Effect of Subcontracting on Construction Scheduling ERKI SOEKOV, IRENE LILL Department of Building Production Tallinn University of Technology Ehitajate Street 5, 19086 Tallinn ESTONIA Erki.Soekov@ttu.ee ; Irene.Lill@ttu.ee ; http://www.ttu.ee Abstract: - The right sequence of construction works and their positioning in time-schedule are unavoidable prerequisites for a high-quality construction process. Often a prepared schedule has serious problems in ignoring the necessary technological sequence of works or, if the technological order is correct, due to a lack of flexibility in case of any unpredicted changes. The necessity of planning the construction process according to various limitations and changes, technological correlations and resources provides a challenge to create a model that would allow preparing flexible schedules for construction tasks. Such a model should take into account the conditions, limitations and possibility of changes for specific construction sites on a case-by-case basis, and thus planning correctly the share of subcontracting. The paper discusses the possibilities for preparing a construction schedule and the effect of subcontracting within it. Also, the initial conditions and parameters of the simulation model for evaluation of different management strategies are determined. Key-Words: - job sequence, scheduling, subcontracting, simulation model 1 Introduction Scheduling the construction process demands clear formulation of the desired output and good knowledge of building technology in order to provide the optimal task sequence necessary for achieving the planned duration and quality requirements. As a rule, the construction process is managed by methods of project management due to the project-based nature of construction [1, 2]. The arrangement of the combination and sequence of tasks should enable the production of high-quality buildings, erected within strict time and resources constraints. Thus, Hendrickson [2] differentiates three categories to which special attention should be paid: initial prerequisites for construction, quality of the construction process, and quality of the completed constructions. This paper concentrates on discussing the construction process and understanding the functioning mechanism of this process in order to find ways to improve it. The focus is on general construction works performed on building sites. It does not include the construction of roads, streets, utility networks, highways, bridges, etc. The paper provides an overview of on-going research in the Department of Building Production of the Tallinn University of Technology (TUT), directed towards establishing a simulation model for evaluation of different management strategies from the point of view of determining the share of subcontracted works within a construction project. The simulation model enables the rehearsal and assessment of different management strategies in the lab in order to increase the awareness of the project participants, and thus improve the quality of construction as on-site decisions become more flexible with regard to the management of processes. The term “technology”, as used in construction, means the processing of initial objects in a certain way, in order to produce a desired output; and organising construction works means implementing the chosen management solution on the construction site. We absolutely agree with Howell and Ballard [3] that no solution can be considered to be the only right one in construction; there is always a range of possible alternatives, positioned on a wide spatial scale, but solutions are assessed by projecting them onto a specific situation. The advantages of one solution can outweigh the disadvantages of another and the results of risk assessment can cause an otherwise good solution to be dropped from the set of suitable alternatives. This is why simulation modelling might give the best answers depending on the interests of parties involved. Recent Researches in Social Science, Digital Convergence, Manufacturing and Tourism ISBN: 978-1-61804-003-9 105