“Computational Civil Engineering - "Intersections" International Journal

214 C. NutiuIn 1988 the land measurements have been completed in the entire Romanian highaccuracygeometrical levelling network. In 1990 the phase of adjustment andcreation of the level registers has started for each line. The calculation algorithmfollowed the principles of adjustment by means of indirect observations in freegeodesic networks, applied to the high-accuracy geometrical levelling networks.The creation of the new network determined the need for extending the new levelsystem to the geometric levelling networks of grade 1-4, both in order tohomogenise the accuracy of these networks and to meet the various needs of thenational economy.In order to integrate the Romanian geometric levelling network of grade 1 in theEastern-European U.P.L.N. (E.V.N.S.) this was adjusted to the Baltic Sea referencesystem. The adjustment was made using the method of indirect observation,restricted to the benchmarks with levels in the Baltic Sea system, as a result of theinternational adjustment of the network (E.V.N.S.).The network with the levels specified in the Baltic Sea system consists of thefollowing: 46 nodal benchmarks of the national network, 14 benchmarkspreviously with levels in the (E.V.N.S.) network and the 5 nodal benchmarks of thepolygon of the Tariverde fundamental benchmark, adjusted as a reduced networkfor the 14 benchmarks of the (E.V.N.S.) network. The differences between thelevels calculated in the Black Sea reference system and the Baltic Sea referencesystem are: the minimum difference of 0.13908 m in the nodal point Negru Voda,the maximum difference of 0.17506 m in the nodal point Calafat; averagedifference: 0.14966 m.In the future the creation of a European levelling network (E.U.V.N.) will beproposed, by unifying the Western-European U.E.L.N. network and the Eastern-European U.P.L.N. (E.V.N.S.) network. Our country will take part in this projectwith five points.4. THE LEVELLING DATABASEThe high-accuracy geometrical levelling creates a topographic database andinformation base as a separate domain. This is hierarchically structured on twolevels, as follows: state-owned networks and levelled detail points. For each ofthese levels there will be some databases with functionalities specific to the goaland adapted to the level they are located at. The levels consist of three zones thatwill be created in modular fashion and will be implemented in phases. These zonesare:- zone 1 = the data and information set,- zone 2 = data processing,