Controlling the safe distances between vehicles on freeways can be used to prevent many accidents. In this research, image-processing techniques have been used to develop an online system that calculates the longitudinal distances between vehicles. This system facilitates controlling safe distances between vehicles without the need for high technology devices. Our approach is real-time and simple, but efficient operations have been used to reduce the image occlusion problem. The main concept of this system is using simple, quick, and effective algorithms for calculating the position of each vehicle in each image. In this way, traffic parameters like speed and distances between vehicles can be calculated for each vehicle in real time. In addition, aggregate parameters like average speed, density, and traffic flow can be calculated using gathered data of single vehicles. As an application of the developed system, controlling the safe distance between vehicles has been introduced. In this system, in case of a driver who does not observe the safe distance, the scene of violation is stored and can be used by the police agencies. KEY WORDS: image processing, traffic, longitudinal safe distance, real time, occlusion

The subject of the paper is the improvement of the aircraft future trajectory prediction accuracy for long-range airborne separation assurance. The strategic planning of safe aircraft flights and effective conflict avoidance tactics demand timely and accurate conflict detection based upon future four–dimensional airborne traffic situation prediction which is as accurate as each aircraft flight trajectory prediction. The improved kinematics model of aircraft relative flight considering flight crew intention, aircraft true airspeed variability, and atmosphere conditions is introduced in the paper. The study is focused on improved kinematics model of aircraft relative flight position error estimation. Operational airborne separation capabilities are outlined based on the comparison between the improved and simple model of aircraft relative flight. KEY WORDS: aircraft trajectory prediction, trajectory prediction error, aircraft position prediction error, flight safety

As part of Local Conversion and Implementation Plan which is based on the EUROCONTROL Revised Convention the Republic of Croatia has undertaken to make a plan of implementing the Basic Continuous Descent Approach procedures. This paper addresses the issue of navigational path optimization for the A-319/320 commercial aircraft within the fleet of Croatia Airlines, during the approach part of flight, which has a positive effect on fuel consumption, greenhouse gas emission and area of surface affected by noise. The experiments were carried out in real conditions, using internal sensors onboard (Flight Data Recorder) and independent GPS system. Two types of approach were tested: Continuous Descent Approach (CDA) and Step Down Approach. The implementation of CDA procedures, just for the fleet of Airbus 320/319 aircraft of the Croatia Airlines results in approximate calculation in fuel saving which amounts to 1.5 x 106 kg annually (only on Zagreb airport). In this way, the productiveness of an air carrier, which is an integral part of the traffic process along with the airports and air traffic control, is directly increased, thus fulfilling the purpose of air traffic technology research. KEY WORDS: navigational procedures, continuous descent approach, air traffic, ecology

The purpose of this paper is to show the efficiency of application of system dynamic simulation modelling when researching the behaviour dynamics of the port transhipment process, and finding the optimal solution for cargo handling with regard to the type and scope of cargo traffic, directions of movement, and pace of receiving and shipping of cargo. In view of the potential scientific implementation and verification of the hypotheses about the usage of system dynamic simulation models, the goals are multi-dimensional as they include designing qualitative and quantitative simulation models for a non-linear system, verification of the validity of the behaviour dynamics of the model, application of the simulation models, application of the parameter optimisation of the simulated process, and scientific verification of the results obtained through the simulation of the model. In compliance with the developed system-dynamic, mental-verbal and structural model, using the Powersim Studio system-dynamic flowchart of the port cargo system, in Powersim Studio simulation language, it is possible to conduct a scientific research of the dynamics of the continuous behaviour of the observed port cargo system in an experimental way, i. e. by using computers, simulating various scenarios of likely occurrences in the real world, without jeopardising it. KEY WORDS: system dynamics, modelling, transhipment process, optimisation, continued and discrete simulation

Research in the area of packaged tour services, provided by the national and foreign tour operators has concentrated on mutual relationships among tourist-perceived service quality, satisfaction and repurchase intentions. However, little research in this domain has been done to explain the impact of repurchase intentions of experienced tourists on the relation between perceived quality of service and their satisfaction. This model was tested using substantial data set of experienced tourists with time span of three years. While previous literature has suggested that quality perceptions impose direct effect on tourist satisfaction, this study shows that such effect is more powerful when mediated by repurchase intentions of experienced tourists. The quality of packaged tour services mediated by repurchase intentions of the experienced tourist is expected to be paramount for the retention of the tourist in the long term. KEY WORDS: repurchase intentions, quality, packaged service, services chain, tour operator, retention, tourist satisfaction.

Modern ships are means of transport which, during their entire operational lifespan, need to convey cargo and/or passengers in a safe and reliable way, without jeopardising their safety, and with least possible adverse impacts on the marine environment. The ship’s safety and functionality directly depend on the reliability of her propulsion system, the shafting being the essential unit of the system. The functionality of the ship’s shafting considerably depends on its correct installation. Installation of the ship propulsion shafting is an integral part of the overall positioning (alignment) procedure. Shafting alignment is performed in several stages, starting with the shaft line design, and includes calculating the elastic line and bearing loads, installation of shafting parts onboard ship in compliance with the calculation results, and verifying the alignment results. Procedures are different for ships in service and newly built ships. This paper deals with specific features of the propulsion shafting alignment that is carried out while a ship in service is being converted for a general reason. Unlike a newly built ship, an existing ship imposes additional constraints that should be dealt with in the calculation stage of the process as well as during shafting installation and alignment verification. A calculation approach for ships in service is always different, having specific features from case to case, depending on what is changed and what remains unchanged during the conversion of the ship. The same goes for the implementation and verification of the achieved results. The purpose of this paper is to underline the difference, its contribution being in suggesting the procedure to be followed in case of conversion of an existing vessel. KEY WORDS: ship in service, shafting, alignment, GAP, SAG

The requirements for the prompt usage of traffic infrastructure capacities define the technological frames which ensure updated maintenance and development of new traffic infrastructure capacities by implementing graphical and computer systems. Technical documentation (TD) based on the technology of geographic information systems (GIS) allows fast analysis of graphical and alphanumerical data with the aim of identifying spatial relations among various cartographic elements. The paper analyses and presents the methodological bases of building GIS with the aim of designing the traffic network topology, as well as structural and functional analysis which uses the acquired knowledge to propose concrete solutions on connecting data about the position of infrastructure facilities with their properties in the railway traffic safety. KEY WORDS: technical documentation, geographic information system, structural and functional analysis, software for technical drawing, signalling devices, railway

Fast development of tertiary activities has deleted the borderline between the working and free time, workdays and holidays. The highways reduce the time of individual transport by personal and cargo vehicles due to higher travelling speeds, but toll collection results in time losses due to obligatory stopping of vehicles. The objective of the study presented in the paper is the exact calculation of the time losses caused by toll collection. The simulation method based on the technical characteristics of the vehicles has been combined with the analysis of the register of toll collection dynamics. Since the queuing losses at peak and off-peak periods have not been taken into consideration, the obtained values of losses are minimal. The paper considers various technologies of toll collection. KEYWORDS: travelling speed, acceleration, toll collection, assessment