Before constructing the new railroad, it is necessary to do a great job. first of all, it is necessary to survey carefully the country through which the railroad runs to find the best and most suitable route. then the drawings and plans showing a course of the railroad, stations and other constructions have to be prepared and the total cost has to be estimated. the following that needs to be made, it to mark the railroad and to push aside all obstacles which can be on the way. it is not less important to place hundreds of workers and to transport cars and materials. works usually begin in several places at the same time, and temporary ways on which small locomotives can work are as soon as possible laid. integral part of any railroad is construction of cabins, and the embankment has to be constructed in low places. construction assumes both use of road-building cars. over streams the water throughput canal can be built. but the wide rivers have to be crossed by bridges of a special design. viaducts are made where it is necessary to cross the wide valley, and they are always convenient and difficult in construction. when all constructions are complete, it is possible to lay constant rails and build construction stations. then the railway line is checked and used at first for the movement of freights, then for slow passenger trains and, at last, if it is the main line, for expresses. подчеркнуть подлежащее и сказуемое