Railroads 
31 
bringing iron ore and wheat from the Minnesota mines and prairies and for the lake freighters that 
and along the southern shore of Lake Erie. 
(2) Roadbed, cuts, and bridges. To build a railroad is not merely a 
matter of laying down ties and rails. Although these are expensive, 
they usually cost much less than the roadbed itself. Even in a plain 
the roadbed should be raised a little above the general level, so that it 
will not become muddy in wet weather. Culverts must be provided to 
draw off the rain water where there are no regular streams; cuts are 
needed in almost every mile of road except in the most level regions; 
bridges are a most expensive item; and even the ballast — that is, 
the gravel or crushed rock which covers the roadbed — often costs a 
great deal, especially in regions like the prairies, where there is no 
good surface rock or gravel. 
(3) Special expenses of upkeep. Under certain geographical cir- 
cumstances special kinds of railroad equipment are required. For 
example, among the Sierra Nevada mountains the trains often run for 
miles through snowsheds. In sandy deserts, such as Transcaspia, 
the railroad must sometimes be protected from blowing sand by a 
special kind of desert bush which is planted in hedges and carefully 
tended until it gets a good start. In swamps the roadbed often sinks 
a little and must constantly be built up. For example, for several 
hundred miles the Amur Railway, in eastern Siberia, runs through 
swamps where the upper foot or two consists of peat which acts like a 
blanket and prevents the lower part-of the swamp from melting. 
Thus most of the swamp remains frozen in summer as well as in win- 
ter. In order to build the railroad, the peat had to be taken off. The 
sun in summer warms the ballast which replaces the peat, and thus a 
little of the frozen swamp melts each summer and the railroad sinks a