Some changes of geological and geotechnical nature, mainly hydrogeological, may occur in the mined areas, which by their consequences may cause temporary or permanent disturbances to transportation routes and related structures, such as subsidence (continuous or intermittent), shear, tilting, etc. Such changes and deformations are caused by mining operations (all interventions in the earth's crust to reach mineral deposits) as well as by mining techniques (all interventions in the earth's crust for technical purposes - underground spaces of old urban development, collectors, etc.). Mining gases also appear in hard coal mining areas. The main component of mine gas is "methane". Its occurrence is noted in the area of old mine workings, which are not ventilated, where as a result of leaks mine gases penetrate to the surface.
