Original scientific paper The issue of the optimal management of the traffic flow and the ensuring of an adequate number of parking spaces is present in the majority of highly developed urban areas of the European Union, including the Republic of Croatia. The formation of an adequate raster of the transport network, conditioned by the historical and existing buildings and areas is an extremely challenging task. Similarly, ensuring an adequate availability of free parking capacities in times of rush hours in the very centres of urban areas is also very demanding. However, what often occurs, even when adequate parking capacities are ensured, is a halt on the input and output terminals of parking lots and garage facilities that are derived by a disproportion of their capacities and traffic needs at a specific time. Precisely for that reason, this paper presents a potential model for determining of an optimal number of input service places (terminals) by using the queuing theory.Keywords: queue; queuing system; parking; traffic modelling; traffic planning Model dimenzioniranja broja uslužnih mjesta na ulazima u parkirališta primjenom teorije redova čekanjaIzvorni znanstvni članak Problematika optimalnog vođenja prometnog toka te osiguranja odgovarajućeg broja parkirnih mjesta prisutan je u većini visokorazvijenih urbanih sredina Europske unije pa i Republike Hrvatske. Formiranje odgovarajućeg rastera prometne mreže, uvjetovane povijesnim i postojećim građevinama i zonama izuzetno je izazovan zadatak. Isto tako, zahtjevno je i osiguranje odgovarajuće dostupnosti do slobodnih parkirnih kapaciteta u vremenima vršnih opterećenja u samim središtima urbanih područja. No, vrlo su česti slučajevi u kojima, čak i u trenutku kada se osiguraju odgovarajući parkirni kapaciteti, dolazi do zastoja na ulaznim i izlaznim terminalima parkirališta i garažnih objekata koja su derivirana nesukladnostima njihovih kapaciteta i prometnih potreba u određenom vremenskom trenutku. Upravo iz tog razloga, u radu se predstavlja potencijalni model određivanja optimalnog broja ulaznih uslužnih mjesta (terminala) primjenom teorije redova čekanja.

Since the Republic of Croatia is one of the most popular European and world tourist destinations, the aim of this paper is, from the user’s (n = 596) point of view, to research the importance of stationary traffic in tourist destinations. The purpose of this paper is to point out the possibilities of improving the tourist destination quality and sustainability through an adequate parking service. In order to corroborate constructed scientific hypotheses, a larger number of scientific methods were used from which a polling method, analysis and synthesis method, descriptive statistics method, t-test, and analysis of variance (ANOVA) should be singled out. The major finding of this paper indicates a relatively big importance of stationary traffic (M = 6.51; SD = 2.21) as an element of tourist destination quality. Moreover, regarding the quality of tourist destination, the results of this paper suggest that the parking space availability is more important than the way parking or parking payment are organized. Between the experienced parking problem in a tourist destination and age on one side and evaluation of the importance of stationary traffic as an element of tourist destination quality on the other side, a statistically important connection was established. Gained knowledge can be particularly helpful to hotel industry managers but also to traffic managers whose duty is to provide an adequate number of parking spaces in tourist destinations.

The basic objective of this scientific paper is to explore in both theory and practice the elasticity of demand in urban traffic. We tried to answer whether the elasticity of demand in urban traffic shows a higher intensity of change in the demanded volume of transport services depending on price or income changes. Research results are based on the statistical and mathematical scientific methods. The applicability of the acquired knowledge is tested through a practical research of the elasticity of demand in urban traffic of the city of Rijeka.

The basic aim of this paper is to research the importance of supply chain optimization in the circumstances of the COVID-19 crisis. The research object is the optimum selection of active participants before and after the COVID-19 crisis. The initial hypothesis of this paper is that optimal COVID-19-free supply chains can be formed with a dynamic programming method, the costs of which will be higher than those when this restriction would not exist, but significantly lower than those formed if the optimization principle in the selection of supply chain stakeholders would be neglected. Research results in this scientific discussion paper are based on the analysis and synthesis method, comparative method, and dynamic programming method. The main findings of this paper point to the conclusion that the COVID-19 crisis affected the reduction of goods flow within supply chains, reduction of potential participants in supply chains, reduction of supply chains business safety, and increase in business costs.

Traffic accidents are considered the first cause of death of young people, that is, young drivers. Therefore, this problem needs to be given a lot of attention. Traffic accident which include young drivers must be analyzed as an element of the system, and it is necessary to analyze and investigate potential solutions and improve all elements in order to improve the system itself. In the Republic of Croatia, for the first time in 2004, the term "YOUNG DRIVER" as a driver of a motor vehicle up to the age of 24, who holds a drivers license issued in the Republic of Croatia, was introduced into the Road Traffic Safety Act. The share of young drivers in the population in the Republic of Croatia is 4.3%. Young drivers make up about eight percent of road users, causing a total of 9.6% of traffic accidents, or 12.5% of those with fatalities. This paper will deal with traffic safety in other countries, especially in the surrounding countries. According to statistics related to road accidents, young drivers are over-represented and are at greater risk to themselves, passengers and other participants than other drivers. There is a need to respond in a timely manner and to adopt optimal measures to improve the safety of young drivers in road traffic and thus for the safety of other road users. The aim of this paper is to outline measures that would reduce the number of road accidents involving young drivers, especially in urban areas.