The paper studies the boundary conditions for the standard LWR model describing the traffic flow. The notion of the BLN (Bardos, Leroux and Nédélec) condition is described. In the context of traffic flow the BLN conditions have some natural interpretation. The conditions on the density and on the flow and their meaning in real-life situations are discussed. KEY WORDS: LWR model, traffic flow, hyperbolic conservation law, boundary conditions

Despite the flow fluctuations and increased traffic demand in the Macedonian cities over the last fifteen years, the Republic of Macedonia is one of those countries which still employ only the traditional systems of traffic management and control. Those are fixed control systems that certainly cause problems such as increased travel times and travel expenses as well as environmental degradation. A general call for “…something has to be done…” becomes obvious. The best practices have shown that this can be realized through unconventional solutions i.e. by means of responsive traffic management. A very reasonable example of such a system is the vehicle actuated control system that we have found to be quite challenging to do our research. Thus, we set up two folded research issues in front of us. The first one was to scientifically prove that vehicle actuated signal control can really be a reasonable substitute for a fixed time signal control, which will enhance the overall signalized intersection performance provided the timing parameters and the detector placement ŕrĺ properly designed. The second one was to indicate that such an advanced control system is feasible and sustainable for Macedonian cities. This paper focuses on the first research issue only. For this purpose, a semi-actuated signal control strategy on an appropriately chosen signalized intersection was designed. The primary objective was to determine the way in which the inductive loop detector placement from the STOP line affects the overall intersection performance. To meet the goal, two scenarios were designed: 1. Detector placement at the STOP line, and 2. Detector placement at 8 metres behind the STOP line. Emphasis was placed on the semi-actuated signal control algorithm design. The designed algorithm was then applied in the net of VISSIM in order to simulate the semi-actuated signal control process. Performance comparison analysis with the formerly pre-timed signal control strategy followed. It was concluded that the overall intersection performance could be improved both by adequate inductive loop detector placement and by interaction with signal parameters. Hence, the placement distances would have to be considered under the limitation conditions only. KEYWORDS: signalized intersection, vehicle actuated control, semi-actuated control, inductive loop detectors, simulation, delays, level of service

The existing postal infrastructure cannot efficiently support the requirements of new technologies and the supply of services on the open market of postal services. Post offices do not meet the new needs, therefore requiring an adjustment to new traffic and service requirements. The functioning of the postal system in the Republic of Croatia was carried out in order to adjust the functional equipment of the system to the introduction of the new technologies and services. At the same time a requirement was set to the public postal operator for more efficient performing of the universal postal service. Based on the analyses of the postal system functioning, a modular procedure of designing the postal network units was proposed and it provides the possibility of adjustment to the new technological, organizational and safety requirements of the postal system. KEY WORDS: postal units, module designing, postal traffic efficiency

This paper presents the method for developing matrix model of postal traffic flows (ordinary communication items) in public postal network according to volume and different end-to-end (E2E) processes, which can be used for selecting of relevant model for accessing the public postal network. The presented traffic matrix model can be adjusted after the measurement of real volumes and selecting the numbers of different E2E processes (according to geographical input-output request). During the simulation of the model it could be possible to detect the optimal solution for accessing the public postal network. KEY WORDS: traffic modelling, postal services, access to the public postal network

The paper describes the traffic flow problems in telecommunication networks based on the Internet protocol. The main aim of telecommunication network operator today is to offer an SLA (Service Level Agreement) contract to end users, with provided QoS (Quality of Service) for different classes of services. In order to achieve this, it is necessary to establish the routes between marginal network nodes meeting the network traffic requirements and optimizing the network performances free of simultaneous flows conflicts. In DiffServ/MPLS (Multi-Protocol Label Switching) networks traffic flows traverse the network simultaneously and there may come to collision of concurrent flows. They are distributed among LSPs (Labeled Switching Paths) related to service classes. In LSP creation the IGP (Interior Gateway Protocol) uses simple on-line routing algorithms based on the shortest path methodology. In highly loaded networks this becomes an insufficient technique. In this suggested approach LSP need not necessarily be the shortest path solution. It can be pre-computed much earlier, possibly during the SLA negotiation process. In that sense an effective algorithm for collision control is developed. It may find a longer but lightly loaded path, taking care of the collision possibility. It could be a very good solution for collision avoidance and for better load-balancing purpose where links are running close to capacity. The algorithm can be significantly improved through heuristic approach. Heuristic options are compared in test-examples and their application for collision control is explained. KEYWORDS: Telecommunication networks, collision avoidance, multi-constraint route selection, self-organizing systems, MPLS, QoS

In April 2009, the WHO, (World Health Organization) evaluated the available data on the swine influenza A (H1N1), confirmed the outbreak and declared decision on raising the pandemic phase from five to six. IATA, (International Air Transport Association) invited the airlines to support WHO’s reference laboratories around the world in handling specimens should the outbreak expand further. The specimens shall be transported according to the regulations stipulated for acceptance and transportation of dangerous goods by air. The paper analyses the current infrastructural situation at the airports in Croatia, predispositions related to the trained staff and coordination procedures with the relevant institutions. The implementation of activities complying with the international regulations are suggested in order to conduct measures fighting the pandemic in Croatia. KEY WORDS: pandemic outbreak, regulation, recommendation, specimen, responsibilities, transportation and logistic for biological substances

In more advanced countries, the sustainable development concept was accepted both by the politicians and the industrial sector as the underlying philosophy for the preparation of development strategies, practically in all fields. This means using the natural resources within the limits of their renewability, and seeing that the resulting emissions have no negative impact on the environment. The development of Environmental Management Systems (EMS) commenced as a response to global environmental issues and as recognition of awareness that sustainable development is prerequisite for keeping the natural system in proper balance. Road transport of dangerous goods is a very complex activity representing a major potential danger to people and environment. For that very reason, the introduction of certain system tools (standardization of operations), that was a step forward to a safer and more effective operation of the carriers of dangerous goods by road was so welcome. However, this policy requires adequate business environment to be prepared, which is based on transparency and smooth operations as an important marketing advantage that has a bearing on every company’s economic performance. KEY WORDS: sustainable development, road transport of dangerous goods, Environmental Management System (EMS), Responsible Care (RC), ISO 140001, Safety and Quality Assessment System (SQAS).

Positioning of intermodal terminals is of key importance since it affects the very investment into the terminal, ecological, physical issues and the costs of the operation of individual terminals. Detailed analysis has to be performed by decision-making regarding the siting of intermodal terminals. The work analyzes the relevant criteria necessary for the siting of intermodal terminals. The problem of the proposed research is the structure of intermodal systems in the Republic of Croatia with the case study of inland waterways. The research and the study of the characteristics of intermodal terminals network on inland waterways should result in a concept of system reorganization, i.e. terminal planning methodology. By analysing relevant indicators according to the existing facts, and by using scientific methods and methodologies, the relevant criteria necessary to define the position and categories of intermodal terminals on inland waterways in the Republic of Croatia have been defined and evaluated on the examples of Sisak, Osijek, Vukovar and Slavonski Brod. KEY WORDS: intermodal terminal, intermodal transport, location criteria, inland waterways