Railway signs we use today are divided into the following groups in line with applicable standards:
track (kilometer, milepost) signs are used to mark distance or something related to it;
signal signs: it is a very broad category which, in turn, includes permanent and temporary, portable and warning signs;
special signs: they mark the right-of-way boundaries; an approach to the highest water horizon; the presence of hidden structures in the upper layers of the subgrade, and other similar things;
warning signs: usually, they are installed at crossing points and used to explain the rules of giving whistle signals, and so on.
