Dam Modrac is multiple arched reinforced concrete buttress dam, with nine buttresses and ten arches, which by its technical characteristics and volume of the accumulation is considered as one of the high dams. Crown level of spillway is 200.00 m a.s.l. Crest length is 205.00 m, while the maximum height is 27.50 m. To control the water level in the reservoir, under normal hydrological conditions, there are four basic discharges with maximum capacity around Q = 77 m3/s for the projected state. The paper gives an analytical expression of the spillway curve and analytical expressions of amounts of water discharge separately for each bottom outlet, which are obtained by conducted measurings. Special significance of this paper gives volume curves for hydro accumulation Lake Modrac for projected state and the period of use of the system.

The railway Samac - Sarajevo was built in the fifties of the twentieth century, as a significant part of the railway that connects the central part of the former Yugoslavia with the Sava River. Later, in the seventies another track of Doboj and Zenica was built what was the most important by that time. In general the railway is situated on the corridor V, which links the Adriatic Sea via Sarajevo and Budapest. Over time, the tracks are worn, damaged and speed has been reduced to about 40 km/hour. As part of the revitalization of the railway network in the former Yugoslavia, the reconstruction of the Samac - Adriatic Sea began, which is divided by sections. One of these sectionsis the section km 103 + 500 - Maglaj, a more demanding one compared to previous section from Samac to the now named section. The point is that the terrain along the route of the railway needs to be viewed from the aspect of geologi cal features, then the characteristics of the embankment so the geotechnical conditions for the revitalization of the railway line for speeds of 120 km/hour can be provided. Conducted field investigations along the route of the railway, as well as laboratory tests on samples provided enough data in the corridor route, while the wider area could not be perceived because of the mine field. However, the previous studies for the purposes of the General Geological Map, scale 1: 100 000, and field observations along the route line gave a satisfactory level of data for assessment of geological and engineering geological characteristics of the terrain.