This paper deals with some factors that exert influence upon the coefficient of adhesion in rail traction vehicles, as: fluids, speed, induced skidding, presence of particles, material of breaking pedals, forces of forward movement, etc. Knowledge of the value of influence of individual factors makes possible corresponding improvements in making use of available adhesion. The paper further discusses respective methods and devices making it possible. Some practical results are given in graphical presentation. Also, empirical equations are provided for computation of the coefficient of adhesion in the process of working out rail traction vehicle performances.

In order to take active part in the international division of labor it is highly necessary to secure linkage between the Danube navigation system and the Adriatic region. The Adriatic traffic corridor has always been exposed to rigorous international competition and unless adequate quality of services is granted it shall prove impossible for Croatia to attract the traffic from Central Europe when we already report delays regarding the construction of the Rhine-Main-Danube Canal by not having yet started the projects indispensable on the provision of linkage between the Danube navigation system and the Adriatic region.

The paper deals with the interdependent quality of development of telecommunications and tourist trade, their relationships and mutual interests. Contribution of telecommunications is felt in the segment of quality of service, structuring and materialization of business policy of travel trade. Of contrast, the actions of demographic, economic, technological and social/cultural forces integrated by the tourist trade exert major impact upon the functioning and development of telecommunications as its infrastructure factor or specific segment. Travel market directly integrated into the international market most timely reacts to the world development trends and thus the development of telecommunications. The indispensable requirement for the introduction of new services shall further be accentuated in respective changes originating from the integration of twelve national markets of the EC into a single common market, while joining it shall prove possible only upon the elimination of technical obstacles to appearing on this market.

Former stages in the development of modem information systems in support of the transport service provision function have mostly produced intemally-aspected solutions. Such solutions could then be materialized in line with company's proper standardization. A powerful breakthrough in the field of processing and telecommunications technology enabled cooperation on a world-wide scale. The whole world becomes one single market and in this the exchange of people, commodities, and data assumes an entirely new role. A major share in this global linkage belongs to electronic computer systems for whose integrated operation we need the rules agreed-upon in advance: the standards thus become indispensable for inter-company informatization. Transport and commerce are among the first to be considered. The needs develop swiftly, and the concerned parties enter upon alliances as to facilitate negotiations. This grouping together starts with the pairs of companies, forwarding agents, industrial segments, research projects, institutions (UN Commission, ISO, EDI associations) and scientific and professional potentials. This paper deals with the main objective of linkage for purposes of exchanges of messages, meaning essentially two things: firs~ the accomplished aspect of international informatization with own information systems being at an adequately high level in order to make possible the exchange of messages, and second: establishing the prerequisites (standardization, organization, engineering, legal grounds, and infrastructure facilities). Special applications are available for medium and small companies and for big systems.

The world postal system is confronted with the existence of competition which increasingly takes predominance on the market of postal services, so that the posts are referred to the provision i.e. supply of high quality services and unification of their own interests with those of the airlines. In the year 1982 the posts introduced the Express Mail Service in an effort to match a rather aggressive policy of their competitors and organize the carriage of mail by means of the European night mail delivery system. The paper deals with the features and efficiency of the Express Mail Service in conjunction with the introduction of this service in the Croatian Posts. The conditions have been described for the provision of services through the posts while the financial effects reached on the market of express mail delivery have been indicated. The world market of these services is estimated to be worth over USA 14 billion, with a 1 0% annual growth rate. The conclusions section furnishes the recommendations of activities the Croatian Posts should implement on ensuring the prerequisites for an as high as possible utilization of urgent mail delivery.