breakdown structure. Application of correctly located cost buffers with appropriately established reserve costs is justified by the common overrunning of scheduled costs in construction projects. Interpolated cost buffers (CB) as separate tasks have been combined with relevant summary tasks by the start to start (SS) relationship, whereas the time of their execution has been dynamically connected with the time of accomplishment of particular summary tasks using the "paste connection" option. Besides cost buffers linked with the group of tasks assigned to summary tasks, a definition of the cost buffer for the entire project (PCB) has been proposed, i.e. as one initial task of the entire project. Contingency costs corresponding to these buffers, depending on the data that the planner has at his disposal, can be determined using different methods, but always depend on the costs of all tasks protected by each buffer. The paper presents an exemplary schedule for a facility and the method of determining locations and cost for buffers CB and PCB, as well as their influence on the course of the curve illustrating the budgeted cost of work scheduled (BCWS). The proposed solution has been adjusted and presented with consideration of the possibilities created by the scheduling software MS Project, though its general assumptions may be implemented with application of other similar specialist tools.

Due to their complexity and uniqueness, all construction projects are exposed to a high risk. The condition for this risk reduction is an identification of risk events and an evaluation of their occurrence probability and effect.