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In this paper, an experimental study of the determination of the rolling resistance coefficient is carried out. The experiment tests a total of six different types of vehicles and calculates the rolling resistance coefficient depending on the condition of the surface and the type of tires. The main aim of the research is to introduce new values of the rolling resistance coefficient and its impact on fuel consumption in real traffic conditions. Motor vehicles are subjected to a "free stop" method on a horizontal road. In doing so, the vehicle speed is registered every 10 seconds from an initial speed to stopping. In order to eliminate an error of possible roadway inclination or wind impact, the experiment is repeated five times on the same road section as well as in the opposite direction. The experimental study was carried out during December 2016 and January 2017. Three sets of tires were used for each vehicle, the tires with tread depths of 8 mm, 6-7 mm and 4-5 mm, while the type of surface referred to dry and wet conditions of the roadway. Both hypotheses have been confirmed using Analysis of Variances. The results show that the tread depth of tires and the meteorological conditions affect increasing the values of the rolling resistance coefficient.

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The relevance of this topic reflects the fact that individuals should understand the necessity of career change and the creation of individual portfolios. There is a universal understanding that the main characteristic of officers' career is vertical promotion. Officers' career is insufficiently investigated or researched, which includes a frequent change of jobs and assignments that are not related only to vertical career promotion. Both transfers and deployments of the Serbian Armed Forces Geodetic Service Officers (GSO), which are in scope of this paper, in regard to career accomplishment, represent the career matrix. The importance of research refers not only to officers' career, but it can be implemented for understanding and getting an insight into career development, in general, through the career matrix.