Road construction projects on the territory of the Republic of Croatia are characterized by the overrun of planned costs. The experience of the contractor on previous road projects is an important ...element that can help to prevent errors and increase the chances of success in similar future projects. Data on construction costs collected from past projects can be used to estimate costs at different stages of the project life cycle through artificial neural networks. In this paper, artificial neural networks (MLP, GRNN, RBFNN) for estimating road construction costs are modeled. During the modeling, the database of roads constructed on the territory of the Republic of Croatia was used. Comparison of performance of neural networks has shown that the GRNN has obtained the best accuracy with MAPE of 13% and coefficient of determination of 0.9595. The neural network has proven to be a promising approach to use in the initial design phase when there is usually a limited or incomplete set of data for cost analysis, and this method could yield much more accurate results and the estimation error could be reduced.
During earthworks, monitoring and controlling the actual productivity of construction machines enables insight into the progress of tasks, calculation of expected duration and costs, favorable use ...and allocation of machines, and the application of appropriate decisions and corrective measures, which is of great interest to contractors. Excavators and tipper trucks are primarily used in earthworks. Manual collection of data from the construction site to assess the actual productivity of machines is today considered an outdated, time-consuming, and subjective method. Therefore, audio–visual and sensing technology devices are replacing manual data collection. The paper aims to propose an innovative protocol for optimal recording/tracking of the work of excavators and tipper trucks using audio–visual (a video camera or smartphone) and location-sensing technology (GPS). The protocol proposal enables a precise statement of the time cycle of excavators and tipper trucks and an estimate of their actual productivity. The application of the protocol proposal on the construction site demonstrated its practicality and functionality.
This paper aims to examine the opinions of the main recognized stakeholders in the maintenance of school buildings (i.e., the construction experts within the founders’ organization, the school staff, ...and the students), compare their views on the maintenance priorities, and identify certain differences. These data provide information about user needs, can help school founders make maintenance decisions, and are the basis for developing a new, balanced system of maintenance priorities. In the research, the survey questionnaire method was used to collect the data, whereby three groups of stakeholders evaluated the priority of eliminating certain defects in school buildings on a 5-point scale. For the purposes of the questionnaire, a model of 32 defects of the school buildings was created. In the questionnaire, 76 experts, 338 school staff, and 297 students participated. The research is limited to the Republic of Croatia. By conducting non-parametric statistical tests (Kruskal–Wallis and Mann–Whitney), it was shown that there were statistically significant differences in the stakeholders’ attitudes towards most maintenance priorities. There were also defects where statistically significant differences were not recognized, namely, regarding faulty lighting fixtures, faulty toilets, faulty sinks, faulty space cooling systems, faulty space heating systems, and faulty hot water heating systems. According to the experts, it is most urgent to remove faulty electrical installations, while according to the school staff, the highest priority is faulty sewage installations. The students believe that the priority is faulty toilets. The lowest priority is removing damage to the external environment (experts) and the facade (school staff and students).
This study deals with the condition examination of elementary school buildings in Primorje-Gorski Kotar County, Croatia. For schools to be functional and of high quality, adequate maintenance is ...mandatory. Therefore, school maintenance programs need information on the building's condition based on systematic and comprehensive assessments as a primary input. This study aims to establish a framework for assessing the condition of school buildings, based on which information can be obtained quickly and practically regarding the condition of all critical facility elements. To this end, a database on schools and their conditions was created. The conditions of school buildings in terms of damage and defects and their causes were determined. Descriptive and inferential statistical operations were performed on the collected data. A condition assessment of the buildings was performed using a questionnaire survey among the principals, based on the school buildings division model developed in this study; the model presents building elements and a systematic visual condition rating scale. According to the available data, this is Croatia's first condition assessment on elementary school buildings. The main results show that on average, the examined schools are in good condition. Moreover, according to the results, the school building condition is most affected by dilapidation and lack of financial resources.
Due to their educational purpose, impact on users and quality of education, school buildings are vital institutions in the community, and their adequate maintenance should be mandatory. Studies ...conducted around the world point to specific inadequacies that occur in the school maintenance segment, however studies that examine the entire maintenance management process in detail are rare. With such studies, it is possible to observe all components of maintenance and its management in the observed buildings, it is possible to get a detailed insight into the present inadequacies and problems, and give the best possible answer to them. Observing the territory of the Republic of Croatia, it was noticed that there are no adequate databases on school building maintenance. Given all the above, this paper aims to establish a methodological framework and analyze the entire maintenance management process in Croatian schools to detect potential inadequacies, reveal problems, and identify areas for action to improve maintenance performance and carry out maintenance more efficiently. The current maintenance management process of elementary school buildings in the Primorje-Gorski Kotar County, Republic of Croatia, was examined based on the developed methodological framework. Data on the management process were collected through a questionnaire survey among school principals. The questionnaire was compiled based on an extensive literature review. Maintenance performance through management functions was investigated, namely: maintenance planning, maintenance organization, maintenance directing, and maintenance controlling. Important management factors within each of the mentioned functions were observed. The data analysis revealed specific inadequacies and problems in the maintenance process, and it was shown that maintenance management is not entirely effective. Recommendations were given to improve the current situation. In this way, it is possible to quickly and easily examine the entire management process and identify measures that need to be introduced in schools to improve their business in the maintenance segment. The developed methodological framework can be applied to schools from other areas as well as to other types of buildings.
Local self-government units (LSGUs) often view project management as an accompanying activity not really giving it the appropriate level of importance. Challenges of traditional project management ...where the projects are segmented into discrete paths each dependent on the completion of the previous phase but without feedback or iteration can be overwhelming in a rigid governmental organizational structures. Such could be avoided by changing the way the projects are managed and/or changing the organizational structure. In both cases agile approach can be helpful. However, a priori implementation can cause more damage than good. It is the thinking behind the Agile principles that would adapt to the needs and particularities of the work environment it is implemented in, especially in light of the variety of activities of government bodies. The proposed model, Hybrid Agile Model, aims at defining a new, flexible, management structure for local self-government units, based on the development of human resources and constant change of culture, never neglecting the regular activities of such bodies, and all while making them more reliable and effective. The model has been described in detail along with the implementation process that has been tested on LSGU City of Porec.
In the paper, an analysis of the time aspect of the baseline plan for the execution of reinforced concrete works was carried out on a case study. The case study covers the construction of a public ...school in the Republic of Croatia, which was completed in 2023. By analyzing the baseline plan, it was determined that it has shortcomings and that the duration of the activities does not correlate with those actually achieved. Compared to the initial 86 working days, the baseline plan actually lasted 272 working days, which is an overrun of 216.28%. The leading causes of overruns in individual activities were identified, and lack of communication between project participants proved to be one of the particularly frequent ones. Recommendations were given for better time planning and for reducing deviations from planned durations, which can improve the processes of time management and project management in general.
The need of respecting the construction time as one of the construction contract elements points out that early prediction of construction time is of crucial importance for the construction project ...participants’ business. Thus, having a model for early prediction of construction time is useful not only for the participants involved in the construction contracting process, but also for other participants in the construction project realization. Regarding that, this paper aims to present a hybrid method for predicting construction time in the early project phase, which is a combination of process-based and data-driven models. Five hybrid models have been developed, and the most accurate one was the BTC-GRNN model, which uses Bromilow’s time-cost (BTC) model as a process-based model and the general regression neural network (GRNN) as a data-driven model. For evaluating the quality of the models, the 10-fold cross-validation method has been used. The mean absolute percentage error (MAPE) of the BTC-GRNN is 3.34% and the coefficient of determination R2, which reflects the global fit of the model, is 93.17%. These results show a drastic improvement of the accuracy in comparison to the model when only data-driven model (GRNN) has been used, where MAPE was 31.8% and R2 was 75.64%. This model can be useful to the investors, the contractors, the project managers, and other project participants for construction time prediction in the early project phases, especially in the phases of bidding and contracting, when many factors, that can determine the construction project realization, are unknown.
Cilj rada je prikazati model praćenja vremenskih i troškovnih aspekata gradnjestambenog niza u Štinjanu. Modelom će biti obuhvaćena izrada strukturne raščlambeprojekta, planirana troškovna krivulja ...te vremenski plan radova primjenom metodeprethodnih aktivnosti. Osim krivulje planiranih, izradit će se i krivulja ostvarenihvrijednosti. Utvrđena odstupanja će se analizirati, utvrditi rizici koji su ih uzrokovali tepredložiti mjere da se odstupanja umanje ili u potpunosti eliminiraju.
The aim of work is to present a model for monitoring the construction time and costaspects of terraced houses in Štinjan. The model will include the development of astructural breakdown of the project, planned cost curve and time plan of works usingthe method of past activities. In addition to the curve of planned values, the curve ofrealized values will also be created. The identified deviations will be analyzed, therisks that caused them will be identified, and appropriate measures, to reduce oreliminate the deviations, shall be proposed.
Time and price of contracted construction as well as their overrun are among highly pronounced issues in the construction practice. Numerous studies indicate that there is a dependency between these ...parameters at various construction markets. The paper shows the results of a research conducted on a group of 40 projects related to water supply systems carried out in the Federation of Bosnia and Herzegovina from 2001 to 2012. Collected data, obtained through interviewing chief engineers of construction companies, have been used as input parameters for implementation of single linear regression by applying the BTC (Bromilow time-cost) algorithm. The final result is a model in the form of an exponential equation. Whereas it was obtained based on effectuated values, it can be considered appropriate for assessing and testing the construction time in the early planning stage, as well as at work contracting. Since the parameter values in the model depend on circumstances of the specific area under consideration, the application of the model is recommended primarily in the area where the research was conducted. Results of the price overrun and construction overrun interdependence have not resulted in determining the exponential model. The paper also proposes application recommendations and guidelines for further research.
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